1 | /* |
2 | ** 2007 October 14 |
3 | ** |
4 | ** The author disclaims copyright to this source code. In place of |
5 | ** a legal notice, here is a blessing: |
6 | ** |
7 | ** May you do good and not evil. |
8 | ** May you find forgiveness for yourself and forgive others. |
9 | ** May you share freely, never taking more than you give. |
10 | ** |
11 | ************************************************************************* |
12 | ** This file contains the C functions that implement a memory |
13 | ** allocation subsystem for use by SQLite. |
14 | ** |
15 | ** This version of the memory allocation subsystem omits all |
16 | ** use of malloc(). The SQLite user supplies a block of memory |
17 | ** before calling sqlite3_initialize() from which allocations |
18 | ** are made and returned by the xMalloc() and xRealloc() |
19 | ** implementations. Once sqlite3_initialize() has been called, |
20 | ** the amount of memory available to SQLite is fixed and cannot |
21 | ** be changed. |
22 | ** |
23 | ** This version of the memory allocation subsystem is included |
24 | ** in the build only if SQLITE_ENABLE_MEMSYS3 is defined. |
25 | */ |
26 | #include "sqliteInt.h" |
27 | |
28 | /* |
29 | ** This version of the memory allocator is only built into the library |
30 | ** SQLITE_ENABLE_MEMSYS3 is defined. Defining this symbol does not |
31 | ** mean that the library will use a memory-pool by default, just that |
32 | ** it is available. The mempool allocator is activated by calling |
33 | ** sqlite3_config(). |
34 | */ |
35 | #ifdef SQLITE_ENABLE_MEMSYS3 |
36 | |
37 | /* |
38 | ** Maximum size (in Mem3Blocks) of a "small" chunk. |
39 | */ |
40 | #define MX_SMALL 10 |
41 | |
42 | |
43 | /* |
44 | ** Number of freelist hash slots |
45 | */ |
46 | #define N_HASH 61 |
47 | |
48 | /* |
49 | ** A memory allocation (also called a "chunk") consists of two or |
50 | ** more blocks where each block is 8 bytes. The first 8 bytes are |
51 | ** a header that is not returned to the user. |
52 | ** |
53 | ** A chunk is two or more blocks that is either checked out or |
54 | ** free. The first block has format u.hdr. u.hdr.size4x is 4 times the |
55 | ** size of the allocation in blocks if the allocation is free. |
56 | ** The u.hdr.size4x&1 bit is true if the chunk is checked out and |
57 | ** false if the chunk is on the freelist. The u.hdr.size4x&2 bit |
58 | ** is true if the previous chunk is checked out and false if the |
59 | ** previous chunk is free. The u.hdr.prevSize field is the size of |
60 | ** the previous chunk in blocks if the previous chunk is on the |
61 | ** freelist. If the previous chunk is checked out, then |
62 | ** u.hdr.prevSize can be part of the data for that chunk and should |
63 | ** not be read or written. |
64 | ** |
65 | ** We often identify a chunk by its index in mem3.aPool[]. When |
66 | ** this is done, the chunk index refers to the second block of |
67 | ** the chunk. In this way, the first chunk has an index of 1. |
