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1 | /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- |
2 | * vim: set ts=8 sw=4 et tw=78: |
3 | * |
4 | * ***** BEGIN LICENSE BLOCK ***** |
5 | * Version: MPL 1.1/GPL 2.0/LGPL 2.1 |
6 | * |
7 | * The contents of this file are subject to the Mozilla Public License Version |
8 | * 1.1 (the "License"); you may not use this file except in compliance with |
9 | * the License. You may obtain a copy of the License at |
10 | * http://www.mozilla.org/MPL/ |
11 | * |
12 | * Software distributed under the License is distributed on an "AS IS" basis, |
13 | * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License |
14 | * for the specific language governing rights and limitations under the |
15 | * License. |
16 | * |
17 | * The Original Code is Mozilla Communicator client code, released |
18 | * March 31, 1998. |
19 | * |
20 | * The Initial Developer of the Original Code is |
21 | * Netscape Communications Corporation. |
22 | * Portions created by the Initial Developer are Copyright (C) 1998 |
23 | * the Initial Developer. All Rights Reserved. |
24 | * |
25 | * Contributor(s): |
26 | * |
27 | * Alternatively, the contents of this file may be used under the terms of |
28 | * either of the GNU General Public License Version 2 or later (the "GPL"), |
29 | * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"), |
30 | * in which case the provisions of the GPL or the LGPL are applicable instead |
31 | * of those above. If you wish to allow use of your version of this file only |
32 | * under the terms of either the GPL or the LGPL, and not to allow others to |
33 | * use your version of this file under the terms of the MPL, indicate your |
34 | * decision by deleting the provisions above and replace them with the notice |
35 | * and other provisions required by the GPL or the LGPL. If you do not delete |
36 | * the provisions above, a recipient may use your version of this file under |
37 | * the terms of any one of the MPL, the GPL or the LGPL. |
38 | * |
39 | * ***** END LICENSE BLOCK ***** */ |
40 | |
41 | /* |
42 | * JS Mark-and-Sweep Garbage Collector. |
43 | * |
44 | * This GC allocates fixed-sized things with sizes up to GC_NBYTES_MAX (see |
45 | * jsgc.h). It allocates from a special GC arena pool with each arena allocated |
46 | * using malloc. It uses an ideally parallel array of flag bytes to hold the |
47 | * mark bit, finalizer type index, etc. |
48 | * |
49 | * XXX swizzle page to freelist for better locality of reference |
50 | */ |
51 | #include <stdlib.h> /* for free */ |
52 | #include <math.h> |
53 | #include <string.h> /* for memset used when DEBUG */ |
54 | #include "jstypes.h" |
55 | #include "jsstdint.h" |
56 | #include "jsutil.h" /* Added by JSIFY */ |
57 | #include "jshash.h" /* Added by JSIFY */ |
58 | #include "jsbit.h" |
59 | #include "jsclist.h" |
60 | #include "jsprf.h" |
61 | #include "jsapi.h" |
62 | #include "jsatom.h" |
63 | #include "jscntxt.h" |
64 | #include "jsversion.h" |
65 | #include "jsdbgapi.h" |
66 | #include "jsexn.h" |
67 | #include "jsfun.h" |
68 | #include "jsgc.h" |
69 | #include "jsinterp.h" |
70 | #include "jsiter.h" |
71 | #include "jslock.h" |
72 | #include "jsnum.h" |
73 | #include "jsobj.h" |
74 | #include "jsparse.h" |
75 | #include "jsscope.h" |
76 | #include "jsscript.h" |
77 | #include "jsstaticcheck.h" |
78 | #include "jsstr.h" |
79 | #include "jstask.h" |
80 | #include "jstracer.h" |
81 | |
82 | #if JS_HAS_XML_SUPPORT |
83 | #include "jsxml.h" |
84 | #endif |
85 | |
86 | #ifdef INCLUDE_MOZILLA_DTRACE |
87 | #include "jsdtracef.h" |
88 | #endif |
89 | |
90 | /* |
91 | * Check if posix_memalign is available. |
92 | */ |
93 | #if _POSIX_C_SOURCE >= 200112L || _XOPEN_SOURCE >= 600 || MOZ_MEMORY |
94 | # define HAS_POSIX_MEMALIGN 1 |
95 | #else |
96 | # define HAS_POSIX_MEMALIGN 0 |
97 | #endif |
98 | |
99 | /* |
100 | * jemalloc provides posix_memalign. |
101 | */ |
102 | #ifdef MOZ_MEMORY |
103 | extern "C" { |
104 | #include "../../memory/jemalloc/jemalloc.h" |
105 | } |
106 | #endif |
107 | |
108 | /* |
109 | * Include the headers for mmap unless we have posix_memalign and do not |
110 | * insist on mmap. |
111 | */ |
112 | #if JS_GC_USE_MMAP || (!defined JS_GC_USE_MMAP && !HAS_POSIX_MEMALIGN) |
113 | # if defined(XP_WIN) |
114 | # ifndef JS_GC_USE_MMAP |
115 | # define JS_GC_USE_MMAP 1 |
116 | # endif |
117 | # include <windows.h> |
118 | # elif defined(__SYMBIAN32__) |
119 | // Symbian's OpenC has mmap (and #defines _POSIX_MAPPED_FILES), but |
120 | // doesn't implement MAP_ANON. If we have MOZ_MEMORY, then we can use |
121 | // posix_memalign; we've defined HAS_POSIX_MEMALIGN above. Otherwise, |
122 | // we overallocate. |
123 | # else |
124 | # if defined(XP_UNIX) || defined(XP_BEOS) |
125 | # include <unistd.h> |
126 | # endif |
127 | # if _POSIX_MAPPED_FILES > 0 |
128 | # ifndef JS_GC_USE_MMAP |
129 | # define JS_GC_USE_MMAP 1 |
130 | # endif |
131 | # include <sys/mman.h> |
132 | |
133 | /* On Mac OS X MAP_ANONYMOUS is not defined. */ |
134 | # if !defined(MAP_ANONYMOUS) && defined(MAP_ANON) |
135 | # define MAP_ANONYMOUS MAP_ANON |
136 | # endif |
137 | # if !defined(MAP_ANONYMOUS) |
138 | # define MAP_ANONYMOUS 0 |
139 | # endif |
140 | # else |
141 | # if JS_GC_USE_MMAP |
142 | # error "JS_GC_USE_MMAP is set when mmap is not available" |
143 | # endif |
144 | # endif |
145 | # endif |
146 | #endif |
147 | |
148 | /* |
149 | * Check JSTempValueUnion has the size of jsval and void * so we can |
150 | * reinterpret jsval as void* GC-thing pointer and use JSTVU_SINGLE for |
151 | * different GC-things. |
152 | */ |
153 | JS_STATIC_ASSERT(sizeof(JSTempValueUnion) == sizeof(jsval)); |
154 | JS_STATIC_ASSERT(sizeof(JSTempValueUnion) == sizeof(void *)); |
155 | |
156 | /* |
157 | * Check that JSTRACE_XML follows JSTRACE_OBJECT, JSTRACE_DOUBLE and |
158 | * JSTRACE_STRING. |
159 | */ |
160 | JS_STATIC_ASSERT(JSTRACE_OBJECT == 0); |
161 | JS_STATIC_ASSERT(JSTRACE_DOUBLE == 1); |
162 | JS_STATIC_ASSERT(JSTRACE_STRING == 2); |
163 | JS_STATIC_ASSERT(JSTRACE_XML == 3); |
164 | |
165 | /* |
166 | * JS_IS_VALID_TRACE_KIND assumes that JSTRACE_STRING is the last non-xml |
167 | * trace kind when JS_HAS_XML_SUPPORT is false. |
168 | */ |
169 | JS_STATIC_ASSERT(JSTRACE_STRING + 1 == JSTRACE_XML); |
170 | |
171 | /* |
172 | * The number of used GCX-types must stay within GCX_LIMIT. |
173 | */ |
174 | JS_STATIC_ASSERT(GCX_NTYPES <= GCX_LIMIT); |
175 | |
176 | |
177 | /* |
178 | * Check that we can reinterpret double as JSGCDoubleCell. |
179 | */ |
180 | JS_STATIC_ASSERT(sizeof(JSGCDoubleCell) == sizeof(double)); |
181 | |
182 | /* |
183 | * Check that we can use memset(p, 0, ...) to implement JS_CLEAR_WEAK_ROOTS. |
184 | */ |
185 | JS_STATIC_ASSERT(JSVAL_NULL == 0); |
186 | |
187 | |
188 | /* |
189 | * A GC arena contains a fixed number of flag bits for each thing in its heap, |
190 | * and supports O(1) lookup of a flag given its thing's address. |
191 | * |
192 | * To implement this, we allocate things of the same size from a GC arena |
193 | * containing GC_ARENA_SIZE bytes aligned on GC_ARENA_SIZE boundary. The |
194 | * following picture shows arena's layout: |
195 | * |
196 | * +------------------------------+--------------------+---------------+ |
197 | * | allocation area for GC thing | flags of GC things | JSGCArenaInfo | |
198 | * +------------------------------+--------------------+---------------+ |
199 | * |
200 | * To find the flag bits for the thing we calculate the thing index counting |
201 | * from arena's start using: |
202 | * |
203 | * thingIndex = (thingAddress & GC_ARENA_MASK) / thingSize |
204 | * |
205 | * The details of flag's lookup depend on thing's kind. For all GC things |
206 | * except doubles we use one byte of flags where the 4 bits determine thing's |
207 | * type and the rest is used to implement GC marking, finalization and |
208 | * locking. We calculate the address of flag's byte using: |
209 | * |
210 | * flagByteAddress = |
211 | * (thingAddress | GC_ARENA_MASK) - sizeof(JSGCArenaInfo) - thingIndex |
212 | * |
213 | * where |
214 | * |
215 | * (thingAddress | GC_ARENA_MASK) - sizeof(JSGCArenaInfo) |
216 | * |
217 | * is the last byte of flags' area. |
218 | * |
219 | * This implies that the things are allocated from the start of their area and |
220 | * flags are allocated from the end. This arrangement avoids a relatively |
221 | * expensive calculation of the location of the boundary separating things and |
222 | * flags. The boundary's offset from the start of the arena is given by: |
223 | * |
224 | * thingsPerArena * thingSize |
225 | * |
226 | * where thingsPerArena is the number of things that the arena can hold: |
227 | * |
228 | * (GC_ARENA_SIZE - sizeof(JSGCArenaInfo)) / (thingSize + 1). |
229 | * |
230 | * To allocate doubles we use a specialized arena. It can contain only numbers |
231 | * so we do not need the type bits. Moreover, since the doubles do not require |
232 | * a finalizer and very few of them are locked via js_LockGCThing API, we use |
233 | * just one bit of flags per double to denote if it was marked during the |
234 | * marking phase of the GC. The locking is implemented via a hash table. Thus |
235 | * for doubles the flag area becomes a bitmap. |
236 | * |
237 | * JS_GC_USE_MMAP macro governs the choice of the aligned arena allocator. |
238 | * When it is true, a platform-dependent function like mmap is used to get |
239 | * memory aligned on CPU page boundaries. If the macro is false or undefined, |
240 | * posix_memalign is used when available. Otherwise the code uses malloc to |
241 | * over-allocate a chunk with js_gcArenasPerChunk aligned arenas. The |
242 | * approximate space overhead of this is 1/js_gcArenasPerChunk. For details, |
243 | * see NewGCChunk/DestroyGCChunk below. |
244 | * |
245 | * The code also allocates arenas in chunks when JS_GC_USE_MMAP is 1 to |
246 | * minimize the overhead of mmap/munmap. In this case js_gcArenasPerChunk can |
247 | * not be a compile-time constant as the system page size is not known until |
248 | * runtime. |
249 | */ |
250 | #if JS_GC_USE_MMAP |
251 | static uint32 js_gcArenasPerChunk = 0; |
252 | static JSBool js_gcUseMmap = JS_FALSE; |
253 | #elif HAS_POSIX_MEMALIGN |
254 | # define js_gcArenasPerChunk 1 |
255 | #else |
256 | # define js_gcArenasPerChunk 7 |
257 | #endif |
258 | |
259 | #if defined(js_gcArenasPerChunk) && js_gcArenasPerChunk == 1 |
260 | # define CHUNKED_ARENA_ALLOCATION 0 |
261 | #else |
262 | # define CHUNKED_ARENA_ALLOCATION 1 |
263 | #endif |
264 | |
265 | #define GC_ARENA_SHIFT 12 |
266 | #define GC_ARENA_MASK ((jsuword) JS_BITMASK(GC_ARENA_SHIFT)) |
267 | #define GC_ARENA_SIZE JS_BIT(GC_ARENA_SHIFT) |
268 | |
269 | /* |
270 | * JS_GC_ARENA_PAD defines the number of bytes to pad JSGCArenaInfo structure. |
271 | * It is used to improve allocation efficiency when using posix_memalign. If |
272 | * malloc's implementation uses internal headers, then calling |
273 | * |
274 | * posix_memalign(&p, GC_ARENA_SIZE, GC_ARENA_SIZE * js_gcArenasPerChunk) |
275 | * |
276 | * in a sequence leaves holes between allocations of the size GC_ARENA_SIZE |
277 | * due to the need to fit headers. JS_GC_ARENA_PAD mitigates that so the code |
278 | * calls |
279 | * |
280 | * posix_memalign(&p, GC_ARENA_SIZE, |
281 | * GC_ARENA_SIZE * js_gcArenasPerChunk - JS_GC_ARENA_PAD) |
282 | * |
283 | * When JS_GC_ARENA_PAD is equal or greater than the number of words in the |
284 | * system header, the system can pack all allocations together without holes. |
285 | * |
286 | * With JS_GC_USE_MEMALIGN we want at least 2 word pad unless posix_memalign |
287 | * comes from jemalloc that does not use any headers/trailers. |
288 | */ |
289 | #ifndef JS_GC_ARENA_PAD |
290 | # if HAS_POSIX_MEMALIGN && !MOZ_MEMORY |
291 | # define JS_GC_ARENA_PAD (2 * JS_BYTES_PER_WORD) |
292 | # else |
293 | # define JS_GC_ARENA_PAD 0 |
294 | # endif |
295 | #endif |
296 | |
297 | struct JSGCArenaInfo { |
298 | /* |
299 | * Allocation list for the arena or NULL if the arena holds double values. |
300 | */ |
301 | JSGCArenaList *list; |
302 | |
303 | /* |
304 | * Pointer to the previous arena in a linked list. The arena can either |
305 | * belong to one of JSContext.gcArenaList lists or, when it does not have |
306 | * any allocated GC things, to the list of free arenas in the chunk with |
307 | * head stored in JSGCChunkInfo.lastFreeArena. |
308 | */ |
309 | JSGCArenaInfo *prev; |
310 | |
311 | #if !CHUNKED_ARENA_ALLOCATION |
312 | jsuword prevUntracedPage; |
313 | #else |
314 | /* |
315 | * A link field for the list of arenas with marked but not yet traced |
316 | * things. The field is encoded as arena's page to share the space with |
317 | * firstArena and arenaIndex fields. |
318 | */ |
319 | jsuword prevUntracedPage : JS_BITS_PER_WORD - GC_ARENA_SHIFT; |
320 | |
321 | /* |
322 | * When firstArena is false, the index of arena in the chunk. When |
323 | * firstArena is true, the index of a free arena holding JSGCChunkInfo or |
324 | * NO_FREE_ARENAS if there are no free arenas in the chunk. |
325 | * |
326 | * GET_ARENA_INDEX and GET_CHUNK_INFO_INDEX are convenience macros to |
327 | * access either of indexes. |
328 | */ |
329 | jsuword arenaIndex : GC_ARENA_SHIFT - 1; |
330 | |
331 | /* Flag indicating if the arena is the first in the chunk. */ |
332 | jsuword firstArena : 1; |
333 | #endif |
334 | |
335 | union { |
336 | jsuword untracedThings; /* bitset for fast search of marked |
337 | but not yet traced things */ |
338 | JSBool hasMarkedDoubles; /* the arena has marked doubles */ |
339 | } u; |
340 | |
341 | #if JS_GC_ARENA_PAD != 0 |
342 | uint8 pad[JS_GC_ARENA_PAD]; |
343 | #endif |
344 | }; |
345 | |
346 | /* |
347 | * Verify that the bit fields are indeed shared and JSGCArenaInfo is as small |
348 | * as possible. The code does not rely on this check so if on a particular |
349 | * platform this does not compile, then, as a workaround, comment the assert |
350 | * out and submit a bug report. |
351 | */ |
352 | JS_STATIC_ASSERT(offsetof(JSGCArenaInfo, u) == 3 * sizeof(jsuword)); |
353 | |
354 | /* |
355 | * Macros to convert between JSGCArenaInfo, the start address of the arena and |
356 | * arena's page defined as (start address) >> GC_ARENA_SHIFT. |
357 | */ |
358 | #define ARENA_INFO_OFFSET (GC_ARENA_SIZE - (uint32) sizeof(JSGCArenaInfo)) |
359 | |
360 | #define IS_ARENA_INFO_ADDRESS(arena) \ |
361 | (((jsuword) (arena) & GC_ARENA_MASK) == ARENA_INFO_OFFSET) |
362 | |
363 | #define ARENA_START_TO_INFO(arenaStart) \ |
364 | (JS_ASSERT(((arenaStart) & (jsuword) GC_ARENA_MASK) == 0), \ |
365 | (JSGCArenaInfo *) ((arenaStart) + (jsuword) ARENA_INFO_OFFSET)) |
366 | |
367 | #define ARENA_INFO_TO_START(arena) \ |
368 | (JS_ASSERT(IS_ARENA_INFO_ADDRESS(arena)), \ |
369 | (jsuword) (arena) & ~(jsuword) GC_ARENA_MASK) |
370 | |
371 | #define ARENA_PAGE_TO_INFO(arenaPage) \ |
372 | (JS_ASSERT(arenaPage != 0), \ |
373 | JS_ASSERT(!((jsuword)(arenaPage) >> (JS_BITS_PER_WORD-GC_ARENA_SHIFT))), \ |
374 | ARENA_START_TO_INFO((arenaPage) << GC_ARENA_SHIFT)) |
375 | |
376 | #define ARENA_INFO_TO_PAGE(arena) \ |
377 | (JS_ASSERT(IS_ARENA_INFO_ADDRESS(arena)), \ |
378 | ((jsuword) (arena) >> GC_ARENA_SHIFT)) |
379 | |
380 | #define GET_ARENA_INFO(chunk, index) \ |
381 | (JS_ASSERT((index) < js_gcArenasPerChunk), \ |
382 | ARENA_START_TO_INFO(chunk + ((index) << GC_ARENA_SHIFT))) |
383 | |
384 | #if CHUNKED_ARENA_ALLOCATION |
