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| 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 ** $Id: mem3.c,v 1.25 2008/11/19 16:52:44 danielk1977 Exp $ | |
| 27 */ | |
| 28 #include "sqliteInt.h" | |
| 29 | |
| 30 /* | |
| 31 ** This version of the memory allocator is only built into the library | |
| 32 ** SQLITE_ENABLE_MEMSYS3 is defined. Defining this symbol does not | |
| 33 ** mean that the library will use a memory-pool by default, just that | |
| 34 ** it is available. The mempool allocator is activated by calling | |
| 35 ** sqlite3_config(). | |
| 36 */ | |
| 37 #ifdef SQLITE_ENABLE_MEMSYS3 | |
| 38 | |
| 39 /* | |
| 40 ** Maximum size (in Mem3Blocks) of a "small" chunk. | |
| 41 */ | |
| 42 #define MX_SMALL 10 | |
| 43 | |
| 44 | |
| 45 /* | |
| 46 ** Number of freelist hash slots | |
| 47 */ | |
| 48 #define N_HASH 61 | |
| 49 | |
| 50 /* | |
| 51 ** A memory allocation (also called a "chunk") consists of two or | |
| 52 ** more blocks where each block is 8 bytes. The first 8 bytes are | |
| 53 ** a header that is not returned to the user. | |
| 54 ** | |
| 55 ** A chunk is two or more blocks that is either checked out or | |
| 56 ** free. The first block has format u.hdr. u.hdr.size4x is 4 times the | |
| 57 ** size of the allocation in blocks if the allocation is free. | |
| 58 ** The u.hdr.size4x&1 bit is true if the chunk is checked out and | |
| 59 ** false if the chunk is on the freelist. The u.hdr.size4x&2 bit | |
| 60 ** is true if the previous chunk is checked out and false if the | |
| 61 ** previous chunk is free. The u.hdr.prevSize field is the size of | |
| 62 ** the previous chunk in blocks if the previous chunk is on the | |
| 63 ** freelist. If the previous chunk is checked out, then | |
| 64 ** u.hdr.prevSize can be part of the data for that chunk and should | |
| 65 ** not be read or written. | |
| 66 ** | |
| 67 ** We often identify a chunk by its index in mem3.aPool[]. When | |
| 68 ** this is done, the chunk index refers to the second block of | |
| 69 ** the chunk. In this way, the first chunk has an index of 1. | |
| 70 ** A chunk index of 0 means "no such chunk" and is the equivalent | |
| 71 ** of a NULL pointer. | |
| 72 ** | |
| 73 ** The second block of free chunks is of the form u.list. The | |
| 74 ** two fields form a double-linked list of chunks of related sizes. | |
| 75 ** Pointers to the head of the list are stored in mem3.aiSmall[] | |
| 76 ** for smaller chunks and mem3.aiHash[] for larger chunks. | |
| 77 ** | |
| 78 ** The second block of a chunk is user data if the chunk is checked | |
| 79 ** out. If a chunk is checked out, the user data may extend into | |
| 80 ** the u.hdr.prevSize value of the following chunk. | |
| 81 */ | |
| 82 typedef struct Mem3Block Mem3Block; | |
| 83 struct Mem3Block { | |
| 84 union { | |
| 85 struct { | |
| 86 u32 prevSize; /* Size of previous chunk in Mem3Block elements */ | |
| 87 u32 size4x; /* 4x the size of current chunk in Mem3Block elements */ | |
| 88 } hdr; | |
| 89 struct { | |
| 90 u32 next; /* Index in mem3.aPool[] of next free chunk */ | |
