Merge lp:~akopytov/percona-server/bug1070856-5.1 into lp:percona-server/5.1

[Alexey Kopytov]

    Bug #1070856: Temporary files created by binary log cache are not purged
                  after transaction commit

    The problem was that the temporary file used to cache transactions for
    the binary log was initialized once (when the in-memory buffer was
    exceeded) and close (and thus, removed) only when closing the
    connection. Which might lead to problems with large temporary files
    being created and not removed in case of persistent connections and
    large transactions (i.e. LOAD DATA INFILE).

    Fixed by truncating the temporary file, if used for a binary log
    transaction cache, when committing or rolling back a statement or a
    transaction.

[Alexey Kopytov (akopytov)]

http://jenkins.percona.com/view/PS%205.1/job/percona-server-5.1-param/453/

[Alexey Kopytov (akopytov)]

ST 26926

[Vlad Lesin (vlad-lesin)]

Looks good.

It would be great if there would be possibility to test it. Maybe it would me reasonable to add I_S that would show the size of current session cache size?

[Alexey Kopytov (akopytov)]

Vlad,

I agree that having an I_S table or a status variable would make creating an automated test possible. But the amount of code and time required to implement, test and document that table/variable look unreasonably high for such a small fix.

Btw, why did you just added a comment without adding yourself as a reviewer?

[Vlad Lesin (vlad-lesin)]

I agree.

review: Approve

[George Ormond Lorch III (gl-az)]

review: Approve (g2)

[Laurynas Biveinis (laurynas-biveinis)]

review: Approve

=== modified file 'Percona-Server/include/my_sys.h'
--- Percona-Server/include/my_sys.h	2011-11-24 02:01:56 +0000
+++ Percona-Server/include/my_sys.h	2012-10-26 05:10:26 +0000
@@ -801,6 +801,7 @@
 				 const char *prefix, size_t cache_size,
 				 myf cache_myflags);
 extern my_bool real_open_cached_file(IO_CACHE *cache);
+extern my_bool truncate_cached_file(IO_CACHE *cache, my_off_t pos);
 extern void close_cached_file(IO_CACHE *cache);
 File create_temp_file(char *to, const char *dir, const char *pfx,
 		      int mode, myf MyFlags);
 
=== modified file 'Percona-Server/mysys/mf_cache.c'
--- Percona-Server/mysys/mf_cache.c	2007-05-10 09:59:39 +0000
+++ Percona-Server/mysys/mf_cache.c	2012-10-26 05:10:26 +0000
@@ -119,3 +119,21 @@
   }
   DBUG_VOID_RETURN;
 }
+
+/*
+  Truncate the cached file to a given offset. The cache must be reinitialized
+  with reinit_io_cache() after this call.
+*/
+
+my_bool truncate_cached_file(IO_CACHE *cache, my_off_t pos)
+{
+  DBUG_ENTER("truncate_cached_file");
+
+  if (my_b_inited(cache) && cache->file > -1)
+  {
+    if (my_chsize(cache->file, pos, 0, MYF(MY_WME)))
+      DBUG_RETURN(TRUE);
+  }
+
+  DBUG_RETURN(FALSE);
+}
 
=== modified file 'Percona-Server/sql/log.cc'
--- Percona-Server/sql/log.cc	2012-08-20 03:14:02 +0000
+++ Percona-Server/sql/log.cc	2012-10-26 05:10:26 +0000
@@ -187,7 +187,14 @@
       delete pending();
     }
     set_pending(0);
+
+    /*
+      Truncate the temporary file to reclaim disk space occupied by cached
+      transactions on COMMIT/ROLLBACK.
+    */
+    truncate_cached_file(&trans_log, pos);
     reinit_io_cache(&trans_log, WRITE_CACHE, pos, 0, 0);
+
     trans_log.end_of_file= max_binlog_cache_size;
     if (pos < before_stmt_pos)
       before_stmt_pos= MY_OFF_T_UNDEF;