385 | /* |
386 | * Definitions for allocating arenas in chunks. |
387 | * |
388 | * All chunks that have at least one free arena are put on the doubly-linked |
389 | * list with the head stored in JSRuntime.gcChunkList. JSGCChunkInfo contains |
390 | * the head of the chunk's free arena list together with the link fields for |
391 | * gcChunkList. |
392 | * |
393 | * Structure stored in one of chunk's free arenas. GET_CHUNK_INFO_INDEX gives |
394 | * the index of this arena. When all arenas in the chunk are used, it is |
395 | * removed from the list and the index is set to NO_FREE_ARENAS indicating |
396 | * that the chunk is not on gcChunkList and has no JSGCChunkInfo available. |
397 | */ |
398 | |
399 | struct JSGCChunkInfo { |
400 | JSGCChunkInfo **prevp; |
401 | JSGCChunkInfo *next; |
402 | JSGCArenaInfo *lastFreeArena; |
403 | uint32 numFreeArenas; |
404 | }; |
405 | |
406 | #define NO_FREE_ARENAS JS_BITMASK(GC_ARENA_SHIFT - 1) |
407 | |
408 | #ifdef js_gcArenasPerChunk |
409 | JS_STATIC_ASSERT(1 <= js_gcArenasPerChunk && |
410 | js_gcArenasPerChunk <= NO_FREE_ARENAS); |
411 | #endif |
412 | |
413 | #define GET_ARENA_CHUNK(arena, index) \ |
414 | (JS_ASSERT(GET_ARENA_INDEX(arena) == index), \ |
415 | ARENA_INFO_TO_START(arena) - ((index) << GC_ARENA_SHIFT)) |
416 | |
417 | #define GET_ARENA_INDEX(arena) \ |
418 | ((arena)->firstArena ? 0 : (uint32) (arena)->arenaIndex) |
419 | |
420 | #define GET_CHUNK_INFO_INDEX(chunk) \ |
421 | ((uint32) ARENA_START_TO_INFO(chunk)->arenaIndex) |
422 | |
423 | #define SET_CHUNK_INFO_INDEX(chunk, index) \ |
424 | (JS_ASSERT((index) < js_gcArenasPerChunk || (index) == NO_FREE_ARENAS), \ |
425 | (void) (ARENA_START_TO_INFO(chunk)->arenaIndex = (jsuword) (index))) |
426 | |
427 | #define GET_CHUNK_INFO(chunk, infoIndex) \ |
428 | (JS_ASSERT(GET_CHUNK_INFO_INDEX(chunk) == (infoIndex)), \ |
429 | JS_ASSERT((uint32) (infoIndex) < js_gcArenasPerChunk), \ |
430 | (JSGCChunkInfo *) ((chunk) + ((infoIndex) << GC_ARENA_SHIFT))) |
431 | |
432 | #define CHUNK_INFO_TO_INDEX(ci) \ |
433 | GET_ARENA_INDEX(ARENA_START_TO_INFO((jsuword)ci)) |
434 | |
435 | #endif |
436 | |
437 | /* |
438 | * Macros for GC-thing operations. |
439 | */ |
440 | #define THINGS_PER_ARENA(thingSize) \ |
441 | ((GC_ARENA_SIZE - (uint32) sizeof(JSGCArenaInfo)) / ((thingSize) + 1U)) |
442 | |
443 | #define THING_TO_ARENA(thing) \ |
444 | (JS_ASSERT(!JSString::isStatic(thing)), \ |
445 | (JSGCArenaInfo *)(((jsuword) (thing) | GC_ARENA_MASK) \ |
446 | + 1 - sizeof(JSGCArenaInfo))) |
447 | |
448 | #define THING_TO_INDEX(thing, thingSize) \ |
449 | ((uint32) ((jsuword) (thing) & GC_ARENA_MASK) / (uint32) (thingSize)) |
450 | |
451 | #define THING_FLAGS_END(arena) ((uint8 *)(arena)) |
452 | |
453 | #define THING_FLAGP(arena, thingIndex) \ |
454 | (JS_ASSERT((jsuword) (thingIndex) \ |
455 | < (jsuword) THINGS_PER_ARENA((arena)->list->thingSize)), \ |
456 | (uint8 *)(arena) - 1 - (thingIndex)) |
457 | |
458 | #define THING_TO_FLAGP(thing, thingSize) \ |
459 | THING_FLAGP(THING_TO_ARENA(thing), THING_TO_INDEX(thing, thingSize)) |
460 | |
461 | #define FLAGP_TO_ARENA(flagp) THING_TO_ARENA(flagp) |
462 | |
463 | #define FLAGP_TO_INDEX(flagp) \ |
464 | (JS_ASSERT(((jsuword) (flagp) & GC_ARENA_MASK) < ARENA_INFO_OFFSET), \ |
465 | (ARENA_INFO_OFFSET - 1 - (uint32) ((jsuword) (flagp) & GC_ARENA_MASK))) |
466 | |
467 | #define FLAGP_TO_THING(flagp, thingSize) \ |
468 | (JS_ASSERT(((jsuword) (flagp) & GC_ARENA_MASK) >= \ |
469 | (ARENA_INFO_OFFSET - THINGS_PER_ARENA(thingSize))), \ |
470 | (JSGCThing *)(((jsuword) (flagp) & ~GC_ARENA_MASK) + \ |
471 | (thingSize) * FLAGP_TO_INDEX(flagp))) |
472 | |
473 | /* |
474 | * Macros for the specialized arena for doubles. |
475 | * |
476 | * DOUBLES_PER_ARENA defines the maximum number of doubles that the arena can |
477 | * hold. We find it as the following. Let n be the number of doubles in the |
478 | * arena. Together with the bitmap of flags and JSGCArenaInfo they should fit |
479 | * the arena. Hence DOUBLES_PER_ARENA or n_max is the maximum value of n for |
480 | * which the following holds: |
481 | * |
482 | * n*s + ceil(n/B) <= M (1) |
483 | * |
484 | * where "/" denotes normal real division, |
485 | * ceil(r) gives the least integer not smaller than the number r, |
486 | * s is the number of words in jsdouble, |
487 | * B is number of bits per word or B == JS_BITS_PER_WORD |
488 | * M is the number of words in the arena before JSGCArenaInfo or |
489 | * M == (GC_ARENA_SIZE - sizeof(JSGCArenaInfo)) / sizeof(jsuword). |
490 | * M == ARENA_INFO_OFFSET / sizeof(jsuword) |
491 | * |
492 | * We rewrite the inequality as |
493 | * |
494 | * n*B*s/B + ceil(n/B) <= M, |
495 | * ceil(n*B*s/B + n/B) <= M, |
496 | * ceil(n*(B*s + 1)/B) <= M (2) |
497 | * |
498 | * We define a helper function e(n, s, B), |
499 | * |
500 | * e(n, s, B) := ceil(n*(B*s + 1)/B) - n*(B*s + 1)/B, 0 <= e(n, s, B) < 1. |
501 | * |
502 | * It gives: |
503 | * |
504 | * n*(B*s + 1)/B + e(n, s, B) <= M, |
505 | * n + e*B/(B*s + 1) <= M*B/(B*s + 1) |
506 | * |
507 | * We apply the floor function to both sides of the last equation, where |
508 | * floor(r) gives the biggest integer not greater than r. As a consequence we |
509 | * have: |
510 | * |
511 | * floor(n + e*B/(B*s + 1)) <= floor(M*B/(B*s + 1)), |
512 | * n + floor(e*B/(B*s + 1)) <= floor(M*B/(B*s + 1)), |
513 | * n <= floor(M*B/(B*s + 1)), (3) |
514 | * |
515 | * where floor(e*B/(B*s + 1)) is zero as e*B/(B*s + 1) < B/(B*s + 1) < 1. |
516 | * Thus any n that satisfies the original constraint (1) or its equivalent (2), |
517 | * must also satisfy (3). That is, we got an upper estimate for the maximum |
518 | * value of n. Lets show that this upper estimate, |
519 | * |
520 | * floor(M*B/(B*s + 1)), (4) |
521 | * |
522 | * also satisfies (1) and, as such, gives the required maximum value. |
523 | * Substituting it into (2) gives: |
524 | * |
525 | * ceil(floor(M*B/(B*s + 1))*(B*s + 1)/B) == ceil(floor(M/X)*X) |
526 | * |
527 | * where X == (B*s + 1)/B > 1. But then floor(M/X)*X <= M/X*X == M and |
528 | * |
529 | * ceil(floor(M/X)*X) <= ceil(M) == M. |
530 | * |
531 | * Thus the value of (4) gives the maximum n satisfying (1). |
532 | * |
533 | * For the final result we observe that in (4) |
534 | * |
535 | * M*B == ARENA_INFO_OFFSET / sizeof(jsuword) * JS_BITS_PER_WORD |
536 | * == ARENA_INFO_OFFSET * JS_BITS_PER_BYTE |
537 | * |
538 | * and |
539 | * |
540 | * B*s == JS_BITS_PER_WORD * sizeof(jsdouble) / sizeof(jsuword) |
541 | * == JS_BITS_PER_DOUBLE. |
542 | */ |
543 | #define DOUBLES_PER_ARENA \ |
544 | ((ARENA_INFO_OFFSET * JS_BITS_PER_BYTE) / (JS_BITS_PER_DOUBLE + 1)) |
545 | |
546 | /* |
547 | * Check that ARENA_INFO_OFFSET and sizeof(jsdouble) divides sizeof(jsuword). |
548 | */ |
549 | JS_STATIC_ASSERT(ARENA_INFO_OFFSET % sizeof(jsuword) == 0); |
550 | JS_STATIC_ASSERT(sizeof(jsdouble) % sizeof(jsuword) == 0); |
551 | JS_STATIC_ASSERT(sizeof(jsbitmap) == sizeof(jsuword)); |
552 | |
553 | #define DOUBLES_ARENA_BITMAP_WORDS \ |
554 | (JS_HOWMANY(DOUBLES_PER_ARENA, JS_BITS_PER_WORD)) |
555 | |
556 | /* Check that DOUBLES_PER_ARENA indeed maximises (1). */ |
557 | JS_STATIC_ASSERT(DOUBLES_PER_ARENA * sizeof(jsdouble) + |
558 | DOUBLES_ARENA_BITMAP_WORDS * sizeof(jsuword) <= |
559 | ARENA_INFO_OFFSET); |
560 | |
561 | JS_STATIC_ASSERT((DOUBLES_PER_ARENA + 1) * sizeof(jsdouble) + |
562 | sizeof(jsuword) * |
563 | JS_HOWMANY((DOUBLES_PER_ARENA + 1), JS_BITS_PER_WORD) > |
564 | ARENA_INFO_OFFSET); |
565 | |
566 | /* |
567 | * When DOUBLES_PER_ARENA % BITS_PER_DOUBLE_FLAG_UNIT != 0, some bits in the |
568 | * last byte of the occupation bitmap are unused. |
569 | */ |
570 | #define UNUSED_DOUBLE_BITMAP_BITS \ |
571 | (DOUBLES_ARENA_BITMAP_WORDS * JS_BITS_PER_WORD - DOUBLES_PER_ARENA) |
572 | |
573 | JS_STATIC_ASSERT(UNUSED_DOUBLE_BITMAP_BITS < JS_BITS_PER_WORD); |
574 | |
575 | #define DOUBLES_ARENA_BITMAP_OFFSET \ |
576 | (ARENA_INFO_OFFSET - DOUBLES_ARENA_BITMAP_WORDS * sizeof(jsuword)) |
577 | |
578 | #define CHECK_DOUBLE_ARENA_INFO(arenaInfo) \ |
579 | (JS_ASSERT(IS_ARENA_INFO_ADDRESS(arenaInfo)), \ |
580 | JS_ASSERT(!(arenaInfo)->list)) \ |
581 | |
582 | /* |
583 | * Get the start of the bitmap area containing double mark flags in the arena. |
584 | * To access the flag the code uses |
585 | * |
586 | * JS_TEST_BIT(bitmapStart, index) |
587 | * |
588 | * That is, compared with the case of arenas with non-double things, we count |
589 | * flags from the start of the bitmap area, not from the end. |
590 | */ |
591 | #define DOUBLE_ARENA_BITMAP(arenaInfo) \ |
592 | (CHECK_DOUBLE_ARENA_INFO(arenaInfo), \ |
593 | (jsbitmap *) arenaInfo - DOUBLES_ARENA_BITMAP_WORDS) |
594 | |
595 | #define DOUBLE_THING_TO_INDEX(thing) \ |
596 | (CHECK_DOUBLE_ARENA_INFO(THING_TO_ARENA(thing)), \ |
597 | JS_ASSERT(((jsuword) (thing) & GC_ARENA_MASK) < \ |
598 | DOUBLES_ARENA_BITMAP_OFFSET), \ |
599 | ((uint32) (((jsuword) (thing) & GC_ARENA_MASK) / sizeof(jsdouble)))) |
600 | |
601 | static void |
602 | ClearDoubleArenaFlags(JSGCArenaInfo *a) |
603 | { |
604 | jsbitmap *bitmap, mask; |
605 | uintN nused; |
606 | |
607 | /* |
608 | * When some high bits in the last byte of the double occupation bitmap |
609 | * are unused, we must set them. Otherwise RefillDoubleFreeList will |
610 | * assume that they corresponds to some free cells and tries to allocate |
611 | * them. |
612 | * |
613 | * Note that the code works correctly with UNUSED_DOUBLE_BITMAP_BITS == 0. |
614 | */ |
615 | bitmap = DOUBLE_ARENA_BITMAP(a); |
616 | memset(bitmap, 0, (DOUBLES_ARENA_BITMAP_WORDS - 1) * sizeof *bitmap); |
617 | mask = ((jsbitmap) 1 << UNUSED_DOUBLE_BITMAP_BITS) - 1; |
618 | nused = JS_BITS_PER_WORD - UNUSED_DOUBLE_BITMAP_BITS; |
619 | bitmap[DOUBLES_ARENA_BITMAP_WORDS - 1] = mask << nused; |
620 | } |
621 | |
622 | static JS_ALWAYS_INLINE JSBool |
623 | IsMarkedDouble(JSGCArenaInfo *a, uint32 index) |
624 | { |
625 | jsbitmap *bitmap; |
626 | |
627 | JS_ASSERT(a->u.hasMarkedDoubles); |
628 | bitmap = DOUBLE_ARENA_BITMAP(a); |
629 | return JS_TEST_BIT(bitmap, index); |
630 | } |
631 | |
632 | /* |
633 | * JSRuntime.gcDoubleArenaList.nextDoubleFlags points either to: |
634 | * |
635 | * 1. The next byte in the bitmap area for doubles to check for unmarked |
636 | * (or free) doubles. |
637 | * 2. Or to the end of the bitmap area when all GC cells of the arena are |
638 | * allocated. |
639 | * 3. Or to a special sentinel value indicating that there are no arenas |
640 | * to check for unmarked doubles. |
641 | * |
642 | * We set the sentinel to ARENA_INFO_OFFSET so the single check |
643 | * |
644 | * ((jsuword) nextDoubleFlags & GC_ARENA_MASK) == ARENA_INFO_OFFSET |
645 | * |
646 | * will cover both the second and the third cases. |
647 | */ |
648 | #define DOUBLE_BITMAP_SENTINEL ((jsbitmap *) ARENA_INFO_OFFSET) |
649 | |
650 | #ifdef JS_THREADSAFE |
651 | /* |
652 | * The maximum number of things to put on the local free list by taking |
653 | * several things from the global free list or from the tail of the last |
654 | * allocated arena to amortize the cost of rt->gcLock. |
655 | */ |
656 | #define MAX_THREAD_LOCAL_THINGS 64 |
657 | |
658 | #endif |
659 | |
660 | JS_STATIC_ASSERT(sizeof(JSStackHeader) >= 2 * sizeof(jsval)); |
661 | |
662 | JS_STATIC_ASSERT(sizeof(JSGCThing) >= sizeof(JSString)); |
663 | JS_STATIC_ASSERT(sizeof(JSGCThing) >= sizeof(jsdouble)); |
664 | |
665 | /* We want to use all the available GC thing space for object's slots. */ |
666 | JS_STATIC_ASSERT(sizeof(JSObject) % sizeof(JSGCThing) == 0); |
667 | |
668 | /* |
669 | * Ensure that JSObject is allocated from a different GC-list rather than |
670 | * jsdouble and JSString so we can easily finalize JSObject before these 2 |
671 | * types of GC things. See comments in js_GC. |
672 | */ |
673 | JS_STATIC_ASSERT(GC_FREELIST_INDEX(sizeof(JSString)) != |
674 | GC_FREELIST_INDEX(sizeof(JSObject))); |
675 | JS_STATIC_ASSERT(GC_FREELIST_INDEX(sizeof(jsdouble)) != |
676 | GC_FREELIST_INDEX(sizeof(JSObject))); |
677 | |
678 | /* |
679 | * JSPtrTable capacity growth descriptor. The table grows by powers of two |
680 | * starting from capacity JSPtrTableInfo.minCapacity, but switching to linear |
681 | * growth when capacity reaches JSPtrTableInfo.linearGrowthThreshold. |
682 | */ |
683 | typedef struct JSPtrTableInfo { |
684 | uint16 minCapacity; |
685 | uint16 linearGrowthThreshold; |
686 | } JSPtrTableInfo; |
687 | |
688 | #define GC_ITERATOR_TABLE_MIN 4 |
689 | #define GC_ITERATOR_TABLE_LINEAR 1024 |
690 | |
691 | static const JSPtrTableInfo iteratorTableInfo = { |
692 | GC_ITERATOR_TABLE_MIN, |
693 | GC_ITERATOR_TABLE_LINEAR |
694 | }; |
695 | |
696 | /* Calculate table capacity based on the current value of JSPtrTable.count. */ |
697 | static size_t |
698 | PtrTableCapacity(size_t count, const JSPtrTableInfo *info) |
699 | { |
700 | size_t linear, log, capacity; |
701 | |
702 | linear = info->linearGrowthThreshold; |
703 | JS_ASSERT(info->minCapacity <= linear); |
704 | |
705 | if (count == 0) { |
706 | capacity = 0; |
707 | } else if (count < linear) { |
708 | log = JS_CEILING_LOG2W(count); |
709 | JS_ASSERT(log != JS_BITS_PER_WORD); |
710 | capacity = (size_t)1 << log; |
711 | if (capacity < info->minCapacity) |
712 | capacity = info->minCapacity; |
713 | } else { |
714 | capacity = JS_ROUNDUP(count, linear); |
715 | } |
716 | |
717 | JS_ASSERT(capacity >= count); |
718 | return capacity; |
719 | } |
720 | |
721 | static void |
722 | FreePtrTable(JSPtrTable *table, const JSPtrTableInfo *info) |
723 | { |
724 | if (table->array) { |
725 | JS_ASSERT(table->count > 0); |
726 | js_free(table->array); |
727 | table->array = NULL; |
728 | table->count = 0; |
729 | } |
730 | JS_ASSERT(table->count == 0); |
731 | } |
732 | |
733 | static JSBool |
734 | AddToPtrTable(JSContext *cx, JSPtrTable *table, const JSPtrTableInfo *info, |
735 | void *ptr) |
736 | { |
737 | size_t count, capacity; |
738 | void **array; |
739 | |
740 | count = table->count; |
741 | capacity = PtrTableCapacity(count, info); |
742 | |
743 | if (count == capacity) { |
744 | if (capacity < info->minCapacity) { |
745 | JS_ASSERT(capacity == 0); |
746 | JS_ASSERT(!table->array); |
747 | capacity = info->minCapacity; |
748 | } else { |
749 | /* |
750 | * Simplify the overflow detection assuming pointer is bigger |
751 | * than byte. |
752 | */ |
753 | JS_STATIC_ASSERT(2 <= sizeof table->array[0]); |
754 | capacity = (capacity < info->linearGrowthThreshold) |
755 | ? 2 * capacity |
756 | : capacity + info->linearGrowthThreshold; |
757 | if (capacity > (size_t)-1 / sizeof table->array[0]) |
758 | goto bad; |
759 | } |
760 | array = (void **) js_realloc(table->array, |
761 | capacity * sizeof table->array[0]); |
762 | if (!array) |
763 | goto bad; |
764 | #ifdef DEBUG |
765 | memset(array + count, JS_FREE_PATTERN, |
766 | (capacity - count) * sizeof table->array[0]); |
767 | #endif |
768 | table->array = array; |
769 | } |
770 | |
771 | table->array[count] = ptr; |
772 | table->count = count + 1; |
773 | |
774 | return JS_TRUE; |
775 | |
776 | bad: |
777 | JS_ReportOutOfMemory(cx); |
778 | return JS_FALSE; |
779 | } |
780 | |
781 | static void |
782 | ShrinkPtrTable(JSPtrTable *table, const JSPtrTableInfo *info, |
783 | size_t newCount) |
784 | { |
785 | size_t oldCapacity, capacity; |
786 | void **array; |
787 | |
788 | JS_ASSERT(newCount <= table->count); |
789 | if (newCount == table->count) |
790 | return; |
791 | |
