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Overview
| Comment: | Merge change to drop the mutex on the multiplexor before entering the xRead VFS call, in order to enhance parallelizability. |
|---|---|
| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | trunk |
| Files: | files | file ages | folders |
| SHA1: |
3c566e41e4c9c66960cc5a3ddee85568 |
| User & Date: | drh 2013-11-08 12:14:50 |
Context
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2013-11-08
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| 15:19 | Performance improvements: Avoid unnecessary seeks when doing a single-row UPDATE on a WITHOUT ROWID table. check-in: 6f187a0f user: drh tags: trunk | |
| 12:14 | Merge change to drop the mutex on the multiplexor before entering the xRead VFS call, in order to enhance parallelizability. check-in: 3c566e41 user: drh tags: trunk | |
| 01:09 | Optimize out a NotExists/NotFound opcode that occurs in UPDATE processing after constraint checks if there is no possiblity that the constraint checking code might have moved the cursor. check-in: 74e3ee2e user: drh tags: trunk | |
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2013-10-21
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| 13:15 | Drop the mutex on the multiplexor before entering the xRead VFS call. Closed-Leaf check-in: a00d2ed4 user: drh tags: multiplex-parallel-read | |
Changes
Changes to src/test_multiplex.c.
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void *pBuf,
int iAmt,
sqlite3_int64 iOfst
){
multiplexConn *p = (multiplexConn*)pConn;
multiplexGroup *pGroup = p->pGroup;
int rc = SQLITE_OK;
multiplexEnter();
if( !pGroup->bEnabled ){
sqlite3_file *pSubOpen = multiplexSubOpen(pGroup, 0, &rc, NULL, 0);
if( pSubOpen==0 ){
rc = SQLITE_IOERR_READ;
}else{
rc = pSubOpen->pMethods->xRead(pSubOpen, pBuf, iAmt, iOfst);
}
}else{
while( iAmt > 0 ){
int i = (int)(iOfst / pGroup->szChunk);
sqlite3_file *pSubOpen = multiplexSubOpen(pGroup, i, &rc, NULL, 1);
if( pSubOpen ){
int extra = ((int)(iOfst % pGroup->szChunk) + iAmt) - pGroup->szChunk;
if( extra<0 ) extra = 0;
iAmt -= extra;
rc = pSubOpen->pMethods->xRead(pSubOpen, pBuf, iAmt,
iOfst % pGroup->szChunk);
if( rc!=SQLITE_OK ) break;
................................................................................
iAmt = extra;
}else{
rc = SQLITE_IOERR_READ;
break;
}
}
}
multiplexLeave();
return rc;
}
/* Pass xWrite requests thru to the original VFS after
** determining the correct chunk to operate on.
** Break up writes across chunk boundaries.
*/
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void *pBuf,
int iAmt,
sqlite3_int64 iOfst
){
multiplexConn *p = (multiplexConn*)pConn;
multiplexGroup *pGroup = p->pGroup;
int rc = SQLITE_OK;
int nMutex = 0;
multiplexEnter(); nMutex++;
if( !pGroup->bEnabled ){
sqlite3_file *pSubOpen = multiplexSubOpen(pGroup, 0, &rc, NULL, 0);
multiplexLeave(); nMutex--;
if( pSubOpen==0 ){
rc = SQLITE_IOERR_READ;
}else{
rc = pSubOpen->pMethods->xRead(pSubOpen, pBuf, iAmt, iOfst);
}
}else{
while( iAmt > 0 ){
int i = (int)(iOfst / pGroup->szChunk);
if( nMutex==0 ){ multiplexEnter(); nMutex++; }
sqlite3_file *pSubOpen = multiplexSubOpen(pGroup, i, &rc, NULL, 1);
multiplexLeave(); nMutex--;
if( pSubOpen ){
int extra = ((int)(iOfst % pGroup->szChunk) + iAmt) - pGroup->szChunk;
if( extra<0 ) extra = 0;
iAmt -= extra;
rc = pSubOpen->pMethods->xRead(pSubOpen, pBuf, iAmt,
iOfst % pGroup->szChunk);
if( rc!=SQLITE_OK ) break;
................................................................................
iAmt = extra;
}else{
rc = SQLITE_IOERR_READ;
break;
}
}
}
assert( nMutex==0 || nMutex==1 );
if( nMutex ) multiplexLeave();
return rc;
}
/* Pass xWrite requests thru to the original VFS after
** determining the correct chunk to operate on.
** Break up writes across chunk boundaries.
*/
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