68 | ** A chunk index of 0 means "no such chunk" and is the equivalent |
69 | ** of a NULL pointer. |
70 | ** |
71 | ** The second block of free chunks is of the form u.list. The |
72 | ** two fields form a double-linked list of chunks of related sizes. |
73 | ** Pointers to the head of the list are stored in mem3.aiSmall[] |
74 | ** for smaller chunks and mem3.aiHash[] for larger chunks. |
75 | ** |
76 | ** The second block of a chunk is user data if the chunk is checked |
77 | ** out. If a chunk is checked out, the user data may extend into |
78 | ** the u.hdr.prevSize value of the following chunk. |
79 | */ |
80 | typedef struct Mem3Block Mem3Block; |
81 | struct Mem3Block { |
82 | union { |
83 | struct { |
84 | u32 prevSize; /* Size of previous chunk in Mem3Block elements */ |
85 | u32 size4x; /* 4x the size of current chunk in Mem3Block elements */ |
86 | } hdr; |
87 | struct { |
88 | u32 next; /* Index in mem3.aPool[] of next free chunk */ |
89 | u32 prev; /* Index in mem3.aPool[] of previous free chunk */ |
90 | } list; |
91 | } u; |
92 | }; |
93 | |
94 | /* |
95 | ** All of the static variables used by this module are collected |
96 | ** into a single structure named "mem3". This is to keep the |
97 | ** static variables organized and to reduce namespace pollution |
98 | ** when this module is combined with other in the amalgamation. |
99 | */ |
100 | static SQLITE_WSD struct Mem3Global { |
101 | /* |
102 | ** Memory available for allocation. nPool is the size of the array |
103 | ** (in Mem3Blocks) pointed to by aPool less 2. |
104 | */ |
105 | u32 nPool; |
106 | Mem3Block *aPool; |
107 | |
108 | /* |
109 | ** True if we are evaluating an out-of-memory callback. |
110 | */ |
111 | int alarmBusy; |
112 | |
113 | /* |
114 | ** Mutex to control access to the memory allocation subsystem. |
115 | */ |
116 | sqlite3_mutex *mutex; |
117 | |
118 | /* |
119 | ** The minimum amount of free space that we have seen. |
120 | */ |
121 | u32 mnKeyBlk; |
122 | |
123 | /* |
124 | ** iKeyBlk is the index of the key chunk. Most new allocations |
125 | ** occur off of this chunk. szKeyBlk is the size (in Mem3Blocks) |
126 | ** of the current key chunk. iKeyBlk is 0 if there is no key chunk. |
127 | ** The key chunk is not in either the aiHash[] or aiSmall[]. |
128 | */ |
129 | u32 iKeyBlk; |
130 | u32 szKeyBlk; |
131 | |
132 | /* |
133 | ** Array of lists of free blocks according to the block size |
134 | ** for smaller chunks, or a hash on the block size for larger |
135 | ** chunks. |
136 | */ |
137 | u32 aiSmall[MX_SMALL-1]; /* For sizes 2 through MX_SMALL, inclusive */ |
138 | u32 aiHash[N_HASH]; /* For sizes MX_SMALL+1 and larger */ |
139 | } mem3 = { 97535575 }; |
140 | |
141 | #define mem3 GLOBAL(struct Mem3Global, mem3) |
142 | |
143 | /* |
144 | ** Unlink the chunk at mem3.aPool[i] from list it is currently |
145 | ** on. *pRoot is the list that i is a member of. |
146 | */ |
147 | static void memsys3UnlinkFromList(u32 i, u32 *pRoot){ |
148 | u32 next = mem3.aPool[i].u.list.next; |
