BUG#11757032 - 49030: OPTIMIZE TABLE BREAKS MYISAM TABLE WHEN

USING MYISAM_USE_MMAP ON WINDOWS

When OPTIMIZE/REPAIR TABLE is switching to new data file,
old data file is removed while memory mapping is still
active.

With 5.1 implementation of nt_share_delete() it is not
permitted to remove mmaped file.

This fix disables memory mapping for mi_repair() operations.

mysql-test/r/myisam.result:
  A test case for BUG#11757032.
mysql-test/t/myisam.test:
  A test case for BUG#11757032.
storage/myisam/ha_myisam.cc:
  mi_repair*() functions family use file I/O even if memory
  mapping is available.
  
  Since mixing mmap I/O and file I/O may cause various artifacts,
  memory mapping must be disabled.
storage/myisam/mi_delete_all.c:
  Clean-up: do not attempt to remap file after truncate, since
  there is nothing to map.

mysql-test/r/myisam.result

@@ -2412,4 +2412,28 @@ CARDINALITY
 DROP TABLE t1;
 SET myisam_sort_buffer_size=@@global.myisam_sort_buffer_size;
 SET myisam_repair_threads=@@global.myisam_repair_threads;
+#
+# BUG#11757032 - 49030: OPTIMIZE TABLE BREAKS MYISAM TABLE WHEN
+#                USING MYISAM_USE_MMAP ON WINDOWS
+#
+SET GLOBAL myisam_use_mmap=1;
+CREATE TABLE t1(a INT);
+INSERT INTO t1 VALUES(1),(2);
+DELETE FROM t1 WHERE a=1;
+FLUSH TABLE t1;
+LOCK TABLE t1 WRITE;
+OPTIMIZE TABLE t1;
+Table	Op	Msg_type	Msg_text
+test.t1	optimize	status	OK
+INSERT INTO t1 VALUES(3);
+UNLOCK TABLES;
+SELECT * FROM t1;
+a
+2
+3
+CHECK TABLE t1;
+Table	Op	Msg_type	Msg_text
+test.t1	check	status	OK
+DROP TABLE t1;
+SET GLOBAL myisam_use_mmap=default;
 End of 5.1 tests

mysql-test/t/myisam.test

@@ -1645,4 +1645,22 @@ DROP TABLE t1;
 SET myisam_sort_buffer_size=@@global.myisam_sort_buffer_size;
 SET myisam_repair_threads=@@global.myisam_repair_threads;
 
+--echo #
+--echo # BUG#11757032 - 49030: OPTIMIZE TABLE BREAKS MYISAM TABLE WHEN
+--echo #                USING MYISAM_USE_MMAP ON WINDOWS
+--echo #
+SET GLOBAL myisam_use_mmap=1;
+CREATE TABLE t1(a INT);
+INSERT INTO t1 VALUES(1),(2);
+DELETE FROM t1 WHERE a=1;
+FLUSH TABLE t1;
+LOCK TABLE t1 WRITE;
+OPTIMIZE TABLE t1;
+INSERT INTO t1 VALUES(3);
+UNLOCK TABLES;
+SELECT * FROM t1;
+CHECK TABLE t1;
+DROP TABLE t1;
+SET GLOBAL myisam_use_mmap=default;
+
 --echo End of 5.1 tests

storage/myisam/ha_myisam.cc

@@ -1135,6 +1135,18 @@ int ha_myisam::repair(THD *thd, MI_CHECK &param, bool do_optimize)
 			mi_get_mask_all_keys_active(share->base.keys) :
 			share->state.key_map);
     uint testflag=param.testflag;
+#ifdef HAVE_MMAP
+    bool remap= test(share->file_map);
+    /*
+      mi_repair*() functions family use file I/O even if memory
+      mapping is available.
+
+      Since mixing mmap I/O and file I/O may cause various artifacts,
+      memory mapping must be disabled.
+    */
+    if (remap)
+      mi_munmap_file(file);
+#endif
     if (mi_test_if_sort_rep(file,file->state->records,key_map,0) &&
 	(local_testflag & T_REP_BY_SORT))
     {
@@ -1166,6 +1178,10 @@ int ha_myisam::repair(THD *thd, MI_CHECK &param, bool do_optimize)
       error=  mi_repair(&param, file, fixed_name,
 			param.testflag & T_QUICK);
     }
+#ifdef HAVE_MMAP
+    if (remap)
+      mi_dynmap_file(file, file->state->data_file_length);
+#endif
     param.testflag=testflag;
     optimize_done=1;
   }

storage/myisam/mi_delete_all.c

@@ -63,11 +63,6 @@ int mi_delete_all_rows(MI_INFO *info)
       my_chsize(share->kfile, share->base.keystart, 0, MYF(MY_WME))  )
     goto err;
   VOID(_mi_writeinfo(info,WRITEINFO_UPDATE_KEYFILE));
-#ifdef HAVE_MMAP
-  /* Map again */
-  if (share->file_map)
-    mi_dynmap_file(info, (my_off_t) 0);
-#endif
   allow_break();			/* Allow SIGHUP & SIGINT */
   DBUG_RETURN(0);