diff options
| author | Robert Haas | 2022-05-24 14:55:01 +0000 |
|---|---|---|
| committer | Robert Haas | 2022-05-31 12:46:54 +0000 |
| commit | f5bfba5413f51b4fa0a7b0dc879d39ae6881d8be (patch) | |
| tree | 5a0c0d269117effd3dbb178055af372867a127bd | |
| parent | 0a050ee000b6783ac4b78e9eadb47a4e72912672 (diff) | |
shm_mq_sendv: Fix flushing bug when receiver not yet attached.
With the old logic, when the reciever had not yet attached, we would
never call shm_mq_inc_bytes_written(), even if force_flush = true
was specified. That could result in a situation where data that the
sender believes it has sent is never received.
Along the way, remove a useless function prototype for a nonexistent
function from shm_mq.h.
Commit 46846433a03dff4f2e08c8a161e54a842da360d6 introduced these
problems.
Pavan Deolasee, with a few changes by me.
Discussion: https://postgr.es/m/CABOikdPkwtLLCTnzzmpSMXo3QZa2yXq0J7Q61ssdLFAJYrOVvQ@mail.gmail.com
| -rw-r--r-- | src/backend/storage/ipc/shm_mq.c | 11 | ||||
| -rw-r--r-- | src/include/storage/shm_mq.h | 1 |
2 files changed, 5 insertions, 7 deletions
diff --git a/src/backend/storage/ipc/shm_mq.c b/src/backend/storage/ipc/shm_mq.c index 6139c622e0b..8ca24de8d62 100644 --- a/src/backend/storage/ipc/shm_mq.c +++ b/src/backend/storage/ipc/shm_mq.c @@ -518,8 +518,7 @@ shm_mq_sendv(shm_mq_handle *mqh, shm_mq_iovec *iov, int iovcnt, bool nowait, /* * If the counterparty is known to have attached, we can read mq_receiver - * without acquiring the spinlock and assume it isn't NULL. Otherwise, - * more caution is needed. + * without acquiring the spinlock. Otherwise, more caution is needed. */ if (mqh->mqh_counterparty_attached) receiver = mq->mq_receiver; @@ -528,9 +527,8 @@ shm_mq_sendv(shm_mq_handle *mqh, shm_mq_iovec *iov, int iovcnt, bool nowait, SpinLockAcquire(&mq->mq_mutex); receiver = mq->mq_receiver; SpinLockRelease(&mq->mq_mutex); - if (receiver == NULL) - return SHM_MQ_SUCCESS; - mqh->mqh_counterparty_attached = true; + if (receiver != NULL) + mqh->mqh_counterparty_attached = true; } /* @@ -541,7 +539,8 @@ shm_mq_sendv(shm_mq_handle *mqh, shm_mq_iovec *iov, int iovcnt, bool nowait, if (force_flush || mqh->mqh_send_pending > (mq->mq_ring_size >> 2)) { shm_mq_inc_bytes_written(mq, mqh->mqh_send_pending); - SetLatch(&receiver->procLatch); + if (receiver != NULL) + SetLatch(&receiver->procLatch); mqh->mqh_send_pending = 0; } diff --git a/src/include/storage/shm_mq.h b/src/include/storage/shm_mq.h index f5220baa781..b6fe68725d2 100644 --- a/src/include/storage/shm_mq.h +++ b/src/include/storage/shm_mq.h @@ -76,7 +76,6 @@ extern shm_mq_result shm_mq_sendv(shm_mq_handle *mqh, shm_mq_iovec *iov, int iovcnt, bool nowait, bool force_flush); extern shm_mq_result shm_mq_receive(shm_mq_handle *mqh, Size *nbytesp, void **datap, bool nowait); -extern void shm_mq_flush(shm_mq_handle *mqh); /* Wait for our counterparty to attach to the queue. */ extern shm_mq_result shm_mq_wait_for_attach(shm_mq_handle *mqh); |