| 91 u32 prev; /* Index in mem3.aPool[] of previous free chunk */ | |
| 92 } list; | |
| 93 } u; | |
| 94 }; | |
| 95 | |
| 96 /* | |
| 97 ** All of the static variables used by this module are collected | |
| 98 ** into a single structure named "mem3". This is to keep the | |
| 99 ** static variables organized and to reduce namespace pollution | |
| 100 ** when this module is combined with other in the amalgamation. | |
| 101 */ | |
| 102 static SQLITE_WSD struct Mem3Global { | |
| 103 /* | |
| 104 ** Memory available for allocation. nPool is the size of the array | |
| 105 ** (in Mem3Blocks) pointed to by aPool less 2. | |
| 106 */ | |
| 107 u32 nPool; | |
| 108 Mem3Block *aPool; | |
| 109 | |
| 110 /* | |
| 111 ** True if we are evaluating an out-of-memory callback. | |
| 112 */ | |
| 113 int alarmBusy; | |
| 114 | |
| 115 /* | |
| 116 ** Mutex to control access to the memory allocation subsystem. | |
| 117 */ | |
| 118 sqlite3_mutex *mutex; | |
| 119 | |
| 120 /* | |
| 121 ** The minimum amount of free space that we have seen. | |
| 122 */ | |
| 123 u32 mnMaster; | |
| 124 | |
| 125 /* | |
| 126 ** iMaster is the index of the master chunk. Most new allocations | |
| 127 ** occur off of this chunk. szMaster is the size (in Mem3Blocks) | |
| 128 ** of the current master. iMaster is 0 if there is not master chunk. | |
| 129 ** The master chunk is not in either the aiHash[] or aiSmall[]. | |
| 130 */ | |
| 131 u32 iMaster; | |
| 132 u32 szMaster; | |
| 133 | |
| 134 /* | |
| 135 ** Array of lists of free blocks according to the block size | |
| 136 ** for smaller chunks, or a hash on the block size for larger | |
| 137 ** chunks. | |
| 138 */ | |
| 139 u32 aiSmall[MX_SMALL-1]; /* For sizes 2 through MX_SMALL, inclusive */ | |
| 140 u32 aiHash[N_HASH]; /* For sizes MX_SMALL+1 and larger */ | |
| 141 } mem3 = { 97535575 }; | |
| 142 | |
| 143 #define mem3 GLOBAL(struct Mem3Global, mem3) | |
| 144 | |
| 145 /* | |
| 146 ** Unlink the chunk at mem3.aPool[i] from list it is currently | |
| 147 ** on. *pRoot is the list that i is a member of. | |
| 148 */ | |
| 149 static void memsys3UnlinkFromList(u32 i, u32 *pRoot){ | |
| 150 u32 next = mem3.aPool[i].u.list.next; | |
| 151 u32 prev = mem3.aPool[i].u.list.prev; | |
| 152 assert( sqlite3_mutex_held(mem3.mutex) ); | |
| 153 if( prev==0 ){ | |
| 154 *pRoot = next; | |
| 155 }else{ | |
| 156 mem3.aPool[prev].u.list.next = next; | |
| 157 } | |
| 158 if( next ){ | |
| 159 mem3.aPool[next].u.list.prev = prev; | |
| 160 } | |
| 161 mem3.aPool[i].u.list.next = 0; | |
| 162 mem3.aPool[i].u.list.prev = 0; | |
| 163 } | |
| 164 | |
| 165 /* | |
| 166 ** Unlink the chunk at index i from | |
| 167 ** whatever list is currently a member of. | |
| 168 */ | |
| 169 static void memsys3Unlink(u32 i){ | |
| 170 u32 size, hash; | |
| 171 assert( sqlite3_mutex_held(mem3.mutex) ); | |
| 172 assert( (mem3.aPool[i-1].u.hdr.size4x & 1)==0 ); | |
| 173 assert( i>=1 ); | |
| 174 size = mem3.aPool[i-1].u.hdr.size4x/4; | |
| 175 assert( size==mem3.aPool[i+size-1].u.hdr.prevSize ); | |
