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Split the shared-memory array of PGPROC pointers out of the sinval

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communication structure, and make it its own module with its own lock.
This should reduce contention at least a little, and it definitely makes
the code seem cleaner.  Per my recent proposal.
This commit is contained in:
Tom Lane
2005-05-19 21:35:48 +00:00
parent 6910032a56
commit ee3b71f6bc
30 changed files with 923 additions and 860 deletions
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11
src/include/storage/buf_internals.h
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@@ -8,14 +8,13 @@
* Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/storage/buf_internals.h,v 1.77 2005/03/04 20:21:07 tgl Exp $
* $PostgreSQL: pgsql/src/include/storage/buf_internals.h,v 1.78 2005/05/19 21:35:47 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#ifndef BUFMGR_INTERNALS_H
#define BUFMGR_INTERNALS_H
#include "storage/backendid.h"
#include "storage/buf.h"
#include "storage/lwlock.h"
#include "storage/shmem.h"
@@ -94,7 +93,7 @@ typedef struct buftag
* BufferDesc -- shared descriptor/state data for a single shared buffer.
*
* Note: buf_hdr_lock must be held to examine or change the tag, flags,
* usage_count, refcount, or wait_backend_id fields. buf_id field never
* usage_count, refcount, or wait_backend_pid fields. buf_id field never
* changes after initialization, so does not need locking. freeNext is
* protected by the BufFreelistLock not buf_hdr_lock. The LWLocks can take
* care of themselves. The buf_hdr_lock is *not* used to control access to
@@ -108,8 +107,8 @@ typedef struct buftag
*
* We can't physically remove items from a disk page if another backend has
* the buffer pinned. Hence, a backend may need to wait for all other pins
* to go away. This is signaled by storing its own backend ID into
* wait_backend_id and setting flag bit BM_PIN_COUNT_WAITER. At present,
* to go away. This is signaled by storing its own PID into
* wait_backend_pid and setting flag bit BM_PIN_COUNT_WAITER. At present,
* there can be only one such waiter per buffer.
*
* We use this same struct for local buffer headers, but the lock fields
@@ -121,7 +120,7 @@ typedef struct sbufdesc
BufFlags flags; /* see bit definitions above */
uint16 usage_count; /* usage counter for clock sweep code */
unsigned refcount; /* # of backends holding pins on buffer */
BackendId wait_backend_id; /* backend ID of pin-count waiter */
int wait_backend_pid; /* backend PID of pin-count waiter */
slock_t buf_hdr_lock; /* protects the above fields */