From 4b5198d6a1ee5244d5895753a1ea56fc27d28a90 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Fri, 27 Jul 2012 00:22:47 -0400
Subject: [PATCH] Test code for deletes, and associated bug fixes.

---
 contrib/hashtest/hashtest.c    | 64 ++++++++++++++++++++++++++++++----
 src/backend/utils/hash/chash.c |  4 +--
 2 files changed, 60 insertions(+), 8 deletions(-)

diff --git a/contrib/hashtest/hashtest.c b/contrib/hashtest/hashtest.c
index d9e5771d8b..7b29a8e3bc 100644
--- a/contrib/hashtest/hashtest.c
+++ b/contrib/hashtest/hashtest.c
@@ -99,7 +99,8 @@ test_chash(PG_FUNCTION_ARGS)
 	hentry	e;
 	instr_time t0,
 			   t1,
-			   t2;
+			   t2,
+			   t3;
 
 	INSTR_TIME_SET_CURRENT(t0);
 
@@ -132,12 +133,29 @@ test_chash(PG_FUNCTION_ARGS)
 	}
 
 	INSTR_TIME_SET_CURRENT(t2);
+
+	for (i = 0; i < 1000000; ++i)
+	{
+		bool ok;
+
+		e.key = i;
+		ok = CHashDelete(chash, &e);
+		if (!ok)
+			elog(LOG, "delete %u: not found", i);
+		ok = CHashDelete(chash, &e);
+		if (ok)
+			elog(LOG, "delete %u: found twice", i);
+	}
+
+	INSTR_TIME_SET_CURRENT(t3);
+	INSTR_TIME_SUBTRACT(t3, t2);
 	INSTR_TIME_SUBTRACT(t2, t1);
 	INSTR_TIME_SUBTRACT(t1, t0);
 
-	elog(LOG, "inserts: %lu us; searches: %lu us",
+	elog(LOG, "inserts: %lu us; searches: %lu us; deletes: %lu us",
 		(unsigned long) INSTR_TIME_GET_MICROSEC(t1),
-		(unsigned long) INSTR_TIME_GET_MICROSEC(t2));
+		(unsigned long) INSTR_TIME_GET_MICROSEC(t2),
+		(unsigned long) INSTR_TIME_GET_MICROSEC(t3));
 
 	PG_RETURN_VOID();
 }
@@ -181,13 +199,31 @@ dynahash_search(uint32 key, uint32 *val)
 	return e != NULL;
 }
 
+static bool
+dynahash_delete(uint32 key)
+{
+	uint32	hashcode;
+	hentry *e;
+	LWLockId	lockid;
+
+	hashcode = get_hash_value(dynahash, (void *) &key);
+ 	lockid = dynahash_get_lock(hashcode);
+	LWLockAcquire(lockid, LW_SHARED);
+	e = hash_search_with_hash_value(dynahash, (void *) &key,
+									hashcode, HASH_REMOVE, NULL);
+	LWLockRelease(lockid);
+
+	return e != NULL;
+}
+
 Datum
 test_dynahash(PG_FUNCTION_ARGS)
 {
 	uint32	i;
 	instr_time t0,
 			   t1,
-			   t2;
+			   t2,
+			   t3;
 
 	INSTR_TIME_SET_CURRENT(t0);
 
@@ -218,12 +254,28 @@ test_dynahash(PG_FUNCTION_ARGS)
 	}
 
 	INSTR_TIME_SET_CURRENT(t2);
+
+	for (i = 0; i < 1000000; ++i)
+	{
+		bool	ok;
+
+		ok = dynahash_delete(i);
+		if (!ok)
+			elog(LOG, "delete %u: not found", i);
+		ok = dynahash_delete(i);
+		if (ok)
+			elog(LOG, "delete %u: found twice", i);
+	}
+
+	INSTR_TIME_SET_CURRENT(t3);
+	INSTR_TIME_SUBTRACT(t3, t2);
 	INSTR_TIME_SUBTRACT(t2, t1);
 	INSTR_TIME_SUBTRACT(t1, t0);
 
-	elog(LOG, "inserts: %lu us; searches: %lu us",
+	elog(LOG, "inserts: %lu us; searches: %lu us; deletes: %lu us",
 		(unsigned long) INSTR_TIME_GET_MICROSEC(t1),
-		(unsigned long) INSTR_TIME_GET_MICROSEC(t2));
+		(unsigned long) INSTR_TIME_GET_MICROSEC(t2),
+		(unsigned long) INSTR_TIME_GET_MICROSEC(t3));
 
 	PG_RETURN_VOID();
 }
diff --git a/src/backend/utils/hash/chash.c b/src/backend/utils/hash/chash.c
index d9067a5892..c7b970dab4 100644
--- a/src/backend/utils/hash/chash.c
+++ b/src/backend/utils/hash/chash.c
@@ -513,7 +513,7 @@ CHashDelete(CHashTable table, void *entry)
 			/* Someone else deleted it before we did. */
 			scan.found = false;
 		}
-		else if (__sync_bool_compare_and_swap(&scan.target_node,
+		else if (__sync_bool_compare_and_swap(&scan.target_node->next,
 											  next,
 											  CHashPtrMark(next)))
 		{
@@ -825,7 +825,7 @@ CHashAllocate(CHashTable table)
 				{
 					oldhead = *b;
 					n->un.gcnext = oldhead;
-				} while (__sync_bool_compare_and_swap(b, oldhead, fhead));
+				} while (!__sync_bool_compare_and_swap(b, oldhead, fhead));
 			}
 
 			/* Return the element we saved for ourselves. */
-- 
2.39.5