149 | u32 prev = mem3.aPool[i].u.list.prev; |
150 | assert( sqlite3_mutex_held(mem3.mutex) ); |
151 | if( prev==0 ){ |
152 | *pRoot = next; |
153 | }else{ |
154 | mem3.aPool[prev].u.list.next = next; |
155 | } |
156 | if( next ){ |
157 | mem3.aPool[next].u.list.prev = prev; |
158 | } |
159 | mem3.aPool[i].u.list.next = 0; |
160 | mem3.aPool[i].u.list.prev = 0; |
161 | } |
162 | |
163 | /* |
164 | ** Unlink the chunk at index i from |
165 | ** whatever list is currently a member of. |
166 | */ |
167 | static void memsys3Unlink(u32 i){ |
168 | u32 size, hash; |
169 | assert( sqlite3_mutex_held(mem3.mutex) ); |
170 | assert( (mem3.aPool[i-1].u.hdr.size4x & 1)==0 ); |
171 | assert( i>=1 ); |
172 | size = mem3.aPool[i-1].u.hdr.size4x/4; |
173 | assert( size==mem3.aPool[i+size-1].u.hdr.prevSize ); |
174 | assert( size>=2 ); |
175 | if( size <= MX_SMALL ){ |
176 | memsys3UnlinkFromList(i, &mem3.aiSmall[size-2]); |
177 | }else{ |
178 | hash = size % N_HASH; |
179 | memsys3UnlinkFromList(i, &mem3.aiHash[hash]); |
180 | } |
181 | } |
182 | |
183 | /* |
184 | ** Link the chunk at mem3.aPool[i] so that is on the list rooted |
185 | ** at *pRoot. |
186 | */ |
187 | static void memsys3LinkIntoList(u32 i, u32 *pRoot){ |
188 | assert( sqlite3_mutex_held(mem3.mutex) ); |
189 | mem3.aPool[i].u.list.next = *pRoot; |
190 | mem3.aPool[i].u.list.prev = 0; |
191 | if( *pRoot ){ |
192 | mem3.aPool[*pRoot].u.list.prev = i; |
193 | } |
194 | *pRoot = i; |
195 | } |
196 | |
197 | /* |
198 | ** Link the chunk at index i into either the appropriate |
199 | ** small chunk list, or into the large chunk hash table. |
200 | */ |
201 | static void memsys3Link(u32 i){ |
202 | u32 size, hash; |
203 | assert( sqlite3_mutex_held(mem3.mutex) ); |
204 | assert( i>=1 ); |
205 | assert( (mem3.aPool[i-1].u.hdr.size4x & 1)==0 ); |
206 | size = mem3.aPool[i-1].u.hdr.size4x/4; |
207 | assert( size==mem3.aPool[i+size-1].u.hdr.prevSize ); |
208 | assert( size>=2 ); |
209 | if( size <= MX_SMALL ){ |
210 | memsys3LinkIntoList(i, &mem3.aiSmall[size-2]); |
211 | }else{ |
212 | hash = size % N_HASH; |
213 | memsys3LinkIntoList(i, &mem3.aiHash[hash]); |
214 | } |
215 | } |
216 | |
217 | /* |
218 | ** If the STATIC_MEM mutex is not already held, obtain it now. The mutex |
219 | ** will already be held (obtained by code in malloc.c) if |
220 | ** sqlite3GlobalConfig.bMemStat is true. |
221 | */ |
222 | static void memsys3Enter(void){ |
223 | if( sqlite3GlobalConfig.bMemstat==0 && mem3.mutex==0 ){ |
224 | mem3.mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MEM); |
225 | } |
226 | sqlite3_mutex_enter(mem3.mutex); |
227 | } |
228 | static void memsys3Leave(void){ |
229 | sqlite3_mutex_leave(mem3.mutex); |
230 | } |
231 | |
232 | /* |
233 | ** Called when we are unable to satisfy an allocation of nBytes. |
234 | */ |
235 | static void memsys3OutOfMemory(int nByte){ |
236 | if( !mem3.alarmBusy ){ |
237 | mem3.alarmBusy = 1; |
238 | assert( sqlite3_mutex_held(mem3.mutex) ); |
239 | sqlite3_mutex_leave(mem3.mutex); |
