branches/zip: Merge revisions 3930:4005 from branches/5.1:

  ------------------------------------------------------------------------
  r4004 | marko | 2009-01-20 16:19:00 +0200 (Tue, 20 Jan 2009) | 12 lines

  branches/5.1: Merge r4003 from branches/5.0:

  rec_set_nth_field(): When the field already is SQL null,
  do nothing when it is being changed to SQL null. (Bug #41571)

  Normally, MySQL does not pass "do-nothing" updates to the storage engine.
  When it does and a column of an InnoDB table that is in ROW_FORMAT=COMPACT
  is being updated from NULL to NULL, the InnoDB buffer pool will be corrupted
  without this fix.

  rb://81 approved by Heikki Tuuri
  ------------------------------------------------------------------------
  r4005 | marko | 2009-01-20 16:22:36 +0200 (Tue, 20 Jan 2009) | 8 lines

  branches/5.1: lock_is_table_exclusive(): Acquire kernel_mutex before
  accessing table->locks and release kernel_mutex before returning from
  the function.  This fixes a portential race condition in the
  "commit every 10,000 rows" in ALTER TABLE, CREATE INDEX, DROP INDEX,
  and OPTIMIZE TABLE. (Bug #42152)

  rb://80 approved by Heikki Tuuri
  ------------------------------------------------------------------------

include/rem0rec.h

@@ -506,8 +506,9 @@ rec_offs_n_extern(
 /***************************************************************
 This is used to modify the value of an already existing field in a record.
 The previous value must have exactly the same size as the new value. If len
-is UNIV_SQL_NULL then the field is treated as an SQL null for old-style
-records. For new-style records, len must not be UNIV_SQL_NULL. */
+is UNIV_SQL_NULL then the field is treated as an SQL null.
+For records in ROW_FORMAT=COMPACT (new-style records), len must not be
+UNIV_SQL_NULL unless the field already is SQL null. */
 UNIV_INLINE
 void
 rec_set_nth_field(
@@ -516,11 +517,7 @@ rec_set_nth_field(
 	const ulint*	offsets,/* in: array returned by rec_get_offsets() */
 	ulint		n,	/* in: index number of the field */
 	const void*	data,	/* in: pointer to the data if not SQL null */
-	ulint		len);	/* in: length of the data or UNIV_SQL_NULL.
-				If not SQL null, must have the same
-				length as the previous value.
-				If SQL null, previous value must be
-				SQL null. */
+	ulint		len);	/* in: length of the data or UNIV_SQL_NULL */
 /**************************************************************
 The following function returns the data size of an old-style physical
 record, that is the sum of field lengths. SQL null fields

include/rem0rec.ic

@@ -1326,8 +1326,9 @@ rec_get_nth_field_size(
 /***************************************************************
 This is used to modify the value of an already existing field in a record.
 The previous value must have exactly the same size as the new value. If len
-is UNIV_SQL_NULL then the field is treated as an SQL null for old-style
-records. For new-style records, len must not be UNIV_SQL_NULL. */
+is UNIV_SQL_NULL then the field is treated as an SQL null.
+For records in ROW_FORMAT=COMPACT (new-style records), len must not be
+UNIV_SQL_NULL unless the field already is SQL null. */
 UNIV_INLINE
 void
 rec_set_nth_field(
@@ -1337,11 +1338,7 @@ rec_set_nth_field(
 	ulint		n,	/* in: index number of the field */
 	const void*	data,	/* in: pointer to the data
 				if not SQL null */
-	ulint		len)	/* in: length of the data or UNIV_SQL_NULL.
-				If not SQL null, must have the same
-				length as the previous value.
-				If SQL null, previous value must be
-				SQL null. */
+	ulint		len)	/* in: length of the data or UNIV_SQL_NULL */
 {
 	byte*	data2;
 	ulint	len2;
@@ -1349,9 +1346,11 @@ rec_set_nth_field(
 	ut_ad(rec);
 	ut_ad(rec_offs_validate(rec, NULL, offsets));
 
-	if (len == UNIV_SQL_NULL) {
-		ut_ad(!rec_offs_comp(offsets));
+	if (UNIV_UNLIKELY(len == UNIV_SQL_NULL)) {
+		if (!rec_offs_nth_sql_null(offsets, n)) {
+			ut_a(!rec_offs_comp(offsets));
 			rec_set_nth_field_sql_null(rec, n);
+		}
 
 		return;
 	}

lock/lock0lock.c

@@ -699,7 +699,10 @@ lock_is_table_exclusive(
 	const lock_t*	lock;
 	ibool		ok	= FALSE;
 
-	ut_ad(table && trx);
+	ut_ad(table);
+	ut_ad(trx);
+
+	lock_mutex_enter_kernel();
 
 	for (lock = UT_LIST_GET_FIRST(table->locks);
 	     lock;
@@ -707,7 +710,7 @@ lock_is_table_exclusive(
 		if (lock->trx != trx) {
 			/* A lock on the table is held
 			by some other transaction. */
-			return(FALSE);
+			goto not_ok;
 		}
 
 		if (!(lock_get_type_low(lock) & LOCK_TABLE)) {
@@ -724,11 +727,16 @@ lock_is_table_exclusive(
 			auto_increment lock. */
 			break;
 		default:
+not_ok:
 			/* Other table locks than LOCK_IX are not allowed. */
-			return(FALSE);
+			ok = FALSE;
+			goto func_exit;
 		}
 	}
 
+func_exit:
+	lock_mutex_exit_kernel();
+
 	return(ok);
 }