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Overview
Comment: | Avoid unnecessary zeroing of fields in the MemPage object that are going to be reinitialized before use anyhow. A smaller and faster binary results. |
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Downloads: | Tarball | ZIP archive |
Timelines: | family | ancestors | descendants | both | trunk |
Files: | files | file ages | folders |
SHA1: |
01ada3d1068476f90dcae02cb089001e |
User & Date: | drh 2016-12-09 16:02:00.219 |
Context
2016-12-09
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16:12 | Fix an fts5 bug that could cause a crash following an OOM error or sqlite3_interrupt() interrupt. (check-in: 0ea3ece988 user: dan tags: trunk) | |
16:02 | Avoid unnecessary zeroing of fields in the MemPage object that are going to be reinitialized before use anyhow. A smaller and faster binary results. (check-in: 01ada3d106 user: drh tags: trunk) | |
00:15 | Fix an obscure problem in range estimation with STAT4. (check-in: 1f16c9a76b user: drh tags: trunk) | |
Changes
Changes to src/btree.c.
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2278 2279 2280 2281 2282 2283 2284 | pBt = sqlite3MallocZero( sizeof(*pBt) ); if( pBt==0 ){ rc = SQLITE_NOMEM_BKPT; goto btree_open_out; } rc = sqlite3PagerOpen(pVfs, &pBt->pPager, zFilename, | | | 2278 2279 2280 2281 2282 2283 2284 2285 2286 2287 2288 2289 2290 2291 2292 | pBt = sqlite3MallocZero( sizeof(*pBt) ); if( pBt==0 ){ rc = SQLITE_NOMEM_BKPT; goto btree_open_out; } rc = sqlite3PagerOpen(pVfs, &pBt->pPager, zFilename, sizeof(MemPage), flags, vfsFlags, pageReinit); if( rc==SQLITE_OK ){ sqlite3PagerSetMmapLimit(pBt->pPager, db->szMmap); rc = sqlite3PagerReadFileheader(pBt->pPager,sizeof(zDbHeader),zDbHeader); } if( rc!=SQLITE_OK ){ goto btree_open_out; } |
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6255 6256 6257 6258 6259 6260 6261 | u32 pc; /* Offset to cell content of cell being deleted */ u8 *data; /* pPage->aData */ u8 *ptr; /* Used to move bytes around within data[] */ int rc; /* The return code */ int hdr; /* Beginning of the header. 0 most pages. 100 page 1 */ if( *pRC ) return; | < | 6255 6256 6257 6258 6259 6260 6261 6262 6263 6264 6265 6266 6267 6268 | u32 pc; /* Offset to cell content of cell being deleted */ u8 *data; /* pPage->aData */ u8 *ptr; /* Used to move bytes around within data[] */ int rc; /* The return code */ int hdr; /* Beginning of the header. 0 most pages. 100 page 1 */ if( *pRC ) return; assert( idx>=0 && idx<pPage->nCell ); assert( CORRUPT_DB || sz==cellSize(pPage, idx) ); assert( sqlite3PagerIswriteable(pPage->pDbPage) ); assert( sqlite3_mutex_held(pPage->pBt->mutex) ); data = pPage->aData; ptr = &pPage->aCellIdx[2*idx]; pc = get2byte(ptr); |
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6339 6340 6341 6342 6343 6344 6345 | memcpy(pTemp, pCell, sz); pCell = pTemp; } if( iChild ){ put4byte(pCell, iChild); } j = pPage->nOverflow++; | > > > | | 6338 6339 6340 6341 6342 6343 6344 6345 6346 6347 6348 6349 6350 6351 6352 6353 6354 6355 | memcpy(pTemp, pCell, sz); pCell = pTemp; } if( iChild ){ put4byte(pCell, iChild); } j = pPage->nOverflow++; /* Comparison against ArraySize-1 since we hold back one extra slot ** as a contingency. In other words, never need more than 3 overflow ** slots but 4 are allocated, just to be safe. */ assert( j < ArraySize(pPage->apOvfl)-1 ); pPage->apOvfl[j] = pCell; pPage->aiOvfl[j] = (u16)i; /* When multiple overflows occur, they are always sequential and in ** sorted order. This invariants arise because multiple overflows can ** only occur when inserting divider cells into the parent page during ** balancing, and the dividers are adjacent and sorted. |
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Changes to src/btreeInt.h.
