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Change the SHM VFS logic in os_unix.c so that it does not hold an exclusive

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lock n the mapped memory when also holding a CHECKPOINT lock.  This
improves concurrency between readers and checkpointers.

FossilOrigin-Name: 8660cda6f8ef43bd276897ef3b5fc2376b5684dc
This commit is contained in:
drh
2010-04-30 17:47:51 +00:00
parent 1b48aa49a4
commit 6dea3248ae
3 changed files with 19 additions and 13 deletions
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12
src/os_unix.c
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@@ -5140,7 +5140,10 @@ static int unixShmGet(
unixShmFile *pFile = p->pFile;
int rc = SQLITE_OK;
sqlite3_mutex_enter(pFile->mutexBuf);
if( p->lockState!=SQLITE_SHM_CHECKPOINT ){
sqlite3_mutex_enter(pFile->mutexBuf);
p->hasMutexBuf = 1;
}
sqlite3_mutex_enter(pFile->mutex);
if( pFile->szMap==0 || reqMapSize>pFile->szMap ){
int actualSize;
@@ -5168,8 +5171,11 @@ static int unixShmGet(
*/
static int unixShmRelease(sqlite3_shm *pSharedMem){
unixShm *p = (unixShm*)pSharedMem;
unixShmFile *pFile = p->pFile;
sqlite3_mutex_leave(pFile->mutexBuf);
if( p->hasMutexBuf ){
unixShmFile *pFile = p->pFile;
sqlite3_mutex_leave(pFile->mutexBuf);
p->hasMutexBuf = 0;
}
return SQLITE_OK;
}