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Two-phase commit. Original patch by Heikki Linnakangas, with additional

Browse Source 
hacking by Alvaro Herrera and Tom Lane.
This commit is contained in:
Tom Lane
2005-06-17 22:32:51 +00:00
parent 5495575903
commit d0a89683a3
61 changed files with 4454 additions and 439 deletions
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27
src/backend/storage/ipc/ipci.c
View File

@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/storage/ipc/ipci.c,v 1.76 2005/05/19 21:35:46 tgl Exp $
* $PostgreSQL: pgsql/src/backend/storage/ipc/ipci.c,v 1.77 2005/06/17 22:32:45 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -17,6 +17,7 @@
#include "access/clog.h"
#include "access/multixact.h"
#include "access/subtrans.h"
#include "access/twophase.h"
#include "access/xlog.h"
#include "miscadmin.h"
#include "postmaster/bgwriter.h"
@@ -54,9 +55,7 @@
* memory. This is true for a standalone backend, false for a postmaster.
*/
void
CreateSharedMemoryAndSemaphores(bool makePrivate,
int maxBackends,
int port)
CreateSharedMemoryAndSemaphores(bool makePrivate, int port)
{
PGShmemHeader *seghdr = NULL;
@@ -72,15 +71,16 @@ CreateSharedMemoryAndSemaphores(bool makePrivate,
*/
size = hash_estimate_size(SHMEM_INDEX_SIZE, sizeof(ShmemIndexEnt));
size += BufferShmemSize();
size += LockShmemSize(maxBackends);
size += ProcGlobalShmemSize(maxBackends);
size += LockShmemSize();
size += ProcGlobalShmemSize();
size += XLOGShmemSize();
size += CLOGShmemSize();
size += SUBTRANSShmemSize();
size += TwoPhaseShmemSize();
size += MultiXactShmemSize();
size += LWLockShmemSize();
size += ProcArrayShmemSize(maxBackends);
size += SInvalShmemSize(maxBackends);
size += ProcArrayShmemSize();
size += SInvalShmemSize(MaxBackends);
size += FreeSpaceShmemSize();
size += BgWriterShmemSize();
#ifdef EXEC_BACKEND
@@ -100,7 +100,7 @@ CreateSharedMemoryAndSemaphores(bool makePrivate,
/*
* Create semaphores
*/
numSemas = ProcGlobalSemas(maxBackends);
numSemas = ProcGlobalSemas();
numSemas += SpinlockSemas();
PGReserveSemaphores(numSemas, port);
}
@@ -144,6 +144,7 @@ CreateSharedMemoryAndSemaphores(bool makePrivate,
XLOGShmemInit();
CLOGShmemInit();
SUBTRANSShmemInit();
TwoPhaseShmemInit();
MultiXactShmemInit();
InitBufferPool();
@@ -151,18 +152,18 @@ CreateSharedMemoryAndSemaphores(bool makePrivate,
* Set up lock manager
*/
InitLocks();
InitLockTable(maxBackends);
InitLockTable();
/*
* Set up process table
*/
InitProcGlobal(maxBackends);
CreateSharedProcArray(maxBackends);
InitProcGlobal();
CreateSharedProcArray();
/*
* Set up shared-inval messaging
*/
CreateSharedInvalidationState(maxBackends);
CreateSharedInvalidationState(MaxBackends);
/*
* Set up free-space map

140
src/backend/storage/ipc/procarray.c
View File

@@ -11,6 +11,11 @@
* Because of various subtle race conditions it is critical that a backend
* hold the correct locks while setting or clearing its MyProc->xid field.
* See notes in GetSnapshotData.
*
* The process array now also includes PGPROC structures representing
* prepared transactions. The xid and subxids fields of these are valid,
* as is the procLocks list. They can be distinguished from regular backend
* PGPROCs at need by checking for pid == 0.
*
*
* Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
@@ -18,13 +23,14 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/storage/ipc/procarray.c,v 1.2 2005/05/19 23:57:11 tgl Exp $
* $PostgreSQL: pgsql/src/backend/storage/ipc/procarray.c,v 1.3 2005/06/17 22:32:45 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "access/subtrans.h"
#include "access/twophase.h"
#include "miscadmin.h"
#include "storage/proc.h"
#include "storage/procarray.h"
@@ -76,25 +82,23 @@ static void DisplayXidCache(void);
* Report shared-memory space needed by CreateSharedProcArray.
