commit into MySQL/Maria:mysql-maria branch (guilhem:2651) Bug#35801, Bug#35823

[Guilhem Bichot]

#At bzr+ssh://bk-internal.mysql.com/bzrroot/server/mysql-maria/

 2651 Guilhem Bichot	2008-06-12
      Fix for BUG#35801 "Maria: unreadable log during tests" and
      BUG#35823 "Maria: log handler assertion (page[page_offset] & (3 << 6)) ==
0x00... fails"
      Both random problems can be explained by the REDO phase starting from a log horizon
which is not a LSN,
      which is the bug fixed here.
modified:
  storage/maria/ma_recovery.c

per-file comments:
  storage/maria/ma_recovery.c
    In Recovery, REDO phase needs to start log reading from a LSN, not a log horizon:
start_address was only
    guaranteed to be a horizon, not necessarily a LSN.
    On some machine and test, it happened that start_address was only a log horizon, and
run_redo_phase()
    tried to read from there, and log handler naturally refused that:
    ma_loghandler.c:6797: translog_read_record_header_from_buffer: Assertion
`translog_is_LSN_chunk(page[page_offset])' failed. And in non-debug build, just the "redo
phase failed" message in the error log.
    This was random, because depended on amount of checkpoints which is timing-dependent;
also depended on Maria tests
    ran or skipped (so, debug or non-debug builds)... Bad code was introduced by me end of
December so it's likely
    to explain lots of random log handler errors we observed since.
=== modified file 'storage/maria/ma_recovery.c'
--- a/storage/maria/ma_recovery.c	2008-06-02 20:53:25 +0000
+++ b/storage/maria/ma_recovery.c	2008-06-12 13:49:19 +0000
@@ -3060,7 +3060,8 @@ static LSN parse_checkpoint_record(LSN l
     Find LSN higher or equal to this TRANSLOG_ADDRESS, suitable for
     translog_read_record() functions.
   */
-  checkpoint_start= translog_next_LSN(start_address, LSN_IMPOSSIBLE);
+  start_address= checkpoint_start=
+    translog_next_LSN(start_address, LSN_IMPOSSIBLE);
   if (checkpoint_start == LSN_IMPOSSIBLE)
   {
     /*