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Implement new 'lightweight lock manager' that's intermediate between

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existing lock manager and spinlocks: it understands exclusive vs shared
lock but has few other fancy features.  Replace most uses of spinlocks
with lightweight locks.  All remaining uses of spinlocks have very short
lock hold times (a few dozen instructions), so tweak spinlock backoff
code to work efficiently given this assumption.  All per my proposal on
pghackers 26-Sep-01.
This commit is contained in:
Tom Lane
2001-09-29 04:02:27 +00:00
parent 818fb55ac4
commit 499abb0c0f
46 changed files with 1595 additions and 1355 deletions
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28
src/include/storage/lock.h
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@@ -7,15 +7,15 @@
* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $Id: lock.h,v 1.52 2001/09/27 16:29:13 tgl Exp $
* $Id: lock.h,v 1.53 2001/09/29 04:02:26 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#ifndef LOCK_H_
#define LOCK_H_
#include "storage/ipc.h"
#include "storage/itemptr.h"
#include "storage/lwlock.h"
#include "storage/shmem.h"
@@ -26,12 +26,10 @@ typedef struct PROC_QUEUE
int size; /* number of entries in list */
} PROC_QUEUE;
/* struct proc is declared in storage/proc.h, but must forward-reference it */
typedef struct proc PROC;
/* struct PROC is declared in storage/proc.h, but must forward-reference it */
typedef struct PROC PROC;
extern SPINLOCK LockMgrLock;
extern int max_locks_per_xact;
#ifdef LOCK_DEBUG
@@ -51,11 +49,7 @@ typedef int LOCKMETHOD;
/* MAX_LOCKMODES cannot be larger than the # of bits in LOCKMASK */
#define MAX_LOCKMODES 10
/*
* MAX_LOCK_METHODS corresponds to the number of spin locks allocated in
* CreateSpinLocks() or the number of shared memory locations allocated
* for lock table spin locks in the case of machines with TAS instructions.
*/
/* MAX_LOCK_METHODS is the number of distinct lock control tables allowed */
#define MAX_LOCK_METHODS 3
#define INVALID_TABLEID 0
@@ -69,7 +63,7 @@ typedef int LOCKMETHOD;
* If user locks are enabled, an additional lock method is present.
*
* LOCKMETHODCTL and LOCKMETHODTABLE are split because the first lives
* in shared memory. This is because it contains a spinlock.
* in shared memory. (There isn't any really good reason for the split.)
* LOCKMETHODTABLE exists in private memory. Both are created by the
* postmaster and should be the same in all backends.
*/
@@ -93,7 +87,7 @@ typedef int LOCKMETHOD;
* writers can be given priority over readers (to avoid
* starvation). XXX this field is not actually used at present!
*
* masterlock -- synchronizes access to the table
* masterLock -- synchronizes access to the table
*/
typedef struct LOCKMETHODCTL
{
@@ -101,7 +95,7 @@ typedef struct LOCKMETHODCTL
int numLockModes;
int conflictTab[MAX_LOCKMODES];
int prio[MAX_LOCKMODES];
SPINLOCK masterLock;
LWLockId masterLock;
} LOCKMETHODCTL;
/*
@@ -235,11 +229,6 @@ typedef struct HOLDER
(((LOCK *) MAKE_PTR((holder).tag.lock))->tag.lockmethod)
#define LockLockTable() SpinAcquire(LockMgrLock)
#define UnlockLockTable() SpinRelease(LockMgrLock)
/*
* function prototypes
*/
@@ -267,7 +256,6 @@ extern void InitDeadLockChecking(void);
#ifdef LOCK_DEBUG
extern void DumpLocks(void);
extern void DumpAllLocks(void);
#endif
#endif /* LOCK_H */