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255 256 257 258 259 260 261 | */ #define PTF_INTKEY 0x01 #define PTF_ZERODATA 0x02 #define PTF_LEAFDATA 0x04 #define PTF_LEAF 0x08 /* | | | | | | | < | > > > | | | < < < < < < < < | 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 | */ #define PTF_INTKEY 0x01 #define PTF_ZERODATA 0x02 #define PTF_LEAFDATA 0x04 #define PTF_LEAF 0x08 /* ** An instance of this object stores information about each a single database ** page that has been loaded into memory. The information in this object ** is derived from the raw on-disk page content. ** ** As each database page is loaded into memory, the pager allocats an ** instance of this object and zeros the first 8 bytes. (This is the ** "extra" information associated with each page of the pager.) ** ** Access to all fields of this structure is controlled by the mutex ** stored in MemPage.pBt->mutex. */ struct MemPage { u8 isInit; /* True if previously initialized. MUST BE FIRST! */ u8 bBusy; /* Prevent endless loops on corrupt database files */ u8 intKey; /* True if table b-trees. False for index b-trees */ u8 intKeyLeaf; /* True if the leaf of an intKey table */ Pgno pgno; /* Page number for this page */ /* Only the first 8 bytes (above) are zeroed by pager.c when a new page ** is allocated. All fields that follow must be initialized before use */ u8 leaf; /* True if a leaf page */ u8 hdrOffset; /* 100 for page 1. 0 otherwise */ u8 childPtrSize; /* 0 if leaf==1. 4 if leaf==0 */ u8 max1bytePayload; /* min(maxLocal,127) */ u8 nOverflow; /* Number of overflow cell bodies in aCell[] */ u16 maxLocal; /* Copy of BtShared.maxLocal or BtShared.maxLeaf */ u16 minLocal; /* Copy of BtShared.minLocal or BtShared.minLeaf */ u16 cellOffset; /* Index in aData of first cell pointer */ u16 nFree; /* Number of free bytes on the page */ u16 nCell; /* Number of cells on this page, local and ovfl */ u16 maskPage; /* Mask for page offset */ u16 aiOvfl[4]; /* Insert the i-th overflow cell before the aiOvfl-th ** non-overflow cell */ u8 *apOvfl[4]; /* Pointers to the body of overflow cells */ BtShared *pBt; /* Pointer to BtShared that this page is part of */ u8 *aData; /* Pointer to disk image of the page data */ u8 *aDataEnd; /* One byte past the end of usable data */ u8 *aCellIdx; /* The cell index area */ u8 *aDataOfst; /* Same as aData for leaves. aData+4 for interior */ DbPage *pDbPage; /* Pager page handle */ u16 (*xCellSize)(MemPage*,u8*); /* cellSizePtr method */ void (*xParseCell)(MemPage*,u8*,CellInfo*); /* btreeParseCell method */ }; /* ** A linked list of the following structures is stored at BtShared.pLock. ** Locks are added (or upgraded from READ_LOCK to WRITE_LOCK) when a cursor ** is opened on the table with root page BtShared.iTable. Locks are removed ** from this list when a transaction is committed or rolled back, or when ** a btree handle is closed. */ |
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Changes to src/pager.c.
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3951 3952 3953 3954 3955 3956 3957 | ){ PgHdr *p; /* Memory mapped page to return */ if( pPager->pMmapFreelist ){ *ppPage = p = pPager->pMmapFreelist; pPager->pMmapFreelist = p->pDirty; p->pDirty = 0; | > | | 3951 3952 3953 3954 3955 3956 3957 3958 3959 3960 3961 3962 3963 3964 3965 3966 | ){ PgHdr *p; /* Memory mapped page to return */ if( pPager->pMmapFreelist ){ *ppPage = p = pPager->pMmapFreelist; pPager->pMmapFreelist = p->pDirty; p->pDirty = 0; assert( pPager->nExtra>=8 ); memset(p->pExtra, 0, 8); }else{ *ppPage = p = (PgHdr *)sqlite3MallocZero(sizeof(PgHdr) + pPager->nExtra); if( p==0 ){ sqlite3OsUnfetch(pPager->fd, (i64)(pgno-1) * pPager->pageSize, pData); return SQLITE_NOMEM_BKPT; } p->pExtra = (void *)&p[1]; |
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4551 4552 4553 4554 4555 4556 4557 | ** and used as the file to be cached. Temporary files are be deleted ** automatically when they are closed. If zFilename is ":memory:" then ** all information is held in cache. It is never written to disk. ** This can be used to implement an in-memory database. ** ** The nExtra parameter specifies the number of bytes of space allocated ** along with each page reference. This space is available to the user | | > > | 4552 4553 4554 4555 4556 4557 4558 4559 4560 4561 4562 4563 4564 4565 4566 4567 4568 | ** and used as the file to be cached. Temporary files are be deleted ** automatically when they are closed. If zFilename is ":memory:" then ** all information is held in cache. It is never written to disk. ** This can be used to implement an in-memory database. ** ** The nExtra parameter specifies the number of bytes of space allocated ** along with each page reference. This space is available to the user ** via the sqlite3PagerGetExtra() API. When a new page is allocated, the ** first 8 bytes of this space are zeroed but the remainder is uninitialized. ** (The extra space is used by btree as the MemPage object.) ** ** The flags argument is used to specify properties that affect the ** operation of the pager. It should be passed some bitwise combination ** of the PAGER_* flags. ** ** The vfsFlags parameter is a bitmask to pass to the flags parameter ** of the xOpen() method of the supplied VFS when opening files. |
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4781 4782 4783 4784 4785 4786 4787 | assert( pPager->memDb==0 ); rc = sqlite3PagerSetPagesize(pPager, &szPageDflt, -1); testcase( rc!=SQLITE_OK ); } /* Initialize the PCache object. */ if( rc==SQLITE_OK ){ | < > | 4784 4785 4786 4787 4788 4789 4790 4791 4792 4793 4794 4795 4796 4797 4798 4799 | assert( pPager->memDb==0 ); rc = sqlite3PagerSetPagesize(pPager, &szPageDflt, -1); testcase( rc!=SQLITE_OK ); } /* Initialize the PCache object. */ if( rc==SQLITE_OK ){ nExtra = ROUND8(nExtra); assert( nExtra>=8 && nExtra<1000 ); rc = sqlite3PcacheOpen(szPageDflt, nExtra, !memDb, !memDb?pagerStress:0, (void *)pPager, pPager->pPCache); } /* If an error occurred above, free the Pager structure and close the file. */ if( rc!=SQLITE_OK ){ |
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Changes to src/pcache.c.
