BUG#21726: Incorrect result with multiple invocations of LAST_INSERT_ID.

Note: bug#21726 does not directly apply to 4.1, as it doesn't have stored
procedures.  However, 4.1 had some bugs that were fixed in 5.0 by the
patch for bug#21726, and this patch is a backport of those fixes.
Namely, in 4.1 it fixes:

  - LAST_INSERT_ID(expr) didn't return value of expr (4.1 specific).

  - LAST_INSERT_ID() could return the value generated by current
    statement if the call happens after the generation, like in

      CREATE TABLE t1 (i INT AUTO_INCREMENT PRIMARY KEY, j INT);
      INSERT INTO t1 VALUES (NULL, 0), (NULL, LAST_INSERT_ID());

  - Redundant binary log LAST_INSERT_ID_EVENTs could be generated.


mysql-test/r/rpl_insert_id.result:
  Add result for bug#21726: Incorrect result with multiple invocations
  of LAST_INSERT_ID.
mysql-test/t/rpl_insert_id.test:
  Add test case for bug#21726: Incorrect result with multiple invocations
  of LAST_INSERT_ID.
sql/item_func.cc:
  Add implementation of Item_func_last_insert_id::fix_fields(), where we
  set THD::last_insert_id_used when statement calls LAST_INSERT_ID().
  In Item_func_last_insert_id::val_int(), return THD::current_insert_id
  if called like LAST_INSERT_ID(), otherwise return value of argument if
  called like LAST_INSERT_ID(expr).
sql/item_func.h:
  Add declaration of Item_func_last_insert_id::fix_fields().
sql/log_event.cc:
  Do not set THD::last_insert_id_used on LAST_INSERT_ID_EVENT.  Though we
  know the statement will call LAST_INSERT_ID(), it wasn't called yet.
sql/set_var.cc:
  In sys_var_last_insert_id::value_ptr(), set THD::last_insert_id_used,
  and return THD::current_insert_id for @@LAST_INSERT_ID.
sql/sql_class.h:
  Update comments.
  Remove THD::insert_id(), as it has lost its purpose now.
sql/sql_insert.cc:
  Now it is OK to read THD::last_insert_id directly.
sql/sql_load.cc:
  Now it is OK to read THD::last_insert_id directly.
sql/sql_parse.cc:
  In mysql_execute_command(), remember THD::last_insert_id (first
  generated value of the previous statement) in THD::current_insert_id,
  which then will be returned for LAST_INSERT_ID() and @@LAST_INSERT_ID.
sql/sql_select.cc:
  If "IS NULL" is replaced with "= <LAST_INSERT_ID>", use right value,
  which is THD::current_insert_id, and also set THD::last_insert_id_used
  to issue binary log LAST_INSERT_ID_EVENT.
sql/sql_update.cc:
  Now it is OK to read THD::last_insert_id directly.
tests/mysql_client_test.c:
  Add test case for bug#21726: Incorrect result with multiple invocations
  of LAST_INSERT_ID.

1 files changed, 33 insertions, 15 deletions

diff --git a/sql/sql_class.h b/sql/sql_class.h
index a995a492bc8..5c4c3af7acb 100644
--- a/sql/sql_class.h
+++ b/sql/sql_class.h
@@ -835,17 +835,29 @@ public:
     generated auto_increment value in handler.cc
   */
   ulonglong  next_insert_id;
+
   /*
-    The insert_id used for the last statement or set by SET LAST_INSERT_ID=#
-    or SELECT LAST_INSERT_ID(#).  Used for binary log and returned by
-    LAST_INSERT_ID()
+    At the beginning of the statement last_insert_id holds the first
+    generated value of the previous statement.  During statement
+    execution it is updated to the value just generated, but then
+    restored to the value that was generated first, so for the next
+    statement it will again be "the first generated value of the
+    previous statement".
+
+    It may also be set with "LAST_INSERT_ID(expr)" or
+    "@@LAST_INSERT_ID= expr", but the effect of such setting will be
+    seen only in the next statement.
   */
   ulonglong  last_insert_id;
+
   /*
-    Set to the first value that LAST_INSERT_ID() returned for the last
-    statement.  When this is set, last_insert_id_used is set to true.
+    current_insert_id remembers the first generated value of the
+    previous statement, and does not change during statement
+    execution.  Its value returned from LAST_INSERT_ID() and
+    @@LAST_INSERT_ID.
   */
   ulonglong  current_insert_id;
+
   ulonglong  limit_found_rows;
   ha_rows    cuted_fields,
              sent_row_count, examined_row_count;
@@ -896,7 +908,22 @@ public:
   bool	     locked, some_tables_deleted;
   bool       last_cuted_field;
   bool	     no_errors, password, is_fatal_error;
-  bool	     query_start_used,last_insert_id_used,insert_id_used,rand_used;
+  bool	     query_start_used, rand_used;
+
+  /*
+    last_insert_id_used is set when current statement calls
+    LAST_INSERT_ID() or reads @@LAST_INSERT_ID, so that binary log
+    LAST_INSERT_ID_EVENT be generated.
+  */
+  bool	     last_insert_id_used;
+
+  /*
+    insert_id_used is set when current statement updates
+    THD::last_insert_id, so that binary log INSERT_ID_EVENT be
+    generated.
+  */
+  bool       insert_id_used;
+
   /* for IS NULL => = last_insert_id() fix in remove_eq_conds() */
   bool       substitute_null_with_insert_id;
   bool	     time_zone_used;
@@ -996,15 +1023,6 @@ public:
     insert_id_used=1;
     substitute_null_with_insert_id= TRUE;
   }
-  inline ulonglong insert_id(void)
-  {
-    if (!last_insert_id_used)
-    {      
-      last_insert_id_used=1;
-      current_insert_id=last_insert_id;
-    }
-    return last_insert_id;
-  }
   inline ulonglong found_rows(void)
   {
     return limit_found_rows;