Many files:

Push the patch of Jan Lindstrom: better comments
ha_innodb.cc:
  Partial fix for Bug #12263 : we let InnoDB always to perform a rollback on the trx object if MySQL closes a connection; but we do print a warning to the .err log if an InnoDB transaction was active; we may remove that print later, since the situation really is not a bug; MySQL just is not aware that some cursor operation started an InnoDB transaction

innobase/include/read0read.h

@@ -68,7 +68,6 @@ void
 read_view_print(
 /*============*/
 	read_view_t*	view);	/* in: read view */
-
 /*************************************************************************
 Create a consistent cursor view for mysql to be used in cursors. In this 
 consistent read view modifications done by the creating transaction or future
@@ -78,10 +77,9 @@ cursor_view_t*
 read_cursor_view_create_for_mysql(
 /*==============================*/
 	trx_t*		cr_trx);/* in: trx where cursor view is created */
-
 /*************************************************************************
-Close a given consistent cursor view for and restore global read view
+Close a given consistent cursor view for mysql and restore global read view
-back to a transaction. */
+back to a transaction read view. */
 
 void
 read_cursor_view_close_for_mysql(
@@ -90,7 +88,7 @@ read_cursor_view_close_for_mysql(
 	cursor_view_t*	curview);	/* in: cursor view to be closed */
 /*************************************************************************
 This function sets a given consistent cursor view to a transaction
-read view if given consistent cursor view is not null. Otherwice, function
+read view if given consistent cursor view is not NULL. Otherwise, function
 restores a global read view to a transaction read view. */
 
 void 

innobase/include/trx0trx.h

@@ -606,14 +606,13 @@ struct trx_struct{
 					/* memory heap for the global read 
 					view */
 	read_view_t*	global_read_view;
-					/* consistent read view used in the
+					/* consistent read view associated
-					transaction is stored here if
+					to a transaction or NULL */
-					transaction is using a consistent
-					read view associated to a cursor */
 	read_view_t*	read_view;	/* consistent read view used in the
 					transaction or NULL, this read view
-					can be normal read view associated
+					if defined can be normal read view 
-					to a transaction or read view
+					associated to a transaction (i.e. 
+					same as global_read_view) or read view
 					associated to a cursor */
 	/*------------------------------*/
 	UT_LIST_BASE_NODE_T(trx_named_savept_t) 

innobase/read/read0read.c

@@ -347,8 +347,8 @@ read_cursor_view_create_for_mysql(
 }
 
 /*************************************************************************
-Close a given consistent cursor view for and restore global read view
+Close a given consistent cursor view for mysql and restore global read view
-back to a transaction. */
+back to a transaction read view. */
 
 void
 read_cursor_view_close_for_mysql(
@@ -372,7 +372,7 @@ read_cursor_view_close_for_mysql(
 	
 /*************************************************************************
 This function sets a given consistent cursor view to a transaction
-read view if given consistent cursor view is not null. Otherwice, function
+read view if given consistent cursor view is not NULL. Otherwise, function
 restores a global read view to a transaction read view. */
 
 void 

innobase/row/row0sel.c

@@ -3100,6 +3100,13 @@ row_search_for_mysql(
 "http://dev.mysql.com/doc/mysql/en/InnoDB_troubleshooting_datadict.html\n"
 "InnoDB: how you can resolve the problem.\n",
 				prebuilt->table->name);
+
+		/* Restore a global read view back to a transaction. This 
+		forces MySQL always to set a cursor view before fetch from
+		a cursor. */
+
+		trx->read_view = trx->global_read_view;
+
 		return(DB_ERROR);
 	}
 
@@ -4091,8 +4098,9 @@ normal_return:
 	}
 
 func_exit:
-	/* Restore a global read view back to transaction. This forces
+	/* Restore a global read view back to a transaction. This 
-	MySQL always to set cursor view before fetch if it is used. */
+	forces MySQL always to set a cursor view before fetch from
+	a cursor. */
 
 	trx->read_view = trx->global_read_view;
 

innobase/srv/srv0srv.c

@@ -1711,6 +1711,10 @@ srv_printf_innodb_monitor(
 	fprintf(file, "%ld queries inside InnoDB, %lu queries in queue\n",
        		       (long) srv_conc_n_threads,
 		       (ulong) srv_conc_n_waiting_threads);
+
+	fprintf(file, "%lu read views open inside InnoDB\n",
+			UT_LIST_GET_LEN(trx_sys->view_list));
+
         n_reserved = fil_space_get_n_reserved_extents(0);
         if (n_reserved > 0) {
                 fprintf(file,

innobase/srv/srv0start.c

@@ -1833,6 +1833,16 @@ innobase_shutdown_for_mysql(void)
 	srv_free();
 	os_sync_free();
 