792 | oldCapacity = PtrTableCapacity(table->count, info); |
793 | table->count = newCount; |
794 | capacity = PtrTableCapacity(newCount, info); |
795 | |
796 | if (oldCapacity != capacity) { |
797 | array = table->array; |
798 | JS_ASSERT(array); |
799 | if (capacity == 0) { |
800 | js_free(array); |
801 | table->array = NULL; |
802 | return; |
803 | } |
804 | array = (void **) js_realloc(array, capacity * sizeof array[0]); |
805 | if (array) |
806 | table->array = array; |
807 | } |
808 | #ifdef DEBUG |
809 | memset(table->array + newCount, JS_FREE_PATTERN, |
810 | (capacity - newCount) * sizeof table->array[0]); |
811 | #endif |
812 | } |
813 | |
814 | #ifdef JS_GCMETER |
815 | # define METER(x) ((void) (x)) |
816 | # define METER_IF(condition, x) ((void) ((condition) && (x))) |
817 | #else |
818 | # define METER(x) ((void) 0) |
819 | # define METER_IF(condition, x) ((void) 0) |
820 | #endif |
821 | |
822 | #define METER_UPDATE_MAX(maxLval, rval) \ |
823 | METER_IF((maxLval) < (rval), (maxLval) = (rval)) |
824 | |
825 | #if JS_GC_USE_MMAP || !HAS_POSIX_MEMALIGN |
826 | |
827 | /* |
828 | * For chunks allocated via over-sized malloc, get a pointer to store the gap |
829 | * between the malloc's result and the first arena in the chunk. |
830 | */ |
831 | static uint32 * |
832 | GetMallocedChunkGapPtr(jsuword chunk) |
833 | { |
834 | JS_ASSERT((chunk & GC_ARENA_MASK) == 0); |
835 | |
836 | /* Use the memory after the chunk, see NewGCChunk for details. */ |
837 | return (uint32 *) (chunk + (js_gcArenasPerChunk << GC_ARENA_SHIFT)); |
838 | } |
839 | |
840 | #endif |
841 | |
842 | static jsuword |
843 | NewGCChunk(void) |
844 | { |
845 | void *p; |
846 | |
847 | #if JS_GC_USE_MMAP |
848 | if (js_gcUseMmap) { |
849 | # if defined(XP_WIN) |
850 | p = VirtualAlloc(NULL, js_gcArenasPerChunk << GC_ARENA_SHIFT, |
851 | MEM_COMMIT | MEM_RESERVE, PAGE_READWRITE); |
852 | return (jsuword) p; |
853 | # else |
854 | p = mmap(NULL, js_gcArenasPerChunk << GC_ARENA_SHIFT, |
855 | PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); |
856 | return (p == MAP_FAILED) ? 0 : (jsuword) p; |
857 | # endif |
858 | } |
859 | #endif |
860 | |
861 | #if HAS_POSIX_MEMALIGN |
862 | if (0 != posix_memalign(&p, GC_ARENA_SIZE, |
863 | GC_ARENA_SIZE * js_gcArenasPerChunk - |
864 | JS_GC_ARENA_PAD)) { |
865 | return 0; |
866 | } |
867 | return (jsuword) p; |
868 | #else |
869 | /* |
870 | * Implement chunk allocation using oversized malloc if mmap and |
871 | * posix_memalign are not available. |
872 | * |
873 | * Since malloc allocates pointers aligned on the word boundary, to get |
874 | * js_gcArenasPerChunk aligned arenas, we need to malloc only |
875 | * |
876 | * ((js_gcArenasPerChunk + 1) << GC_ARENA_SHIFT) - sizeof(size_t) |
877 | * |
878 | * bytes. But since we stores the gap between the malloced pointer and the |
879 | * first arena in the chunk after the chunk, we need to ask for |
880 | * |
881 | * ((js_gcArenasPerChunk + 1) << GC_ARENA_SHIFT) |
882 | * |
883 | * bytes to ensure that we always have room to store the gap. |
884 | */ |
885 | p = js_malloc((js_gcArenasPerChunk + 1) << GC_ARENA_SHIFT); |
886 | if (!p) |
887 | return 0; |
888 | |
889 | { |
890 | jsuword chunk; |
891 | |
892 | chunk = ((jsuword) p + GC_ARENA_MASK) & ~GC_ARENA_MASK; |
893 | *GetMallocedChunkGapPtr(chunk) = (uint32) (chunk - (jsuword) p); |
894 | return chunk; |
895 | } |
896 | #endif |
897 | } |
898 | |
899 | static void |
900 | DestroyGCChunk(jsuword chunk) |
901 | { |
902 | JS_ASSERT((chunk & GC_ARENA_MASK) == 0); |
903 | #if JS_GC_USE_MMAP |
904 | if (js_gcUseMmap) { |
905 | # if defined(XP_WIN) |
906 | VirtualFree((void *) chunk, 0, MEM_RELEASE); |
907 | # elif defined(SOLARIS) |
908 | munmap((char *) chunk, js_gcArenasPerChunk << GC_ARENA_SHIFT); |
909 | # else |
910 | munmap((void *) chunk, js_gcArenasPerChunk << GC_ARENA_SHIFT); |
911 | # endif |
912 | return; |
913 | } |
914 | #endif |
915 | |
916 | #if HAS_POSIX_MEMALIGN |
917 | js_free((void *) chunk); |
918 | #else |
919 | /* See comments in NewGCChunk. */ |
920 | JS_ASSERT(*GetMallocedChunkGapPtr(chunk) < GC_ARENA_SIZE); |
921 | js_free((void *) (chunk - *GetMallocedChunkGapPtr(chunk))); |
922 | #endif |
923 | } |
924 | |
925 | #if CHUNKED_ARENA_ALLOCATION |
926 | |
927 | static void |
928 | AddChunkToList(JSRuntime *rt, JSGCChunkInfo *ci) |
929 | { |
930 | ci->prevp = &rt->gcChunkList; |
931 | ci->next = rt->gcChunkList; |
932 | if (rt->gcChunkList) { |
933 | JS_ASSERT(rt->gcChunkList->prevp == &rt->gcChunkList); |
934 | rt->gcChunkList->prevp = &ci->next; |
935 | } |
936 | rt->gcChunkList = ci; |
937 | } |
938 | |
939 | static void |
940 | RemoveChunkFromList(JSRuntime *rt, JSGCChunkInfo *ci) |
941 | { |
942 | *ci->prevp = ci->next; |
943 | if (ci->next) { |
944 | JS_ASSERT(ci->next->prevp == &ci->next); |
945 | ci->next->prevp = ci->prevp; |
946 | } |
947 | } |
948 | |
949 | #endif |
950 | |
951 | static JSGCArenaInfo * |
952 | NewGCArena(JSRuntime *rt) |
953 | { |
954 | jsuword chunk; |
955 | JSGCArenaInfo *a; |
956 | |
957 | if (rt->gcBytes >= rt->gcMaxBytes) |
958 | return NULL; |
959 | |
960 | #if CHUNKED_ARENA_ALLOCATION |
961 | if (js_gcArenasPerChunk == 1) { |
962 | #endif |
963 | chunk = NewGCChunk(); |
964 | if (chunk == 0) |
965 | return NULL; |
966 | a = ARENA_START_TO_INFO(chunk); |
967 | #if CHUNKED_ARENA_ALLOCATION |
968 | } else { |
969 | JSGCChunkInfo *ci; |
970 | uint32 i; |
971 | JSGCArenaInfo *aprev; |
972 | |
973 | ci = rt->gcChunkList; |
974 | if (!ci) { |
975 | chunk = NewGCChunk(); |
976 | if (chunk == 0) |
977 | return NULL; |
978 | JS_ASSERT((chunk & GC_ARENA_MASK) == 0); |
979 | a = GET_ARENA_INFO(chunk, 0); |
980 | a->firstArena = JS_TRUE; |
981 | a->arenaIndex = 0; |
982 | aprev = NULL; |
983 | i = 0; |
984 | do { |
985 | a->prev = aprev; |
986 | aprev = a; |
987 | ++i; |
988 | a = GET_ARENA_INFO(chunk, i); |
989 | a->firstArena = JS_FALSE; |
990 | a->arenaIndex = i; |
991 | } while (i != js_gcArenasPerChunk - 1); |
992 | ci = GET_CHUNK_INFO(chunk, 0); |
993 | ci->lastFreeArena = aprev; |
994 | ci->numFreeArenas = js_gcArenasPerChunk - 1; |
995 | AddChunkToList(rt, ci); |
996 | } else { |
997 | JS_ASSERT(ci->prevp == &rt->gcChunkList); |
998 | a = ci->lastFreeArena; |
999 | aprev = a->prev; |
1000 | if (!aprev) { |
1001 | JS_ASSERT(ci->numFreeArenas == 1); |
1002 | JS_ASSERT(ARENA_INFO_TO_START(a) == (jsuword) ci); |
1003 | RemoveChunkFromList(rt, ci); |
1004 | chunk = GET_ARENA_CHUNK(a, GET_ARENA_INDEX(a)); |
1005 | SET_CHUNK_INFO_INDEX(chunk, NO_FREE_ARENAS); |
1006 | } else { |
1007 | JS_ASSERT(ci->numFreeArenas >= 2); |
1008 | JS_ASSERT(ARENA_INFO_TO_START(a) != (jsuword) ci); |
1009 | ci->lastFreeArena = aprev; |
1010 | ci->numFreeArenas--; |
1011 | } |
1012 | } |
1013 | } |
1014 | #endif |
1015 | |
1016 | rt->gcBytes += GC_ARENA_SIZE; |
1017 | a->prevUntracedPage = 0; |
1018 | memset(&a->u, 0, sizeof(a->u)); |
1019 | |
1020 | return a; |
1021 | } |
1022 | |
1023 | static void |
1024 | DestroyGCArenas(JSRuntime *rt, JSGCArenaInfo *last) |
1025 | { |
1026 | JSGCArenaInfo *a; |
1027 | |
1028 | while (last) { |
1029 | a = last; |
1030 | last = last->prev; |
1031 | |
1032 | METER(rt->gcStats.afree++); |
1033 | JS_ASSERT(rt->gcBytes >= GC_ARENA_SIZE); |
1034 | rt->gcBytes -= GC_ARENA_SIZE; |
1035 | |
1036 | #if CHUNKED_ARENA_ALLOCATION |
1037 | if (js_gcArenasPerChunk == 1) { |
1038 | #endif |
1039 | DestroyGCChunk(ARENA_INFO_TO_START(a)); |
1040 | #if CHUNKED_ARENA_ALLOCATION |
1041 | } else { |
1042 | uint32 arenaIndex; |
1043 | jsuword chunk; |
1044 | uint32 chunkInfoIndex; |
1045 | JSGCChunkInfo *ci; |
1046 | # ifdef DEBUG |
1047 | jsuword firstArena; |
1048 | |
1049 | firstArena = a->firstArena; |
1050 | arenaIndex = a->arenaIndex; |
1051 | memset((void *) ARENA_INFO_TO_START(a), JS_FREE_PATTERN, |
1052 | GC_ARENA_SIZE - JS_GC_ARENA_PAD); |
1053 | a->firstArena = firstArena; |
1054 | a->arenaIndex = arenaIndex; |
1055 | # endif |
1056 | arenaIndex = GET_ARENA_INDEX(a); |
1057 | chunk = GET_ARENA_CHUNK(a, arenaIndex); |
1058 | chunkInfoIndex = GET_CHUNK_INFO_INDEX(chunk); |
1059 | if (chunkInfoIndex == NO_FREE_ARENAS) { |
1060 | chunkInfoIndex = arenaIndex; |
1061 | SET_CHUNK_INFO_INDEX(chunk, arenaIndex); |
1062 | ci = GET_CHUNK_INFO(chunk, chunkInfoIndex); |
1063 | a->prev = NULL; |
1064 | ci->lastFreeArena = a; |
1065 | ci->numFreeArenas = 1; |
1066 | AddChunkToList(rt, ci); |
1067 | } else { |
1068 | JS_ASSERT(chunkInfoIndex != arenaIndex); |
1069 | ci = GET_CHUNK_INFO(chunk, chunkInfoIndex); |
1070 | JS_ASSERT(ci->numFreeArenas != 0); |
1071 | JS_ASSERT(ci->lastFreeArena); |
1072 | JS_ASSERT(a != ci->lastFreeArena); |
1073 | if (ci->numFreeArenas == js_gcArenasPerChunk - 1) { |
1074 | RemoveChunkFromList(rt, ci); |
1075 | DestroyGCChunk(chunk); |
1076 | } else { |
1077 | ++ci->numFreeArenas; |
1078 | a->prev = ci->lastFreeArena; |
1079 | ci->lastFreeArena = a; |
1080 | } |
1081 | } |
1082 | } |
1083 | # endif |
1084 | } |
1085 | } |
1086 | |
1087 | static void |
1088 | InitGCArenaLists(JSRuntime *rt) |
1089 | { |
1090 | uintN i, thingSize; |
1091 | JSGCArenaList *arenaList; |
1092 | |
1093 | for (i = 0; i < GC_NUM_FREELISTS; i++) { |
1094 | arenaList = &rt->gcArenaList[i]; |
1095 | thingSize = GC_FREELIST_NBYTES(i); |
1096 | arenaList->last = NULL; |
1097 | arenaList->lastCount = THINGS_PER_ARENA(thingSize); |
1098 | arenaList->thingSize = thingSize; |
1099 | arenaList->freeList = NULL; |
1100 | } |
1101 | rt->gcDoubleArenaList.first = NULL; |
1102 | rt->gcDoubleArenaList.nextDoubleFlags = DOUBLE_BITMAP_SENTINEL; |
1103 | } |
1104 | |
1105 | static void |
1106 | FinishGCArenaLists(JSRuntime *rt) |
1107 | { |
1108 | uintN i; |
1109 | JSGCArenaList *arenaList; |
1110 | |
1111 | for (i = 0; i < GC_NUM_FREELISTS; i++) { |
1112 | arenaList = &rt->gcArenaList[i]; |
1113 | DestroyGCArenas(rt, arenaList->last); |
1114 | arenaList->last = NULL; |
1115 | arenaList->lastCount = THINGS_PER_ARENA(arenaList->thingSize); |
1116 | arenaList->freeList = NULL; |
1117 | } |
1118 | DestroyGCArenas(rt, rt->gcDoubleArenaList.first); |
1119 | rt->gcDoubleArenaList.first = NULL; |
1120 | rt->gcDoubleArenaList.nextDoubleFlags = DOUBLE_BITMAP_SENTINEL; |
1121 | |
1122 | rt->gcBytes = 0; |
1123 | JS_ASSERT(rt->gcChunkList == 0); |
1124 | } |
1125 | |
1126 | /* |
1127 | * This function must not be called when thing is jsdouble. |
1128 | */ |
1129 | static uint8 * |
1130 | GetGCThingFlags(void *thing) |
1131 | { |
1132 | JSGCArenaInfo *a; |
1133 | uint32 index; |
1134 | |
1135 | a = THING_TO_ARENA(thing); |
1136 | index = THING_TO_INDEX(thing, a->list->thingSize); |
1137 | return THING_FLAGP(a, index); |
1138 | } |
1139 | |
1140 | /* |
1141 | * This function returns null when thing is jsdouble. |
1142 | */ |
1143 | static uint8 * |
1144 | GetGCThingFlagsOrNull(void *thing) |
1145 | { |
1146 | JSGCArenaInfo *a; |
1147 | uint32 index; |
1148 | |
1149 | if (JSString::isStatic(thing)) |
1150 | return NULL; |
1151 | a = THING_TO_ARENA(thing); |
1152 | if (!a->list) |
1153 | return NULL; |
1154 | index = THING_TO_INDEX(thing, a->list->thingSize); |
1155 | return THING_FLAGP(a, index); |
1156 | } |
1157 | |
1158 | intN |
1159 | js_GetExternalStringGCType(JSString *str) |
1160 | { |
1161 | JS_ASSERT(!JSString::isStatic(str)); |
1162 | |
1163 | uintN type = (uintN) *GetGCThingFlags(str) & GCF_TYPEMASK; |
1164 | JS_ASSERT(type == GCX_STRING || type >= GCX_EXTERNAL_STRING); |
1165 | return (type == GCX_STRING) ? -1 : (intN) (type - GCX_EXTERNAL_STRING); |
1166 | } |
1167 | |
1168 | static uint32 |
1169 | MapGCFlagsToTraceKind(uintN flags) |
1170 | { |
1171 | uint32 type; |
1172 | |
1173 | type = flags & GCF_TYPEMASK; |
1174 | JS_ASSERT(type != GCX_DOUBLE); |
1175 | JS_ASSERT(type < GCX_NTYPES); |
1176 | return (type < GCX_EXTERNAL_STRING) ? type : JSTRACE_STRING; |
1177 | } |
1178 | |
1179 | JS_FRIEND_API(uint32) |
1180 | js_GetGCThingTraceKind(void *thing) |
1181 | { |
1182 | JSGCArenaInfo *a; |
1183 | uint32 index; |
1184 | |
1185 | if (JSString::isStatic(thing)) |
1186 | return JSTRACE_STRING; |
1187 | |
1188 | a = THING_TO_ARENA(thing); |
1189 | if (!a->list) |
1190 | return JSTRACE_DOUBLE; |
1191 | |
1192 | index = THING_TO_INDEX(thing, a->list->thingSize); |
1193 | return MapGCFlagsToTraceKind(*THING_FLAGP(a, index)); |
1194 | } |
1195 | |
1196 | JSRuntime* |
1197 | js_GetGCStringRuntime(JSString *str) |
1198 | { |
1199 | JSGCArenaList *list; |
1200 | |
1201 | list = THING_TO_ARENA(str)->list; |
1202 | |
1203 | JS_ASSERT(list->thingSize == sizeof(JSGCThing)); |
1204 | JS_ASSERT(GC_FREELIST_INDEX(sizeof(JSGCThing)) == 0); |
1205 | |
1206 | return (JSRuntime *)((uint8 *)list - offsetof(JSRuntime, gcArenaList)); |
1207 | } |
1208 | |
1209 | JSBool |
1210 | js_IsAboutToBeFinalized(JSContext *cx, void *thing) |
1211 | { |
1212 | JSGCArenaInfo *a; |
1213 | uint32 index, flags; |
1214 | |
1215 | if (JSString::isStatic(thing)) |
1216 | return false; |
1217 | |
1218 | a = THING_TO_ARENA(thing); |
1219 | if (!a->list) { |
1220 | /* |
1221 | * Check if arena has no marked doubles. In that case the bitmap with |
1222 | * the mark flags contains all garbage as it is initialized only when |
1223 | * marking the first double in the arena. |
1224 | */ |
1225 | if (!a->u.hasMarkedDoubles) |
1226 | return JS_TRUE; |
1227 | index = DOUBLE_THING_TO_INDEX(thing); |
1228 | return !IsMarkedDouble(a, index); |
1229 | } |
1230 | index = THING_TO_INDEX(thing, a->list->thingSize); |
1231 | flags = *THING_FLAGP(a, index); |
1232 | return !(flags & (GCF_MARK | GCF_LOCK | GCF_FINAL)); |
1233 | } |
1234 | |
1235 | /* This is compatible with JSDHashEntryStub. */ |
1236 | typedef struct JSGCRootHashEntry { |
1237 | JSDHashEntryHdr hdr; |
1238 | void *root; |
1239 | const char *name; |
1240 | } JSGCRootHashEntry; |
1241 | |
1242 | /* Initial size of the gcRootsHash table (SWAG, small enough to amortize). */ |
1243 | #define GC_ROOTS_SIZE 256 |
1244 | |
1245 | #if CHUNKED_ARENA_ALLOCATION |
1246 | |
1247 | /* |
1248 | * For a CPU with extremely large pages using them for GC things wastes |
1249 | * too much memory. |
1250 | */ |
1251 | # define GC_ARENAS_PER_CPU_PAGE_LIMIT JS_BIT(18 - GC_ARENA_SHIFT) |
1252 | |
1253 | JS_STATIC_ASSERT(GC_ARENAS_PER_CPU_PAGE_LIMIT <= NO_FREE_ARENAS); |
1254 | |
1255 | #endif |
1256 | |
1257 | JSBool |
1258 | js_InitGC(JSRuntime *rt, uint32 maxbytes) |
1259 | { |
1260 | #if JS_GC_USE_MMAP |
1261 | if (js_gcArenasPerChunk == 0) { |
1262 | size_t cpuPageSize, arenasPerPage; |
1263 | # if defined(XP_WIN) |
1264 | SYSTEM_INFO si; |
1265 | |
1266 | GetSystemInfo(&si); |
1267 | cpuPageSize = si.dwPageSize; |
1268 | |
1269 | # elif defined(XP_UNIX) || defined(XP_BEOS) |
1270 | cpuPageSize = (size_t) sysconf(_SC_PAGESIZE); |
1271 | # else |
1272 | # error "Not implemented" |
1273 | # endif |
1274 | /* cpuPageSize is a power of 2. */ |
1275 | JS_ASSERT((cpuPageSize & (cpuPageSize - 1)) == 0); |
1276 | arenasPerPage = cpuPageSize >> GC_ARENA_SHIFT; |
1277 | #ifdef DEBUG |
1278 | if (arenasPerPage == 0) { |
1279 | fprintf(stderr, |
1280 | "JS engine warning: the size of the CPU page, %u bytes, is too low to use\n" |
1281 | "paged allocation for the garbage collector. Please report this.\n", |
1282 | (unsigned) cpuPageSize); |
1283 | } |
1284 | #endif |
1285 | if (arenasPerPage - 1 <= (size_t) (GC_ARENAS_PER_CPU_PAGE_LIMIT - 1)) { |
1286 | /* |
1287 | * Use at least 4 GC arenas per paged allocation chunk to minimize |
1288 | * the overhead of mmap/VirtualAlloc. |
1289 | */ |
1290 | js_gcUseMmap = JS_TRUE; |