240 | sqlite3_release_memory(nByte); |
241 | sqlite3_mutex_enter(mem3.mutex); |
242 | mem3.alarmBusy = 0; |
243 | } |
244 | } |
245 | |
246 | |
247 | /* |
248 | ** Chunk i is a free chunk that has been unlinked. Adjust its |
249 | ** size parameters for check-out and return a pointer to the |
250 | ** user portion of the chunk. |
251 | */ |
252 | static void *memsys3Checkout(u32 i, u32 nBlock){ |
253 | u32 x; |
254 | assert( sqlite3_mutex_held(mem3.mutex) ); |
255 | assert( i>=1 ); |
256 | assert( mem3.aPool[i-1].u.hdr.size4x/4==nBlock ); |
257 | assert( mem3.aPool[i+nBlock-1].u.hdr.prevSize==nBlock ); |
258 | x = mem3.aPool[i-1].u.hdr.size4x; |
259 | mem3.aPool[i-1].u.hdr.size4x = nBlock*4 | 1 | (x&2); |
260 | mem3.aPool[i+nBlock-1].u.hdr.prevSize = nBlock; |
261 | mem3.aPool[i+nBlock-1].u.hdr.size4x |= 2; |
262 | return &mem3.aPool[i]; |
263 | } |
264 | |
265 | /* |
266 | ** Carve a piece off of the end of the mem3.iKeyBlk free chunk. |
267 | ** Return a pointer to the new allocation. Or, if the key chunk |
268 | ** is not large enough, return 0. |
269 | */ |
270 | static void *memsys3FromKeyBlk(u32 nBlock){ |
271 | assert( sqlite3_mutex_held(mem3.mutex) ); |
272 | assert( mem3.szKeyBlk>=nBlock ); |
273 | if( nBlock>=mem3.szKeyBlk-1 ){ |
274 | /* Use the entire key chunk */ |
275 | void *p = memsys3Checkout(mem3.iKeyBlk, mem3.szKeyBlk); |
276 | mem3.iKeyBlk = 0; |
277 | mem3.szKeyBlk = 0; |
278 | mem3.mnKeyBlk = 0; |
279 | return p; |
280 | }else{ |
281 | /* Split the key block. Return the tail. */ |
282 | u32 newi, x; |
283 | newi = mem3.iKeyBlk + mem3.szKeyBlk - nBlock; |
284 | assert( newi > mem3.iKeyBlk+1 ); |
285 | mem3.aPool[mem3.iKeyBlk+mem3.szKeyBlk-1].u.hdr.prevSize = nBlock; |
286 | mem3.aPool[mem3.iKeyBlk+mem3.szKeyBlk-1].u.hdr.size4x |= 2; |
287 | mem3.aPool[newi-1].u.hdr.size4x = nBlock*4 + 1; |
288 | mem3.szKeyBlk -= nBlock; |
289 | mem3.aPool[newi-1].u.hdr.prevSize = mem3.szKeyBlk; |
290 | x = mem3.aPool[mem3.iKeyBlk-1].u.hdr.size4x & 2; |
291 | mem3.aPool[mem3.iKeyBlk-1].u.hdr.size4x = mem3.szKeyBlk*4 | x; |
292 | if( mem3.szKeyBlk < mem3.mnKeyBlk ){ |
293 | mem3.mnKeyBlk = mem3.szKeyBlk; |
294 | } |
295 | return (void*)&mem3.aPool[newi]; |
296 | } |
297 | } |
298 | |
299 | /* |
300 | ** *pRoot is the head of a list of free chunks of the same size |
301 | ** or same size hash. In other words, *pRoot is an entry in either |
302 | ** mem3.aiSmall[] or mem3.aiHash[]. |
303 | ** |
304 | ** This routine examines all entries on the given list and tries |
305 | ** to coalesce each entries with adjacent free chunks. |
306 | ** |
307 | ** If it sees a chunk that is larger than mem3.iKeyBlk, it replaces |
308 | ** the current mem3.iKeyBlk with the new larger chunk. In order for |
309 | ** this mem3.iKeyBlk replacement to work, the key chunk must be |
310 | ** linked into the hash tables. That is not the normal state of |
311 | ** affairs, of course. The calling routine must link the key |
312 | ** chunk before invoking this routine, then must unlink the (possibly |
