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Relax the requirement that all lwlocks be stored in a single array.

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This makes it possible to store lwlocks as part of some other data
structure in the main shared memory segment, or in a dynamic shared
memory segment.  There is still a main LWLock array and this patch does
not move anything out of it, but it provides necessary infrastructure
for doing that in the future.

This change is likely to increase the size of LWLockPadded on some
platforms, especially 32-bit platforms where it was previously only
16 bytes.

Patch by me.  Review by Andres Freund and KaiGai Kohei.
This commit is contained in:
Robert Haas
2014-01-27 11:07:44 -05:00
parent f62eba204f
commit ea9df812d8
18 changed files with 523 additions and 317 deletions
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8
src/backend/storage/buffer/bufmgr.c
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@ -146,7 +146,7 @@ PrefetchBuffer(Relation reln, ForkNumber forkNum, BlockNumber blockNum)
{
BufferTag newTag; /* identity of requested block */
uint32 newHash; /* hash value for newTag */
LWLockId newPartitionLock; /* buffer partition lock for it */
LWLock *newPartitionLock; /* buffer partition lock for it */
int buf_id;
/* create a tag so we can lookup the buffer */
@ -539,10 +539,10 @@ BufferAlloc(SMgrRelation smgr, char relpersistence, ForkNumber forkNum,
{
BufferTag newTag; /* identity of requested block */
uint32 newHash; /* hash value for newTag */
LWLockId newPartitionLock; /* buffer partition lock for it */
LWLock *newPartitionLock; /* buffer partition lock for it */
BufferTag oldTag; /* previous identity of selected buffer */
uint32 oldHash; /* hash value for oldTag */
LWLockId oldPartitionLock; /* buffer partition lock for it */
LWLock *oldPartitionLock; /* buffer partition lock for it */
BufFlags oldFlags;
int buf_id;
volatile BufferDesc *buf;
@ -891,7 +891,7 @@ InvalidateBuffer(volatile BufferDesc *buf)
{
BufferTag oldTag;
uint32 oldHash; /* hash value for oldTag */
LWLockId oldPartitionLock; /* buffer partition lock for it */
LWLock *oldPartitionLock; /* buffer partition lock for it */
BufFlags oldFlags;
/* Save the original buffer tag before dropping the spinlock */