1291 | js_gcArenasPerChunk = JS_MAX((uint32) arenasPerPage, 4); |
1292 | } else { |
1293 | js_gcUseMmap = JS_FALSE; |
1294 | js_gcArenasPerChunk = 7; |
1295 | } |
1296 | } |
1297 | JS_ASSERT(1 <= js_gcArenasPerChunk && |
1298 | js_gcArenasPerChunk <= NO_FREE_ARENAS); |
1299 | #endif |
1300 | |
1301 | InitGCArenaLists(rt); |
1302 | if (!JS_DHashTableInit(&rt->gcRootsHash, JS_DHashGetStubOps(), NULL, |
1303 | sizeof(JSGCRootHashEntry), GC_ROOTS_SIZE)) { |
1304 | rt->gcRootsHash.ops = NULL; |
1305 | return JS_FALSE; |
1306 | } |
1307 | rt->gcLocksHash = NULL; /* create lazily */ |
1308 | |
1309 | /* |
1310 | * Separate gcMaxMallocBytes from gcMaxBytes but initialize to maxbytes |
1311 | * for default backward API compatibility. |
1312 | */ |
1313 | rt->gcMaxBytes = rt->gcMaxMallocBytes = maxbytes; |
1314 | rt->gcEmptyArenaPoolLifespan = 30000; |
1315 | |
1316 | /* |
1317 | * By default the trigger factor gets maximum possible value. This |
1318 | * means that GC will not be triggered by growth of GC memory (gcBytes). |
1319 | */ |
1320 | rt->setGCTriggerFactor((uint32) -1); |
1321 | |
1322 | /* |
1323 | * The assigned value prevents GC from running when GC memory is too low |
1324 | * (during JS engine start). |
1325 | */ |
1326 | rt->setGCLastBytes(8192); |
1327 | |
1328 | METER(memset(&rt->gcStats, 0, sizeof rt->gcStats)); |
1329 | return JS_TRUE; |
1330 | } |
1331 | |
1332 | #ifdef JS_GCMETER |
1333 | |
1334 | static void |
1335 | UpdateArenaStats(JSGCArenaStats *st, uint32 nlivearenas, uint32 nkilledArenas, |
1336 | uint32 nthings) |
1337 | { |
1338 | size_t narenas; |
1339 | |
1340 | narenas = nlivearenas + nkilledArenas; |
1341 | JS_ASSERT(narenas >= st->livearenas); |
1342 | |
1343 | st->newarenas = narenas - st->livearenas; |
1344 | st->narenas = narenas; |
1345 | st->livearenas = nlivearenas; |
1346 | if (st->maxarenas < narenas) |
1347 | st->maxarenas = narenas; |
1348 | st->totalarenas += narenas; |
1349 | |
1350 | st->nthings = nthings; |
1351 | if (st->maxthings < nthings) |
1352 | st->maxthings = nthings; |
1353 | st->totalthings += nthings; |
1354 | } |
1355 | |
1356 | JS_FRIEND_API(void) |
1357 | js_DumpGCStats(JSRuntime *rt, FILE *fp) |
1358 | { |
1359 | int i; |
1360 | size_t sumArenas, sumTotalArenas; |
1361 | size_t sumThings, sumMaxThings; |
1362 | size_t sumThingSize, sumTotalThingSize; |
1363 | size_t sumArenaCapacity, sumTotalArenaCapacity; |
1364 | JSGCArenaStats *st; |
1365 | size_t thingSize, thingsPerArena; |
1366 | size_t sumAlloc, sumLocalAlloc, sumFail, sumRetry; |
1367 | |
1368 | fprintf(fp, "\nGC allocation statistics:\n"); |
1369 | |
1370 | #define UL(x) ((unsigned long)(x)) |
1371 | #define ULSTAT(x) UL(rt->gcStats.x) |
1372 | #define PERCENT(x,y) (100.0 * (double) (x) / (double) (y)) |
1373 | |
1374 | sumArenas = 0; |
1375 | sumTotalArenas = 0; |
1376 | sumThings = 0; |
1377 | sumMaxThings = 0; |
1378 | sumThingSize = 0; |
1379 | sumTotalThingSize = 0; |
1380 | sumArenaCapacity = 0; |
1381 | sumTotalArenaCapacity = 0; |
1382 | sumAlloc = 0; |
1383 | sumLocalAlloc = 0; |
1384 | sumFail = 0; |
1385 | sumRetry = 0; |
1386 | for (i = -1; i < (int) GC_NUM_FREELISTS; i++) { |
1387 | if (i == -1) { |
1388 | thingSize = sizeof(jsdouble); |
1389 | thingsPerArena = DOUBLES_PER_ARENA; |
1390 | st = &rt->gcStats.doubleArenaStats; |
1391 | fprintf(fp, |
1392 | "Arena list for double values (%lu doubles per arena):", |
1393 | UL(thingsPerArena)); |
1394 | } else { |
1395 | thingSize = rt->gcArenaList[i].thingSize; |
1396 | thingsPerArena = THINGS_PER_ARENA(thingSize); |
1397 | st = &rt->gcStats.arenaStats[i]; |
1398 | fprintf(fp, |
1399 | "Arena list %d (thing size %lu, %lu things per arena):", |
1400 | i, UL(GC_FREELIST_NBYTES(i)), UL(thingsPerArena)); |
1401 | } |
1402 | if (st->maxarenas == 0) { |
1403 | fputs(" NEVER USED\n", fp); |
1404 | continue; |
1405 | } |
1406 | putc('\n', fp); |
1407 | fprintf(fp, " arenas before GC: %lu\n", UL(st->narenas)); |
1408 | fprintf(fp, " new arenas before GC: %lu (%.1f%%)\n", |
1409 | UL(st->newarenas), PERCENT(st->newarenas, st->narenas)); |
1410 | fprintf(fp, " arenas after GC: %lu (%.1f%%)\n", |
1411 | UL(st->livearenas), PERCENT(st->livearenas, st->narenas)); |
1412 | fprintf(fp, " max arenas: %lu\n", UL(st->maxarenas)); |
1413 | fprintf(fp, " things: %lu\n", UL(st->nthings)); |
1414 | fprintf(fp, " GC cell utilization: %.1f%%\n", |
1415 | PERCENT(st->nthings, thingsPerArena * st->narenas)); |
1416 | fprintf(fp, " average cell utilization: %.1f%%\n", |
1417 | PERCENT(st->totalthings, thingsPerArena * st->totalarenas)); |
1418 | fprintf(fp, " max things: %lu\n", UL(st->maxthings)); |
1419 | fprintf(fp, " alloc attempts: %lu\n", UL(st->alloc)); |
1420 | fprintf(fp, " alloc without locks: %1u (%.1f%%)\n", |
1421 | UL(st->localalloc), PERCENT(st->localalloc, st->alloc)); |
1422 | sumArenas += st->narenas; |
1423 | sumTotalArenas += st->totalarenas; |
1424 | sumThings += st->nthings; |
1425 | sumMaxThings += st->maxthings; |
1426 | sumThingSize += thingSize * st->nthings; |
1427 | sumTotalThingSize += thingSize * st->totalthings; |
1428 | sumArenaCapacity += thingSize * thingsPerArena * st->narenas; |
1429 | sumTotalArenaCapacity += thingSize * thingsPerArena * st->totalarenas; |
1430 | sumAlloc += st->alloc; |
1431 | sumLocalAlloc += st->localalloc; |
1432 | sumFail += st->fail; |
1433 | sumRetry += st->retry; |
1434 | } |
1435 | fprintf(fp, "TOTAL STATS:\n"); |
1436 | fprintf(fp, " bytes allocated: %lu\n", UL(rt->gcBytes)); |
1437 | fprintf(fp, " total GC arenas: %lu\n", UL(sumArenas)); |
1438 | fprintf(fp, " total GC things: %lu\n", UL(sumThings)); |
1439 | fprintf(fp, " max total GC things: %lu\n", UL(sumMaxThings)); |
1440 | fprintf(fp, " GC cell utilization: %.1f%%\n", |
1441 | PERCENT(sumThingSize, sumArenaCapacity)); |
1442 | fprintf(fp, " average cell utilization: %.1f%%\n", |
1443 | PERCENT(sumTotalThingSize, sumTotalArenaCapacity)); |
1444 | fprintf(fp, "allocation retries after GC: %lu\n", UL(sumRetry)); |
1445 | fprintf(fp, " alloc attempts: %lu\n", UL(sumAlloc)); |
1446 | fprintf(fp, " alloc without locks: %1u (%.1f%%)\n", |
1447 | UL(sumLocalAlloc), PERCENT(sumLocalAlloc, sumAlloc)); |
1448 | fprintf(fp, " allocation failures: %lu\n", UL(sumFail)); |
1449 | fprintf(fp, " things born locked: %lu\n", ULSTAT(lockborn)); |
1450 | fprintf(fp, " valid lock calls: %lu\n", ULSTAT(lock)); |
1451 | fprintf(fp, " valid unlock calls: %lu\n", ULSTAT(unlock)); |
1452 | fprintf(fp, " mark recursion depth: %lu\n", ULSTAT(depth)); |
1453 | fprintf(fp, " maximum mark recursion: %lu\n", ULSTAT(maxdepth)); |
1454 | fprintf(fp, " mark C recursion depth: %lu\n", ULSTAT(cdepth)); |
1455 | fprintf(fp, " maximum mark C recursion: %lu\n", ULSTAT(maxcdepth)); |
1456 | fprintf(fp, " delayed tracing calls: %lu\n", ULSTAT(untraced)); |
1457 | #ifdef DEBUG |
1458 | fprintf(fp, " max trace later count: %lu\n", ULSTAT(maxuntraced)); |
1459 | #endif |
1460 | fprintf(fp, " maximum GC nesting level: %lu\n", ULSTAT(maxlevel)); |
1461 | fprintf(fp, "potentially useful GC calls: %lu\n", ULSTAT(poke)); |
1462 | fprintf(fp, " thing arenas freed so far: %lu\n", ULSTAT(afree)); |
1463 | fprintf(fp, " stack segments scanned: %lu\n", ULSTAT(stackseg)); |
1464 | fprintf(fp, "stack segment slots scanned: %lu\n", ULSTAT(segslots)); |
1465 | fprintf(fp, "reachable closeable objects: %lu\n", ULSTAT(nclose)); |
1466 | fprintf(fp, " max reachable closeable: %lu\n", ULSTAT(maxnclose)); |
1467 | fprintf(fp, " scheduled close hooks: %lu\n", ULSTAT(closelater)); |
1468 | fprintf(fp, " max scheduled close hooks: %lu\n", ULSTAT(maxcloselater)); |
1469 | |
1470 | #undef UL |
1471 | #undef ULSTAT |
1472 | #undef PERCENT |
1473 | |
1474 | #ifdef JS_ARENAMETER |
1475 | JS_DumpArenaStats(fp); |
1476 | #endif |
1477 | } |
1478 | #endif |
1479 | |
1480 | #ifdef DEBUG |
1481 | static void |
1482 | CheckLeakedRoots(JSRuntime *rt); |
1483 | #endif |
1484 | |
1485 | void |
1486 | js_FinishGC(JSRuntime *rt) |
1487 | { |
1488 | #ifdef JS_ARENAMETER |
1489 | JS_DumpArenaStats(stdout); |
1490 | #endif |
1491 | #ifdef JS_GCMETER |
1492 | js_DumpGCStats(rt, stdout); |
1493 | #endif |
1494 | |
1495 | FreePtrTable(&rt->gcIteratorTable, &iteratorTableInfo); |
1496 | FinishGCArenaLists(rt); |
1497 | |
1498 | if (rt->gcRootsHash.ops) { |
1499 | #ifdef DEBUG |
1500 | CheckLeakedRoots(rt); |
1501 | #endif |
1502 | JS_DHashTableFinish(&rt->gcRootsHash); |
1503 | rt->gcRootsHash.ops = NULL; |
1504 | } |
1505 | if (rt->gcLocksHash) { |
1506 | JS_DHashTableDestroy(rt->gcLocksHash); |
1507 | rt->gcLocksHash = NULL; |
1508 | } |
1509 | } |
1510 | |
1511 | JSBool |
1512 | js_AddRoot(JSContext *cx, void *rp, const char *name) |
1513 | { |
1514 | JSBool ok = js_AddRootRT(cx->runtime, rp, name); |
1515 | if (!ok) |
1516 | JS_ReportOutOfMemory(cx); |
1517 | return ok; |
1518 | } |
1519 | |
1520 | JSBool |
1521 | js_AddRootRT(JSRuntime *rt, void *rp, const char *name) |
1522 | { |
1523 | JSBool ok; |
1524 | JSGCRootHashEntry *rhe; |
1525 | |
1526 | /* |
1527 | * Due to the long-standing, but now removed, use of rt->gcLock across the |
1528 | * bulk of js_GC, API users have come to depend on JS_AddRoot etc. locking |
1529 | * properly with a racing GC, without calling JS_AddRoot from a request. |
1530 | * We have to preserve API compatibility here, now that we avoid holding |
1531 | * rt->gcLock across the mark phase (including the root hashtable mark). |
1532 | */ |
1533 | JS_LOCK_GC(rt); |
1534 | js_WaitForGC(rt); |
1535 | rhe = (JSGCRootHashEntry *) |
1536 | JS_DHashTableOperate(&rt->gcRootsHash, rp, JS_DHASH_ADD); |
1537 | if (rhe) { |
1538 | rhe->root = rp; |
1539 | rhe->name = name; |
1540 | ok = JS_TRUE; |
1541 | } else { |
1542 | ok = JS_FALSE; |
1543 | } |
1544 | JS_UNLOCK_GC(rt); |
1545 | return ok; |
1546 | } |
1547 | |
1548 | JSBool |
1549 | js_RemoveRoot(JSRuntime *rt, void *rp) |
1550 | { |
1551 | /* |
1552 | * Due to the JS_RemoveRootRT API, we may be called outside of a request. |
1553 | * Same synchronization drill as above in js_AddRoot. |
1554 | */ |
1555 | JS_LOCK_GC(rt); |
1556 | js_WaitForGC(rt); |
1557 | (void) JS_DHashTableOperate(&rt->gcRootsHash, rp, JS_DHASH_REMOVE); |
1558 | rt->gcPoke = JS_TRUE; |
1559 | JS_UNLOCK_GC(rt); |
1560 | return JS_TRUE; |
1561 | } |
1562 | |
1563 | #ifdef DEBUG |
1564 | |
1565 | static JSDHashOperator |
1566 | js_root_printer(JSDHashTable *table, JSDHashEntryHdr *hdr, uint32 i, void *arg) |
1567 | { |
1568 | uint32 *leakedroots = (uint32 *)arg; |
1569 | JSGCRootHashEntry *rhe = (JSGCRootHashEntry *)hdr; |
1570 | |
1571 | (*leakedroots)++; |
1572 | fprintf(stderr, |
1573 | "JS engine warning: leaking GC root \'%s\' at %p\n", |
1574 | rhe->name ? (char *)rhe->name : "", rhe->root); |
1575 | |
1576 | return JS_DHASH_NEXT; |
1577 | } |
1578 | |
1579 | static void |
1580 | CheckLeakedRoots(JSRuntime *rt) |
1581 | { |
1582 | uint32 leakedroots = 0; |
1583 | |
1584 | /* Warn (but don't assert) debug builds of any remaining roots. */ |
1585 | JS_DHashTableEnumerate(&rt->gcRootsHash, js_root_printer, |
1586 | &leakedroots); |
1587 | if (leakedroots > 0) { |
1588 | if (leakedroots == 1) { |
1589 | fprintf(stderr, |
1590 | "JS engine warning: 1 GC root remains after destroying the JSRuntime at %p.\n" |
1591 | " This root may point to freed memory. Objects reachable\n" |
1592 | " through it have not been finalized.\n", |
1593 | (void *) rt); |
1594 | } else { |
1595 | fprintf(stderr, |
1596 | "JS engine warning: %lu GC roots remain after destroying the JSRuntime at %p.\n" |
1597 | " These roots may point to freed memory. Objects reachable\n" |
1598 | " through them have not been finalized.\n", |
1599 | (unsigned long) leakedroots, (void *) rt); |
1600 | } |
1601 | } |
1602 | } |
1603 | |
1604 | typedef struct NamedRootDumpArgs { |
1605 | void (*dump)(const char *name, void *rp, void *data); |
1606 | void *data; |
1607 | } NamedRootDumpArgs; |
1608 | |
1609 | static JSDHashOperator |
1610 | js_named_root_dumper(JSDHashTable *table, JSDHashEntryHdr *hdr, uint32 number, |
1611 | void *arg) |
1612 | { |
1613 | NamedRootDumpArgs *args = (NamedRootDumpArgs *) arg; |
1614 | JSGCRootHashEntry *rhe = (JSGCRootHashEntry *)hdr; |
1615 | |
1616 | if (rhe->name) |
1617 | args->dump(rhe->name, rhe->root, args->data); |
1618 | return JS_DHASH_NEXT; |
1619 | } |
1620 | |
1621 | JS_BEGIN_EXTERN_C |
1622 | void |
1623 | js_DumpNamedRoots(JSRuntime *rt, |
1624 | void (*dump)(const char *name, void *rp, void *data), |
1625 | void *data) |
1626 | { |
1627 | NamedRootDumpArgs args; |
1628 | |
1629 | args.dump = dump; |
1630 | args.data = data; |
1631 | JS_DHashTableEnumerate(&rt->gcRootsHash, js_named_root_dumper, &args); |
1632 | } |
1633 | JS_END_EXTERN_C |
1634 | |
1635 | #endif /* DEBUG */ |
1636 | |
1637 | typedef struct GCRootMapArgs { |
1638 | JSGCRootMapFun map; |
1639 | void *data; |
1640 | } GCRootMapArgs; |
1641 | |
1642 | static JSDHashOperator |
1643 | js_gcroot_mapper(JSDHashTable *table, JSDHashEntryHdr *hdr, uint32 number, |
1644 | void *arg) |
1645 | { |
1646 | GCRootMapArgs *args = (GCRootMapArgs *) arg; |
1647 | JSGCRootHashEntry *rhe = (JSGCRootHashEntry *)hdr; |
1648 | intN mapflags; |
1649 | int op; |
1650 | |
1651 | mapflags = args->map(rhe->root, rhe->name, args->data); |
1652 | |
1653 | #if JS_MAP_GCROOT_NEXT == JS_DHASH_NEXT && \ |
1654 | JS_MAP_GCROOT_STOP == JS_DHASH_STOP && \ |
1655 | JS_MAP_GCROOT_REMOVE == JS_DHASH_REMOVE |
1656 | op = (JSDHashOperator)mapflags; |
1657 | #else |
1658 | op = JS_DHASH_NEXT; |
1659 | if (mapflags & JS_MAP_GCROOT_STOP) |
1660 | op |= JS_DHASH_STOP; |
1661 | if (mapflags & JS_MAP_GCROOT_REMOVE) |
1662 | op |= JS_DHASH_REMOVE; |
1663 | #endif |
1664 | |
1665 | return (JSDHashOperator) op; |
1666 | } |
1667 | |
1668 | uint32 |
1669 | js_MapGCRoots(JSRuntime *rt, JSGCRootMapFun map, void *data) |
1670 | { |
1671 | GCRootMapArgs args; |
1672 | uint32 rv; |
1673 | |
1674 | args.map = map; |
1675 | args.data = data; |
1676 | JS_LOCK_GC(rt); |
1677 | rv = JS_DHashTableEnumerate(&rt->gcRootsHash, js_gcroot_mapper, &args); |
1678 | JS_UNLOCK_GC(rt); |
1679 | return rv; |
1680 | } |
1681 | |
1682 | JSBool |
1683 | js_RegisterCloseableIterator(JSContext *cx, JSObject *obj) |
1684 | { |
1685 | JSRuntime *rt; |
1686 | JSBool ok; |
1687 | |
1688 | rt = cx->runtime; |
1689 | JS_ASSERT(!rt->gcRunning); |
1690 | |
1691 | JS_LOCK_GC(rt); |
1692 | ok = AddToPtrTable(cx, &rt->gcIteratorTable, &iteratorTableInfo, obj); |
1693 | JS_UNLOCK_GC(rt); |
1694 | return ok; |
1695 | } |
1696 | |
1697 | static void |
1698 | CloseNativeIterators(JSContext *cx) |
1699 | { |
1700 | JSRuntime *rt; |
1701 | size_t count, newCount, i; |
1702 | void **array; |
1703 | JSObject *obj; |
1704 | |
1705 | rt = cx->runtime; |
1706 | count = rt->gcIteratorTable.count; |
1707 | array = rt->gcIteratorTable.array; |
1708 | |
1709 | newCount = 0; |
1710 | for (i = 0; i != count; ++i) { |
1711 | obj = (JSObject *)array[i]; |
1712 | if (js_IsAboutToBeFinalized(cx, obj)) |
1713 | js_CloseNativeIterator(cx, obj); |
1714 | else |
1715 | array[newCount++] = obj; |
1716 | } |
1717 | ShrinkPtrTable(&rt->gcIteratorTable, &iteratorTableInfo, newCount); |
1718 | } |
1719 | |
1720 | #if defined(DEBUG_brendan) || defined(DEBUG_timeless) |
1721 | #define DEBUG_gchist |
1722 | #endif |
1723 | |
1724 | #ifdef DEBUG_gchist |
1725 | #define NGCHIST 64 |
1726 | |
1727 | static struct GCHist { |
1728 | bool lastDitch; |
1729 | JSGCThing *freeList; |
1730 | } gchist[NGCHIST]; |
1731 | |
1732 | unsigned gchpos = 0; |