313 | ** changed) key chunk once this routine has finished. |
314 | */ |
315 | static void memsys3Merge(u32 *pRoot){ |
316 | u32 iNext, prev, size, i, x; |
317 | |
318 | assert( sqlite3_mutex_held(mem3.mutex) ); |
319 | for(i=*pRoot; i>0; i=iNext){ |
320 | iNext = mem3.aPool[i].u.list.next; |
321 | size = mem3.aPool[i-1].u.hdr.size4x; |
322 | assert( (size&1)==0 ); |
323 | if( (size&2)==0 ){ |
324 | memsys3UnlinkFromList(i, pRoot); |
325 | assert( i > mem3.aPool[i-1].u.hdr.prevSize ); |
326 | prev = i - mem3.aPool[i-1].u.hdr.prevSize; |
327 | if( prev==iNext ){ |
328 | iNext = mem3.aPool[prev].u.list.next; |
329 | } |
330 | memsys3Unlink(prev); |
331 | size = i + size/4 - prev; |
332 | x = mem3.aPool[prev-1].u.hdr.size4x & 2; |
333 | mem3.aPool[prev-1].u.hdr.size4x = size*4 | x; |
334 | mem3.aPool[prev+size-1].u.hdr.prevSize = size; |
335 | memsys3Link(prev); |
336 | i = prev; |
337 | }else{ |
338 | size /= 4; |
339 | } |
340 | if( size>mem3.szKeyBlk ){ |
341 | mem3.iKeyBlk = i; |
342 | mem3.szKeyBlk = size; |
343 | } |
344 | } |
345 | } |
346 | |
347 | /* |
348 | ** Return a block of memory of at least nBytes in size. |
349 | ** Return NULL if unable. |
350 | ** |
351 | ** This function assumes that the necessary mutexes, if any, are |
352 | ** already held by the caller. Hence "Unsafe". |
353 | */ |
354 | static void *memsys3MallocUnsafe(int nByte){ |
355 | u32 i; |
356 | u32 nBlock; |
357 | u32 toFree; |
358 | |
359 | assert( sqlite3_mutex_held(mem3.mutex) ); |
360 | assert( sizeof(Mem3Block)==8 ); |
361 | if( nByte<=12 ){ |
362 | nBlock = 2; |
363 | }else{ |
364 | nBlock = (nByte + 11)/8; |
365 | } |
366 | assert( nBlock>=2 ); |
367 | |
368 | /* STEP 1: |
369 | ** Look for an entry of the correct size in either the small |
370 | ** chunk table or in the large chunk hash table. This is |
371 | ** successful most of the time (about 9 times out of 10). |
372 | */ |
373 | if( nBlock <= MX_SMALL ){ |
374 | i = mem3.aiSmall[nBlock-2]; |
375 | if( i>0 ){ |
376 | memsys3UnlinkFromList(i, &mem3.aiSmall[nBlock-2]); |
377 | return memsys3Checkout(i, nBlock); |
378 | } |
379 | }else{ |
380 | int hash = nBlock % N_HASH; |
381 | for(i=mem3.aiHash[hash]; i>0; i=mem3.aPool[i].u.list.next){ |
382 | if( mem3.aPool[i-1].u.hdr.size4x/4==nBlock ){ |
383 | memsys3UnlinkFromList(i, &mem3.aiHash[hash]); |
384 | return memsys3Checkout(i, nBlock); |
385 | } |
386 | } |
387 | } |
388 | |
389 | /* STEP 2: |
390 | ** Try to satisfy the allocation by carving a piece off of the end |
391 | ** of the key chunk. This step usually works if step 1 fails. |
392 | */ |
393 | if( mem3.szKeyBlk>=nBlock ){ |
394 | return memsys3FromKeyBlk(nBlock); |
395 | } |
396 | |
397 | |
398 | /* STEP 3: |
399 | ** Loop through the entire memory pool. Coalesce adjacent free |
400 | ** chunks. Recompute the key chunk as the largest free chunk. |
401 | ** Then try again to satisfy the allocation by carving a piece off |
402 | ** of the end of the key chunk. This step happens very |
