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Overview
Comment: | More simplifications and performance improvements to cell allocation logic associated with allocateSpace(). |
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Downloads: | Tarball | ZIP archive |
Timelines: | family | ancestors | descendants | both | trunk |
Files: | files | file ages | folders |
SHA1: |
78da0f69cb3289e332018864004f319f |
User & Date: | drh 2015-06-25 18:36:13.826 |
Context
2015-06-25
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19:53 | Simplifications and performance improvements in insertCell(). (check-in: 7d02e6c992 user: drh tags: trunk) | |
18:36 | More simplifications and performance improvements to cell allocation logic associated with allocateSpace(). (check-in: 78da0f69cb user: drh tags: trunk) | |
16:01 | Reorder the terms of a conditional for a small performance gain. (check-in: d67b0ed105 user: drh tags: trunk) | |
Changes
Changes to src/btree.c.
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1347 1348 1349 1350 1351 1352 1353 | ** from the free-list. ** ** If no suitable space can be found on the free-list, return NULL. ** ** This function may detect corruption within pPg. If corruption is ** detected then *pRc is set to SQLITE_CORRUPT and NULL is returned. ** | | > | < | | > | < > > < | | < < | > > | | 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 | ** from the free-list. ** ** If no suitable space can be found on the free-list, return NULL. ** ** This function may detect corruption within pPg. If corruption is ** detected then *pRc is set to SQLITE_CORRUPT and NULL is returned. ** ** Slots on the free list that are between 1 and 3 bytes larger than nByte ** will be ignored if adding the extra space to the fragmentation count ** causes the fragmentation count to exceed 60. */ static u8 *pageFindSlot(MemPage *pPg, int nByte, int *pRc){ const int hdr = pPg->hdrOffset; u8 * const aData = pPg->aData; int iAddr = hdr + 1; int pc = get2byte(&aData[iAddr]); int x; int usableSize = pPg->pBt->usableSize; assert( pc>0 ); do{ int size; /* Size of the free slot */ /* EVIDENCE-OF: R-06866-39125 Freeblocks are always connected in order of ** increasing offset. */ if( pc>usableSize-4 || pc<iAddr+4 ){ *pRc = SQLITE_CORRUPT_BKPT; return 0; } /* EVIDENCE-OF: R-22710-53328 The third and fourth bytes of each ** freeblock form a big-endian integer which is the size of the freeblock ** in bytes, including the 4-byte header. */ size = get2byte(&aData[pc+2]); if( (x = size - nByte)>=0 ){ testcase( x==4 ); testcase( x==3 ); if( pc < pPg->cellOffset+2*pPg->nCell || size+pc > usableSize ){ *pRc = SQLITE_CORRUPT_BKPT; return 0; }else if( x<4 ){ /* EVIDENCE-OF: R-11498-58022 In a well-formed b-tree page, the total ** number of bytes in fragments may not exceed 60. */ if( aData[hdr+7]>57 ) return 0; /* Remove the slot from the free-list. Update the number of ** fragmented bytes within the page. */ memcpy(&aData[iAddr], &aData[pc], 2); aData[hdr+7] += (u8)x; }else{ /* The slot remains on the free-list. Reduce its size to account ** for the portion used by the new allocation. */ put2byte(&aData[pc+2], x); } return &aData[pc + x]; } iAddr = pc; pc = get2byte(&aData[pc]); }while( pc ); return 0; } /* ** Allocate nByte bytes of space from within the B-Tree page passed ** as the first argument. Write into *pIdx the index into pPage->aData[] |
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1454 1455 1456 1457 1458 1459 1460 | ** array entry offset, and if the freelist is not empty, then search the ** freelist looking for a free slot big enough to satisfy the request. */ testcase( gap+2==top ); testcase( gap+1==top ); testcase( gap==top ); if( (data[hdr+2] || data[hdr+1]) && gap+2<=top ){ | < | < < > > < | 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 | ** array entry offset, and if the freelist is not empty, then search the ** freelist looking for a free slot big enough to satisfy the request. */ testcase( gap+2==top ); testcase( gap+1==top ); testcase( gap==top ); if( (data[hdr+2] || data[hdr+1]) && gap+2<=top ){ u8 *pSpace = pageFindSlot(pPage, nByte, &rc); if( pSpace ){ assert( pSpace>=data && (pSpace - data)<65536 ); *pIdx = (int)(pSpace - data); return SQLITE_OK; }else if( rc ){ return rc; } } /* The request could not be fulfilled using a freelist slot. Check ** to see if defragmentation is necessary. */ testcase( gap+2+nByte==top ); if( gap+2+nByte>top ){ assert( pPage->nCell>0 || CORRUPT_DB ); rc = defragmentPage(pPage); if( rc ) return rc; top = get2byteNotZero(&data[hdr+5]); assert( gap+nByte<=top ); } |
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6410 6411 6412 6413 6414 6415 6416 | int iFirst, /* Index of first cell to add */ int nCell, /* Number of cells to add to pPg */ CellArray *pCArray /* Array of cells */ ){ int i; u8 *aData = pPg->aData; u8 *pData = *ppData; | < | | 6409 6410 6411 6412 6413 6414 6415 6416 6417 6418 6419 6420 6421 6422 6423 6424 6425 6426 6427 6428 6429 | int iFirst, /* Index of first cell to add */ int nCell, /* Number of cells to add to pPg */ CellArray *pCArray /* Array of cells */ ){ int i; u8 *aData = pPg->aData; u8 *pData = *ppData; int iEnd = iFirst + nCell; assert( CORRUPT_DB || pPg->hdrOffset==0 ); /* Never called on page 1 */ for(i=iFirst; i<iEnd; i++){ int sz, rc; u8 *pSlot; sz = cachedCellSize(pCArray, i); if( (aData[1]==0 && aData[2]==0) || (pSlot = pageFindSlot(pPg,sz,&rc))==0 ){ pData -= sz; if( pData<pBegin ) return 1; pSlot = pData; } memcpy(pSlot, pCArray->apCell[i], sz); put2byte(pCellptr, (pSlot - aData)); pCellptr += 2; |
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