1733 | #endif |
1734 | |
1735 | void |
1736 | JSRuntime::setGCTriggerFactor(uint32 factor) |
1737 | { |
1738 | JS_ASSERT(factor >= 100); |
1739 | |
1740 | gcTriggerFactor = factor; |
1741 | setGCLastBytes(gcLastBytes); |
1742 | } |
1743 | |
1744 | void |
1745 | JSRuntime::setGCLastBytes(size_t lastBytes) |
1746 | { |
1747 | gcLastBytes = lastBytes; |
1748 | uint64 triggerBytes = uint64(lastBytes) * uint64(gcTriggerFactor / 100); |
1749 | if (triggerBytes != size_t(triggerBytes)) |
1750 | triggerBytes = size_t(-1); |
1751 | gcTriggerBytes = size_t(triggerBytes); |
1752 | } |
1753 | |
1754 | static JS_INLINE bool |
1755 | IsGCThresholdReached(JSRuntime *rt) |
1756 | { |
1757 | #ifdef JS_GC_ZEAL |
1758 | if (rt->gcZeal >= 1) |
1759 | return true; |
1760 | #endif |
1761 | |
1762 | /* |
1763 | * Since the initial value of the gcLastBytes parameter is not equal to |
1764 | * zero (see the js_InitGC function) the return value is false when |
1765 | * the gcBytes value is close to zero at the JS engine start. |
1766 | */ |
1767 | return rt->gcMallocBytes >= rt->gcMaxMallocBytes || |
1768 | rt->gcBytes >= rt->gcTriggerBytes; |
1769 | } |
1770 | |
1771 | template <class T> static JS_INLINE T* |
1772 | NewGCThing(JSContext *cx, uintN flags) |
1773 | { |
1774 | JSRuntime *rt; |
1775 | bool doGC; |
1776 | JSGCThing *thing; |
1777 | uint8 *flagp; |
1778 | JSGCArenaList *arenaList; |
1779 | JSGCArenaInfo *a; |
1780 | uintN thingsLimit; |
1781 | JSLocalRootStack *lrs; |
1782 | #ifdef JS_GCMETER |
1783 | JSGCArenaStats *astats; |
1784 | #endif |
1785 | #ifdef JS_THREADSAFE |
1786 | JSBool gcLocked; |
1787 | uintN localMallocBytes; |
1788 | JSGCThing **lastptr; |
1789 | JSGCThing *tmpthing; |
1790 | uint8 *tmpflagp; |
1791 | uintN maxFreeThings; /* max to take from the global free list */ |
1792 | #endif |
1793 | |
1794 | JS_ASSERT((flags & GCF_TYPEMASK) != GCX_DOUBLE); |
1795 | rt = cx->runtime; |
1796 | size_t nbytes = sizeof(T); |
1797 | JS_ASSERT(JS_ROUNDUP(nbytes, sizeof(JSGCThing)) == nbytes); |
1798 | uintN flindex = GC_FREELIST_INDEX(nbytes); |
1799 | |
1800 | /* Updates of metering counters here may not be thread-safe. */ |
1801 | METER(astats = &cx->runtime->gcStats.arenaStats[flindex]); |
1802 | METER(astats->alloc++); |
1803 | |
1804 | #ifdef JS_THREADSAFE |
1805 | gcLocked = JS_FALSE; |
1806 | JS_ASSERT(cx->thread); |
1807 | |
1808 | JSGCThing *&freeList = cx->thread->gcFreeLists[flindex]; |
1809 | thing = freeList; |
1810 | localMallocBytes = JS_THREAD_DATA(cx)->gcMallocBytes; |
1811 | if (thing && rt->gcMaxMallocBytes - rt->gcMallocBytes > localMallocBytes) { |
1812 | flagp = thing->flagp; |
1813 | freeList = thing->next; |
1814 | METER(astats->localalloc++); |
1815 | goto success; |
1816 | } |
1817 | |
1818 | JS_LOCK_GC(rt); |
1819 | gcLocked = JS_TRUE; |
1820 | |
1821 | /* Transfer thread-local counter to global one. */ |
1822 | if (localMallocBytes != 0) { |
1823 | JS_THREAD_DATA(cx)->gcMallocBytes = 0; |
1824 | if (rt->gcMaxMallocBytes - rt->gcMallocBytes < localMallocBytes) |
1825 | rt->gcMallocBytes = rt->gcMaxMallocBytes; |
1826 | else |
1827 | rt->gcMallocBytes += localMallocBytes; |
1828 | } |
1829 | #endif |
1830 | JS_ASSERT(!rt->gcRunning); |
1831 | if (rt->gcRunning) { |
1832 | METER(rt->gcStats.finalfail++); |
1833 | JS_UNLOCK_GC(rt); |
1834 | return NULL; |
1835 | } |
1836 | |
1837 | #if defined JS_GC_ZEAL && defined JS_TRACER |
1838 | if (rt->gcZeal >= 1 && JS_TRACE_MONITOR(cx).useReservedObjects) |
1839 | goto testReservedObjects; |
1840 | #endif |
1841 | |
1842 | arenaList = &rt->gcArenaList[flindex]; |
1843 | doGC = IsGCThresholdReached(rt); |
1844 | for (;;) { |
1845 | if (doGC |
1846 | #ifdef JS_TRACER |
1847 | && !JS_ON_TRACE(cx) && !JS_TRACE_MONITOR(cx).useReservedObjects |
1848 | #endif |
1849 | ) { |
1850 | /* |
1851 | * Keep rt->gcLock across the call into js_GC so we don't starve |
1852 | * and lose to racing threads who deplete the heap just after |
1853 | * js_GC has replenished it (or has synchronized with a racing |
1854 | * GC that collected a bunch of garbage). This unfair scheduling |
1855 | * can happen on certain operating systems. For the gory details, |
1856 | * see bug 162779 at https://bugzilla.mozilla.org/. |
1857 | */ |
1858 | js_GC(cx, GC_LAST_DITCH); |
1859 | METER(astats->retry++); |
1860 | } |
1861 | |
1862 | /* Try to get thing from the free list. */ |
1863 | thing = arenaList->freeList; |
1864 | if (thing) { |
1865 | arenaList->freeList = thing->next; |
1866 | flagp = thing->flagp; |
1867 | JS_ASSERT(*flagp & GCF_FINAL); |
1868 | |
1869 | #ifdef JS_THREADSAFE |
1870 | /* |
1871 | * Refill the local free list by taking several things from the |
1872 | * global free list unless the free list is already populated or |
1873 | * we are still at rt->gcMaxMallocBytes barrier. The former is |
1874 | * caused via allocating new things in gcCallback(cx, JSGC_END). |
1875 | * The latter happens when GC is canceled due to |
1876 | * gcCallback(cx, JSGC_BEGIN) returning false. |
1877 | */ |
1878 | if (freeList || rt->gcMallocBytes >= rt->gcMaxMallocBytes) |
1879 | break; |
1880 | |
1881 | tmpthing = arenaList->freeList; |
1882 | if (tmpthing) { |
1883 | maxFreeThings = MAX_THREAD_LOCAL_THINGS; |
1884 | do { |
1885 | if (!tmpthing->next) |
1886 | break; |
1887 | tmpthing = tmpthing->next; |
1888 | } while (--maxFreeThings != 0); |
1889 | |
1890 | freeList = arenaList->freeList; |
1891 | arenaList->freeList = tmpthing->next; |
1892 | tmpthing->next = NULL; |
1893 | } |
1894 | #endif |
1895 | break; |
1896 | } |
1897 | |
1898 | /* |
1899 | * Try to allocate things from the last arena. If it is fully used, |
1900 | * check if we can allocate a new one and, if we cannot, consider |
1901 | * doing a "last ditch" GC unless already tried. |
1902 | */ |
1903 | thingsLimit = THINGS_PER_ARENA(nbytes); |
1904 | if (arenaList->lastCount != thingsLimit) { |
1905 | JS_ASSERT(arenaList->lastCount < thingsLimit); |
1906 | a = arenaList->last; |
1907 | } else { |
1908 | #ifdef JS_TRACER |
1909 | if (JS_TRACE_MONITOR(cx).useReservedObjects) { |
1910 | #ifdef JS_GC_ZEAL |
1911 | testReservedObjects: |
1912 | #endif |
1913 | JSTraceMonitor *tm = &JS_TRACE_MONITOR(cx); |
1914 | |
1915 | thing = (JSGCThing *) tm->reservedObjects; |
1916 | flagp = GetGCThingFlags(thing); |
1917 | JS_ASSERT(thing); |
1918 | tm->reservedObjects = JSVAL_TO_OBJECT(tm->reservedObjects->fslots[0]); |
1919 | break; |
1920 | } |
1921 | #endif |
1922 | |
1923 | a = NewGCArena(rt); |
1924 | if (!a) { |
1925 | if (doGC || JS_ON_TRACE(cx)) |
1926 | goto fail; |
1927 | doGC = true; |
1928 | continue; |
1929 | } |
1930 | a->list = arenaList; |
1931 | a->prev = arenaList->last; |
1932 | a->prevUntracedPage = 0; |
1933 | a->u.untracedThings = 0; |
1934 | arenaList->last = a; |
1935 | arenaList->lastCount = 0; |
1936 | } |
1937 | |
1938 | flagp = THING_FLAGP(a, arenaList->lastCount); |
1939 | thing = FLAGP_TO_THING(flagp, nbytes); |
1940 | arenaList->lastCount++; |
1941 | |
1942 | #ifdef JS_THREADSAFE |
1943 | /* |
1944 | * Refill the local free list by taking free things from the last |
1945 | * arena. Prefer to order free things by ascending address in the |
1946 | * (unscientific) hope of better cache locality. |
1947 | */ |
1948 | if (freeList || rt->gcMallocBytes >= rt->gcMaxMallocBytes) |
1949 | break; |
1950 | lastptr = &freeList; |
1951 | maxFreeThings = thingsLimit - arenaList->lastCount; |
1952 | if (maxFreeThings > MAX_THREAD_LOCAL_THINGS) |
1953 | maxFreeThings = MAX_THREAD_LOCAL_THINGS; |
1954 | uint32 lastCount = arenaList->lastCount; |
1955 | while (maxFreeThings != 0) { |
1956 | --maxFreeThings; |
1957 | |
1958 | tmpflagp = THING_FLAGP(a, lastCount); |
1959 | tmpthing = FLAGP_TO_THING(tmpflagp, nbytes); |
1960 | lastCount++; |
1961 | tmpthing->flagp = tmpflagp; |
1962 | *tmpflagp = GCF_FINAL; /* signifying that thing is free */ |
1963 | |
1964 | *lastptr = tmpthing; |
1965 | lastptr = &tmpthing->next; |
1966 | } |
1967 | *lastptr = NULL; |
1968 | arenaList->lastCount = lastCount; |
1969 | #endif |
1970 | break; |
1971 | } |
1972 | |
1973 | /* We successfully allocated the thing. */ |
1974 | #ifdef JS_THREADSAFE |
1975 | success: |
1976 | #endif |
1977 | lrs = cx->localRootStack; |
1978 | if (lrs) { |
1979 | /* |
1980 | * If we're in a local root scope, don't set newborn[type] at all, to |
1981 | * avoid entraining garbage from it for an unbounded amount of time |
1982 | * on this context. A caller will leave the local root scope and pop |
1983 | * this reference, allowing thing to be GC'd if it has no other refs. |
1984 | * See JS_EnterLocalRootScope and related APIs. |
1985 | */ |
1986 | if (js_PushLocalRoot(cx, lrs, (jsval) thing) < 0) { |
1987 | /* |
1988 | * When we fail for a thing allocated through the tail of the last |
1989 | * arena, thing's flag byte is not initialized. So to prevent GC |
1990 | * accessing the uninitialized flags during the finalization, we |
1991 | * always mark the thing as final. See bug 337407. |
1992 | */ |
1993 | *flagp = GCF_FINAL; |
1994 | goto fail; |
1995 | } |
1996 | } else { |
1997 | /* |
1998 | * No local root scope, so we're stuck with the old, fragile model of |
1999 | * depending on a pigeon-hole newborn per type per context. |
2000 | */ |
2001 | cx->weakRoots.newborn[flags & GCF_TYPEMASK] = thing; |
2002 | } |
2003 | |
2004 | /* We can't fail now, so update flags. */ |
2005 | *flagp = (uint8)flags; |
2006 | |
2007 | #ifdef DEBUG_gchist |
2008 | gchist[gchpos].lastDitch = doGC; |
2009 | gchist[gchpos].freeList = rt->gcArenaList[flindex].freeList; |
2010 | if (++gchpos == NGCHIST) |
2011 | gchpos = 0; |
2012 | #endif |
2013 | |
2014 | /* This is not thread-safe for thread-local allocations. */ |
2015 | METER_IF(flags & GCF_LOCK, rt->gcStats.lockborn++); |
2016 | |
2017 | #ifdef JS_THREADSAFE |
2018 | if (gcLocked) |
2019 | JS_UNLOCK_GC(rt); |
2020 | #endif |
2021 | return (T*)thing; |
2022 | |
2023 | fail: |
2024 | #ifdef JS_THREADSAFE |
2025 | if (gcLocked) |
2026 | JS_UNLOCK_GC(rt); |
2027 | #endif |
2028 | METER(astats->fail++); |
2029 | js_ReportOutOfMemory(cx); |
2030 | return NULL; |
2031 | } |
2032 | |
2033 | extern JSObject* js_NewGCObject(JSContext *cx, uintN flags) |
2034 | { |
2035 | return NewGCThing<JSObject>(cx, flags); |
2036 | } |
2037 | |
2038 | extern JSString* js_NewGCString(JSContext *cx, uintN flags) |
2039 | { |
2040 | return NewGCThing<JSString>(cx, flags); |
2041 | } |
2042 | |
2043 | extern JSFunction* js_NewGCFunction(JSContext *cx, uintN flags) |
2044 | { |
2045 | return NewGCThing<JSFunction>(cx, flags); |
2046 | } |
2047 | |
2048 | extern JSXML* js_NewGCXML(JSContext *cx, uintN flags) |
2049 | { |
2050 | return NewGCThing<JSXML>(cx, flags); |
2051 | } |
2052 | |
2053 | static JSGCDoubleCell * |
2054 | RefillDoubleFreeList(JSContext *cx) |
2055 | { |
2056 | JSRuntime *rt; |
2057 | jsbitmap *doubleFlags, usedBits; |
2058 | JSBool didGC = JS_FALSE; |
2059 | JSGCArenaInfo *a; |
2060 | uintN bit, index; |
2061 | JSGCDoubleCell *cell, *list, *lastcell; |
2062 | |
2063 | JS_ASSERT(!cx->doubleFreeList); |
2064 | |
2065 | rt = cx->runtime; |
2066 | JS_LOCK_GC(rt); |
2067 | |
2068 | JS_ASSERT(!rt->gcRunning); |
2069 | if (rt->gcRunning) { |
2070 | METER(rt->gcStats.finalfail++); |
2071 | JS_UNLOCK_GC(rt); |
2072 | return NULL; |
2073 | } |
2074 | |
2075 | if (IsGCThresholdReached(rt)) |
2076 | goto do_gc; |
2077 | |
2078 | /* |
2079 | * Loop until we find a flag bitmap byte with unset bits indicating free |
2080 | * double cells, then set all bits as used and put the cells to the free |
2081 | * list for the current context. |
2082 | */ |
2083 | doubleFlags = rt->gcDoubleArenaList.nextDoubleFlags; |
2084 | for (;;) { |
2085 | if (((jsuword) doubleFlags & GC_ARENA_MASK) == |
2086 | ARENA_INFO_OFFSET) { |
2087 | if (doubleFlags == DOUBLE_BITMAP_SENTINEL || |
2088 | !((JSGCArenaInfo *) doubleFlags)->prev) { |
2089 | a = NewGCArena(rt); |
2090 | if (!a) { |
2091 | do_gc: |
2092 | if (didGC || JS_ON_TRACE(cx)) { |
2093 | METER(rt->gcStats.doubleArenaStats.fail++); |
2094 | JS_UNLOCK_GC(rt); |
2095 | js_ReportOutOfMemory(cx); |
2096 | return NULL; |
2097 | } |
2098 | js_GC(cx, GC_LAST_DITCH); |
2099 | METER(rt->gcStats.doubleArenaStats.retry++); |
2100 | doubleFlags = rt->gcDoubleArenaList.nextDoubleFlags; |
2101 | didGC = JS_TRUE; |
2102 | continue; |
2103 | } |
2104 | a->list = NULL; |
2105 | a->prev = NULL; |
2106 | if (doubleFlags == DOUBLE_BITMAP_SENTINEL) { |
2107 | JS_ASSERT(!rt->gcDoubleArenaList.first); |
2108 | rt->gcDoubleArenaList.first = a; |
2109 | } else { |
2110 | JS_ASSERT(rt->gcDoubleArenaList.first); |
2111 | ((JSGCArenaInfo *) doubleFlags)->prev = a; |
2112 | } |
2113 | ClearDoubleArenaFlags(a); |
2114 | doubleFlags = DOUBLE_ARENA_BITMAP(a); |
2115 | break; |
2116 | } |
2117 | doubleFlags = |
2118 | DOUBLE_ARENA_BITMAP(((JSGCArenaInfo *) doubleFlags)->prev); |
2119 | } |
2120 | |
2121 | /* |
2122 | * When doubleFlags points the last bitmap's word in the arena, its |
2123 | * high bits corresponds to non-existing cells. ClearDoubleArenaFlags |
2124 | * sets such bits to 1. Thus even for this last word its bit is unset |
2125 | * iff the corresponding cell exists and free. |
2126 | */ |
2127 | if (*doubleFlags != (jsbitmap) -1) |
2128 | break; |
2129 | ++doubleFlags; |
2130 | } |
2131 | |
2132 | rt->gcDoubleArenaList.nextDoubleFlags = doubleFlags + 1; |
2133 | usedBits = *doubleFlags; |
2134 | JS_ASSERT(usedBits != (jsbitmap) -1); |
2135 | *doubleFlags = (jsbitmap) -1; |
2136 | JS_UNLOCK_GC(rt); |
2137 | |
2138 | /* |
2139 | * Find the index corresponding to the first bit in *doubleFlags. The last |
2140 | * bit will have "index + JS_BITS_PER_WORD - 1". |
2141 | */ |
2142 | index = ((uintN) ((jsuword) doubleFlags & GC_ARENA_MASK) - |
2143 | DOUBLES_ARENA_BITMAP_OFFSET) * JS_BITS_PER_BYTE; |
2144 | cell = (JSGCDoubleCell *) ((jsuword) doubleFlags & ~GC_ARENA_MASK) + index; |
2145 | |
2146 | if (usedBits == 0) { |
2147 | /* The common case when all doubles from *doubleFlags are free. */ |
2148 | JS_ASSERT(index + JS_BITS_PER_WORD <= DOUBLES_PER_ARENA); |
2149 | list = cell; |
2150 | for (lastcell = cell + JS_BITS_PER_WORD - 1; cell != lastcell; ++cell) |
2151 | cell->link = cell + 1; |
2152 | lastcell->link = NULL; |
2153 | } else { |
2154 | /* |
2155 | * Assemble the free list from free cells from *doubleFlags starting |
2156 | * from the tail. In the loop |
2157 | * |
2158 | * index + bit >= DOUBLES_PER_ARENA |
2159 | * |
2160 | * when bit is one of the unused bits. We do not check for such bits |
2161 | * explicitly as they must be set and the "if" check filters them out. |
2162 | */ |
2163 | JS_ASSERT(index + JS_BITS_PER_WORD <= |
2164 | DOUBLES_PER_ARENA + UNUSED_DOUBLE_BITMAP_BITS); |
2165 | bit = JS_BITS_PER_WORD; |
2166 | cell += bit; |
2167 | list = NULL; |
2168 | do { |
2169 | --bit; |
2170 | --cell; |
2171 | if (!(((jsbitmap) 1 << bit) & usedBits)) { |
2172 | JS_ASSERT(index + bit < DOUBLES_PER_ARENA); |
2173 | JS_ASSERT_IF(index + bit == DOUBLES_PER_ARENA - 1, !list); |
2174 | cell->link = list; |
2175 | list = cell; |
2176 | } |
2177 | } while (bit != 0); |
2178 | } |
2179 | JS_ASSERT(list); |
2180 | |
2181 | /* |
2182 | * We delegate assigning cx->doubleFreeList to js_NewDoubleInRootedValue as |
2183 | * it immediately consumes the head of the list. |
2184 | */ |
2185 | return list; |
2186 | } |
2187 | |
2188 | JSBool |
2189 | js_NewDoubleInRootedValue(JSContext *cx, jsdouble d, jsval *vp) |
2190 | { |
