/*
** Initialize iterator pIter to scan through the PMA stored in file pFile
** starting at offset iStart and ending at offset iEof-1. This function
** leaves the iterator pointing to the first key in the PMA (or EOF if the
** PMA is empty).
*/
static int vdbeSorterIterInit(
sqlite3 *db, /* Database handle */
VdbeSorter *pSorter, /* Sorter object */
i64 iStart, /* Start offset in pFile */
VdbeSorterIter *pIter, /* Iterator to populate */
i64 *pnByte /* IN/OUT: Increment this value by PMA size */
){
int rc;
assert( pSorter->iWriteOff>iStart );
assert( pIter->aAlloc==0 );
pIter->pFile = pSorter->pTemp1;
pIter->iReadOff = iStart;
pIter->nAlloc = 128;
pIter->aAlloc = (u8 *)sqlite3DbMallocRaw(db, pIter->nAlloc);
if( !pIter->aAlloc ){
rc = SQLITE_NOMEM;
}else{
i64 nByte; /* Total size of PMA in bytes */
rc = vdbeSorterReadVarint(pSorter->pTemp1, &pIter->iReadOff, &nByte);
*pnByte += nByte;
pIter->iEof = pIter->iReadOff + nByte;
}
if( rc==SQLITE_OK ){
rc = vdbeSorterIterNext(db, pIter);
}
return rc;
}
/*
** Initialize iterator pIter to scan through the PMA stored in file pFile
** starting at offset iStart and ending at offset iEof-1. This function
** leaves the iterator pointing to the first key in the PMA (or EOF if the
** PMA is empty).
*/
static int vdbeSorterIterInit(
sqlite3 *db, /* Database handle */
const VdbeSorter *pSorter, /* Sorter object */
i64 iStart, /* Start offset in pFile */
VdbeSorterIter *pIter, /* Iterator to populate */
i64 *pnByte /* IN/OUT: Increment this value by PMA size */
){
int rc = SQLITE_OK;
int nBuf;
nBuf = sqlite3BtreeGetPageSize(db->aDb[0].pBt);
assert( pSorter->iWriteOff>iStart );
assert( pIter->aAlloc==0 );
assert( pIter->aBuffer==0 );
pIter->pFile = pSorter->pTemp1;
pIter->iReadOff = iStart;
pIter->nAlloc = 128;
pIter->aAlloc = (u8 *)sqlite3DbMallocRaw(db, pIter->nAlloc);
pIter->nBuffer = nBuf;
pIter->aBuffer = (u8 *)sqlite3DbMallocRaw(db, nBuf);
if( !pIter->aBuffer ){
rc = SQLITE_NOMEM;
}else{
int iBuf;
iBuf = iStart % nBuf;
if( iBuf ){
int nRead = nBuf - iBuf;
if( (iStart + nRead) > pSorter->iWriteOff ){
nRead = (int)(pSorter->iWriteOff - iStart);
}
rc = sqlite3OsRead(
pSorter->pTemp1, &pIter->aBuffer[iBuf], nRead, iStart
);
assert( rc!=SQLITE_IOERR_SHORT_READ );
}
if( rc==SQLITE_OK ){
u64 nByte; /* Size of PMA in bytes */
pIter->iEof = pSorter->iWriteOff;
rc = vdbeSorterIterVarint(db, pIter, &nByte);
pIter->iEof = pIter->iReadOff + nByte;
*pnByte += nByte;
}
}
if( rc==SQLITE_OK ){
rc = vdbeSorterIterNext(db, pIter);
}
return rc;
}
/*
** Advance to the next element in the sorter.
*/
int sqlite3VdbeSorterNext(sqlite3 *db, VdbeCursor *pCsr, int *pbEof){
VdbeSorter *pSorter = pCsr->pSorter;
int rc; /* Return code */
if( pSorter->aTree ){
int iPrev = pSorter->aTree[1];/* Index of iterator to advance */
int i; /* Index of aTree[] to recalculate */
rc = vdbeSorterIterNext(db, &pSorter->aIter[iPrev]);
for(i=(pSorter->nTree+iPrev)/2; rc==SQLITE_OK && i>0; i=i/2){
rc = vdbeSorterDoCompare(pCsr, i);
}
*pbEof = (pSorter->aIter[pSorter->aTree[1]].pFile==0);
}else{
SorterRecord *pFree = pSorter->pRecord;
pSorter->pRecord = pFree->pNext;
pFree->pNext = 0;
vdbeSorterRecordFree(db, pFree);
*pbEof = !pSorter->pRecord;
rc = SQLITE_OK;
}
return rc;
}