Andres Freund 2d115e47c8 Fix various shortcomings of the new PrivateRefCount infrastructure. ... As noted by Tom Lane the improvements in 4b4b680c3d had the problem that in some situations we searched, entered and modified entries in the private refcount hash while holding a spinlock. I had tried to keep the logic entirely local to PinBuffer_Locked(), but that's not really possible given it's called with a spinlock held... Besides being disadvantageous from a performance point of view, this also has problems with error handling safety. If we failed inserting an entry into the hashtable due to an out of memory error, we'd error out with a held spinlock. Not good. Change the way private refcounts are manipulated: Before a buffer can be tracked an entry has to be reserved using ReservePrivateRefCountEntry(); then, if a entry is not found using GetPrivateRefCountEntry(), it can be entered with NewPrivateRefCountEntry(). Also take advantage of the fact that PinBuffer_Locked() currently is never called for buffers that already have been pinned by the current backend and don't search the private refcount entries for preexisting local pins. That results in a small, but measurable, performance improvement. Additionally make ReleaseBuffer() always call UnpinBuffer() for shared buffers. That avoids duplicating work in an eventual UnpinBuffer() call that already has been done in ReleaseBuffer() and also saves some code. Per discussion with Tom Lane. Discussion: 15028.1418772313@sss.pgh.pa.us		2015-01-19 23:59:41 +01:00
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buffer	Fix various shortcomings of the new PrivateRefCount infrastructure.	2015-01-19 23:59:41 +01:00
file	Update copyright for 2015	2015-01-06 11:43:47 -05:00
freespace	Update copyright for 2015	2015-01-06 11:43:47 -05:00
ipc	Add a default local latch for use in signal handlers.	2015-01-14 18:45:22 +01:00
large_object	Update copyright for 2015	2015-01-06 11:43:47 -05:00
lmgr	Add a default local latch for use in signal handlers.	2015-01-14 18:45:22 +01:00
page	Update copyright for 2015	2015-01-06 11:43:47 -05:00
smgr	Update copyright for 2015	2015-01-06 11:43:47 -05:00
Makefile	Remove cvs keywords from all files.	2010-09-20 22:08:53 +02:00