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Provide a way to predefine LWLock tranche IDs. 

It's a bit cumbersome to use LWLockNewTrancheId(), because the returned
value needs to be shared between backends so that each backend can call
LWLockRegisterTranche() with the correct ID.  So, for built-in tranches,
use a hard-coded value instead.

This is motivated by an upcoming patch adding further built-in tranches.

Andres Freund and Robert Haas
This commit is contained in:
Robert Haas 2015-12-15 11:32:13 -05:00
parent 43cd468cf0
commit 3fed417452
3 changed files with 18 additions and 10 deletions
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10
src/backend/access/transam/xlog.c
View File

@ -512,7 +512,6 @@ typedef struct XLogCtlInsert
*/
WALInsertLockPadded *WALInsertLocks;
LWLockTranche WALInsertLockTranche;
int WALInsertLockTrancheId;
} XLogCtlInsert;
/*
@ -4653,7 +4652,7 @@ XLOGShmemInit(void)
/* Initialize local copy of WALInsertLocks and register the tranche */
WALInsertLocks = XLogCtl->Insert.WALInsertLocks;
LWLockRegisterTranche(XLogCtl->Insert.WALInsertLockTrancheId,
LWLockRegisterTranche(LWTRANCHE_WAL_INSERT,
&XLogCtl->Insert.WALInsertLockTranche);
return;
}
@ -4677,17 +4676,14 @@ XLOGShmemInit(void)
(WALInsertLockPadded *) allocptr;
allocptr += sizeof(WALInsertLockPadded) * NUM_XLOGINSERT_LOCKS;
XLogCtl->Insert.WALInsertLockTrancheId = LWLockNewTrancheId();
XLogCtl->Insert.WALInsertLockTranche.name = "WALInsertLocks";
XLogCtl->Insert.WALInsertLockTranche.array_base = WALInsertLocks;
XLogCtl->Insert.WALInsertLockTranche.array_stride = sizeof(WALInsertLockPadded);
LWLockRegisterTranche(XLogCtl->Insert.WALInsertLockTrancheId, &XLogCtl->Insert.WALInsertLockTranche);
LWLockRegisterTranche(LWTRANCHE_WAL_INSERT, &XLogCtl->Insert.WALInsertLockTranche);
for (i = 0; i < NUM_XLOGINSERT_LOCKS; i++)
{
LWLockInitialize(&WALInsertLocks[i].l.lock,
XLogCtl->Insert.WALInsertLockTrancheId);
LWLockInitialize(&WALInsertLocks[i].l.lock, LWTRANCHE_WAL_INSERT);
WALInsertLocks[i].l.insertingAt = InvalidXLogRecPtr;
}

7
src/backend/storage/lmgr/lwlock.c
View File

@ -445,7 +445,7 @@ CreateLWLocks(void)
/* Initialize all LWLocks in main array */
for (id = 0, lock = MainLWLockArray; id < numLocks; id++, lock++)
LWLockInitialize(&lock->lock, 0);
LWLockInitialize(&lock->lock, LWTRANCHE_MAIN);
/*
* Initialize the dynamic-allocation counters, which are stored just
@ -457,7 +457,7 @@ CreateLWLocks(void)
LWLockCounter = (int *) ((char *) MainLWLockArray - 3 * sizeof(int));
LWLockCounter[0] = NUM_FIXED_LWLOCKS;
LWLockCounter[1] = numLocks;
LWLockCounter[2] = 1; /* 0 is the main array */
LWLockCounter[2] = LWTRANCHE_FIRST_USER_DEFINED;
}
if (LWLockTrancheArray == NULL)
@ -466,12 +466,13 @@ CreateLWLocks(void)
LWLockTrancheArray = (LWLockTranche **)
MemoryContextAlloc(TopMemoryContext,
LWLockTranchesAllocated * sizeof(LWLockTranche *));
Assert(LWLockTranchesAllocated >= LWTRANCHE_FIRST_USER_DEFINED);
}
MainLWLockTranche.name = "main";
MainLWLockTranche.array_base = MainLWLockArray;
MainLWLockTranche.array_stride = sizeof(LWLockPadded);
LWLockRegisterTranche(0, &MainLWLockTranche);
LWLockRegisterTranche(LWTRANCHE_MAIN, &MainLWLockTranche);
}
/*

11
src/include/storage/lwlock.h
View File

@ -176,6 +176,17 @@ extern int LWLockNewTrancheId(void);
extern void LWLockRegisterTranche(int tranche_id, LWLockTranche *tranche);
extern void LWLockInitialize(LWLock *lock, int tranche_id);
/*
* We reserve a few predefined tranche IDs. A call to LWLockNewTrancheId
* will never return a value less than LWTRANCHE_FIRST_USER_DEFINED.
*/
typedef enum BuiltinTrancheIds
{
LWTRANCHE_MAIN,
LWTRANCHE_WAL_INSERT,
LWTRANCHE_FIRST_USER_DEFINED
} BuiltinTrancheIds;
/*
* Prior to PostgreSQL 9.4, we used an enum type called LWLockId to refer
* to LWLocks. New code should instead use LWLock *. However, for the