*/
int
ProcArrayShmemSize(int maxBackends)
ProcArrayShmemSize(void)
{
/* sizeof(ProcArrayStruct) includes the first array element */
return MAXALIGN(sizeof(ProcArrayStruct) +
(maxBackends - 1) * sizeof(PGPROC *));
return MAXALIGN(offsetof(ProcArrayStruct, procs) +
(MaxBackends + max_prepared_xacts) * sizeof(PGPROC *));
}
/*
* Initialize the shared PGPROC array during postmaster startup.
*/
void
CreateSharedProcArray(int maxBackends)
CreateSharedProcArray(void)
{
bool found;
/* Create or attach to the ProcArray shared structure */
procArray = (ProcArrayStruct *)
ShmemInitStruct("Proc Array", ProcArrayShmemSize(maxBackends),
&found);
ShmemInitStruct("Proc Array", ProcArrayShmemSize(), &found);
if (!found)
{
@@ -102,18 +106,15 @@ CreateSharedProcArray(int maxBackends)
* We're the first - initialize.
*/
procArray->numProcs = 0;
procArray->maxProcs = maxBackends;
procArray->maxProcs = MaxBackends + max_prepared_xacts;
}
}
/*
* Add my own PGPROC (found in the global MyProc) to the shared array.
*
* This must be called during backend startup, after fully initializing
* the contents of MyProc.
* Add the specified PGPROC to the shared array.
*/
void
ProcArrayAddMyself(void)
ProcArrayAdd(PGPROC *proc)
{
ProcArrayStruct *arrayP = procArray;
@@ -132,32 +133,32 @@ ProcArrayAddMyself(void)
errmsg("sorry, too many clients already")));
}
arrayP->procs[arrayP->numProcs] = MyProc;
arrayP->procs[arrayP->numProcs] = proc;
arrayP->numProcs++;
LWLockRelease(ProcArrayLock);
}
/*
* Remove my own PGPROC (found in the global MyProc) from the shared array.
*
* This must be called during backend shutdown.
* Remove the specified PGPROC from the shared array.
*/
void
ProcArrayRemoveMyself(void)
ProcArrayRemove(PGPROC *proc)
{
ProcArrayStruct *arrayP = procArray;
int index;
#ifdef XIDCACHE_DEBUG
DisplayXidCache();
/* dump stats at backend shutdown, but not prepared-xact end */
if (proc->pid != 0)
DisplayXidCache();
#endif
LWLockAcquire(ProcArrayLock, LW_EXCLUSIVE);
for (index = 0; index < arrayP->numProcs; index++)
{
if (arrayP->procs[index] == MyProc)
if (arrayP->procs[index] == proc)
{
arrayP->procs[index] = arrayP->procs[arrayP->numProcs - 1];
arrayP->numProcs--;
@@ -169,7 +170,7 @@ ProcArrayRemoveMyself(void)
/* Ooops */
LWLockRelease(ProcArrayLock);
elog(LOG, "failed to find my own proc %p in ProcArray", MyProc);
elog(LOG, "failed to find proc %p in ProcArray", proc);
}
@@ -329,6 +330,55 @@ result_known:
return result;
}
/*
* TransactionIdIsActive -- is xid the top-level XID of an active backend?
*
* This differs from TransactionIdIsInProgress in that it ignores prepared
* transactions. Also, we ignore subtransactions since that's not needed
* for current uses.
*/
bool
TransactionIdIsActive(TransactionId xid)
{
bool result = false;
ProcArrayStruct *arrayP = procArray;
int i;
/*
* Don't bother checking a transaction older than RecentXmin; it
* could not possibly still be running.