| 176 assert( size>=2 ); | |
| 177 if( size <= MX_SMALL ){ | |
| 178 memsys3UnlinkFromList(i, &mem3.aiSmall[size-2]); | |
| 179 }else{ | |
| 180 hash = size % N_HASH; | |
| 181 memsys3UnlinkFromList(i, &mem3.aiHash[hash]); | |
| 182 } | |
| 183 } | |
| 184 | |
| 185 /* | |
| 186 ** Link the chunk at mem3.aPool[i] so that is on the list rooted | |
| 187 ** at *pRoot. | |
| 188 */ | |
| 189 static void memsys3LinkIntoList(u32 i, u32 *pRoot){ | |
| 190 assert( sqlite3_mutex_held(mem3.mutex) ); | |
| 191 mem3.aPool[i].u.list.next = *pRoot; | |
| 192 mem3.aPool[i].u.list.prev = 0; | |
| 193 if( *pRoot ){ | |
| 194 mem3.aPool[*pRoot].u.list.prev = i; | |
| 195 } | |
| 196 *pRoot = i; | |
| 197 } | |
| 198 | |
| 199 /* | |
| 200 ** Link the chunk at index i into either the appropriate | |
| 201 ** small chunk list, or into the large chunk hash table. | |
| 202 */ | |
| 203 static void memsys3Link(u32 i){ | |
| 204 u32 size, hash; | |
| 205 assert( sqlite3_mutex_held(mem3.mutex) ); | |
| 206 assert( i>=1 ); | |
| 207 assert( (mem3.aPool[i-1].u.hdr.size4x & 1)==0 ); | |
| 208 size = mem3.aPool[i-1].u.hdr.size4x/4; | |
| 209 assert( size==mem3.aPool[i+size-1].u.hdr.prevSize ); | |
| 210 assert( size>=2 ); | |
| 211 if( size <= MX_SMALL ){ | |
| 212 memsys3LinkIntoList(i, &mem3.aiSmall[size-2]); | |
| 213 }else{ | |
| 214 hash = size % N_HASH; | |
| 215 memsys3LinkIntoList(i, &mem3.aiHash[hash]); | |
| 216 } | |
| 217 } | |
| 218 | |
| 219 /* | |
| 220 ** If the STATIC_MEM mutex is not already held, obtain it now. The mutex | |
| 221 ** will already be held (obtained by code in malloc.c) if | |
| 222 ** sqlite3GlobalConfig.bMemStat is true. | |
| 223 */ | |
| 224 static void memsys3Enter(void){ | |
| 225 if( sqlite3GlobalConfig.bMemstat==0 && mem3.mutex==0 ){ | |
| 226 mem3.mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MEM); | |
| 227 } | |
| 228 sqlite3_mutex_enter(mem3.mutex); | |
| 229 } | |
| 230 static void memsys3Leave(void){ | |
| 231 sqlite3_mutex_leave(mem3.mutex); | |
| 232 } | |
| 233 | |
| 234 /* | |
| 235 ** Called when we are unable to satisfy an allocation of nBytes. | |
| 236 */ | |
| 237 static void memsys3OutOfMemory(int nByte){ | |
| 238 if( !mem3.alarmBusy ){ | |
| 239 mem3.alarmBusy = 1; | |
| 240 assert( sqlite3_mutex_held(mem3.mutex) ); | |
| 241 sqlite3_mutex_leave(mem3.mutex); | |
| 242 sqlite3_release_memory(nByte); | |
| 243 sqlite3_mutex_enter(mem3.mutex); | |
| 244 mem3.alarmBusy = 0; | |
| 245 } | |
| 246 } | |
| 247 | |
| 248 | |
| 249 /* | |
| 250 ** Chunk i is a free chunk that has been unlinked. Adjust its | |
| 251 ** size parameters for check-out and return a pointer to the | |
| 252 ** user portion of the chunk. | |
| 253 */ | |
| 254 static void *memsys3Checkout(u32 i, u32 nBlock){ | |
| 255 u32 x; | |
| 256 assert( sqlite3_mutex_held(mem3.mutex) ); | |
| 257 assert( i>=1 ); | |
| 258 assert( mem3.aPool[i-1].u.hdr.size4x/4==nBlock ); | |
| 259 assert( mem3.aPool[i+nBlock-1].u.hdr.prevSize==nBlock ); | |
| 260 x = mem3.aPool[i-1].u.hdr.size4x; | |
