Folks: As I study the source of LockBuffer in bufmgr.c I came across
the following code snippet for the case of releasing a
shared (read) lock:
if (mode == BUFFER_LOCK_UNLOCK) { if (*buflock & BL_R_LOCK) {
Assert(buf->r_locks > 0); Assert(!(buf->w_lock)); Assert(!(*buflock &
(BL_W_LOCK| BL_RI_LOCK))); (buf->r_locks)--; *buflock &= ~BL_R_LOCK;
This code resets BL_R_LOCK on the first release of a shared lock.
I think it should check that the count of readers be zero:
( something like
if (mode == BUFFER_LOCK_UNLOCK) { if (*buflock & BL_R_LOCK) {
Assert(buf->r_locks > 0); Assert(!(buf->w_lock)); Assert(!(*buflock &
(BL_W_LOCK| BL_RI_LOCK))); (buf->r_locks)--; if (!buf->r_locks)
*buflock &= ~BL_R_LOCK;
Or I am missing something...
thanks regards Mauricio
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