403 | ** rarely (we hope!) |
404 | */ |
405 | for(toFree=nBlock*16; toFree<(mem3.nPool*16); toFree *= 2){ |
406 | memsys3OutOfMemory(toFree); |
407 | if( mem3.iKeyBlk ){ |
408 | memsys3Link(mem3.iKeyBlk); |
409 | mem3.iKeyBlk = 0; |
410 | mem3.szKeyBlk = 0; |
411 | } |
412 | for(i=0; i<N_HASH; i++){ |
413 | memsys3Merge(&mem3.aiHash[i]); |
414 | } |
415 | for(i=0; i<MX_SMALL-1; i++){ |
416 | memsys3Merge(&mem3.aiSmall[i]); |
417 | } |
418 | if( mem3.szKeyBlk ){ |
419 | memsys3Unlink(mem3.iKeyBlk); |
420 | if( mem3.szKeyBlk>=nBlock ){ |
421 | return memsys3FromKeyBlk(nBlock); |
422 | } |
423 | } |
424 | } |
425 | |
426 | /* If none of the above worked, then we fail. */ |
427 | return 0; |
428 | } |
429 | |
430 | /* |
431 | ** Free an outstanding memory allocation. |
432 | ** |
433 | ** This function assumes that the necessary mutexes, if any, are |
434 | ** already held by the caller. Hence "Unsafe". |
435 | */ |
436 | static void memsys3FreeUnsafe(void *pOld){ |
437 | Mem3Block *p = (Mem3Block*)pOld; |
438 | int i; |
439 | u32 size, x; |
440 | assert( sqlite3_mutex_held(mem3.mutex) ); |
441 | assert( p>mem3.aPool && p<&mem3.aPool[mem3.nPool] ); |
442 | i = p - mem3.aPool; |
443 | assert( (mem3.aPool[i-1].u.hdr.size4x&1)==1 ); |
444 | size = mem3.aPool[i-1].u.hdr.size4x/4; |
445 | assert( i+size<=mem3.nPool+1 ); |
446 | mem3.aPool[i-1].u.hdr.size4x &= ~1; |
447 | mem3.aPool[i+size-1].u.hdr.prevSize = size; |
448 | mem3.aPool[i+size-1].u.hdr.size4x &= ~2; |
449 | memsys3Link(i); |
450 | |
451 | /* Try to expand the key using the newly freed chunk */ |
452 | if( mem3.iKeyBlk ){ |
453 | while( (mem3.aPool[mem3.iKeyBlk-1].u.hdr.size4x&2)==0 ){ |
454 | size = mem3.aPool[mem3.iKeyBlk-1].u.hdr.prevSize; |
455 | mem3.iKeyBlk -= size; |
456 | mem3.szKeyBlk += size; |
457 | memsys3Unlink(mem3.iKeyBlk); |
458 | x = mem3.aPool[mem3.iKeyBlk-1].u.hdr.size4x & 2; |
459 | mem3.aPool[mem3.iKeyBlk-1].u.hdr.size4x = mem3.szKeyBlk*4 | x; |
460 | mem3.aPool[mem3.iKeyBlk+mem3.szKeyBlk-1].u.hdr.prevSize = mem3.szKeyBlk; |
461 | } |
462 | x = mem3.aPool[mem3.iKeyBlk-1].u.hdr.size4x & 2; |
463 | while( (mem3.aPool[mem3.iKeyBlk+mem3.szKeyBlk-1].u.hdr.size4x&1)==0 ){ |
464 | memsys3Unlink(mem3.iKeyBlk+mem3.szKeyBlk); |
465 | mem3.szKeyBlk += mem3.aPool[mem3.iKeyBlk+mem3.szKeyBlk-1].u.hdr.size4x/4; |
466 | mem3.aPool[mem3.iKeyBlk-1].u.hdr.size4x = mem3.szKeyBlk*4 | x; |
467 | mem3.aPool[mem3.iKeyBlk+mem3.szKeyBlk-1].u.hdr.prevSize = mem3.szKeyBlk; |
468 | } |
469 | } |
470 | } |
471 | |
472 | /* |
473 | ** Return the size of an outstanding allocation, in bytes. The |
474 | ** size returned omits the 8-byte header overhead. This only |
475 | ** works for chunks that are currently checked out. |
476 | */ |
477 | static int memsys3Size(void *p){ |
478 | Mem3Block *pBlock; |
479 | assert( p!=0 ); |
480 | pBlock = (Mem3Block*)p; |
481 | assert( (pBlock[-1].u.hdr.size4x&1)!=0 ); |
482 | return (pBlock[-1].u.hdr.size4x&~3)*2 - 4; |
483 | } |
484 | |
485 | /* |
486 | ** Round up a request size to the next valid allocation size. |