*/
if (TransactionIdPrecedes(xid, RecentXmin))
return false;
LWLockAcquire(ProcArrayLock, LW_SHARED);
for (i = 0; i < arrayP->numProcs; i++)
{
PGPROC *proc = arrayP->procs[i];
/* Fetch xid just once - see GetNewTransactionId */
TransactionId pxid = proc->xid;
if (!TransactionIdIsValid(pxid))
continue;
if (proc->pid == 0)
continue; /* ignore prepared transactions */
if (TransactionIdEquals(pxid, xid))
{
result = true;
break;
}
}
LWLockRelease(ProcArrayLock);
return result;
}
/*
* GetOldestXmin -- returns oldest transaction that was running
* when any current transaction was started.
@@ -441,12 +491,12 @@ GetSnapshotData(Snapshot snapshot, bool serializable)
TransactionIdIsValid(MyProc->xmin));
/*
* Allocating space for MaxBackends xids is usually overkill;
* Allocating space for maxProcs xids is usually overkill;
* numProcs would be sufficient. But it seems better to do the
* malloc while not holding the lock, so we can't look at numProcs.
*
* This does open a possibility for avoiding repeated malloc/free: since
* MaxBackends does not change at runtime, we can simply reuse the
* maxProcs does not change at runtime, we can simply reuse the
* previous xip array if any. (This relies on the fact that all
* callers pass static SnapshotData structs.)
*/
@@ -456,7 +506,7 @@ GetSnapshotData(Snapshot snapshot, bool serializable)
* First call for this snapshot
*/
snapshot->xip = (TransactionId *)
malloc(MaxBackends * sizeof(TransactionId));
malloc(arrayP->maxProcs * sizeof(TransactionId));
if (snapshot->xip == NULL)
ereport(ERROR,
(errcode(ERRCODE_OUT_OF_MEMORY),
@@ -602,14 +652,21 @@ DatabaseHasActiveBackends(Oid databaseId, bool ignoreMyself)
/*
* BackendPidGetProc -- get a backend's PGPROC given its PID
*
* Returns NULL if not found. Note that it is up to the caller to be
* sure that the question remains meaningful for long enough for the
* answer to be used ...
*/
struct PGPROC *
PGPROC *
BackendPidGetProc(int pid)
{
PGPROC *result = NULL;
ProcArrayStruct *arrayP = procArray;
int index;
if (pid == 0) /* never match dummy PGPROCs */
return NULL;
LWLockAcquire(ProcArrayLock, LW_SHARED);
for (index = 0; index < arrayP->numProcs; index++)
@@ -642,10 +699,8 @@ IsBackendPid(int pid)
* active transactions. This is used as a heuristic to decide if
* a pre-XLOG-flush delay is worthwhile during commit.
*
* An active transaction is something that has written at least one XLOG
* record; read-only transactions don't count. Also, do not count backends
* that are blocked waiting for locks, since they are not going to get to
* run until someone else commits.
* Do not count backends that are blocked waiting for locks, since they are
* not going to get to run until someone else commits.
*/
int
CountActiveBackends(void)
@@ -656,7 +711,7 @@ CountActiveBackends(void)
/*
* Note: for speed, we don't acquire ProcArrayLock. This is a little bit
* bogus, but since we are only testing xrecoff for zero or nonzero,
* bogus, but since we are only testing fields for zero or nonzero,
* it should be OK. The result is only used for heuristic purposes
* anyway...
*/
@@ -666,7 +721,9 @@ CountActiveBackends(void)
if (proc == MyProc)
continue; /* do not count myself */
if (proc->logRec.xrecoff == 0)
if (proc->pid == 0)
continue; /* do not count prepared xacts */
if (proc->xid == InvalidTransactionId)
continue; /* do not count if not in a transaction */
if (proc->waitLock != NULL)
continue; /* do not count if blocked on a lock */
@@ -676,25 +733,6 @@ CountActiveBackends(void)
return count;
}
/*
* CountEmptyBackendSlots - count empty slots in backend process table
*
* Acquiring the lock here is almost certainly overkill, but just in
* case fetching an int is not atomic on your machine ...
*/
int
CountEmptyBackendSlots(void)
{
int count;
LWLockAcquire(ProcArrayLock, LW_SHARED);
count = procArray->maxProcs - procArray->numProcs;
LWLockRelease(ProcArrayLock);
return count;
}
#define XidCacheRemove(i) \
do { \