On Wed, Jan 8, 2020 at 7:10 AM Dan Kennedy <danielk1...@gmail.com> wrote:
> > On 8/1/63 20:29, J Decker wrote: > > The documentation isn't very clear on what the intent of an xUnlock( > > SQLITE_LOCK_NONE ) is intended to do. Is it unlock everything? Is it the > > same as remove a shared lock? > > That's right. xUnlock(fd, SQLITE_LOCK_NONE) should completely unlock the > file. xUnlock(fd, SQLITE_LOCK_SHARED) should fall back to a SHARED lock > from RESERVED/PENDING/EXCLUSIVE. > > Thank you... the second thing there confuses me... xLock(SHARED) xLock(SHARED) xLock(PENDING) xUnlock( SHARED) - clear pending, and add a shared for total of 3? or is xUnlock always remove (this file handle's) locks? I haven't finished implementing the first part to get a 'real' sequence... Also; I suppose I should return SQLITE_BUSY instead of waiting on the lock myself? expected return values aren't covered well either. Dan. > > > > > > > The first few operations are xLock( SQLITE_LOCK_SHARED ) followed by > > xUnlock(SQLITE_LOCK_NONE)... > > > > sqlite.h.in > > https://github.com/mackyle/sqlite/blob/master/src/sqlite.h.in#L627 > > where the constants are defined... says 'one of these are used...' > > > > and describing locking levels... > > https://github.com/mackyle/sqlite/blob/master/src/sqlite.h.in#L708-L720 > > > > > > https://www.sqlite.org/c3ref/io_methods.html > > xLock() increases the lock. xUnlock() decreases the lock. The > > xCheckReservedLock() method checks whether any database connection, > either > > in this process or in some other process, is holding a RESERVED, PENDING, > > or EXCLUSIVE lock on the file. It returns true if such a lock exists and > > false otherwise. > > > > https://www.sqlite.org/lockingv3.html > > has description of what locking states are intended to be... there's > > 'UNLOCKED' but not LOCK_NONE > > > > I did find another page that had lock state transitions, and information > > about when the busy callback would be called... but that also didn't say > > anything about the transition to unlock states... > > > > There was a note around the .C code in the pager unlocking using > LOCK_NONE, > > but I cna't find that, it just says, see note above... and that didn't > > really say what the intent was. > > > > I searched the nabble mailing list archive for 'SQLITE_LOCK_NONE' and > found > > 0 hits. > > _______________________________________________ > > sqlite-users mailing list > > sqlite-users@mailinglists.sqlite.org > > http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users > _______________________________________________ > sqlite-users mailing list > sqlite-users@mailinglists.sqlite.org > http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users > _______________________________________________ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