| 261 mem3.aPool[i-1].u.hdr.size4x = nBlock*4 | 1 | (x&2); | |
| 262 mem3.aPool[i+nBlock-1].u.hdr.prevSize = nBlock; | |
| 263 mem3.aPool[i+nBlock-1].u.hdr.size4x |= 2; | |
| 264 return &mem3.aPool[i]; | |
| 265 } | |
| 266 | |
| 267 /* | |
| 268 ** Carve a piece off of the end of the mem3.iMaster free chunk. | |
| 269 ** Return a pointer to the new allocation. Or, if the master chunk | |
| 270 ** is not large enough, return 0. | |
| 271 */ | |
| 272 static void *memsys3FromMaster(u32 nBlock){ | |
| 273 assert( sqlite3_mutex_held(mem3.mutex) ); | |
| 274 assert( mem3.szMaster>=nBlock ); | |
| 275 if( nBlock>=mem3.szMaster-1 ){ | |
| 276 /* Use the entire master */ | |
| 277 void *p = memsys3Checkout(mem3.iMaster, mem3.szMaster); | |
| 278 mem3.iMaster = 0; | |
| 279 mem3.szMaster = 0; | |
| 280 mem3.mnMaster = 0; | |
| 281 return p; | |
| 282 }else{ | |
| 283 /* Split the master block. Return the tail. */ | |
| 284 u32 newi, x; | |
| 285 newi = mem3.iMaster + mem3.szMaster - nBlock; | |
| 286 assert( newi > mem3.iMaster+1 ); | |
| 287 mem3.aPool[mem3.iMaster+mem3.szMaster-1].u.hdr.prevSize = nBlock; | |
| 288 mem3.aPool[mem3.iMaster+mem3.szMaster-1].u.hdr.size4x |= 2; | |
| 289 mem3.aPool[newi-1].u.hdr.size4x = nBlock*4 + 1; | |
| 290 mem3.szMaster -= nBlock; | |
| 291 mem3.aPool[newi-1].u.hdr.prevSize = mem3.szMaster; | |
| 292 x = mem3.aPool[mem3.iMaster-1].u.hdr.size4x & 2; | |
| 293 mem3.aPool[mem3.iMaster-1].u.hdr.size4x = mem3.szMaster*4 | x; | |
| 294 if( mem3.szMaster < mem3.mnMaster ){ | |
| 295 mem3.mnMaster = mem3.szMaster; | |
| 296 } | |
| 297 return (void*)&mem3.aPool[newi]; | |
| 298 } | |
| 299 } | |
| 300 | |
| 301 /* | |
| 302 ** *pRoot is the head of a list of free chunks of the same size | |
| 303 ** or same size hash. In other words, *pRoot is an entry in either | |
| 304 ** mem3.aiSmall[] or mem3.aiHash[]. | |
| 305 ** | |
| 306 ** This routine examines all entries on the given list and tries | |
| 307 ** to coalesce each entries with adjacent free chunks. | |
| 308 ** | |
| 309 ** If it sees a chunk that is larger than mem3.iMaster, it replaces | |
| 310 ** the current mem3.iMaster with the new larger chunk. In order for | |
| 311 ** this mem3.iMaster replacement to work, the master chunk must be | |
| 312 ** linked into the hash tables. That is not the normal state of | |
| 313 ** affairs, of course. The calling routine must link the master | |
| 314 ** chunk before invoking this routine, then must unlink the (possibly | |
| 315 ** changed) master chunk once this routine has finished. | |
| 316 */ | |
| 317 static void memsys3Merge(u32 *pRoot){ | |
| 318 u32 iNext, prev, size, i, x; | |
| 319 | |
| 320 assert( sqlite3_mutex_held(mem3.mutex) ); | |
| 321 for(i=*pRoot; i>0; i=iNext){ | |
| 322 iNext = mem3.aPool[i].u.list.next; | |
| 323 size = mem3.aPool[i-1].u.hdr.size4x; | |
| 324 assert( (size&1)==0 ); | |
| 325 if( (size&2)==0 ){ | |
| 326 memsys3UnlinkFromList(i, pRoot); | |
| 327 assert( i > mem3.aPool[i-1].u.hdr.prevSize ); | |
| 328 prev = i - mem3.aPool[i-1].u.hdr.prevSize; | |
| 329 if( prev==iNext ){ | |
