Port r371 and r372 from branches/fts:

Add support for the EXIT keyword in InnoDB's SQL parser.

Add short introduction to query graphs.

eval/eval0proc.c

@@ -212,6 +212,38 @@ for_step(
 	return(thr);
 }
 
+/**************************************************************************
+Performs an execution step of an exit statement node. */
+
+que_thr_t*
+exit_step(
+/*======*/
+				/* out: query thread to run next or NULL */
+	que_thr_t*	thr)	/* in: query thread */
+{
+	exit_node_t*	node;
+	que_node_t*	loop_node;
+
+	ut_ad(thr);
+
+	node = thr->run_node;
+
+	ut_ad(que_node_get_type(node) == QUE_NODE_EXIT);
+
+	/* Loops exit by setting thr->run_node as the loop node's parent, so
+	find our containing loop node and get its parent. */
+
+	loop_node = que_node_get_containing_loop_node(node);
+
+	/* If someone uses an EXIT statement outside of a loop, this will
+	trigger. */
+	ut_a(loop_node);
+
+	thr->run_node = que_node_get_parent(loop_node);
+
+	return(thr);
+}
+
 /**************************************************************************
 Performs an execution step of a return-statement node. */
 

include/eval0proc.h

@@ -63,6 +63,14 @@ proc_eval_step(
 				/* out: query thread to run next or NULL */
 	que_thr_t*	thr);	/* in: query thread */
 /**************************************************************************
+Performs an execution step of an exit statement node. */
+
+que_thr_t*
+exit_step(
+/*======*/
+				/* out: query thread to run next or NULL */
+	que_thr_t*	thr);	/* in: query thread */
+/**************************************************************************
 Performs an execution step of a return-statement node. */
 
 que_thr_t*

include/pars0grm.h

@@ -115,7 +115,8 @@
      PARS_ROLLBACK_TOKEN = 341,
      PARS_WORK_TOKEN = 342,
      PARS_UNSIGNED_TOKEN = 343,
-     NEG = 344
+     PARS_EXIT_TOKEN = 344,
+     NEG = 345
    };
 #endif
 #define PARS_INT_LIT 258
@@ -204,7 +205,8 @@
 #define PARS_ROLLBACK_TOKEN 341
 #define PARS_WORK_TOKEN 342
 #define PARS_UNSIGNED_TOKEN 343
-#define NEG 344
+#define PARS_EXIT_TOKEN 344
+#define NEG 345
 
 
 

include/pars0pars.h

@@ -269,6 +269,13 @@ pars_while_statement(
 	que_node_t*	cond,		/* in: while-condition */
 	que_node_t*	stat_list);	/* in: statement list */
 /*************************************************************************
+Parses an exit statement. */
+
+exit_node_t*
+pars_exit_statement(void);
+/*=====================*/
+					/* out: exit statement node */
+/*************************************************************************
 Parses a return-statement. */
 
 return_node_t*
@@ -500,6 +507,11 @@ struct for_node_struct{
 	que_node_t*	stat_list;	/* statement list */
 };
 
+/* exit statement node */
+struct exit_node_struct{
+	que_common_t	common;		/* type: QUE_NODE_EXIT */
+};
+
 /* return-statement node */
 struct return_node_struct{
 	que_common_t	common;		/* type: QUE_NODE_RETURN */

include/pars0types.h

@@ -19,6 +19,7 @@ typedef struct elsif_node_struct	elsif_node_t;
 typedef struct if_node_struct		if_node_t;
 typedef struct while_node_struct	while_node_t;
 typedef struct for_node_struct		for_node_t;
+typedef struct exit_node_struct		exit_node_t;
 typedef struct return_node_struct	return_node_t;
 typedef struct assign_node_struct	assign_node_t;
 typedef struct col_assign_node_struct	col_assign_node_t;

include/que0que.h

@@ -277,6 +277,15 @@ que_node_get_parent(
 /*================*/
 				/* out: parent node or NULL */
 	que_node_t*	node);	/* in: node */
+/********************************************************************
+Get the first containing loop node (e.g. while_node_t or for_node_t) for the
+given node, or NULL if the node is not within a loop. */
+
+que_node_t*
+que_node_get_containing_loop_node(
+/*==============================*/
+				/* out: containing loop node, or NULL. */
+	que_node_t*	node);	/* in: node */
 /*************************************************************************
 Catenates a query graph node to a list of them, possible empty list. */
 UNIV_INLINE
@@ -469,6 +478,7 @@ struct que_fork_struct{
 #define QUE_NODE_ROW_PRINTF	29
 #define QUE_NODE_ELSIF		30
 #define QUE_NODE_CALL		31
+#define QUE_NODE_EXIT		32
 
