branches/zip:

Merge 2537:2605 from branches/5.1:

  ------------------------------------------------------------------------
  r2545 | vasil | 2008-07-25 17:24:23 +0300 (Fri, 25 Jul 2008) | 37 lines
  Changed paths:
     M /branches/5.1/handler/ha_innodb.cc
  
  branches/5.1:
  
  Fix Bug#38185 ha_innobase::info can hold locks even when called with HA_STATUS_NO_LOCK
  
  The fix is to call fsp_get_available_space_in_free_extents() from
  ha_innobase::info() only if HA_STATUS_NO_LOCK is not present in the flag
  *AND*
  change get_schema_tables_record() in MySQL's sql/sql_show.cc to call
  ::info() *without* HA_STATUS_NO_LOCK whenever a user issues SELECT FROM
  information_schema.tables;
  
  Without the change to sql/sql_show.cc this patch would lead to Bug#32440
  resurfacing. I.e. delete_length would never be updated in ::info() and
  will remain 0 forever, resulting in the free space not being shown
  anywhere.
  
  This is the change to sql/sql_show.cc for reference, it needs to be
  committed to the MySQL repo before or at the same time with this change
  to ha_innodb.cc:
  
   --- patch begins here ---
   --- sql/sql_show.cc.orig	2008-07-23 09:32:14.000000000 +0300
   +++ sql/sql_show.cc	2008-07-23 09:32:19.000000000 +0300
   @@ -3549,8 +3549,7 @@ static int get_schema_tables_record(THD 
    
        if(file)
        {
   -      file->info(HA_STATUS_VARIABLE | HA_STATUS_TIME | HA_STATUS_AUTO |
   -                 HA_STATUS_NO_LOCK);
   +      file->info(HA_STATUS_VARIABLE | HA_STATUS_TIME | HA_STATUS_AUTO);
          enum row_type row_type = file->get_row_type();
          switch (row_type) {
          case ROW_TYPE_NOT_USED:
   --- patch ends here ---
  
  Approved by:	Heikki
  
  ------------------------------------------------------------------------
  r2603 | marko | 2008-08-21 16:25:05 +0300 (Thu, 21 Aug 2008) | 10 lines
  Changed paths:
     M /branches/5.1/handler/ha_innodb.cc
     M /branches/5.1/include/ha_prototypes.h
     M /branches/5.1/row/row0sel.c
  
  branches/5.1: Identify SELECT statements by thd_sql_command() == SQLCOM_SELECT
  instead of parsing the query string.  This fixes MySQL Bug #37885 without
  us having to implement lexical analysis of SQL comments in yet another place.
  
  thd_is_select(): A new predicate.
  
  row_search_for_mysql(): Use thd_is_select().
  
  Approved by Heikki.
  
  ------------------------------------------------------------------------

handler/ha_innodb.cc

@@ -641,6 +641,18 @@ thd_has_edited_nontrans_tables(
 	return((ibool) thd_non_transactional_update((THD*) thd));
 }
 
+/**********************************************************************
+Returns true if the thread is executing a SELECT statement. */
+extern "C"
+ibool
+thd_is_select(
+/*==========*/
+				/* out: true if thd is executing SELECT */
+	const void*	thd)	/* in: thread handle (THD*) */
+{
+	return(thd_sql_command((const THD*) thd) == SQLCOM_SELECT);
+}
+
 /************************************************************************
 Obtain the InnoDB transaction of a MySQL thread. */
 inline
@@ -6659,9 +6671,21 @@ ha_innobase::info(
 		stats.index_file_length = ((ulonglong)
 				ib_table->stat_sum_of_other_index_sizes)
 					* UNIV_PAGE_SIZE;
-		stats.delete_length =
-			fsp_get_available_space_in_free_extents(
-				ib_table->space) * 1024;
+
+		/* Since fsp_get_available_space_in_free_extents() is
+		acquiring latches inside InnoDB, we do not call it if we
+		are asked by MySQL to avoid locking. Another reason to
+		avoid the call is that it uses quite a lot of CPU.
+		See Bug#38185.
+		We do not update delete_length if no locking is requested
+		so the "old" value can remain. delete_length is initialized
+		to 0 in the ha_statistics' constructor. */
+		if (!(flag & HA_STATUS_NO_LOCK)) {
+			stats.delete_length =
+				fsp_get_available_space_in_free_extents(
+					ib_table->space) * 1024;
+		}
+
 		stats.check_time = 0;
 
 		if (stats.records == 0) {

include/ha_prototypes.h

@@ -158,5 +158,15 @@ innobase_strcasecmp(
 				/* out: 0 if a=b, <0 if a<b, >1 if a>b */
 	const char*	a,	/* in: first string to compare */
 	const char*	b);	/* in: second string to compare */
+
+/**********************************************************************
+Returns true if the thread is executing a SELECT statement. */
+
+ibool
+thd_is_select(
+/*==========*/
+				/* out: true if thd is executing SELECT */
+	const void*	thd);	/* in: thread handle (THD*) */
+
 #endif
 #endif

row/row0sel.c

@@ -32,6 +32,7 @@ Created 12/19/1997 Heikki Tuuri
 #include "row0mysql.h"
 #include "read0read.h"
 #include "buf0lru.h"
+#include "ha_prototypes.h"
 
 /* Maximum number of rows to prefetch; MySQL interface has another parameter */
 #define SEL_MAX_N_PREFETCH	16
@@ -3699,19 +3700,11 @@ shortcut_fails_too_big_rec:
 	if (trx->isolation_level <= TRX_ISO_READ_COMMITTED
 	    && prebuilt->select_lock_type != LOCK_NONE
 	    && trx->mysql_thd != NULL
-	    && trx->mysql_query_str != NULL
-	    && *trx->mysql_query_str != NULL) {
+	    && thd_is_select(trx->mysql_thd)) {
+		/* It is a plain locking SELECT and the isolation
+		level is low: do not lock gaps */
 
-		/* Scan the MySQL query string; check if SELECT is the first
-		word there */
-
-		if (dict_str_starts_with_keyword(
-			    trx->mysql_thd, *trx->mysql_query_str, "SELECT")) {
-			/* It is a plain locking SELECT and the isolation
-			level is low: do not lock gaps */
-
-			set_also_gap_locks = FALSE;
-		}
+		set_also_gap_locks = FALSE;
 	}
 
 	/* Note that if the search mode was GE or G, then the cursor