WL#3072 Maria Recovery

- new program maria_read_log to display and apply log records
found in a Maria log (see file's revision comment)
- minor, misc fixes


storage/maria/Makefile.am:
  new program maria_read_log
storage/maria/ha_maria.cc:
  create control file if missing
storage/maria/ma_blockrec.c:
  0 -> LSN_IMPOSSIBLE; comments
storage/maria/ma_checkpoint.h:
  preparations for Checkpoint module
storage/maria/ma_close.c:
  comment
storage/maria/ma_control_file.c:
  renaming constants.
  Possibility to say "open control file but don't create it if it's
  missing" (used by maria_read_log which does not want to create
  anything)
storage/maria/ma_control_file.h:
  renaming constants
storage/maria/ma_create.c:
  I had duplicated "linkname" and "linkname_ptr", now I see it's not
  needed, reverting. Indeed those variables don't contain interesting
  information; fixing log record accordingly (the links are in
  ci->data/index_file_name). Storing keystart in log record is needed,
  to know at which size we must extend the file if we replay
  LOGREC_CREATE_TABLE.
storage/maria/ma_loghandler.c:
  some structures need to be known to maria_read_log.c, taking
  them to ma_loghandler.h
storage/maria/ma_loghandler.h:
  we have page_store, adding page_korr.
  translog_lock() made public, because Checkpoint will need it (to
  write to control file).
  Some structures moved from ma_loghandler.c because maria_read_log.c
  needs them (needs to know the execute-in-REDO-phase hooks of each
  record).
storage/maria/ma_loghandler_lsn.h:
  constants defined in ma_control_file.h serve everywhere,
  and they relate to LSNs, so putting them in ma_loghandler_lsn.h.
  Stronger constraints in LSN_VALID().
storage/maria/ma_pagecache.c:
  renaming constants
storage/maria/ma_recovery.h:
  copyright
storage/maria/ma_test1.c:
  new prototype
storage/maria/ma_test2.c:
  new prototype
storage/maria/trnman_public.h:
  double-inclusion safe
storage/maria/unittest/ma_control_file-t.c:
  constants renamed, new prototype
storage/maria/unittest/ma_test_loghandler-t.c:
  constants renamed, new prototype
storage/maria/unittest/ma_test_loghandler_multigroup-t.c:
  constants renamed, new prototype
storage/maria/unittest/ma_test_loghandler_multithread-t.c:
  constants renamed, new prototype
storage/maria/unittest/ma_test_loghandler_pagecache-t.c:
  constants renamed, new prototype
storage/myisam/mi_close.c:
  comment
storage/maria/maria_read_log.c:
  program to read and print log records from a Maria transaction log,
  and optionally apply them to tables. Very basic, early version.
  Should serve as a base for Recovery's code. Designed to be idempotent.
  Create a log by running maria.test, then cd to var/master-data
  and run "maria_read_log --only-display" to see info about records;
  run "maria_read_log --display-and-apply" to also apply the records
  to tables (it's more interesting if you first wipe out the
  tables in var/master-data/test, to see how they get re-created).
  Only a few records are handled by now: LONG_TRANSACTION_ID,
  COMMIT, FILE_ID, REDO_CREATE_TABLE; place is ready for
  REDO_INSERT_ROW_HEAD where I could use Monty's help (search for
  "Monty" in the file). Note: changes to the index pages, index's header
  and bitmap pages are not properly logged yet, so don't expect
  the program to work with that.

1 files changed, 57 insertions, 10 deletions

diff --git a/storage/maria/ma_checkpoint.h b/storage/maria/ma_checkpoint.h
index 1ce2ccb7012..c011c8234b7 100644
--- a/storage/maria/ma_checkpoint.h
+++ b/storage/maria/ma_checkpoint.h
@@ -1,4 +1,4 @@
-/* Copyright (C) 2006 MySQL AB & MySQL Finland AB & TCX DataKonsult AB
+/* Copyright (C) 2006,2007 MySQL AB
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -21,14 +21,61 @@
 
 /* This is the interface of this module. */
 
-typedef enum enum_checkpoint_level {
-  NONE=-1,
-  INDIRECT, /* just write dirty_pages, transactions table and sync files */
-  MEDIUM, /* also flush all dirty pages which were already dirty at prev checkpoint*/
-  FULL /* also flush all dirty pages */
+typedef enum enum_ma_checkpoint_level {
+  CHECKPOINT_NONE= 0,
+  /* just write dirty_pages, transactions table and sync files */
+  CHECKPOINT_INDIRECT,
+  /* also flush all dirty pages which were already dirty at prev checkpoint */
+  CHECKPOINT_MEDIUM,
+  /* also flush all dirty pages */
+  CHECKPOINT_FULL
 } CHECKPOINT_LEVEL;
 
-void request_asynchronous_checkpoint(CHECKPOINT_LEVEL level);
-my_bool execute_synchronous_checkpoint(CHECKPOINT_LEVEL level);
-my_bool execute_asynchronous_checkpoint_if_any();
-/* that's all that's needed in the interface */
+C_MODE_START
+int ma_checkpoint_init();
+void ma_checkpoint_end();
+int ma_checkpoint_execute(CHECKPOINT_LEVEL level, my_bool no_wait);
+C_MODE_END
+
+/**
+   @brief reads some LSNs with special trickery
+
+   If a 64-bit variable transitions between both halves being zero to both
+   halves being non-zero, and back, this function can be used to do a read of
+   it (without mutex, without atomic load) which always produces a correct
+   (though maybe slightly old) value (even on 32-bit CPUs). The value is at
+   least as new as the latest mutex unlock done by the calling thread.
+   The assumption is that the system sets both 4-byte halves either at the
+   same time, or one after the other (in any order), but NOT some bytes of the
+   first half then some bytes of the second half then the rest of bytes of the
+   first half. With this assumption, the function can detect when it is
+   seeing an inconsistent value.
+
+   @param LSN              pointer to the LSN variable to read
+
+   @return LSN part (most significant byte always 0)
+*/
+#if ( SIZEOF_CHARP >= 8 )
+/* 64-bit CPU, 64-bit reads are atomic */
+#define lsn_read_non_atomic LSN_WITH_FLAGS_TO_LSN
+#else
+static inline LSN lsn_read_non_atomic_32(const volatile LSN *x)
+{
+  /*
+    32-bit CPU, 64-bit reads may give a mixed of old half and new half (old
+    low bits and new high bits, or the contrary).
+  */
+  for (;;) /* loop until no atomicity problems */
+  {
+    /*
+      Remove most significant byte in case this is a LSN_WITH_FLAGS object.
+      Those flags in TRN::first_undo_lsn break the condition on transitions so
+      they must be removed below.
+    */
+    LSN y= LSN_WITH_FLAGS_TO_LSN(*x);
+    if (likely((y == LSN_IMPOSSIBLE) || LSN_VALID(y)))
+      return y;
+  }
+}
+#define lsn_read_non_atomic(x) lsn_read_non_atomic_32(&x)
+#endif