 /* Query thread states */
 #define QUE_THR_RUNNING		1

pars/pars0grm.h

@@ -115,7 +115,8 @@
      PARS_ROLLBACK_TOKEN = 341,
      PARS_WORK_TOKEN = 342,
      PARS_UNSIGNED_TOKEN = 343,
-     NEG = 344
+     PARS_EXIT_TOKEN = 344,
+     NEG = 345
    };
 #endif
 #define PARS_INT_LIT 258
@@ -204,7 +205,8 @@
 #define PARS_ROLLBACK_TOKEN 341
 #define PARS_WORK_TOKEN 342
 #define PARS_UNSIGNED_TOKEN 343
-#define NEG 344
+#define PARS_EXIT_TOKEN 344
+#define NEG 345
 
 
 

pars/pars0grm.y

@@ -116,6 +116,7 @@ yylex(void);
 %token PARS_ROLLBACK_TOKEN
 %token PARS_WORK_TOKEN
 %token PARS_UNSIGNED_TOKEN
+%token PARS_EXIT_TOKEN
 
 %left PARS_AND_TOKEN PARS_OR_TOKEN
 %left PARS_NOT_TOKEN
@@ -134,6 +135,7 @@ statement:
 	| predefined_procedure_call ';'
 	| while_statement ';'
 	| for_statement ';'
+	| exit_statement ';'
 	| if_statement ';'
 	| return_statement ';'
 	| assignment_statement ';'
@@ -429,6 +431,10 @@ for_statement:
 				{ $$ = pars_for_statement($2, $4, $6, $8); }
 ;
 
+exit_statement:
+	PARS_EXIT_TOKEN		{ $$ = pars_exit_statement(); }
+;
+
 return_statement:
 	PARS_RETURN_TOKEN	{ $$ = pars_return_statement(); }
 ;

pars/pars0lex.l

@@ -466,6 +466,10 @@ In the state 'quoted', only two actions are possible (defined below). */
 			return(PARS_UNSIGNED_TOKEN);
 }
 
+"EXIT"		{
+			return(PARS_EXIT_TOKEN);
+}
+
 {ID}		{
 			yylval = sym_tab_add_id(pars_sym_tab_global,
 							(byte*)yytext,

pars/pars0pars.c

@@ -1352,6 +1352,22 @@ pars_for_statement(
 	return(node);
 }
 
+/*************************************************************************
+Parses an exit statement. */
+
+exit_node_t*
+pars_exit_statement(void)
+/*=====================*/
+					/* out: exit statement node */
+{
+	exit_node_t*	node;
+
+	node = mem_heap_alloc(pars_sym_tab_global->heap, sizeof(exit_node_t));
+	node->common.type = QUE_NODE_EXIT;
+
+	return(node);
+}
+
 /*************************************************************************
 Parses a return-statement. */
 

que/que0que.c

@@ -36,6 +36,50 @@ ibool	que_trace_on		= FALSE;
 
 ibool	que_always_false	= FALSE;
 
