Thread: pgsql: Allow lwlocks to be disowned
Allow lwlocks to be disowned To implement AIO writes, the backend initiating writes needs to transfer the lock ownership to the AIO subsystem, so the lock held during the write can be released in another backend. Other backends need to be able to "complete" an asynchronously started IO to avoid deadlocks (consider e.g. one backend starting IO for a buffer and then waiting for a heavyweight lock held by another relation followed by the current holder of the heavyweight lock waiting for the IO to complete). To that end, this commit adds LWLockDisown() and LWLockReleaseDisowned(). If code uses LWLockDisown() it's the code's responsibility to ensure that the lock is released in case of errors. Reviewed-by: Heikki Linnakangas <hlinnaka@iki.fi> Discussion: https://postgr.es/m/1f6b50a7-38ef-4d87-8246-786d39f46ab9@iki.fi Branch ------ master Details ------- https://git.postgresql.org/pg/commitdiff/f8d7f29b3e81db59b95e4b5baaa6943178c89fd8 Modified Files -------------- src/backend/storage/lmgr/lwlock.c | 75 +++++++++++++++++++++++++++++++++++---- src/include/storage/lwlock.h | 2 ++ 2 files changed, 71 insertions(+), 6 deletions(-)