487 | */ |
488 | static int memsys3Roundup(int n){ |
489 | if( n<=12 ){ |
490 | return 12; |
491 | }else{ |
492 | return ((n+11)&~7) - 4; |
493 | } |
494 | } |
495 | |
496 | /* |
497 | ** Allocate nBytes of memory. |
498 | */ |
499 | static void *memsys3Malloc(int nBytes){ |
500 | sqlite3_int64 *p; |
501 | assert( nBytes>0 ); /* malloc.c filters out 0 byte requests */ |
502 | memsys3Enter(); |
503 | p = memsys3MallocUnsafe(nBytes); |
504 | memsys3Leave(); |
505 | return (void*)p; |
506 | } |
507 | |
508 | /* |
509 | ** Free memory. |
510 | */ |
511 | static void memsys3Free(void *pPrior){ |
512 | assert( pPrior ); |
513 | memsys3Enter(); |
514 | memsys3FreeUnsafe(pPrior); |
515 | memsys3Leave(); |
516 | } |
517 | |
518 | /* |
519 | ** Change the size of an existing memory allocation |
520 | */ |
521 | static void *memsys3Realloc(void *pPrior, int nBytes){ |
522 | int nOld; |
523 | void *p; |
524 | if( pPrior==0 ){ |
525 | return sqlite3_malloc(nBytes); |
526 | } |
527 | if( nBytes<=0 ){ |
528 | sqlite3_free(pPrior); |
529 | return 0; |
530 | } |
531 | nOld = memsys3Size(pPrior); |
532 | if( nBytes<=nOld && nBytes>=nOld-128 ){ |
533 | return pPrior; |
534 | } |
535 | memsys3Enter(); |
536 | p = memsys3MallocUnsafe(nBytes); |
537 | if( p ){ |
538 | if( nOld<nBytes ){ |
539 | memcpy(p, pPrior, nOld); |
540 | }else{ |
541 | memcpy(p, pPrior, nBytes); |
542 | } |
543 | memsys3FreeUnsafe(pPrior); |
544 | } |
545 | memsys3Leave(); |
546 | return p; |
547 | } |
548 | |
549 | /* |
550 | ** Initialize this module. |
551 | */ |
552 | static int memsys3Init(void *NotUsed){ |
553 | UNUSED_PARAMETER(NotUsed); |
554 | if( !sqlite3GlobalConfig.pHeap ){ |
555 | return SQLITE_ERROR; |
556 | } |
557 | |
558 | /* Store a pointer to the memory block in global structure mem3. */ |
559 | assert( sizeof(Mem3Block)==8 ); |
560 | mem3.aPool = (Mem3Block *)sqlite3GlobalConfig.pHeap; |
561 | mem3.nPool = (sqlite3GlobalConfig.nHeap / sizeof(Mem3Block)) - 2; |
562 | |
563 | /* Initialize the key block. */ |
564 | mem3.szKeyBlk = mem3.nPool; |
565 | mem3.mnKeyBlk = mem3.szKeyBlk; |
566 | mem3.iKeyBlk = 1; |
567 | mem3.aPool[0].u.hdr.size4x = (mem3.szKeyBlk<<2) + 2; |
568 | mem3.aPool[mem3.nPool].u.hdr.prevSize = mem3.nPool; |
569 | mem3.aPool[mem3.nPool].u.hdr.size4x = 1; |
570 | |
571 | return SQLITE_OK; |
572 | } |
573 | |
574 | /* |
575 | ** Deinitialize this module. |
576 | */ |
577 | static void memsys3Shutdown(void *NotUsed){ |
578 | UNUSED_PARAMETER(NotUsed); |
579 | mem3.mutex = 0; |
580 | return; |
581 | } |
582 | |
583 | |
584 | |
585 | /* |
586 | ** Open the file indicated and write a log of all unfreed memory |
587 | ** allocations into that log. |
588 | */ |
589 | void sqlite3Memsys3Dump(const char *zFilename){ |
590 | #ifdef SQLITE_DEBUG |
591 | FILE *out; |
592 | u32 i, j; |
593 | u32 size; |
594 | if( zFilename==0 || zFilename[0]==0 ){ |
595 | out = stdout; |
596 | }else{ |
597 | out = fopen(zFilename, "w" ); |
598 | if( out==0 ){ |