+/* Short introduction to query graphs
+   ==================================
+
+A query graph consists of nodes linked to each other in various ways. The
+execution starts at que_run_threads() which takes a que_thr_t parameter.
+que_thr_t contains two fields that control query graph execution: run_node
+and prev_node. run_node is the next node to execute and prev_node is the
+last node executed.
+
+Each node has a pointer to a 'next' statement, i.e., its brother, and a
+pointer to its parent node. The next pointer is NULL in the last statement
+of a block.
+
+Loop nodes contain a link to the first statement of the enclosed statement
+list. While the loop runs, que_thr_step() checks if execution to the loop
+node came from its parent or from one of the statement nodes in the loop. If
+it came from the parent of the loop node it starts executing the first
+statement node in the loop. If it came from one of the statement nodes in
+the loop, then it checks if the statement node has another statement node
+following it, and runs it if so.
+
+To signify loop ending, the loop statements (see e.g. while_step()) set
+que_thr_t->run_node to the loop node's parent node. This is noticed on the
+next call of que_thr_step() and execution proceeds to the node pointed to by
+the loop node's 'next' pointer.
+
+For example, the code:
+
+X := 1;
+WHILE X < 5 LOOP
+ X := X + 1;
+ X := X + 1;
+X := 5
+
+will result in the following node hierarchy, with the X-axis indicating
+'next' links and the Y-axis indicating parent/child links:
+
+A - W - A
+    |
+    |
+    A - A
+
+A = assign_node_t, W = while_node_t. */
+
 /* How a stored procedure containing COMMIT or ROLLBACK commands
 is executed?
 
@@ -583,6 +627,7 @@ que_graph_free_recursive(
 		break;
 
 	case QUE_NODE_ASSIGNMENT:
+	case QUE_NODE_EXIT:
 	case QUE_NODE_RETURN:
 	case QUE_NODE_COMMIT:
 	case QUE_NODE_ROLLBACK:
@@ -1040,6 +1085,37 @@ que_thr_stop_for_mysql_no_error(
 	trx->n_active_thrs--;
 }
 
+/********************************************************************
+Get the first containing loop node (e.g. while_node_t or for_node_t) for the
+given node, or NULL if the node is not within a loop. */
+
+que_node_t*
+que_node_get_containing_loop_node(
+/*==============================*/
+				/* out: containing loop node, or NULL. */
+	que_node_t*	node)	/* in: node */
+{
+	ut_ad(node);
+
+	for (;;) {
+		ulint	type;
+
+		node = que_node_get_parent(node);
+
+		if (!node) {
+			break;
+		}
+
+		type = que_node_get_type(node);
+
+		if ((type == QUE_NODE_FOR) || (type == QUE_NODE_WHILE)) {
+			break;
+		}
+	}
+
+	return(node);
+}
+
 /**************************************************************************
 Prints info of an SQL query graph node. */
 
@@ -1093,6 +1169,8 @@ que_node_print_info(
 		str = "FOR LOOP";
 	} else if (type == QUE_NODE_RETURN) {
 		str = "RETURN";
+	} else if (type == QUE_NODE_EXIT) {
+		str = "EXIT";
 	} else {
 		str = "UNKNOWN NODE TYPE";
 	}
@@ -1120,8 +1198,8 @@ que_thr_step(
 
 	thr->resource++;
 
-	type = que_node_get_type(thr->run_node);
 	node = thr->run_node;
+	type = que_node_get_type(node);
 
 	old_thr = thr;
 
@@ -1160,6 +1238,8 @@ que_thr_step(
 			proc_step(thr);
 		} else if (type == QUE_NODE_WHILE) {
 			while_step(thr);
+		} else {
+			ut_error;
 		}
 	} else if (type == QUE_NODE_ASSIGNMENT) {
 		assign_step(thr);
@@ -1192,6 +1272,8 @@ que_thr_step(
 		thr = row_purge_step(thr);
 	} else if (type == QUE_NODE_RETURN) {
 		thr = return_step(thr);
+	} else if (type == QUE_NODE_EXIT) {
+		thr = exit_step(thr);
 	} else if (type == QUE_NODE_ROLLBACK) {
 		thr = trx_rollback_step(thr);
 	} else if (type == QUE_NODE_CREATE_TABLE) {
@@ -1204,7 +1286,11 @@ que_thr_step(
 		ut_error;
 	}
 
-	old_thr->prev_node = node;
+	if (type == QUE_NODE_EXIT) {
+		old_thr->prev_node = que_node_get_containing_loop_node(node);
+	} else {
+		old_thr->prev_node = node;
+	}
 
 	return(thr);
 }