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Changes to the interface design for the xShmLock method of the VFS.

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FossilOrigin-Name: 348409de26eafe12f5cb1236e8e167a4183d4051
This commit is contained in:
drh
2010-04-28 17:21:33 +00:00
parent 833bf968e3
commit 9beb1584bd
4 changed files with 29 additions and 42 deletions
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src/os_unix.c
+4 -19
View File
@@ -4697,26 +4697,11 @@ static int unixShmRelease(sqlite3_shm *pSharedMem){
*/
static int unixShmLock(
sqlite3_shm *pSharedMem, /* Pointer from unixShmOpen() */
int lockType, /* _RDLK, _WRLK, or _UNLK, possibly ORed _BLOCK */
int ofst, /* Start of lock region */
int nByte /* Size of lock region in bytes */
int desiredLock, /* The locking state desired */
int *pGotLock, /* The locking state actually obtained */
int shouldBlock /* Block for the lock if true and possible */
){
struct unixShm *p = (struct unixShm*)pSharedMem;
struct flock f;
int op;
int rc;
f.l_whence = SEEK_SET;
f.l_start = ofst;
f.l_len = nByte;
switch( lockType & 0x07 ){
case SQLITE_SHM_RDLK: f.l_type = F_RDLCK; break;
case SQLITE_SHM_WRLK: f.l_type = F_WRLCK; break;
case SQLITE_SHM_UNLK: f.l_type = F_UNLCK; break;
}
op = (lockType & 0x08)!=0 ? F_SETLKW : F_SETLK;
rc = fcntl(p->fd.h, op, &f);
return (rc==0) ? SQLITE_OK : SQLITE_BUSY;
return SQLITE_OK;
}
/*
src/sqlite.h.in
+14 -12
View File
@@ -848,7 +848,7 @@ struct sqlite3_vfs {
int (*xShmRelease)(sqlite3_shm*);
int (*xShmPush)(sqlite3_shm*);
int (*xShmPull)(sqlite3_shm*);
int (*xShmLock)(sqlite3_shm*, int lockType, int ofst, int nByte);
int (*xShmLock)(sqlite3_shm*, int desiredLock, int *gotLock, int shouldBlock);
int (*xShmClose)(sqlite3_shm*);
int (*xShmDelete)(sqlite3_vfs*, const char *zName);
int (*xRename)(sqlite3_vfs*, const char *zOld, const char *zNew, int dirSync);
@@ -880,18 +880,20 @@ struct sqlite3_vfs {
/*
** CAPI3REF: Flags for the xShmLock VFS method
**
** These integer constants can be used as the second parameter to
** the xShmLock method of an [sqlite3_vfs] object. They determine
** the specific locking action. Exactly one of the first three
** values must be used ini the lockType parameter. The fourth
** value (SQLITE_SHM_BLOCK) can optionally be ORed into the lockType
** parameter to cause the thread to block until the lock becomes
** available.
** These integer constants define the various locking states that
** an sqlite3_shm object can be in. The SQLITE_SHM_QUERY integer
** is not a valid data - it is a constant pasted to the
** sqlite3_vfs.xShmLock() method for querying the current lock
** state.
*/
#define SQLITE_SHM_RDLK 0x01
#define SQLITE_SHM_WRLK 0x02
#define SQLITE_SHM_UNLK 0x04
#define SQLITE_SHM_BLOCK 0x08
#define SQLITE_SHM_UNLOCK 0
#define SQLITE_SHM_READ_PREFIX 1
#define SQLITE_SHM_READ_FULL 2
#define SQLITE_SHM_WRITE 3
#define SQLITE_SHM_PENDING 4
#define SQLITE_SHM_CHECKPOINT 5
#define SQLITE_SHM_RECOVER 6
#define SQLITE_SHM_QUERY (-1)
/*
** CAPI3REF: Initialize The SQLite Library