599 | fprintf(stderr, "** Unable to output memory debug output log: %s **\n" , |
600 | zFilename); |
601 | return; |
602 | } |
603 | } |
604 | memsys3Enter(); |
605 | fprintf(out, "CHUNKS:\n" ); |
606 | for(i=1; i<=mem3.nPool; i+=size/4){ |
607 | size = mem3.aPool[i-1].u.hdr.size4x; |
608 | if( size/4<=1 ){ |
609 | fprintf(out, "%p size error\n" , &mem3.aPool[i]); |
610 | assert( 0 ); |
611 | break; |
612 | } |
613 | if( (size&1)==0 && mem3.aPool[i+size/4-1].u.hdr.prevSize!=size/4 ){ |
614 | fprintf(out, "%p tail size does not match\n" , &mem3.aPool[i]); |
615 | assert( 0 ); |
616 | break; |
617 | } |
618 | if( ((mem3.aPool[i+size/4-1].u.hdr.size4x&2)>>1)!=(size&1) ){ |
619 | fprintf(out, "%p tail checkout bit is incorrect\n" , &mem3.aPool[i]); |
620 | assert( 0 ); |
621 | break; |
622 | } |
623 | if( size&1 ){ |
624 | fprintf(out, "%p %6d bytes checked out\n" , &mem3.aPool[i], (size/4)*8-8); |
625 | }else{ |
626 | fprintf(out, "%p %6d bytes free%s\n" , &mem3.aPool[i], (size/4)*8-8, |
627 | i==mem3.iKeyBlk ? " **key**" : "" ); |
628 | } |
629 | } |
630 | for(i=0; i<MX_SMALL-1; i++){ |
631 | if( mem3.aiSmall[i]==0 ) continue; |
632 | fprintf(out, "small(%2d):" , i); |
633 | for(j = mem3.aiSmall[i]; j>0; j=mem3.aPool[j].u.list.next){ |
634 | fprintf(out, " %p(%d)" , &mem3.aPool[j], |
635 | (mem3.aPool[j-1].u.hdr.size4x/4)*8-8); |
636 | } |
637 | fprintf(out, "\n" ); |
638 | } |
639 | for(i=0; i<N_HASH; i++){ |
640 | if( mem3.aiHash[i]==0 ) continue; |
641 | fprintf(out, "hash(%2d):" , i); |
642 | for(j = mem3.aiHash[i]; j>0; j=mem3.aPool[j].u.list.next){ |
643 | fprintf(out, " %p(%d)" , &mem3.aPool[j], |
644 | (mem3.aPool[j-1].u.hdr.size4x/4)*8-8); |
645 | } |
646 | fprintf(out, "\n" ); |
647 | } |
648 | fprintf(out, "key=%d\n" , mem3.iKeyBlk); |
649 | fprintf(out, "nowUsed=%d\n" , mem3.nPool*8 - mem3.szKeyBlk*8); |
650 | fprintf(out, "mxUsed=%d\n" , mem3.nPool*8 - mem3.mnKeyBlk*8); |
651 | sqlite3_mutex_leave(mem3.mutex); |
652 | if( out==stdout ){ |
653 | fflush(stdout); |
654 | }else{ |
655 | fclose(out); |
656 | } |
657 | #else |
658 | UNUSED_PARAMETER(zFilename); |
659 | #endif |
660 | } |
661 | |
662 | /* |
663 | ** This routine is the only routine in this file with external |
664 | ** linkage. |
665 | ** |
666 | ** Populate the low-level memory allocation function pointers in |
667 | ** sqlite3GlobalConfig.m with pointers to the routines in this file. The |
668 | ** arguments specify the block of memory to manage. |
669 | ** |
670 | ** This routine is only called by sqlite3_config(), and therefore |
671 | ** is not required to be threadsafe (it is not). |
672 | */ |
673 | const sqlite3_mem_methods *sqlite3MemGetMemsys3(void){ |
674 | static const sqlite3_mem_methods mempoolMethods = { |
675 | memsys3Malloc, |
676 | memsys3Free, |
677 | memsys3Realloc, |
678 | memsys3Size, |
679 | memsys3Roundup, |
680 | memsys3Init, |
681 | memsys3Shutdown, |
682 | 0 |
683 | }; |
684 | return &mempoolMethods; |
685 | } |
686 | |
687 | #endif /* SQLITE_ENABLE_MEMSYS3 */ |
688 | |