Implement MySQL framework to support consistent read views in

cursors. This should fix Bug#11813 when InnoDB part is in 
(tested with a draft patch).
The idea of the patch is that if a storage engine supports
consistent read views, we open one when open a cursor,
set is as the active view when fetch from the cursor, and close
together with cursor close.


sql/examples/ha_archive.cc:
  - extend handlerton with cursors methods; fix coding style
sql/examples/ha_example.cc:
  - extend handlerton with cursors methods; fix coding style
sql/examples/ha_tina.cc:
  - extend handlerton with cursors methods; fix coding style
sql/ha_berkeley.cc:
  - extend handlerton with cursors methods
sql/ha_blackhole.cc:
  - extend handlerton with cursors methods; fix coding style
sql/ha_federated.cc:
  - extend handlerton with cursors methods; fix coding style
sql/ha_heap.cc:
  - extend handlerton with cursors methods; fix coding style
sql/ha_innodb.cc:
  - extend handlerton with cursors methods
sql/ha_myisam.cc:
  - extend handlerton with cursors methods; fix coding style
sql/ha_myisammrg.cc:
  - extend handlerton with cursors methods; fix coding style
sql/ha_ndbcluster.cc:
  - extend handlerton with cursors methods
sql/handler.h:
  - extend handlerton with cursors methods
sql/sql_select.cc:
  - create a consistent read view when we open a cursor,
    set it for a fetch, and free when we closing the cursor.
sql/sql_select.h:
  - add Cursor::ht_info to remember read views used in a cursor.
tests/mysql_client_test.c:
  Disable an assert that will be no longer valid when consistent
  read views in InnoDB are used.

1 files changed, 7 insertions, 2 deletions

diff --git a/sql/handler.h b/sql/handler.h
index 02b2353b890..276f50bde63 100644
--- a/sql/handler.h
+++ b/sql/handler.h
@@ -106,9 +106,11 @@
 
 /*
   Note: the following includes binlog and closing 0.
-  so: innodb+bdb+ndb+binlog+0
+  so: innodb + bdb + ndb + binlog + myisam + myisammrg + archive +
+      example + csv + heap + blackhole + federated + 0
+  (yes, the sum is deliberately inaccurate)
 */
-#define MAX_HA 6
+#define MAX_HA 14
 
 /*
   Bits in index_ddl_flags(KEY *wanted_index)
@@ -349,6 +351,9 @@ typedef struct
    int  (*recover)(XID *xid_list, uint len);
    int  (*commit_by_xid)(XID *xid);
    int  (*rollback_by_xid)(XID *xid);
+   void *(*create_cursor_read_view)();
+   void (*set_cursor_read_view)(void *);
+   void (*close_cursor_read_view)(void *);
    uint32 flags;                                /* global handler flags */
 } handlerton;