| 330 iNext = mem3.aPool[prev].u.list.next; | |
| 331 } | |
| 332 memsys3Unlink(prev); | |
| 333 size = i + size/4 - prev; | |
| 334 x = mem3.aPool[prev-1].u.hdr.size4x & 2; | |
| 335 mem3.aPool[prev-1].u.hdr.size4x = size*4 | x; | |
| 336 mem3.aPool[prev+size-1].u.hdr.prevSize = size; | |
| 337 memsys3Link(prev); | |
| 338 i = prev; | |
| 339 }else{ | |
| 340 size /= 4; | |
| 341 } | |
| 342 if( size>mem3.szMaster ){ | |
| 343 mem3.iMaster = i; | |
| 344 mem3.szMaster = size; | |
| 345 } | |
| 346 } | |
| 347 } | |
| 348 | |
| 349 /* | |
| 350 ** Return a block of memory of at least nBytes in size. | |
| 351 ** Return NULL if unable. | |
| 352 ** | |
| 353 ** This function assumes that the necessary mutexes, if any, are | |
| 354 ** already held by the caller. Hence "Unsafe". | |
| 355 */ | |
| 356 static void *memsys3MallocUnsafe(int nByte){ | |
| 357 u32 i; | |
| 358 u32 nBlock; | |
| 359 u32 toFree; | |
| 360 | |
| 361 assert( sqlite3_mutex_held(mem3.mutex) ); | |
| 362 assert( sizeof(Mem3Block)==8 ); | |
| 363 if( nByte<=12 ){ | |
| 364 nBlock = 2; | |
| 365 }else{ | |
| 366 nBlock = (nByte + 11)/8; | |
| 367 } | |
| 368 assert( nBlock>=2 ); | |
| 369 | |
| 370 /* STEP 1: | |
| 371 ** Look for an entry of the correct size in either the small | |
| 372 ** chunk table or in the large chunk hash table. This is | |
| 373 ** successful most of the time (about 9 times out of 10). | |
| 374 */ | |
| 375 if( nBlock <= MX_SMALL ){ | |
| 376 i = mem3.aiSmall[nBlock-2]; | |
| 377 if( i>0 ){ | |
| 378 memsys3UnlinkFromList(i, &mem3.aiSmall[nBlock-2]); | |
| 379 return memsys3Checkout(i, nBlock); | |
| 380 } | |
| 381 }else{ | |
| 382 int hash = nBlock % N_HASH; | |
| 383 for(i=mem3.aiHash[hash]; i>0; i=mem3.aPool[i].u.list.next){ | |
| 384 if( mem3.aPool[i-1].u.hdr.size4x/4==nBlock ){ | |
| 385 memsys3UnlinkFromList(i, &mem3.aiHash[hash]); | |
| 386 return memsys3Checkout(i, nBlock); | |
| 387 } | |
| 388 } | |
| 389 } | |
| 390 | |
| 391 /* STEP 2: | |
| 392 ** Try to satisfy the allocation by carving a piece off of the end | |
| 393 ** of the master chunk. This step usually works if step 1 fails. | |
| 394 */ | |
| 395 if( mem3.szMaster>=nBlock ){ | |
| 396 return memsys3FromMaster(nBlock); | |
| 397 } | |
| 398 | |
| 399 | |
| 400 /* STEP 3: | |
| 401 ** Loop through the entire memory pool. Coalesce adjacent free | |
| 402 ** chunks. Recompute the master chunk as the largest free chunk. | |
| 403 ** Then try again to satisfy the allocation by carving a piece off | |
| 404 ** of the end of the master chunk. This step happens very | |
| 405 ** rarely (we hope!) | |
| 406 */ | |
| 407 for(toFree=nBlock*16; toFree<(mem3.nPool*16); toFree *= 2){ | |
| 408 memsys3OutOfMemory(toFree); | |
| 409 if( mem3.iMaster ){ | |
| 410 memsys3Link(mem3.iMaster); | |
| 411 mem3.iMaster = 0; | |
| 412 mem3.szMaster = 0; | |
| 413 } | |
| 414 for(i=0; i<N_HASH; i++){ | |
| 415 memsys3Merge(&mem3.aiHash[i]); | |
| 416 } | |
| 417 for(i=0; i<MX_SMALL-1; i++){ | |
| 418 memsys3Merge(&mem3.aiSmall[i]); | |
| 419 } | |
| 420 if( mem3.szMaster ){ | |