+	/* Check that all read views are closed except read view owned
+	by a purge. */
+
+	if (UT_LIST_GET_LEN(trx_sys->view_list) > 1) {
+	        fprintf(stderr,
+"InnoDB: Error: all read views were not closed before shutdown:\n"
+"InnoDB: %lu read views open \n",
+		UT_LIST_GET_LEN(trx_sys->view_list) - 1);
+	}
+
 	/* 5. Free all allocated memory and the os_fast_mutex created in
 	ut0mem.c */
 

innobase/trx/trx0trx.c

@@ -833,26 +833,14 @@ trx_commit_off_kernel(
 
 	lock_release_off_kernel(trx);
 
-	if (trx->read_view) {
+	if (trx->global_read_view) {
-		/* If transaction has a global read view this case
+		read_view_close(trx->global_read_view);
-		means that transaction has been using a consistent
-		read view associated to a cursor. Only the global
-		read view associated to a transaction is closed
-		and read view is then removed from the transaction.
-		If read view associated to a cursor is still used
-		it must be re-registered to another transaction. */
-
-		if (UNIV_LIKELY_NULL(trx->global_read_view)) {
-			trx->read_view = trx->global_read_view;
-		}
-
-		read_view_close(trx->read_view);
-
 		mem_heap_empty(trx->global_read_view_heap);
-		trx->read_view = NULL;
 		trx->global_read_view = NULL;
 	}
 
+	trx->read_view = NULL;
+
 	if (must_flush_log) {
 
 		mutex_exit(&kernel_mutex);

sql/ha_innodb.cc

@@ -538,7 +538,7 @@ innobase_mysql_prepare_print_arbitrary_thd(void)
 }
 
 /*****************************************************************
-Relases the mutex reserved by innobase_mysql_prepare_print_arbitrary_thd().
+Releases the mutex reserved by innobase_mysql_prepare_print_arbitrary_thd().
 NOTE that /mysql/innobase/lock/lock0lock.c must contain the prototype for this
 function! */
 extern "C"
@@ -1700,7 +1700,7 @@ innobase_store_binlog_offset_and_flush_log(
         /* Commits the mini-transaction */
         mtr_commit(&mtr);
 
-	/* Syncronous flush of the log buffer to disk */
+	/* Synchronous flush of the log buffer to disk */
 	log_buffer_flush_to_disk();
 }
 #endif
@@ -2132,15 +2132,34 @@ innobase_savepoint(
 
 /*********************************************************************
 Frees a possible InnoDB trx object associated with the current THD. */
-
+static
-static int
+int
 innobase_close_connection(
 /*======================*/
 			/* out: 0 or error number */
 	THD*	thd)	/* in: handle to the MySQL thread of the user
 			whose resources should be free'd */
 {
-        trx_free_for_mysql((trx_t*)thd->ha_data[innobase_hton.slot]);
+	trx_t*	trx;
+
+	trx = (trx_t*)thd->ha_data[innobase_hton.slot];
+
+	ut_a(trx);
+
+	if (trx->conc_state != TRX_NOT_STARTED) {
+		ut_print_timestamp(stderr);
+
+		fprintf(stderr,
+"  InnoDB: Warning: MySQL is closing a connection"
+"InnoDB: that has an active InnoDB transaction. We roll back that\n"
+"InnoDB: transaction. %lu row modifications to roll back.\n",
+			(ulong)ut_dulint_get_low(trx->undo_no));
+	}
+
+	innobase_rollback_trx(trx);
+
+        trx_free_for_mysql(trx);
+
 	return(0);
 }
 
