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Overview
| Comment: | Avoid a mutex in-and-out in unixShmBarrier() on this branch. Use __sync_synchronize() instead. |
|---|---|
| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | mutexfree-shmlock |
| Files: | files | file ages | folders |
| SHA3-256: |
a8c5fd86ce1d9b5815f82106f2e44797 |
| User & Date: | dan 2018-12-10 09:45:38 |
Context
|
2018-12-10
| ||
| 15:24 | Rework the SQLITE_MUTEXFREE_SHMLOCK code to reduce contention. (check-in: d9157dd1 user: dan tags: mutexfree-shmlock) | |
| 09:45 | Avoid a mutex in-and-out in unixShmBarrier() on this branch. Use __sync_synchronize() instead. (check-in: a8c5fd86 user: dan tags: mutexfree-shmlock) | |
| 09:36 | Avoid a mutex in-and-out in unixShmBarrier() on this branch. Use __sync_synchronize() instead. (check-in: 280d1a72 user: dan tags: begin-concurrent-pnu-mutexfree-shmlock) | |
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2018-12-06
| ||
| 18:58 | Experiment with using an atomic CPU primitive instead of a mutex for intra-process locking with the unix-excl VFS. (check-in: 8f4cb9dd user: dan tags: mutexfree-shmlock) | |
Changes
Changes to src/os_unix.c.
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** All loads and stores begun before the barrier must complete before
** any load or store begun after the barrier.
*/
static void unixShmBarrier(
sqlite3_file *fd /* Database file holding the shared memory */
){
UNUSED_PARAMETER(fd);
sqlite3MemoryBarrier(); /* compiler-defined memory barrier */
assert( fd->pMethods->xLock==nolockLock
|| unixFileMutexNotheld((unixFile*)fd)
);
unixEnterMutex(); /* Also mutex, for redundancy */
unixLeaveMutex();
}
/*
** Close a connection to shared-memory. Delete the underlying
** storage if deleteFlag is true.
**
** If there is no shared memory associated with the connection then this
|
> > > > |
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** All loads and stores begun before the barrier must complete before
** any load or store begun after the barrier.
*/
static void unixShmBarrier(
sqlite3_file *fd /* Database file holding the shared memory */
){
UNUSED_PARAMETER(fd);
#ifdef SQLITE_MUTEXFREE_SHMLOCK
__sync_synchronize();
#else
sqlite3MemoryBarrier(); /* compiler-defined memory barrier */
assert( fd->pMethods->xLock==nolockLock
|| unixFileMutexNotheld((unixFile*)fd)
);
unixEnterMutex(); /* Also mutex, for redundancy */
unixLeaveMutex();
#endif
}
/*
** Close a connection to shared-memory. Delete the underlying
** storage if deleteFlag is true.
**
** If there is no shared memory associated with the connection then this
|