Fix broken cleanup interlock for GIN pending list.

The pending list must (for correctness) always be cleaned up by vacuum, and
should (for the avoidance of surprising behavior) always be cleaned up
by an explicit call to gin_clean_pending_list, but cleanup is optional
when inserting.  The old logic got this backward: cleanup was forced
if (stats == NULL), but that's going to be *false* when vacuuming and
*true* for inserts.

Masahiko Sawada, reviewed by me.

Discussion: http://postgr.es/m/CAD21AoBLUSyiYKnTYtSAbC+F=XDjiaBrOUEGK+zUXdQ8owfPKw@mail.gmail.com

src/backend/access/gin/ginfast.c

@@ -450,8 +450,12 @@ ginHeapTupleFastInsert(GinState *ginstate, GinTupleCollector *collector)
 
 	END_CRIT_SECTION();
 
+	/*
+	 * Since it could contend with concurrent cleanup process we cleanup
+	 * pending list not forcibly.
+	 */
 	if (needCleanup)
-		ginInsertCleanup(ginstate, false, true, NULL);
+		ginInsertCleanup(ginstate, false, true, false, NULL);
 }
 
 /*
@@ -748,7 +752,8 @@ processPendingPage(BuildAccumulator *accum, KeyArray *ka,
  */
 void
 ginInsertCleanup(GinState *ginstate, bool full_clean,
-				 bool fill_fsm, IndexBulkDeleteResult *stats)
+				 bool fill_fsm, bool forceCleanup,
+				 IndexBulkDeleteResult *stats)
 {
 	Relation	index = ginstate->index;
 	Buffer		metabuffer,
@@ -765,7 +770,6 @@ ginInsertCleanup(GinState *ginstate, bool full_clean,
 	bool		cleanupFinish = false;
 	bool		fsm_vac = false;
 	Size		workMemory;
-	bool		inVacuum = (stats == NULL);
 
 	/*
 	 * We would like to prevent concurrent cleanup process. For that we will
@@ -774,7 +778,7 @@ ginInsertCleanup(GinState *ginstate, bool full_clean,
 	 * insertion into pending list
 	 */
 
-	if (inVacuum)
+	if (forceCleanup)
 	{
 		/*
 		 * We are called from [auto]vacuum/analyze or gin_clean_pending_list()
@@ -1036,7 +1040,7 @@ gin_clean_pending_list(PG_FUNCTION_ARGS)
 
 	memset(&stats, 0, sizeof(stats));
 	initGinState(&ginstate, indexRel);
-	ginInsertCleanup(&ginstate, true, true, &stats);
+	ginInsertCleanup(&ginstate, true, true, true, &stats);
 
 	index_close(indexRel, AccessShareLock);
 

src/backend/access/gin/ginvacuum.c

@@ -570,7 +570,7 @@ ginbulkdelete(IndexVacuumInfo *info, IndexBulkDeleteResult *stats,
 		 * and cleanup any pending inserts
 		 */
 		ginInsertCleanup(&gvs.ginstate, !IsAutoVacuumWorkerProcess(),
-						 false, stats);
+						 false, true, stats);
 	}
 
 	/* we'll re-count the tuples each time */
@@ -683,7 +683,7 @@ ginvacuumcleanup(IndexVacuumInfo *info, IndexBulkDeleteResult *stats)
 		if (IsAutoVacuumWorkerProcess())
 		{
 			initGinState(&ginstate, index);
-			ginInsertCleanup(&ginstate, false, true, stats);
+			ginInsertCleanup(&ginstate, false, true, true, stats);
 		}
 		return stats;
 	}
@@ -697,7 +697,7 @@ ginvacuumcleanup(IndexVacuumInfo *info, IndexBulkDeleteResult *stats)
 		stats = (IndexBulkDeleteResult *) palloc0(sizeof(IndexBulkDeleteResult));
 		initGinState(&ginstate, index);
 		ginInsertCleanup(&ginstate, !IsAutoVacuumWorkerProcess(),
-						 false, stats);
+						 false, true, stats);
 	}
 
 	memset(&idxStat, 0, sizeof(idxStat));

src/include/access/gin_private.h

@@ -439,7 +439,7 @@ extern void ginHeapTupleFastCollect(GinState *ginstate,
 						OffsetNumber attnum, Datum value, bool isNull,
 						ItemPointer ht_ctid);
 extern void ginInsertCleanup(GinState *ginstate, bool full_clean,
-				 bool fill_fsm, IndexBulkDeleteResult *stats);
+				 bool fill_fsm, bool forceCleanup, IndexBulkDeleteResult *stats);
 
 /* ginpostinglist.c */