2191 | #ifdef JS_GCMETER |
2192 | JSGCArenaStats *astats; |
2193 | #endif |
2194 | JSGCDoubleCell *cell; |
2195 | |
2196 | /* Updates of metering counters here are not thread-safe. */ |
2197 | METER(astats = &cx->runtime->gcStats.doubleArenaStats); |
2198 | METER(astats->alloc++); |
2199 | cell = cx->doubleFreeList; |
2200 | if (!cell) { |
2201 | cell = RefillDoubleFreeList(cx); |
2202 | if (!cell) { |
2203 | METER(astats->fail++); |
2204 | return JS_FALSE; |
2205 | } |
2206 | } else { |
2207 | METER(astats->localalloc++); |
2208 | } |
2209 | cx->doubleFreeList = cell->link; |
2210 | cell->number = d; |
2211 | *vp = DOUBLE_TO_JSVAL(&cell->number); |
2212 | return JS_TRUE; |
2213 | } |
2214 | |
2215 | jsdouble * |
2216 | js_NewWeaklyRootedDouble(JSContext *cx, jsdouble d) |
2217 | { |
2218 | jsval v; |
2219 | jsdouble *dp; |
2220 | |
2221 | if (!js_NewDoubleInRootedValue(cx, d, &v)) |
2222 | return NULL; |
2223 | |
2224 | JS_ASSERT(JSVAL_IS_DOUBLE(v)); |
2225 | dp = JSVAL_TO_DOUBLE(v); |
2226 | if (cx->localRootStack) { |
2227 | if (js_PushLocalRoot(cx, cx->localRootStack, v) < 0) |
2228 | return NULL; |
2229 | } else { |
2230 | cx->weakRoots.newborn[GCX_DOUBLE] = dp; |
2231 | } |
2232 | return dp; |
2233 | } |
2234 | |
2235 | #ifdef JS_TRACER |
2236 | JSBool |
2237 | js_ReserveObjects(JSContext *cx, size_t nobjects) |
2238 | { |
2239 | /* |
2240 | * Ensure at least nobjects objects are in the list. fslots[1] of each |
2241 | * object on the reservedObjects list is the length of the list from there. |
2242 | */ |
2243 | JSObject *&head = JS_TRACE_MONITOR(cx).reservedObjects; |
2244 | size_t i = head ? JSVAL_TO_INT(head->fslots[1]) : 0; |
2245 | while (i < nobjects) { |
2246 | JSObject *obj = js_NewGCObject(cx, GCX_OBJECT); |
2247 | if (!obj) |
2248 | return JS_FALSE; |
2249 | memset(obj, 0, sizeof(JSObject)); |
2250 | /* The class must be set to something for finalization. */ |
2251 | obj->classword = (jsuword) &js_ObjectClass; |
2252 | obj->fslots[0] = OBJECT_TO_JSVAL(head); |
2253 | i++; |
2254 | obj->fslots[1] = INT_TO_JSVAL(i); |
2255 | head = obj; |
2256 | } |
2257 | |
2258 | return JS_TRUE; |
2259 | } |
2260 | #endif |
2261 | |
2262 | /* |
2263 | * Shallow GC-things can be locked just by setting the GCF_LOCK bit, because |
2264 | * they have no descendants to mark during the GC. Currently the optimization |
2265 | * is only used for non-dependant strings. |
2266 | */ |
2267 | #define GC_THING_IS_SHALLOW(flagp, thing) \ |
2268 | ((flagp) && \ |
2269 | ((*(flagp) & GCF_TYPEMASK) >= GCX_EXTERNAL_STRING || \ |
2270 | ((*(flagp) & GCF_TYPEMASK) == GCX_STRING && \ |
2271 | !((JSString *) (thing))->isDependent()))) |
2272 | |
2273 | /* This is compatible with JSDHashEntryStub. */ |
2274 | typedef struct JSGCLockHashEntry { |
2275 | JSDHashEntryHdr hdr; |
2276 | const void *thing; |
2277 | uint32 count; |
2278 | } JSGCLockHashEntry; |
2279 | |
2280 | JSBool |
2281 | js_LockGCThingRT(JSRuntime *rt, void *thing) |
2282 | { |
2283 | JSBool shallow, ok; |
2284 | uint8 *flagp; |
2285 | JSGCLockHashEntry *lhe; |
2286 | |
2287 | if (!thing) |
2288 | return JS_TRUE; |
2289 | |
2290 | flagp = GetGCThingFlagsOrNull(thing); |
2291 | JS_LOCK_GC(rt); |
2292 | shallow = GC_THING_IS_SHALLOW(flagp, thing); |
2293 | |
2294 | /* |
2295 | * Avoid adding a rt->gcLocksHash entry for shallow things until someone |
2296 | * nests a lock. |
2297 | */ |
2298 | if (shallow && !(*flagp & GCF_LOCK)) { |
2299 | *flagp |= GCF_LOCK; |
2300 | METER(rt->gcStats.lock++); |
2301 | ok = JS_TRUE; |
2302 | goto out; |
2303 | } |
2304 | |
2305 | if (!rt->gcLocksHash) { |
2306 | rt->gcLocksHash = JS_NewDHashTable(JS_DHashGetStubOps(), NULL, |
2307 | sizeof(JSGCLockHashEntry), |
2308 | GC_ROOTS_SIZE); |
2309 | if (!rt->gcLocksHash) { |
2310 | ok = JS_FALSE; |
2311 | goto out; |
2312 | } |
2313 | } |
2314 | |
2315 | lhe = (JSGCLockHashEntry *) |
2316 | JS_DHashTableOperate(rt->gcLocksHash, thing, JS_DHASH_ADD); |
2317 | if (!lhe) { |
2318 | ok = JS_FALSE; |
2319 | goto out; |
2320 | } |
2321 | if (!lhe->thing) { |
2322 | lhe->thing = thing; |
2323 | lhe->count = 1; |
2324 | } else { |
2325 | JS_ASSERT(lhe->count >= 1); |
2326 | lhe->count++; |
2327 | } |
2328 | |
2329 | METER(rt->gcStats.lock++); |
2330 | ok = JS_TRUE; |
2331 | out: |
2332 | JS_UNLOCK_GC(rt); |
2333 | return ok; |
2334 | } |
2335 | |
2336 | JSBool |
2337 | js_UnlockGCThingRT(JSRuntime *rt, void *thing) |
2338 | { |
2339 | uint8 *flagp; |
2340 | JSBool shallow; |
2341 | JSGCLockHashEntry *lhe; |
2342 | |
2343 | if (!thing) |
2344 | return JS_TRUE; |
2345 | |
2346 | flagp = GetGCThingFlagsOrNull(thing); |
2347 | JS_LOCK_GC(rt); |
2348 | shallow = GC_THING_IS_SHALLOW(flagp, thing); |
2349 | |
2350 | if (shallow && !(*flagp & GCF_LOCK)) |
2351 | goto out; |
2352 | if (!rt->gcLocksHash || |
2353 | (lhe = (JSGCLockHashEntry *) |
2354 | JS_DHashTableOperate(rt->gcLocksHash, thing, |
2355 | JS_DHASH_LOOKUP), |
2356 | JS_DHASH_ENTRY_IS_FREE(&lhe->hdr))) { |
2357 | /* Shallow entry is not in the hash -> clear its lock bit. */ |
2358 | if (shallow) |
2359 | *flagp &= ~GCF_LOCK; |
2360 | else |
2361 | goto out; |
2362 | } else { |
2363 | if (--lhe->count != 0) |
2364 | goto out; |
2365 | JS_DHashTableOperate(rt->gcLocksHash, thing, JS_DHASH_REMOVE); |
2366 | } |
2367 | |
2368 | rt->gcPoke = JS_TRUE; |
2369 | METER(rt->gcStats.unlock++); |
2370 | out: |
2371 | JS_UNLOCK_GC(rt); |
2372 | return JS_TRUE; |
2373 | } |
2374 | |
2375 | JS_PUBLIC_API(void) |
2376 | JS_TraceChildren(JSTracer *trc, void *thing, uint32 kind) |
2377 | { |
2378 | switch (kind) { |
2379 | case JSTRACE_OBJECT: { |
2380 | /* If obj has no map, it must be a newborn. */ |
2381 | JSObject *obj = (JSObject *) thing; |
2382 | if (!obj->map) |
2383 | break; |
2384 | obj->map->ops->trace(trc, obj); |
2385 | break; |
2386 | } |
2387 | |
2388 | case JSTRACE_STRING: { |
2389 | JSString *str = (JSString *) thing; |
2390 | if (str->isDependent()) |
2391 | JS_CALL_STRING_TRACER(trc, str->dependentBase(), "base"); |
2392 | break; |
2393 | } |
2394 | |
2395 | #if JS_HAS_XML_SUPPORT |
2396 | case JSTRACE_XML: |
2397 | js_TraceXML(trc, (JSXML *)thing); |
2398 | break; |
2399 | #endif |
2400 | } |
2401 | } |
2402 | |
2403 | /* |
2404 | * Number of things covered by a single bit of JSGCArenaInfo.u.untracedThings. |
2405 | */ |
2406 | #define THINGS_PER_UNTRACED_BIT(thingSize) \ |
2407 | JS_HOWMANY(THINGS_PER_ARENA(thingSize), JS_BITS_PER_WORD) |
2408 | |
2409 | static void |
2410 | DelayTracingChildren(JSRuntime *rt, uint8 *flagp) |
2411 | { |
2412 | JSGCArenaInfo *a; |
2413 | uint32 untracedBitIndex; |
2414 | jsuword bit; |
2415 | |
2416 | /* |
2417 | * Things with children to be traced later are marked with |
2418 | * GCF_MARK | GCF_FINAL flags. |
2419 | */ |
2420 | JS_ASSERT((*flagp & (GCF_MARK | GCF_FINAL)) == GCF_MARK); |
2421 | *flagp |= GCF_FINAL; |
2422 | |
2423 | METER(rt->gcStats.untraced++); |
2424 | #ifdef DEBUG |
2425 | ++rt->gcTraceLaterCount; |
2426 | METER_UPDATE_MAX(rt->gcStats.maxuntraced, rt->gcTraceLaterCount); |
2427 | #endif |
2428 | |
2429 | a = FLAGP_TO_ARENA(flagp); |
2430 | untracedBitIndex = FLAGP_TO_INDEX(flagp) / |
2431 | THINGS_PER_UNTRACED_BIT(a->list->thingSize); |
2432 | JS_ASSERT(untracedBitIndex < JS_BITS_PER_WORD); |
2433 | bit = (jsuword)1 << untracedBitIndex; |
2434 | if (a->u.untracedThings != 0) { |
2435 | JS_ASSERT(rt->gcUntracedArenaStackTop); |
2436 | if (a->u.untracedThings & bit) { |
2437 | /* bit already covers things with children to trace later. */ |
2438 | return; |
2439 | } |
2440 | a->u.untracedThings |= bit; |
2441 | } else { |
2442 | /* |
2443 | * The thing is the first thing with not yet traced children in the |
2444 | * whole arena, so push the arena on the stack of arenas with things |
2445 | * to be traced later unless the arena has already been pushed. We |
2446 | * detect that through checking prevUntracedPage as the field is 0 |
2447 | * only for not yet pushed arenas. To ensure that |
2448 | * prevUntracedPage != 0 |
2449 | * even when the stack contains one element, we make prevUntracedPage |
2450 | * for the arena at the bottom to point to itself. |
2451 | * |
2452 | * See comments in TraceDelayedChildren. |
2453 | */ |
2454 | a->u.untracedThings = bit; |
2455 | if (a->prevUntracedPage == 0) { |
2456 | if (!rt->gcUntracedArenaStackTop) { |
2457 | /* Stack was empty, mark the arena as the bottom element. */ |
2458 | a->prevUntracedPage = ARENA_INFO_TO_PAGE(a); |
2459 | } else { |
2460 | JS_ASSERT(rt->gcUntracedArenaStackTop->prevUntracedPage != 0); |
2461 | a->prevUntracedPage = |
2462 | ARENA_INFO_TO_PAGE(rt->gcUntracedArenaStackTop); |
2463 | } |
2464 | rt->gcUntracedArenaStackTop = a; |
2465 | } |
2466 | } |
2467 | JS_ASSERT(rt->gcUntracedArenaStackTop); |
2468 | } |
2469 | |
2470 | static void |
2471 | TraceDelayedChildren(JSTracer *trc) |
2472 | { |
2473 | JSRuntime *rt; |
2474 | JSGCArenaInfo *a, *aprev; |
2475 | uint32 thingSize; |
2476 | uint32 thingsPerUntracedBit; |
2477 | uint32 untracedBitIndex, thingIndex, indexLimit, endIndex; |
2478 | JSGCThing *thing; |
2479 | uint8 *flagp; |
2480 | |
2481 | rt = trc->context->runtime; |
2482 | a = rt->gcUntracedArenaStackTop; |
2483 | if (!a) { |
2484 | JS_ASSERT(rt->gcTraceLaterCount == 0); |
2485 | return; |
2486 | } |
2487 | |
2488 | for (;;) { |
2489 | /* |
2490 | * The following assert verifies that the current arena belongs to the |
2491 | * untraced stack, since DelayTracingChildren ensures that even for |
2492 | * stack's bottom prevUntracedPage != 0 but rather points to itself. |
2493 | */ |
2494 | JS_ASSERT(a->prevUntracedPage != 0); |
2495 | JS_ASSERT(rt->gcUntracedArenaStackTop->prevUntracedPage != 0); |
2496 | thingSize = a->list->thingSize; |
2497 | indexLimit = (a == a->list->last) |
2498 | ? a->list->lastCount |
2499 | : THINGS_PER_ARENA(thingSize); |
2500 | thingsPerUntracedBit = THINGS_PER_UNTRACED_BIT(thingSize); |
2501 | |
2502 | /* |
2503 | * We cannot use do-while loop here as a->u.untracedThings can be zero |
2504 | * before the loop as a leftover from the previous iterations. See |
2505 | * comments after the loop. |
2506 | */ |
2507 | while (a->u.untracedThings != 0) { |
2508 | untracedBitIndex = JS_FLOOR_LOG2W(a->u.untracedThings); |
2509 | a->u.untracedThings &= ~((jsuword)1 << untracedBitIndex); |
2510 | thingIndex = untracedBitIndex * thingsPerUntracedBit; |
2511 | endIndex = thingIndex + thingsPerUntracedBit; |
2512 | |
2513 | /* |
2514 | * endIndex can go beyond the last allocated thing as the real |
2515 | * limit can be "inside" the bit. |
2516 | */ |
2517 | if (endIndex > indexLimit) |
2518 | endIndex = indexLimit; |
2519 | JS_ASSERT(thingIndex < indexLimit); |
2520 | |
2521 | do { |
2522 | /* |
2523 | * Skip free or already traced things that share the bit |
2524 | * with untraced ones. |
2525 | */ |
2526 | flagp = THING_FLAGP(a, thingIndex); |
2527 | if ((*flagp & (GCF_MARK|GCF_FINAL)) != (GCF_MARK|GCF_FINAL)) |
2528 | continue; |
2529 | *flagp &= ~GCF_FINAL; |
2530 | #ifdef DEBUG |
2531 | JS_ASSERT(rt->gcTraceLaterCount != 0); |
2532 | --rt->gcTraceLaterCount; |
2533 | #endif |
2534 | thing = FLAGP_TO_THING(flagp, thingSize); |
2535 | JS_TraceChildren(trc, thing, MapGCFlagsToTraceKind(*flagp)); |
2536 | } while (++thingIndex != endIndex); |
2537 | } |
2538 | |
2539 | /* |
2540 | * We finished tracing of all things in the the arena but we can only |
2541 | * pop it from the stack if the arena is the stack's top. |
2542 | * |
2543 | * When JS_TraceChildren from the above calls JS_CallTracer that in |
2544 | * turn on low C stack calls DelayTracingChildren and the latter |
2545 | * pushes new arenas to the untraced stack, we have to skip popping |
2546 | * of this arena until it becomes the top of the stack again. |
2547 | */ |
2548 | if (a == rt->gcUntracedArenaStackTop) { |
2549 | aprev = ARENA_PAGE_TO_INFO(a->prevUntracedPage); |
2550 | a->prevUntracedPage = 0; |
2551 | if (a == aprev) { |
2552 | /* |
2553 | * prevUntracedPage points to itself and we reached the |
2554 | * bottom of the stack. |
2555 | */ |
2556 | break; |
2557 | } |
2558 | rt->gcUntracedArenaStackTop = a = aprev; |
2559 | } else { |
2560 | a = rt->gcUntracedArenaStackTop; |
2561 | } |
2562 | } |
2563 | JS_ASSERT(rt->gcUntracedArenaStackTop); |
2564 | JS_ASSERT(rt->gcUntracedArenaStackTop->prevUntracedPage == 0); |
2565 | rt->gcUntracedArenaStackTop = NULL; |
2566 | JS_ASSERT(rt->gcTraceLaterCount == 0); |
2567 | } |
2568 | |
2569 | JS_PUBLIC_API(void) |
2570 | JS_CallTracer(JSTracer *trc, void *thing, uint32 kind) |
2571 | { |
2572 | JSContext *cx; |
2573 | JSRuntime *rt; |
2574 | JSGCArenaInfo *a; |
2575 | uintN index; |
2576 | uint8 *flagp; |
2577 | |
2578 | JS_ASSERT(thing); |
2579 | JS_ASSERT(JS_IS_VALID_TRACE_KIND(kind)); |
2580 | JS_ASSERT(trc->debugPrinter || trc->debugPrintArg); |
2581 | |
2582 | if (!IS_GC_MARKING_TRACER(trc)) { |
2583 | trc->callback(trc, thing, kind); |
2584 | goto out; |
2585 | } |
2586 | |
2587 | cx = trc->context; |
2588 | rt = cx->runtime; |
2589 | JS_ASSERT(rt->gcMarkingTracer == trc); |
2590 | JS_ASSERT(rt->gcLevel > 0); |
2591 | |
2592 | /* |
2593 | * Optimize for string and double as their size is known and their tracing |
2594 | * is not recursive. |
2595 | */ |
2596 | switch (kind) { |
2597 | case JSTRACE_DOUBLE: |
2598 | a = THING_TO_ARENA(thing); |
2599 | JS_ASSERT(!a->list); |
2600 | if (!a->u.hasMarkedDoubles) { |
2601 | ClearDoubleArenaFlags(a); |
2602 | a->u.hasMarkedDoubles = JS_TRUE; |
2603 | } |
2604 | index = DOUBLE_THING_TO_INDEX(thing); |
2605 | JS_SET_BIT(DOUBLE_ARENA_BITMAP(a), index); |
2606 | goto out; |
2607 | |
2608 | case JSTRACE_STRING: |
2609 | for (;;) { |
2610 | if (JSString::isStatic(thing)) |
2611 | goto out; |
2612 | flagp = THING_TO_FLAGP(thing, sizeof(JSGCThing)); |
2613 | JS_ASSERT((*flagp & GCF_FINAL) == 0); |
2614 | JS_ASSERT(kind == MapGCFlagsToTraceKind(*flagp)); |
2615 | if (!((JSString *) thing)->isDependent()) { |
2616 | *flagp |= GCF_MARK; |
2617 | goto out; |
2618 | } |
2619 | if (*flagp & GCF_MARK) |
2620 | goto out; |
2621 | *flagp |= GCF_MARK; |
2622 | thing = ((JSString *) thing)->dependentBase(); |
2623 | } |
2624 | /* NOTREACHED */ |
2625 | } |
2626 | |
2627 | flagp = GetGCThingFlags(thing); |
2628 | JS_ASSERT(kind == MapGCFlagsToTraceKind(*flagp)); |
2629 | if (*flagp & GCF_MARK) |
2630 | goto out; |
2631 | |
2632 | /* |
2633 | * We check for non-final flag only if mark is unset as |
2634 | * DelayTracingChildren uses the flag. See comments in the function. |
2635 | */ |
2636 | JS_ASSERT(*flagp != GCF_FINAL); |
2637 | *flagp |= GCF_MARK; |
2638 | if (!cx->insideGCMarkCallback) { |
2639 | /* |
2640 | * With JS_GC_ASSUME_LOW_C_STACK defined the mark phase of GC always |
2641 | * uses the non-recursive code that otherwise would be called only on |
2642 | * a low C stack condition. |
2643 | */ |
2644 | #ifdef JS_GC_ASSUME_LOW_C_STACK |
2645 | # define RECURSION_TOO_DEEP() JS_TRUE |
2646 | #else |
2647 | int stackDummy; |
2648 | # define RECURSION_TOO_DEEP() (!JS_CHECK_STACK_SIZE(cx, stackDummy)) |
2649 | #endif |
2650 | if (RECURSION_TOO_DEEP()) |
2651 | DelayTracingChildren(rt, flagp); |
2652 | else |
2653 | JS_TraceChildren(trc, thing, kind); |
2654 | } else { |
2655 | /* |
2656 | * For API compatibility we allow for the callback to assume that |
2657 | * after it calls JS_MarkGCThing for the last time, the callback can |
2658 | * start to finalize its own objects that are only referenced by |
2659 | * unmarked GC things. |
2660 | * |