@@ -2834,7 +2853,7 @@ ha_innobase::store_key_val_for_row(
 
 			/* All indexes on BLOB and TEXT are column prefix
 			indexes, and we may need to truncate the data to be
-			stored in the kay value: */
+			stored in the key value: */
 
 			if (blob_len > key_part->length) {
 			        blob_len = key_part->length;
@@ -7117,7 +7136,7 @@ int
 innobase_rollback_by_xid(
 /*=====================*/
 			/* out: 0 or error number */
-	XID	*xid)	/* in: X/Open XA transaction idenfification */
+	XID	*xid)	/* in: X/Open XA transaction identification */
 {
 	trx_t*	trx;
 
@@ -7131,9 +7150,10 @@ innobase_rollback_by_xid(
 }
 
 /***********************************************************************
-This function creates a consistent view for a cursor and start a transaction
+Create a consistent view for a cursor based on current transaction
-if it has not been started. This consistent view is then used inside of MySQL 
+which is created if the corresponding MySQL thread still lacks one.
-when accesing records using a cursor. */
+This consistent view is then used inside of MySQL when accessing records 
+using a cursor. */
 
 void*
 innobase_create_cursor_view(void)
@@ -7145,9 +7165,9 @@ innobase_create_cursor_view(void)
 }
 
 /***********************************************************************
-This function closes the given consistent cursor view. Note that
+Close the given consistent cursor view of a transaction and restore
-global read view is restored to a transaction and a transaction is
+global read view to a transaction read view. Transaction is created if the 
-started if it has not been started. */
+corresponding MySQL thread still lacks one. */
 
 void
 innobase_close_cursor_view(
@@ -7159,13 +7179,15 @@ innobase_close_cursor_view(
 }
 
 /***********************************************************************
-This function sets the given consistent cursor view to a transaction.
+Set the given consistent cursor view to a transaction which is created 
-If a transaction does not exist, transaction is started. */
+if the corresponding MySQL thread still lacks one. If the given 
+consistent cursor view is NULL global read view of a transaction is
+restored to a transaction read view. */
 
 void
 innobase_set_cursor_view(
 /*=====================*/
-	void*	curview)/* in: Consistent cursor view to be closed */
+	void*	curview)/* in: Consistent cursor view to be set */
 {
 	read_cursor_set_for_mysql(check_trx_exists(current_thd), 
 						(cursor_view_t*) curview);

sql/ha_innodb.h

@@ -302,7 +302,7 @@ which is in the prepared state */
 
 int innobase_rollback_by_xid(
 			/* out: 0 or error number */
-	XID	*xid);	/* in : X/Open XA Transaction Idenfification */
+	XID	*xid);	/* in : X/Open XA Transaction Identification */
 
 
 int innobase_xa_end(THD *thd);
@@ -312,9 +312,10 @@ int innobase_repl_report_sent_binlog(THD *thd, char *log_file_name,
                                my_off_t end_offset);
 
 /***********************************************************************
-This function creates a consistent view for a cursor and start a transaction
+Create a consistent view for a cursor based on current transaction
-if it has not been started. This consistent view is then used inside of MySQL 
+which is created if the corresponding MySQL thread still lacks one.
-when accesing records using a cursor. */
+This consistent view is then used inside of MySQL when accessing records 
+using a cursor. */
 
 void*
 innobase_create_cursor_view(void);
@@ -322,9 +323,9 @@ innobase_create_cursor_view(void);
 				/* out: Pointer to cursor view or NULL */
 
 /***********************************************************************
-This function closes the given consistent cursor view. Note that
+Close the given consistent cursor view of a transaction and restore
-global read view is restored to a transaction and a transaction is
+global read view to a transaction read view. Transaction is created if the 
-started if it has not been started. */
+corresponding MySQL thread still lacks one. */
 
 void
 innobase_close_cursor_view(
@@ -332,8 +333,10 @@ innobase_close_cursor_view(
 	void*	curview);	/* in: Consistent read view to be closed */
 
 /***********************************************************************
-This function sets the given consistent cursor view to a transaction.
+Set the given consistent cursor view to a transaction which is created 
-If a transaction does not exist, transaction is started. */
+if the corresponding MySQL thread still lacks one. If the given 
+consistent cursor view is NULL global read view of a transaction is
+restored to a transaction read view. */
 
 void
 innobase_set_cursor_view(