Add lock file.

2025-01-18 18:44:06 +08:00 · 2002-08-17 13:11:43 +00:00 · 2002-08-17 13:11:43 +00:00 · fc68e44062
commit fc68e44062
parent 54124240ae
1 changed files with 146 additions and 0 deletions
--- a/src/backend/utils/adt/lockfuncs.c
+++ b/src/backend/utils/adt/lockfuncs.c
@ -0,0 +1,146 @@
+/*
+ * lockfuncs.c
+ *		Set-returning functions to view the state of locks within the DB.
+ * 
+ * Copyright (c) 2002, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *		$Header: /cvsroot/pgsql/src/backend/utils/adt/lockfuncs.c,v 1.1 2002/08/17 13:11:43 momjian Exp $
+ */
+
+#include "postgres.h"
+#include "fmgr.h"
+#include "funcapi.h"
+#include "storage/lmgr.h"
+#include "storage/lock.h"
+#include "storage/lwlock.h"
+#include "storage/proc.h"
+
+Datum lock_status_srf(PG_FUNCTION_ARGS);
+
+static int next_lock(int locks[]);
+
+Datum
+lock_status_srf(PG_FUNCTION_ARGS)
+{
+	FuncCallContext		*funccxt;
+	LockData			*lockData;
+
+	if (SRF_IS_FIRSTCALL())
+	{
+		MemoryContext	oldcxt;
+		TupleDesc		tupdesc;
+
+		funccxt = SRF_FIRSTCALL_INIT();
+		tupdesc = RelationNameGetTupleDesc("pg_catalog.pg_locks_result");
+		funccxt->slot = TupleDescGetSlot(tupdesc);
+		funccxt->attinmeta = TupleDescGetAttInMetadata(tupdesc);
+
+		oldcxt = MemoryContextSwitchTo(funccxt->fmctx);
+
+		/*
+		 * Preload all the locking information that we will eventually format
+		 * and send out as a result set. This is palloc'ed, but since the
+		 * MemoryContext is reset when the SRF finishes, we don't need to
+		 * free it ourselves.
+		 */
+		funccxt->user_fctx = (LockData *) palloc(sizeof(LockData));
+
+		GetLockStatusData(funccxt->user_fctx);
+
+		MemoryContextSwitchTo(oldcxt);
+	}
+
+	funccxt	= SRF_PERCALL_SETUP();
+	lockData = (LockData *) funccxt->user_fctx;
+
+	while (lockData->currIdx < lockData->nelements)
+	{
+		PROCLOCK		 *holder;
+		LOCK			 *lock;
+		PGPROC			 *proc;
+		HeapTuple		  tuple;
+		Datum			  result;
+		char			**values;
+		LOCKMODE		  mode;
+		int				  num_attrs;
+		int				  i;
+		int				  currIdx = lockData->currIdx;
+
+		holder		= &(lockData->holders[currIdx]);
+		lock		= &(lockData->locks[currIdx]);
+		proc		= &(lockData->procs[currIdx]);
+		num_attrs	= funccxt->attinmeta->tupdesc->natts;
+
+		values = (char **) palloc(sizeof(*values) * num_attrs);
+
+		for (i = 0; i < num_attrs; i++)
+			values[i] = (char *) palloc(32);
+
+		/* The OID of the locked relation */
+		snprintf(values[0], 32, "%u", lock->tag.relId);
+		/* The database the relation is in */
+		snprintf(values[1], 32, "%u", lock->tag.dbId);
+		/* The PID of the backend holding or waiting for the lock */
+		snprintf(values[2], 32, "%d", proc->pid);
+
+		/*
+		 * We need to report both the locks held (i.e. successfully acquired)
+		 * by this holder, as well as the locks upon which it is still
+		 * waiting, if any. Since a single PROCLOCK struct may contain
+		 * multiple locks, we may need to loop several times before we
+		 * advance the array index and continue on.
+		 */
+		if (holder->nHolding > 0)
+		{
+			/* Already held locks */
+			mode = next_lock(holder->holding);
+			holder->holding[mode]--;
+			holder->nHolding--;
+
+			strcpy(values[4], "t");
+		}
+		else if (proc->waitLock != NULL)
+		{
+			/* Lock that is still being waited on */
+			mode = proc->waitLockMode;
+			proc->waitLock = NULL;
+			proc->waitLockMode = NoLock;
+
+			strcpy(values[4], "f");
+		}
+		else
+		{
+			/*
+			 * Okay, we've displayed all the lock's belonging to this PROCLOCK,
+			 * procede to the next one.
+			 */
+			lockData->currIdx++;
+			continue;
+		}
+
+		strncpy(values[3], GetLockmodeName(mode), 32);
+
+		tuple = BuildTupleFromCStrings(funccxt->attinmeta, values);
+		result = TupleGetDatum(funccxt->slot, tuple);
+		SRF_RETURN_NEXT(funccxt, result);
+	}
+
+	SRF_RETURN_DONE(funccxt);
+}
+
+static LOCKMODE
+next_lock(int locks[])
+{
+	LOCKMODE i;
+
+	for (i = 0; i < MAX_LOCKMODES; i++)
+	{
+		if (locks[i] != 0)
+			return i;
+	}
+
+	/* No locks found: this should not occur */
+	Assert(false);
+	return -1;
+}