| 421 memsys3Unlink(mem3.iMaster); | |
| 422 if( mem3.szMaster>=nBlock ){ | |
| 423 return memsys3FromMaster(nBlock); | |
| 424 } | |
| 425 } | |
| 426 } | |
| 427 | |
| 428 /* If none of the above worked, then we fail. */ | |
| 429 return 0; | |
| 430 } | |
| 431 | |
| 432 /* | |
| 433 ** Free an outstanding memory allocation. | |
| 434 ** | |
| 435 ** This function assumes that the necessary mutexes, if any, are | |
| 436 ** already held by the caller. Hence "Unsafe". | |
| 437 */ | |
| 438 void memsys3FreeUnsafe(void *pOld){ | |
| 439 Mem3Block *p = (Mem3Block*)pOld; | |
| 440 int i; | |
| 441 u32 size, x; | |
| 442 assert( sqlite3_mutex_held(mem3.mutex) ); | |
| 443 assert( p>mem3.aPool && p<&mem3.aPool[mem3.nPool] ); | |
| 444 i = p - mem3.aPool; | |
| 445 assert( (mem3.aPool[i-1].u.hdr.size4x&1)==1 ); | |
| 446 size = mem3.aPool[i-1].u.hdr.size4x/4; | |
| 447 assert( i+size<=mem3.nPool+1 ); | |
| 448 mem3.aPool[i-1].u.hdr.size4x &= ~1; | |
| 449 mem3.aPool[i+size-1].u.hdr.prevSize = size; | |
| 450 mem3.aPool[i+size-1].u.hdr.size4x &= ~2; | |
| 451 memsys3Link(i); | |
| 452 | |
| 453 /* Try to expand the master using the newly freed chunk */ | |
| 454 if( mem3.iMaster ){ | |
| 455 while( (mem3.aPool[mem3.iMaster-1].u.hdr.size4x&2)==0 ){ | |
| 456 size = mem3.aPool[mem3.iMaster-1].u.hdr.prevSize; | |
| 457 mem3.iMaster -= size; | |
| 458 mem3.szMaster += size; | |
| 459 memsys3Unlink(mem3.iMaster); | |
| 460 x = mem3.aPool[mem3.iMaster-1].u.hdr.size4x & 2; | |
| 461 mem3.aPool[mem3.iMaster-1].u.hdr.size4x = mem3.szMaster*4 | x; | |
| 462 mem3.aPool[mem3.iMaster+mem3.szMaster-1].u.hdr.prevSize = mem3.szMaster; | |
| 463 } | |
| 464 x = mem3.aPool[mem3.iMaster-1].u.hdr.size4x & 2; | |
| 465 while( (mem3.aPool[mem3.iMaster+mem3.szMaster-1].u.hdr.size4x&1)==0 ){ | |
| 466 memsys3Unlink(mem3.iMaster+mem3.szMaster); | |
| 467 mem3.szMaster += mem3.aPool[mem3.iMaster+mem3.szMaster-1].u.hdr.size4x/4; | |
| 468 mem3.aPool[mem3.iMaster-1].u.hdr.size4x = mem3.szMaster*4 | x; | |
| 469 mem3.aPool[mem3.iMaster+mem3.szMaster-1].u.hdr.prevSize = mem3.szMaster; | |
| 470 } | |
| 471 } | |
| 472 } | |
| 473 | |
| 474 /* | |
| 475 ** Return the size of an outstanding allocation, in bytes. The | |
| 476 ** size returned omits the 8-byte header overhead. This only | |
| 477 ** works for chunks that are currently checked out. | |
| 478 */ | |
| 479 static int memsys3Size(void *p){ | |
| 480 Mem3Block *pBlock; | |
| 481 if( p==0 ) return 0; | |
| 482 pBlock = (Mem3Block*)p; | |
| 483 assert( (pBlock[-1].u.hdr.size4x&1)!=0 ); | |
| 484 return (pBlock[-1].u.hdr.size4x&~3)*2 - 4; | |
| 485 } | |
| 486 | |
| 487 /* | |
| 488 ** Round up a request size to the next valid allocation size. | |
| 489 */ | |
| 490 static int memsys3Roundup(int n){ | |
| 491 if( n<=12 ){ | |
| 492 return 12; | |
| 493 }else{ | |
| 494 return ((n+11)&~7) - 4; | |
| 495 } | |
| 496 } | |
| 497 | |
| 498 /* | |
| 499 ** Allocate nBytes of memory. | |
| 500 */ | |
| 501 static void *memsys3Malloc(int nBytes){ | |
| 502 sqlite3_int64 *p; | |
| 503 assert( nBytes>0 ); /* malloc.c filters out 0 byte requests */ | |
