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Overview
| Comment: | Change the SHM VFS logic in os_unix.c so that it does not hold an exclusive lock n the mapped memory when also holding a CHECKPOINT lock. This improves concurrency between readers and checkpointers. |
|---|---|
| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | wal |
| Files: | files | file ages | folders |
| SHA1: |
8660cda6f8ef43bd276897ef3b5fc237 |
| User & Date: | drh 2010-04-30 17:47:51 |
Context
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2010-04-30
| ||
| 22:28 | Merge in changes from the trunk. (check-in: 76bf0eee user: drh tags: wal) | |
| 17:47 | Change the SHM VFS logic in os_unix.c so that it does not hold an exclusive lock n the mapped memory when also holding a CHECKPOINT lock. This improves concurrency between readers and checkpointers. (check-in: 8660cda6 user: drh tags: wal) | |
| 17:28 | Remove some obsolete debugging parameters. (check-in: a012aed4 user: drh tags: wal) | |
Changes
Changes to src/os_unix.c.
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int *pNewMapSize, /* Write new size of mapping here */
void **ppBuf /* Write mapping buffer origin here */
){
unixShm *p = (unixShm*)pSharedMem;
unixShmFile *pFile = p->pFile;
int rc = SQLITE_OK;
sqlite3_mutex_enter(pFile->mutexBuf);
sqlite3_mutex_enter(pFile->mutex);
if( pFile->szMap==0 || reqMapSize>pFile->szMap ){
int actualSize;
if( unixShmSize(pSharedMem, -1, &actualSize)==SQLITE_OK
&& reqMapSize<actualSize
){
reqMapSize = actualSize;
................................................................................
/*
** Release the lock held on the shared memory segment to that other
** threads are free to resize it if necessary.
*/
static int unixShmRelease(sqlite3_shm *pSharedMem){
unixShm *p = (unixShm*)pSharedMem;
unixShmFile *pFile = p->pFile;
sqlite3_mutex_leave(pFile->mutexBuf);
return SQLITE_OK;
}
/*
** Symbolic names for LOCK states used for debugging.
*/
#ifdef SQLITE_DEBUG
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int *pNewMapSize, /* Write new size of mapping here */
void **ppBuf /* Write mapping buffer origin here */
){
unixShm *p = (unixShm*)pSharedMem;
unixShmFile *pFile = p->pFile;
int rc = SQLITE_OK;
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;
if( unixShmSize(pSharedMem, -1, &actualSize)==SQLITE_OK
&& reqMapSize<actualSize
){
reqMapSize = actualSize;
................................................................................
/*
** Release the lock held on the shared memory segment to that other
** threads are free to resize it if necessary.
*/
static int unixShmRelease(sqlite3_shm *pSharedMem){
unixShm *p = (unixShm*)pSharedMem;
if( p->hasMutexBuf ){
unixShmFile *pFile = p->pFile;
sqlite3_mutex_leave(pFile->mutexBuf);
p->hasMutexBuf = 0;
}
return SQLITE_OK;
}
/*
** Symbolic names for LOCK states used for debugging.
*/
#ifdef SQLITE_DEBUG
|