2661 | * Since we do not know which call from inside the callback is the |
2662 | * last, we ensure that children of all marked things are traced and |
2663 | * call TraceDelayedChildren(trc) after tracing the thing. |
2664 | * |
2665 | * As TraceDelayedChildren unconditionally invokes JS_TraceChildren |
2666 | * for the things with untraced children, calling DelayTracingChildren |
2667 | * is useless here. Hence we always trace thing's children even with a |
2668 | * low native stack. |
2669 | */ |
2670 | cx->insideGCMarkCallback = JS_FALSE; |
2671 | JS_TraceChildren(trc, thing, kind); |
2672 | TraceDelayedChildren(trc); |
2673 | cx->insideGCMarkCallback = JS_TRUE; |
2674 | } |
2675 | |
2676 | out: |
2677 | #ifdef DEBUG |
2678 | trc->debugPrinter = NULL; |
2679 | trc->debugPrintArg = NULL; |
2680 | #endif |
2681 | return; /* to avoid out: right_curl when DEBUG is not defined */ |
2682 | } |
2683 | |
2684 | void |
2685 | js_CallValueTracerIfGCThing(JSTracer *trc, jsval v) |
2686 | { |
2687 | void *thing; |
2688 | uint32 kind; |
2689 | |
2690 | if (JSVAL_IS_DOUBLE(v) || JSVAL_IS_STRING(v)) { |
2691 | thing = JSVAL_TO_TRACEABLE(v); |
2692 | kind = JSVAL_TRACE_KIND(v); |
2693 | JS_ASSERT(kind == js_GetGCThingTraceKind(JSVAL_TO_GCTHING(v))); |
2694 | } else if (JSVAL_IS_OBJECT(v) && v != JSVAL_NULL) { |
2695 | /* v can be an arbitrary GC thing reinterpreted as an object. */ |
2696 | thing = JSVAL_TO_OBJECT(v); |
2697 | kind = js_GetGCThingTraceKind(thing); |
2698 | } else { |
2699 | return; |
2700 | } |
2701 | JS_CallTracer(trc, thing, kind); |
2702 | } |
2703 | |
2704 | static JSDHashOperator |
2705 | gc_root_traversal(JSDHashTable *table, JSDHashEntryHdr *hdr, uint32 num, |
2706 | void *arg) |
2707 | { |
2708 | JSGCRootHashEntry *rhe = (JSGCRootHashEntry *)hdr; |
2709 | JSTracer *trc = (JSTracer *)arg; |
2710 | jsval *rp = (jsval *)rhe->root; |
2711 | jsval v = *rp; |
2712 | |
2713 | /* Ignore null reference, scalar values, and static strings. */ |
2714 | if (!JSVAL_IS_NULL(v) && |
2715 | JSVAL_IS_GCTHING(v) && |
2716 | !JSString::isStatic(JSVAL_TO_GCTHING(v))) { |
2717 | #ifdef DEBUG |
2718 | JSBool root_points_to_gcArenaList = JS_FALSE; |
2719 | jsuword thing = (jsuword) JSVAL_TO_GCTHING(v); |
2720 | JSRuntime *rt; |
2721 | uintN i; |
2722 | JSGCArenaList *arenaList; |
2723 | uint32 thingSize; |
2724 | JSGCArenaInfo *a; |
2725 | size_t limit; |
2726 | |
2727 | rt = trc->context->runtime; |
2728 | for (i = 0; i < GC_NUM_FREELISTS; i++) { |
2729 | arenaList = &rt->gcArenaList[i]; |
2730 | thingSize = arenaList->thingSize; |
2731 | limit = (size_t) arenaList->lastCount * thingSize; |
2732 | for (a = arenaList->last; a; a = a->prev) { |
2733 | if (thing - ARENA_INFO_TO_START(a) < limit) { |
2734 | root_points_to_gcArenaList = JS_TRUE; |
2735 | break; |
2736 | } |
2737 | limit = (size_t) THINGS_PER_ARENA(thingSize) * thingSize; |
2738 | } |
2739 | } |
2740 | if (!root_points_to_gcArenaList) { |
2741 | for (a = rt->gcDoubleArenaList.first; a; a = a->prev) { |
2742 | if (thing - ARENA_INFO_TO_START(a) < |
2743 | DOUBLES_PER_ARENA * sizeof(jsdouble)) { |
2744 | root_points_to_gcArenaList = JS_TRUE; |
2745 | break; |
2746 | } |
2747 | } |
2748 | } |
2749 | if (!root_points_to_gcArenaList && rhe->name) { |
2750 | fprintf(stderr, |
2751 | "JS API usage error: the address passed to JS_AddNamedRoot currently holds an\n" |
2752 | "invalid jsval. This is usually caused by a missing call to JS_RemoveRoot.\n" |
2753 | "The root's name is \"%s\".\n", |
2754 | rhe->name); |
2755 | } |
2756 | JS_ASSERT(root_points_to_gcArenaList); |
2757 | #endif |
2758 | JS_SET_TRACING_NAME(trc, rhe->name ? rhe->name : "root"); |
2759 | js_CallValueTracerIfGCThing(trc, v); |
2760 | } |
2761 | |
2762 | return JS_DHASH_NEXT; |
2763 | } |
2764 | |
2765 | static JSDHashOperator |
2766 | gc_lock_traversal(JSDHashTable *table, JSDHashEntryHdr *hdr, uint32 num, |
2767 | void *arg) |
2768 | { |
2769 | JSGCLockHashEntry *lhe = (JSGCLockHashEntry *)hdr; |
2770 | void *thing = (void *)lhe->thing; |
2771 | JSTracer *trc = (JSTracer *)arg; |
2772 | uint32 traceKind; |
2773 | |
2774 | JS_ASSERT(lhe->count >= 1); |
2775 | traceKind = js_GetGCThingTraceKind(thing); |
2776 | JS_CALL_TRACER(trc, thing, traceKind, "locked object"); |
2777 | return JS_DHASH_NEXT; |
2778 | } |
2779 | |
2780 | #define TRACE_JSVALS(trc, len, vec, name) \ |
2781 | JS_BEGIN_MACRO \ |
2782 | jsval _v, *_vp, *_end; \ |
2783 | \ |
2784 | for (_vp = vec, _end = _vp + len; _vp < _end; _vp++) { \ |
2785 | _v = *_vp; \ |
2786 | if (JSVAL_IS_TRACEABLE(_v)) { \ |
2787 | JS_SET_TRACING_INDEX(trc, name, _vp - (vec)); \ |
2788 | JS_CallTracer(trc, JSVAL_TO_TRACEABLE(_v), \ |
2789 | JSVAL_TRACE_KIND(_v)); \ |
2790 | } \ |
2791 | } \ |
2792 | JS_END_MACRO |
2793 | |
2794 | void |
2795 | js_TraceStackFrame(JSTracer *trc, JSStackFrame *fp) |
2796 | { |
2797 | uintN nslots, minargs, skip; |
2798 | |
2799 | if (fp->callobj) |
2800 | JS_CALL_OBJECT_TRACER(trc, fp->callobj, "call"); |
2801 | if (fp->argsobj) |
2802 | JS_CALL_OBJECT_TRACER(trc, JSVAL_TO_OBJECT(fp->argsobj), "arguments"); |
2803 | if (fp->varobj) |
2804 | JS_CALL_OBJECT_TRACER(trc, fp->varobj, "variables"); |
2805 | if (fp->script) { |
2806 | js_TraceScript(trc, fp->script); |
2807 | |
2808 | /* fp->slots is null for watch pseudo-frames, see js_watch_set. */ |
2809 | if (fp->slots) { |
2810 | /* |
2811 | * Don't mark what has not been pushed yet, or what has been |
2812 | * popped already. |
2813 | */ |
2814 | if (fp->regs && fp->regs->sp) { |
2815 | nslots = (uintN) (fp->regs->sp - fp->slots); |
2816 | JS_ASSERT(nslots >= fp->script->nfixed); |
2817 | } else { |
2818 | nslots = fp->script->nfixed; |
2819 | } |
2820 | TRACE_JSVALS(trc, nslots, fp->slots, "slot"); |
2821 | } |
2822 | } else { |
2823 | JS_ASSERT(!fp->slots); |
2824 | JS_ASSERT(!fp->regs); |
2825 | } |
2826 | |
2827 | /* Allow for primitive this parameter due to JSFUN_THISP_* flags. */ |
2828 | JS_ASSERT(JSVAL_IS_OBJECT((jsval)fp->thisp) || |
2829 | (fp->fun && JSFUN_THISP_FLAGS(fp->fun->flags))); |
2830 | JS_CALL_VALUE_TRACER(trc, (jsval)fp->thisp, "this"); |
2831 | |
2832 | if (fp->argv) { |
2833 | JS_CALL_VALUE_TRACER(trc, fp->argv[-2], "callee"); |
2834 | nslots = fp->argc; |
2835 | skip = 0; |
2836 | if (fp->fun) { |
2837 | minargs = FUN_MINARGS(fp->fun); |
2838 | if (minargs > nslots) |
2839 | nslots = minargs; |
2840 | if (!FUN_INTERPRETED(fp->fun)) { |
2841 | JS_ASSERT(!(fp->fun->flags & JSFUN_FAST_NATIVE)); |
2842 | nslots += fp->fun->u.n.extra; |
2843 | } |
2844 | if (fp->fun->flags & JSFRAME_ROOTED_ARGV) |
2845 | skip = 2 + fp->argc; |
2846 | } |
2847 | TRACE_JSVALS(trc, 2 + nslots - skip, fp->argv - 2 + skip, "operand"); |
2848 | } |
2849 | |
2850 | JS_CALL_VALUE_TRACER(trc, fp->rval, "rval"); |
2851 | if (fp->scopeChain) |
2852 | JS_CALL_OBJECT_TRACER(trc, fp->scopeChain, "scope chain"); |
2853 | if (fp->sharpArray) |
2854 | JS_CALL_OBJECT_TRACER(trc, fp->sharpArray, "sharp array"); |
2855 | } |
2856 | |
2857 | static void |
2858 | TraceWeakRoots(JSTracer *trc, JSWeakRoots *wr) |
2859 | { |
2860 | uint32 i; |
2861 | void *thing; |
2862 | |
2863 | #ifdef DEBUG |
2864 | static const char *weakRootNames[JSTRACE_LIMIT] = { |
2865 | "newborn object", |
2866 | "newborn double", |
2867 | "newborn string", |
2868 | "newborn xml" |
2869 | }; |
2870 | #endif |
2871 | |
2872 | for (i = 0; i != JSTRACE_LIMIT; i++) { |
2873 | thing = wr->newborn[i]; |
2874 | if (thing) |
2875 | JS_CALL_TRACER(trc, thing, i, weakRootNames[i]); |
2876 | } |
2877 | JS_ASSERT(i == GCX_EXTERNAL_STRING); |
2878 | for (; i != GCX_NTYPES; ++i) { |
2879 | thing = wr->newborn[i]; |
2880 | if (thing) { |
2881 | JS_SET_TRACING_INDEX(trc, "newborn external string", |
2882 | i - GCX_EXTERNAL_STRING); |
2883 | JS_CallTracer(trc, thing, JSTRACE_STRING); |
2884 | } |
2885 | } |
2886 | |
2887 | JS_CALL_VALUE_TRACER(trc, wr->lastAtom, "lastAtom"); |
2888 | JS_SET_TRACING_NAME(trc, "lastInternalResult"); |
2889 | js_CallValueTracerIfGCThing(trc, wr->lastInternalResult); |
2890 | } |
2891 | |
2892 | JS_REQUIRES_STACK JS_FRIEND_API(void) |
2893 | js_TraceContext(JSTracer *trc, JSContext *acx) |
2894 | { |
2895 | JSStackFrame *fp, *nextChain; |
2896 | JSStackHeader *sh; |
2897 | JSTempValueRooter *tvr; |
2898 | |
2899 | if (IS_GC_MARKING_TRACER(trc)) { |
2900 | |
2901 | #define FREE_OLD_ARENAS(pool) \ |
2902 | JS_BEGIN_MACRO \ |
2903 | int64 _age; \ |
2904 | JSArena * _a = (pool).current; \ |
2905 | if (_a == (pool).first.next && \ |
2906 | _a->avail == _a->base + sizeof(int64)) { \ |
2907 | _age = JS_Now() - *(int64 *) _a->base; \ |
2908 | if (_age > (int64) acx->runtime->gcEmptyArenaPoolLifespan * \ |
2909 | 1000) \ |
2910 | JS_FreeArenaPool(&(pool)); \ |
2911 | } \ |
2912 | JS_END_MACRO |
2913 | |
2914 | /* |
2915 | * Release the stackPool's arenas if the stackPool has existed for |
2916 | * longer than the limit specified by gcEmptyArenaPoolLifespan. |
2917 | */ |
2918 | FREE_OLD_ARENAS(acx->stackPool); |
2919 | |
2920 | /* |
2921 | * Release the regexpPool's arenas based on the same criterion as for |
2922 | * the stackPool. |
2923 | */ |
2924 | FREE_OLD_ARENAS(acx->regexpPool); |
2925 | |
2926 | /* |
2927 | * Clear the double free list to release all the pre-allocated doubles. |
2928 | */ |
2929 | acx->doubleFreeList = NULL; |
2930 | } |
2931 | |
2932 | /* |
2933 | * Iterate frame chain and dormant chains. |
2934 | * |
2935 | * (NB: see comment on this whole "dormant" thing in js_Execute.) |
2936 | * |
2937 | * Since js_GetTopStackFrame needs to dereference cx->thread to check for |
2938 | * JIT frames, we check for non-null thread here and avoid null checks |
2939 | * there. See bug 471197. |
2940 | */ |
2941 | #ifdef JS_THREADSAFE |
2942 | if (acx->thread) |
2943 | #endif |
2944 | { |
2945 | fp = js_GetTopStackFrame(acx); |
2946 | nextChain = acx->dormantFrameChain; |
2947 | if (!fp) |
2948 | goto next_chain; |
2949 | |
2950 | /* The top frame must not be dormant. */ |
2951 | JS_ASSERT(!fp->dormantNext); |
2952 | for (;;) { |
2953 | do { |
2954 | js_TraceStackFrame(trc, fp); |
2955 | } while ((fp = fp->down) != NULL); |
2956 | |
2957 | next_chain: |
2958 | if (!nextChain) |
2959 | break; |
2960 | fp = nextChain; |
2961 | nextChain = nextChain->dormantNext; |
2962 | } |
2963 | } |
2964 | |
2965 | /* Mark other roots-by-definition in acx. */ |
2966 | if (acx->globalObject && !JS_HAS_OPTION(acx, JSOPTION_UNROOTED_GLOBAL)) |
2967 | JS_CALL_OBJECT_TRACER(trc, acx->globalObject, "global object"); |
2968 | TraceWeakRoots(trc, &acx->weakRoots); |
2969 | if (acx->throwing) { |
2970 | JS_CALL_VALUE_TRACER(trc, acx->exception, "exception"); |
2971 | } else { |
2972 | /* Avoid keeping GC-ed junk stored in JSContext.exception. */ |
2973 | acx->exception = JSVAL_NULL; |
2974 | } |
2975 | #if JS_HAS_LVALUE_RETURN |
2976 | if (acx->rval2set) |
2977 | JS_CALL_VALUE_TRACER(trc, acx->rval2, "rval2"); |
2978 | #endif |
2979 | |
2980 | for (sh = acx->stackHeaders; sh; sh = sh->down) { |
2981 | METER(trc->context->runtime->gcStats.stackseg++); |
2982 | METER(trc->context->runtime->gcStats.segslots += sh->nslots); |
2983 | TRACE_JSVALS(trc, sh->nslots, JS_STACK_SEGMENT(sh), "stack"); |
2984 | } |
2985 | |
2986 | if (acx->localRootStack) |
2987 | js_TraceLocalRoots(trc, acx->localRootStack); |
2988 | |
2989 | for (tvr = acx->tempValueRooters; tvr; tvr = tvr->down) { |
2990 | switch (tvr->count) { |
2991 | case JSTVU_SINGLE: |
2992 | JS_SET_TRACING_NAME(trc, "tvr->u.value"); |
2993 | js_CallValueTracerIfGCThing(trc, tvr->u.value); |
2994 | break; |
2995 | case JSTVU_TRACE: |
2996 | tvr->u.trace(trc, tvr); |
2997 | break; |
2998 | case JSTVU_SPROP: |
2999 | tvr->u.sprop->trace(trc); |
3000 | break; |
3001 | case JSTVU_WEAK_ROOTS: |
3002 | TraceWeakRoots(trc, tvr->u.weakRoots); |
3003 | break; |
3004 | case JSTVU_COMPILER: |
3005 | tvr->u.compiler->trace(trc); |
3006 | break; |
3007 | case JSTVU_SCRIPT: |
3008 | js_TraceScript(trc, tvr->u.script); |
3009 | break; |
3010 | case JSTVU_ENUMERATOR: |
3011 | static_cast<JSAutoEnumStateRooter *>(tvr)->mark(trc); |
3012 | break; |
3013 | default: |
3014 | JS_ASSERT(tvr->count >= 0); |
3015 | TRACE_JSVALS(trc, tvr->count, tvr->u.array, "tvr->u.array"); |
3016 | } |
3017 | } |
3018 | |
3019 | if (acx->sharpObjectMap.depth > 0) |
3020 | js_TraceSharpMap(trc, &acx->sharpObjectMap); |
3021 | |
3022 | js_TraceRegExpStatics(trc, acx); |
3023 | |
3024 | #ifdef JS_TRACER |
3025 | InterpState* state = acx->interpState; |
3026 | while (state) { |
3027 | if (state->nativeVp) |
3028 | TRACE_JSVALS(trc, state->nativeVpLen, state->nativeVp, "nativeVp"); |
3029 | state = state->prev; |
3030 | } |
3031 | #endif |
3032 | } |
3033 | |
3034 | #ifdef JS_TRACER |
3035 | |
3036 | static void |
3037 | MarkReservedGCThings(JSTraceMonitor *tm) |
3038 | { |
3039 | /* Keep reserved doubles. */ |
3040 | for (jsval *ptr = tm->reservedDoublePool; ptr < tm->reservedDoublePoolPtr; ++ptr) { |
3041 | jsdouble* dp = JSVAL_TO_DOUBLE(*ptr); |
3042 | JS_ASSERT(js_GetGCThingTraceKind(dp) == JSTRACE_DOUBLE); |
3043 | |
3044 | JSGCArenaInfo *a = THING_TO_ARENA(dp); |
3045 | JS_ASSERT(!a->list); |
3046 | if (!a->u.hasMarkedDoubles) { |
3047 | ClearDoubleArenaFlags(a); |
3048 | a->u.hasMarkedDoubles = JS_TRUE; |
3049 | } |
3050 | jsuint index = DOUBLE_THING_TO_INDEX(dp); |
3051 | JS_SET_BIT(DOUBLE_ARENA_BITMAP(a), index); |
3052 | } |
3053 | /* Keep reserved objects. */ |
3054 | for (JSObject *obj = tm->reservedObjects; obj; obj = JSVAL_TO_OBJECT(obj->fslots[0])) { |
3055 | uint8 *flagp = GetGCThingFlags(obj); |
3056 | JS_ASSERT((*flagp & GCF_TYPEMASK) == GCX_OBJECT); |
3057 | JS_ASSERT(*flagp != GCF_FINAL); |
3058 | *flagp |= GCF_MARK; |
3059 | } |
3060 | } |
3061 | |
3062 | #ifdef JS_THREADSAFE |
3063 | static JSDHashOperator |
3064 | reserved_gcthings_marker(JSDHashTable *table, JSDHashEntryHdr *hdr, |
3065 | uint32, void *) |
3066 | { |
3067 | JSThread *thread = ((JSThreadsHashEntry *) hdr)->thread; |
3068 | |
3069 | MarkReservedGCThings(&thread->data.traceMonitor); |
3070 | return JS_DHASH_NEXT; |
3071 | } |
3072 | #endif |
3073 | |
3074 | #endif |
3075 | |
3076 | JS_REQUIRES_STACK void |
3077 | js_TraceRuntime(JSTracer *trc, JSBool allAtoms) |
3078 | { |
3079 | JSRuntime *rt = trc->context->runtime; |
3080 | JSContext *iter, *acx; |
3081 | |
3082 | JS_DHashTableEnumerate(&rt->gcRootsHash, gc_root_traversal, trc); |
3083 | if (rt->gcLocksHash) |
3084 | JS_DHashTableEnumerate(rt->gcLocksHash, gc_lock_traversal, trc); |
3085 | js_TraceAtomState(trc, allAtoms); |
3086 | js_TraceRuntimeNumberState(trc); |
3087 | |
3088 | iter = NULL; |
3089 | while ((acx = js_ContextIterator(rt, JS_TRUE, &iter)) != NULL) |
3090 | js_TraceContext(trc, acx); |
3091 | |
3092 | js_TraceThreads(rt, trc); |
3093 | |
3094 | if (rt->gcExtraRootsTraceOp) |
3095 | rt->gcExtraRootsTraceOp(trc, rt->gcExtraRootsData); |
3096 | |
3097 | #ifdef JS_TRACER |
3098 | for (int i = 0; i < JSBUILTIN_LIMIT; i++) { |
3099 | if (rt->builtinFunctions[i]) |
3100 | JS_CALL_OBJECT_TRACER(trc, rt->builtinFunctions[i], "builtin function"); |
3101 | } |
3102 | |
3103 | /* Mark reserved gcthings unless we are shutting down. */ |
3104 | if (IS_GC_MARKING_TRACER(trc) && rt->state != JSRTS_LANDING) { |
3105 | #ifdef JS_THREADSAFE |
3106 | JS_DHashTableEnumerate(&rt->threads, reserved_gcthings_marker, NULL); |
3107 | #else |
3108 | MarkReservedGCThings(&rt->threadData.traceMonitor); |
3109 | #endif |
3110 | } |
3111 | |
3112 | #endif |
3113 | } |
3114 | |
3115 | void |