| 504 memsys3Enter(); | |
| 505 p = memsys3MallocUnsafe(nBytes); | |
| 506 memsys3Leave(); | |
| 507 return (void*)p; | |
| 508 } | |
| 509 | |
| 510 /* | |
| 511 ** Free memory. | |
| 512 */ | |
| 513 void memsys3Free(void *pPrior){ | |
| 514 assert( pPrior ); | |
| 515 memsys3Enter(); | |
| 516 memsys3FreeUnsafe(pPrior); | |
| 517 memsys3Leave(); | |
| 518 } | |
| 519 | |
| 520 /* | |
| 521 ** Change the size of an existing memory allocation | |
| 522 */ | |
| 523 void *memsys3Realloc(void *pPrior, int nBytes){ | |
| 524 int nOld; | |
| 525 void *p; | |
| 526 if( pPrior==0 ){ | |
| 527 return sqlite3_malloc(nBytes); | |
| 528 } | |
| 529 if( nBytes<=0 ){ | |
| 530 sqlite3_free(pPrior); | |
| 531 return 0; | |
| 532 } | |
| 533 nOld = memsys3Size(pPrior); | |
| 534 if( nBytes<=nOld && nBytes>=nOld-128 ){ | |
| 535 return pPrior; | |
| 536 } | |
| 537 memsys3Enter(); | |
| 538 p = memsys3MallocUnsafe(nBytes); | |
| 539 if( p ){ | |
| 540 if( nOld<nBytes ){ | |
| 541 memcpy(p, pPrior, nOld); | |
| 542 }else{ | |
| 543 memcpy(p, pPrior, nBytes); | |
| 544 } | |
| 545 memsys3FreeUnsafe(pPrior); | |
| 546 } | |
| 547 memsys3Leave(); | |
| 548 return p; | |
| 549 } | |
| 550 | |
| 551 /* | |
| 552 ** Initialize this module. | |
| 553 */ | |
| 554 static int memsys3Init(void *NotUsed){ | |
| 555 UNUSED_PARAMETER(NotUsed); | |
| 556 if( !sqlite3GlobalConfig.pHeap ){ | |
| 557 return SQLITE_ERROR; | |
| 558 } | |
| 559 | |
| 560 /* Store a pointer to the memory block in global structure mem3. */ | |
| 561 assert( sizeof(Mem3Block)==8 ); | |
| 562 mem3.aPool = (Mem3Block *)sqlite3GlobalConfig.pHeap; | |
| 563 mem3.nPool = (sqlite3GlobalConfig.nHeap / sizeof(Mem3Block)) - 2; | |
| 564 | |
| 565 /* Initialize the master block. */ | |
| 566 mem3.szMaster = mem3.nPool; | |
| 567 mem3.mnMaster = mem3.szMaster; | |
| 568 mem3.iMaster = 1; | |
| 569 mem3.aPool[0].u.hdr.size4x = (mem3.szMaster<<2) + 2; | |
| 570 mem3.aPool[mem3.nPool].u.hdr.prevSize = mem3.nPool; | |
| 571 mem3.aPool[mem3.nPool].u.hdr.size4x = 1; | |
| 572 | |
| 573 return SQLITE_OK; | |
| 574 } | |
| 575 | |
| 576 /* | |
| 577 ** Deinitialize this module. | |
| 578 */ | |
| 579 static void memsys3Shutdown(void *NotUsed){ | |
| 580 UNUSED_PARAMETER(NotUsed); | |
| 581 return; | |
| 582 } | |
| 583 | |
| 584 | |
| 585 | |
| 586 /* | |
| 587 ** Open the file indicated and write a log of all unfreed memory | |
| 588 ** allocations into that log. | |
| 589 */ | |
| 590 void sqlite3Memsys3Dump(const char *zFilename){ | |
| 591 #ifdef SQLITE_DEBUG | |
| 592 FILE *out; | |
| 593 u32 i, j; | |
| 594 u32 size; | |
| 595 if( zFilename==0 || zFilename[0]==0 ){ | |
| 596 out = stdout; | |
| 597 }else{ | |
| 598 out = fopen(zFilename, "w"); | |
| 599 if( out==0 ){ | |
| 600 fprintf(stderr, "** Unable to output memory debug output log: %s **\n", | |
| 601 zFilename); | |
| 602 return; | |
| 603 } | |
| 604 } | |
| 605 memsys3Enter(); | |
| 606 fprintf(out, "CHUNKS:\n"); | |
| 607 for(i=1; i<=mem3.nPool; i+=size/4){ | |
| 608 size = mem3.aPool[i-1].u.hdr.size4x; | |