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280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 | int sqlite3PcacheSize(void){ return sizeof(PCache); } /* ** Create a new PCache object. Storage space to hold the object ** has already been allocated and is passed in as the p pointer. ** The caller discovers how much space needs to be allocated by ** calling sqlite3PcacheSize(). */ int sqlite3PcacheOpen( int szPage, /* Size of every page */ int szExtra, /* Extra space associated with each page */ int bPurgeable, /* True if pages are on backing store */ int (*xStress)(void*,PgHdr*),/* Call to try to make pages clean */ void *pStress, /* Argument to xStress */ PCache *p /* Preallocated space for the PCache */ ){ memset(p, 0, sizeof(PCache)); p->szPage = 1; p->szExtra = szExtra; p->bPurgeable = bPurgeable; p->eCreate = 2; p->xStress = xStress; p->pStress = pStress; p->szCache = 100; p->szSpill = 1; pcacheTrace(("%p.OPEN szPage %d bPurgeable %d\n",p,szPage,bPurgeable)); | > > > > > > > | 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 | int sqlite3PcacheSize(void){ return sizeof(PCache); } /* ** Create a new PCache object. Storage space to hold the object ** has already been allocated and is passed in as the p pointer. ** The caller discovers how much space needs to be allocated by ** calling sqlite3PcacheSize(). ** ** szExtra is some extra space allocated for each page. The first ** 8 bytes of the extra space will be zeroed as the page is allocated, ** but remaining content will be uninitialized. Though it is opaque ** to this module, the extra space really ends up being the MemPage ** structure in the pager. */ int sqlite3PcacheOpen( int szPage, /* Size of every page */ int szExtra, /* Extra space associated with each page */ int bPurgeable, /* True if pages are on backing store */ int (*xStress)(void*,PgHdr*),/* Call to try to make pages clean */ void *pStress, /* Argument to xStress */ PCache *p /* Preallocated space for the PCache */ ){ memset(p, 0, sizeof(PCache)); p->szPage = 1; p->szExtra = szExtra; assert( szExtra>=8 ); /* First 8 bytes will be zeroed */ p->bPurgeable = bPurgeable; p->eCreate = 2; p->xStress = xStress; p->pStress = pStress; p->szCache = 100; p->szSpill = 1; pcacheTrace(("%p.OPEN szPage %d bPurgeable %d\n",p,szPage,bPurgeable)); |
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461 462 463 464 465 466 467 | assert( pPage!=0 ); pPgHdr = (PgHdr*)pPage->pExtra; assert( pPgHdr->pPage==0 ); memset(&pPgHdr->pDirty, 0, sizeof(PgHdr) - offsetof(PgHdr,pDirty)); pPgHdr->pPage = pPage; pPgHdr->pData = pPage->pBuf; pPgHdr->pExtra = (void *)&pPgHdr[1]; | | | 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 | assert( pPage!=0 ); pPgHdr = (PgHdr*)pPage->pExtra; assert( pPgHdr->pPage==0 ); memset(&pPgHdr->pDirty, 0, sizeof(PgHdr) - offsetof(PgHdr,pDirty)); pPgHdr->pPage = pPage; pPgHdr->pData = pPage->pBuf; pPgHdr->pExtra = (void *)&pPgHdr[1]; memset(pPgHdr->pExtra, 0, 8); pPgHdr->pCache = pCache; pPgHdr->pgno = pgno; pPgHdr->flags = PGHDR_CLEAN; return sqlite3PcacheFetchFinish(pCache,pgno,pPage); } /* |
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