3116 | js_TriggerGC(JSContext *cx, JSBool gcLocked) |
3117 | { |
3118 | JSRuntime *rt = cx->runtime; |
3119 | |
3120 | #ifdef JS_THREADSAFE |
3121 | JS_ASSERT(cx->requestDepth > 0); |
3122 | #endif |
3123 | JS_ASSERT(!rt->gcRunning); |
3124 | if (rt->gcIsNeeded) |
3125 | return; |
3126 | |
3127 | /* |
3128 | * Trigger the GC when it is safe to call an operation callback on any |
3129 | * thread. |
3130 | */ |
3131 | rt->gcIsNeeded = JS_TRUE; |
3132 | js_TriggerAllOperationCallbacks(rt, gcLocked); |
3133 | } |
3134 | |
3135 | static void |
3136 | ProcessSetSlotRequest(JSContext *cx, JSSetSlotRequest *ssr) |
3137 | { |
3138 | JSObject *obj = ssr->obj; |
3139 | JSObject *pobj = ssr->pobj; |
3140 | uint32 slot = ssr->slot; |
3141 | |
3142 | while (pobj) { |
3143 | pobj = js_GetWrappedObject(cx, pobj); |
3144 | if (pobj == obj) { |
3145 | ssr->cycle = true; |
3146 | return; |
3147 | } |
3148 | pobj = JSVAL_TO_OBJECT(STOBJ_GET_SLOT(pobj, slot)); |
3149 | } |
3150 | |
3151 | pobj = ssr->pobj; |
3152 | if (slot == JSSLOT_PROTO) { |
3153 | obj->setProto(pobj); |
3154 | } else { |
3155 | JS_ASSERT(slot == JSSLOT_PARENT); |
3156 | obj->setParent(pobj); |
3157 | } |
3158 | } |
3159 | |
3160 | void |
3161 | js_DestroyScriptsToGC(JSContext *cx, JSThreadData *data) |
3162 | { |
3163 | JSScript **listp, *script; |
3164 | |
3165 | for (size_t i = 0; i != JS_ARRAY_LENGTH(data->scriptsToGC); ++i) { |
3166 | listp = &data->scriptsToGC[i]; |
3167 | while ((script = *listp) != NULL) { |
3168 | *listp = script->u.nextToGC; |
3169 | script->u.nextToGC = NULL; |
3170 | js_DestroyScript(cx, script); |
3171 | } |
3172 | } |
3173 | } |
3174 | |
3175 | static void |
3176 | FinalizeObject(JSContext *cx, JSObject *obj) |
3177 | { |
3178 | /* Cope with stillborn objects that have no map. */ |
3179 | if (!obj->map) |
3180 | return; |
3181 | |
3182 | if (JS_UNLIKELY(cx->debugHooks->objectHook != NULL)) { |
3183 | cx->debugHooks->objectHook(cx, obj, JS_FALSE, |
3184 | cx->debugHooks->objectHookData); |
3185 | } |
3186 | |
3187 | /* Finalize obj first, in case it needs map and slots. */ |
3188 | JSClass *clasp = STOBJ_GET_CLASS(obj); |
3189 | if (clasp->finalize) |
3190 | clasp->finalize(cx, obj); |
3191 | |
3192 | #ifdef INCLUDE_MOZILLA_DTRACE |
3193 | if (JAVASCRIPT_OBJECT_FINALIZE_ENABLED()) |
3194 | jsdtrace_object_finalize(obj); |
3195 | #endif |
3196 | |
3197 | if (JS_LIKELY(OBJ_IS_NATIVE(obj))) |
3198 | OBJ_SCOPE(obj)->drop(cx, obj); |
3199 | js_FreeSlots(cx, obj); |
3200 | } |
3201 | |
3202 | static JSStringFinalizeOp str_finalizers[GCX_NTYPES - GCX_EXTERNAL_STRING] = { |
3203 | NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL |
3204 | }; |
3205 | |
3206 | intN |
3207 | js_ChangeExternalStringFinalizer(JSStringFinalizeOp oldop, |
3208 | JSStringFinalizeOp newop) |
3209 | { |
3210 | uintN i; |
3211 | |
3212 | for (i = 0; i != JS_ARRAY_LENGTH(str_finalizers); i++) { |
3213 | if (str_finalizers[i] == oldop) { |
3214 | str_finalizers[i] = newop; |
3215 | return (intN) i; |
3216 | } |
3217 | } |
3218 | return -1; |
3219 | } |
3220 | |
3221 | /* |
3222 | * cx is NULL when we are called from js_FinishAtomState to force the |
3223 | * finalization of the permanently interned strings. |
3224 | */ |
3225 | void |
3226 | js_FinalizeStringRT(JSRuntime *rt, JSString *str, intN type, JSContext *cx) |
3227 | { |
3228 | jschar *chars; |
3229 | JSBool valid; |
3230 | JSStringFinalizeOp finalizer; |
3231 | |
3232 | JS_RUNTIME_UNMETER(rt, liveStrings); |
3233 | JS_ASSERT(!JSString::isStatic(str)); |
3234 | if (str->isDependent()) { |
3235 | /* A dependent string can not be external and must be valid. */ |
3236 | JS_ASSERT(type < 0); |
3237 | JS_ASSERT(str->dependentBase()); |
3238 | JS_RUNTIME_UNMETER(rt, liveDependentStrings); |
3239 | valid = JS_TRUE; |
3240 | } else { |
3241 | /* A stillborn string has null chars, so is not valid. */ |
3242 | chars = str->flatChars(); |
3243 | valid = (chars != NULL); |
3244 | if (valid) { |
3245 | if (type < 0) { |
3246 | if (cx) |
3247 | cx->free(chars); |
3248 | else |
3249 | rt->free(chars); |
3250 | } else { |
3251 | JS_ASSERT((uintN) type < JS_ARRAY_LENGTH(str_finalizers)); |
3252 | finalizer = str_finalizers[type]; |
3253 | if (finalizer) { |
3254 | /* |
3255 | * Assume that the finalizer for the permanently interned |
3256 | * string knows how to deal with null context. |
3257 | */ |
3258 | finalizer(cx, str); |
3259 | } |
3260 | } |
3261 | } |
3262 | } |
3263 | if (valid && str->isDeflated()) |
3264 | js_PurgeDeflatedStringCache(rt, str); |
3265 | } |
3266 | |
3267 | /* |
3268 | * The gckind flag bit GC_LOCK_HELD indicates a call from js_NewGCThing with |
3269 | * rt->gcLock already held, so the lock should be kept on return. |
3270 | */ |
3271 | void |
3272 | js_GC(JSContext *cx, JSGCInvocationKind gckind) |
3273 | { |
3274 | JSRuntime *rt; |
3275 | JSBool keepAtoms; |
3276 | JSGCCallback callback; |
3277 | uintN i, type; |
3278 | JSTracer trc; |
3279 | uint32 thingSize, indexLimit; |
3280 | JSGCArenaInfo *a, **ap, *emptyArenas; |
3281 | uint8 flags, *flagp; |
3282 | JSGCThing *thing, *freeList; |
3283 | JSGCArenaList *arenaList; |
3284 | JSBool allClear; |
3285 | #ifdef JS_THREADSAFE |
3286 | uint32 requestDebit; |
3287 | #endif |
3288 | #ifdef JS_GCMETER |
3289 | uint32 nlivearenas, nkilledarenas, nthings; |
3290 | #endif |
3291 | |
3292 | JS_ASSERT_IF(gckind == GC_LAST_DITCH, !JS_ON_TRACE(cx)); |
3293 | rt = cx->runtime; |
3294 | |
3295 | #ifdef JS_THREADSAFE |
3296 | /* |
3297 | * We allow js_GC calls outside a request but the context must be bound |
3298 | * to the current thread. |
3299 | */ |
3300 | JS_ASSERT(CURRENT_THREAD_IS_ME(cx->thread)); |
3301 | |
3302 | /* Avoid deadlock. */ |
3303 | JS_ASSERT(!JS_IS_RUNTIME_LOCKED(rt)); |
3304 | #endif |
3305 | |
3306 | if (gckind & GC_KEEP_ATOMS) { |
3307 | /* |
3308 | * The set slot request and last ditch GC kinds preserve all atoms and |
3309 | * weak roots. |
3310 | */ |
3311 | keepAtoms = JS_TRUE; |
3312 | } else { |
3313 | /* Keep atoms when a suspended compile is running on another context. */ |
3314 | keepAtoms = (rt->gcKeepAtoms != 0); |
3315 | JS_CLEAR_WEAK_ROOTS(&cx->weakRoots); |
3316 | } |
3317 | |
3318 | /* |
3319 | * Don't collect garbage if the runtime isn't up, and cx is not the last |
3320 | * context in the runtime. The last context must force a GC, and nothing |
3321 | * should suppress that final collection or there may be shutdown leaks, |
3322 | * or runtime bloat until the next context is created. |
3323 | */ |
3324 | if (rt->state != JSRTS_UP && gckind != GC_LAST_CONTEXT) |
3325 | return; |
3326 | |
3327 | restart_at_beginning: |
3328 | /* |
3329 | * Let the API user decide to defer a GC if it wants to (unless this |
3330 | * is the last context). Invoke the callback regardless. Sample the |
3331 | * callback in case we are freely racing with a JS_SetGCCallback{,RT} on |
3332 | * another thread. |
3333 | */ |
3334 | if (gckind != GC_SET_SLOT_REQUEST && (callback = rt->gcCallback)) { |
3335 | JSBool ok; |
3336 | |
3337 | if (gckind & GC_LOCK_HELD) |
3338 | JS_UNLOCK_GC(rt); |
3339 | ok = callback(cx, JSGC_BEGIN); |
3340 | if (gckind & GC_LOCK_HELD) |
3341 | JS_LOCK_GC(rt); |
3342 | if (!ok && gckind != GC_LAST_CONTEXT) { |
3343 | /* |
3344 | * It's possible that we've looped back to this code from the 'goto |
3345 | * restart_at_beginning' below in the GC_SET_SLOT_REQUEST code and |
3346 | * that rt->gcLevel is now 0. Don't return without notifying! |
3347 | */ |
3348 | if (rt->gcLevel == 0 && (gckind & GC_LOCK_HELD)) |
3349 | JS_NOTIFY_GC_DONE(rt); |
3350 | return; |
3351 | } |
3352 | } |
3353 | |
3354 | /* Lock out other GC allocator and collector invocations. */ |
3355 | if (!(gckind & GC_LOCK_HELD)) |
3356 | JS_LOCK_GC(rt); |
3357 | |
3358 | METER(rt->gcStats.poke++); |
3359 | rt->gcPoke = JS_FALSE; |
3360 | |
3361 | #ifdef JS_THREADSAFE |
3362 | /* |
3363 | * Check if the GC is already running on this or another thread and |
3364 | * delegate the job to it. |
3365 | */ |
3366 | if (rt->gcLevel > 0) { |
3367 | JS_ASSERT(rt->gcThread); |
3368 | |
3369 | /* Bump gcLevel to restart the current GC, so it finds new garbage. */ |
3370 | rt->gcLevel++; |
3371 | METER_UPDATE_MAX(rt->gcStats.maxlevel, rt->gcLevel); |
3372 | |
3373 | /* |
3374 | * If the GC runs on another thread, temporarily suspend the current |
3375 | * request and wait until the GC is done. |
3376 | */ |
3377 | if (rt->gcThread != cx->thread) { |
3378 | requestDebit = js_DiscountRequestsForGC(cx); |
3379 | js_RecountRequestsAfterGC(rt, requestDebit); |
3380 | } |
3381 | if (!(gckind & GC_LOCK_HELD)) |
3382 | JS_UNLOCK_GC(rt); |
3383 | return; |
3384 | } |
3385 | |
3386 | /* No other thread is in GC, so indicate that we're now in GC. */ |
3387 | rt->gcLevel = 1; |
3388 | rt->gcThread = cx->thread; |
3389 | |
3390 | /* |
3391 | * Notify all operation callbacks, which will give them a chance to |
3392 | * yield their current request. Contexts that are not currently |
3393 | * executing will perform their callback at some later point, |
3394 | * which then will be unnecessary, but harmless. |
3395 | */ |
3396 | js_NudgeOtherContexts(cx); |
3397 | |
3398 | /* |
3399 | * Discount all the requests on the current thread from contributing |
3400 | * to rt->requestCount before we wait for all other requests to finish. |
3401 | * JS_NOTIFY_REQUEST_DONE, which will wake us up, is only called on |
3402 | * rt->requestCount transitions to 0. |
3403 | */ |
3404 | requestDebit = js_CountThreadRequests(cx); |
3405 | JS_ASSERT_IF(cx->requestDepth != 0, requestDebit >= 1); |
3406 | rt->requestCount -= requestDebit; |
3407 | while (rt->requestCount > 0) |
3408 | JS_AWAIT_REQUEST_DONE(rt); |
3409 | rt->requestCount += requestDebit; |
3410 | |
3411 | #else /* !JS_THREADSAFE */ |
3412 | |
3413 | /* Bump gcLevel and return rather than nest; the outer gc will restart. */ |
3414 | rt->gcLevel++; |
3415 | METER_UPDATE_MAX(rt->gcStats.maxlevel, rt->gcLevel); |
3416 | if (rt->gcLevel > 1) |
3417 | return; |
3418 | |
3419 | #endif /* !JS_THREADSAFE */ |
3420 | |
3421 | /* |
3422 | * Set rt->gcRunning here within the GC lock, and after waiting for any |
3423 | * active requests to end, so that new requests that try to JS_AddRoot, |
3424 | * JS_RemoveRoot, or JS_RemoveRootRT block in JS_BeginRequest waiting for |
3425 | * rt->gcLevel to drop to zero, while request-less calls to the *Root* |
3426 | * APIs block in js_AddRoot or js_RemoveRoot (see above in this file), |
3427 | * waiting for GC to finish. |
3428 | */ |
3429 | rt->gcRunning = JS_TRUE; |
3430 | |
3431 | if (gckind == GC_SET_SLOT_REQUEST) { |
3432 | JSSetSlotRequest *ssr; |
3433 | |
3434 | while ((ssr = rt->setSlotRequests) != NULL) { |
3435 | rt->setSlotRequests = ssr->next; |
3436 | JS_UNLOCK_GC(rt); |
3437 | ssr->next = NULL; |
3438 | ProcessSetSlotRequest(cx, ssr); |
3439 | JS_LOCK_GC(rt); |
3440 | } |
3441 | |
3442 | /* |
3443 | * We assume here that killing links to parent and prototype objects |
3444 | * does not create garbage (such objects typically are long-lived and |
3445 | * widely shared, e.g. global objects, Function.prototype, etc.). We |
3446 | * collect garbage only if a racing thread attempted GC and is waiting |
3447 | * for us to finish (gcLevel > 1) or if someone already poked us. |
3448 | */ |
3449 | if (rt->gcLevel == 1 && !rt->gcPoke && !rt->gcIsNeeded) |
3450 | goto done_running; |
3451 | |
3452 | rt->gcLevel = 0; |
3453 | rt->gcPoke = JS_FALSE; |
3454 | rt->gcRunning = JS_FALSE; |
3455 | #ifdef JS_THREADSAFE |
3456 | rt->gcThread = NULL; |
3457 | #endif |
3458 | gckind = GC_LOCK_HELD; |
3459 | goto restart_at_beginning; |
3460 | } |
3461 | |
3462 | JS_UNLOCK_GC(rt); |
3463 | |
3464 | #ifdef JS_TRACER |
3465 | if (JS_ON_TRACE(cx)) |
3466 | goto out; |
3467 | #endif |
3468 | VOUCH_HAVE_STACK(); |
3469 | |
3470 | /* Clear gcIsNeeded now, when we are about to start a normal GC cycle. */ |
3471 | rt->gcIsNeeded = JS_FALSE; |
3472 | |
3473 | /* Reset malloc counter. */ |
3474 | rt->gcMallocBytes = 0; |
3475 | |
3476 | #ifdef JS_DUMP_SCOPE_METERS |
3477 | { extern void js_DumpScopeMeters(JSRuntime *rt); |
3478 | js_DumpScopeMeters(rt); |
3479 | } |
3480 | #endif |
3481 | |
3482 | #ifdef JS_TRACER |
3483 | js_PurgeJITOracle(); |
3484 | #endif |
3485 | |
3486 | restart: |
3487 | rt->gcNumber++; |
3488 | JS_ASSERT(!rt->gcUntracedArenaStackTop); |
3489 | JS_ASSERT(rt->gcTraceLaterCount == 0); |
3490 | |
3491 | /* |
3492 | * Reset the property cache's type id generator so we can compress ids. |
3493 | * Same for the protoHazardShape proxy-shape standing in for all object |
3494 | * prototypes having readonly or setter properties. |
3495 | */ |
3496 | if (rt->shapeGen & SHAPE_OVERFLOW_BIT |
3497 | #ifdef JS_GC_ZEAL |
3498 | || rt->gcZeal >= 1 |
3499 | #endif |
3500 | ) { |
3501 | rt->gcRegenShapes = true; |
3502 | rt->gcRegenShapesScopeFlag ^= JSScope::SHAPE_REGEN; |
3503 | rt->shapeGen = 0; |
3504 | rt->protoHazardShape = 0; |
3505 | } |
3506 | |
3507 | js_PurgeThreads(cx); |
3508 | #ifdef JS_TRACER |
3509 | if (gckind == GC_LAST_CONTEXT) { |
3510 | /* Clear builtin functions, which are recreated on demand. */ |
3511 | memset(rt->builtinFunctions, 0, sizeof rt->builtinFunctions); |
3512 | } |
3513 | #endif |
3514 | |
3515 | /* |
3516 | * Mark phase. |
3517 | */ |
3518 | JS_TRACER_INIT(&trc, cx, NULL); |
3519 | rt->gcMarkingTracer = &trc; |
3520 | JS_ASSERT(IS_GC_MARKING_TRACER(&trc)); |
3521 | |
3522 | for (a = rt->gcDoubleArenaList.first; a; a = a->prev) |
3523 | a->u.hasMarkedDoubles = JS_FALSE; |
3524 | |
3525 | js_TraceRuntime(&trc, keepAtoms); |
3526 | js_MarkScriptFilenames(rt, keepAtoms); |
3527 | |
3528 | /* |
3529 | * Mark children of things that caused too deep recursion during the above |
3530 | * tracing. |
3531 | */ |
3532 | TraceDelayedChildren(&trc); |
3533 | |
3534 | JS_ASSERT(!cx->insideGCMarkCallback); |
3535 | if (rt->gcCallback) { |
3536 | cx->insideGCMarkCallback = JS_TRUE; |
3537 | (void) rt->gcCallback(cx, JSGC_MARK_END); |
3538 | JS_ASSERT(cx->insideGCMarkCallback); |
3539 | cx->insideGCMarkCallback = JS_FALSE; |
3540 | } |
3541 | JS_ASSERT(rt->gcTraceLaterCount == 0); |
3542 | |
3543 | rt->gcMarkingTracer = NULL; |
3544 | |
3545 | #ifdef JS_THREADSAFE |
3546 | cx->createDeallocatorTask(); |
3547 | #endif |
3548 | |
3549 | /* |
3550 | * Sweep phase. |
3551 | * |
3552 | * Finalize as we sweep, outside of rt->gcLock but with rt->gcRunning set |
3553 | * so that any attempt to allocate a GC-thing from a finalizer will fail, |
3554 | * rather than nest badly and leave the unmarked newborn to be swept. |
3555 | * |
3556 | * We first sweep atom state so we can use js_IsAboutToBeFinalized on |
3557 | * JSString or jsdouble held in a hashtable to check if the hashtable |
3558 | * entry can be freed. Note that even after the entry is freed, JSObject |
3559 | * finalizers can continue to access the corresponding jsdouble* and |
3560 | * JSString* assuming that they are unique. This works since the |
3561 | * atomization API must not be called during GC. |
3562 | */ |
3563 | js_SweepAtomState(cx); |
3564 | |
3565 | /* Finalize iterator states before the objects they iterate over. */ |
3566 | CloseNativeIterators(cx); |
3567 | |
3568 | /* Finalize watch points associated with unreachable objects. */ |
3569 | js_SweepWatchPoints(cx); |
3570 | |
3571 | #ifdef DEBUG |
3572 | /* Save the pre-sweep count of scope-mapped properties. */ |
3573 | rt->liveScopePropsPreSweep = rt->liveScopeProps; |
3574 | #endif |