| 609 if( size/4<=1 ){ | |
| 610 fprintf(out, "%p size error\n", &mem3.aPool[i]); | |
| 611 assert( 0 ); | |
| 612 break; | |
| 613 } | |
| 614 if( (size&1)==0 && mem3.aPool[i+size/4-1].u.hdr.prevSize!=size/4 ){ | |
| 615 fprintf(out, "%p tail size does not match\n", &mem3.aPool[i]); | |
| 616 assert( 0 ); | |
| 617 break; | |
| 618 } | |
| 619 if( ((mem3.aPool[i+size/4-1].u.hdr.size4x&2)>>1)!=(size&1) ){ | |
| 620 fprintf(out, "%p tail checkout bit is incorrect\n", &mem3.aPool[i]); | |
| 621 assert( 0 ); | |
| 622 break; | |
| 623 } | |
| 624 if( size&1 ){ | |
| 625 fprintf(out, "%p %6d bytes checked out\n", &mem3.aPool[i], (size/4)*8-8); | |
| 626 }else{ | |
| 627 fprintf(out, "%p %6d bytes free%s\n", &mem3.aPool[i], (size/4)*8-8, | |
| 628 i==mem3.iMaster ? " **master**" : ""); | |
| 629 } | |
| 630 } | |
| 631 for(i=0; i<MX_SMALL-1; i++){ | |
| 632 if( mem3.aiSmall[i]==0 ) continue; | |
| 633 fprintf(out, "small(%2d):", i); | |
| 634 for(j = mem3.aiSmall[i]; j>0; j=mem3.aPool[j].u.list.next){ | |
| 635 fprintf(out, " %p(%d)", &mem3.aPool[j], | |
| 636 (mem3.aPool[j-1].u.hdr.size4x/4)*8-8); | |
| 637 } | |
| 638 fprintf(out, "\n"); | |
| 639 } | |
| 640 for(i=0; i<N_HASH; i++){ | |
| 641 if( mem3.aiHash[i]==0 ) continue; | |
| 642 fprintf(out, "hash(%2d):", i); | |
| 643 for(j = mem3.aiHash[i]; j>0; j=mem3.aPool[j].u.list.next){ | |
| 644 fprintf(out, " %p(%d)", &mem3.aPool[j], | |
| 645 (mem3.aPool[j-1].u.hdr.size4x/4)*8-8); | |
| 646 } | |
| 647 fprintf(out, "\n"); | |
| 648 } | |
| 649 fprintf(out, "master=%d\n", mem3.iMaster); | |
| 650 fprintf(out, "nowUsed=%d\n", mem3.nPool*8 - mem3.szMaster*8); | |
| 651 fprintf(out, "mxUsed=%d\n", mem3.nPool*8 - mem3.mnMaster*8); | |
| 652 sqlite3_mutex_leave(mem3.mutex); | |
| 653 if( out==stdout ){ | |
| 654 fflush(stdout); | |
| 655 }else{ | |
| 656 fclose(out); | |
| 657 } | |
| 658 #else | |
| 659 UNUSED_PARAMETER(zFilename); | |
| 660 #endif | |
| 661 } | |
| 662 | |
| 663 /* | |
| 664 ** This routine is the only routine in this file with external | |
| 665 ** linkage. | |
| 666 ** | |
| 667 ** Populate the low-level memory allocation function pointers in | |
| 668 ** sqlite3GlobalConfig.m with pointers to the routines in this file. The | |
| 669 ** arguments specify the block of memory to manage. | |
| 670 ** | |
| 671 ** This routine is only called by sqlite3_config(), and therefore | |
| 672 ** is not required to be threadsafe (it is not). | |
| 673 */ | |
| 674 const sqlite3_mem_methods *sqlite3MemGetMemsys3(void){ | |
| 675 static const sqlite3_mem_methods mempoolMethods = { | |
| 676 memsys3Malloc, | |
| 677 memsys3Free, | |
| 678 memsys3Realloc, | |
| 679 memsys3Size, | |
| 680 memsys3Roundup, | |
| 681 memsys3Init, | |
| 682 memsys3Shutdown, | |
| 683 0 | |
| 684 }; | |
| 685 return &mempoolMethods; | |
| 686 } | |
| 687 | |
| 688 #endif /* SQLITE_ENABLE_MEMSYS3 */ | |
| OLD | NEW |
|---|
Chromium Code Reviews
Issue 3108030:
Move bundled copy of sqlite one level deeper to better separate it... (Closed)
Base URL: svn://svn.chromium.org/chrome/trunk/src/