Code cleanups and add some caching of functions to speed up things

Detailed description:
- Added more function comments and fixed types in some old comments
- Removed an outdated comment
- Cleaned up some functions in records.cc
  - Replaced "while" with "if"
  - Reused error code
  - Made functions similar
- Added caching of pfs_batch_update()
- Simplified some rowid_filter code
  - Only call build_range_rowid_filter() if rowid filter will be used
  - Replaced tab->is_rowid_filter_built with need_to_build_rowid_filter.
    We only have to test need_to_build_rowid_filter to know if we have
    to build the filter. Old code needed two tests
  - Added function 'clear_range_rowid_filter' to disable rowid filter.
    Made things simpler as we can now clear all rowid filter variables
    in one place.
- Removed some 'if' in sub_select()

sql/records.cc

@@ -400,11 +400,8 @@ static int rr_handle_error(READ_RECORD *info, int error)
 static int rr_quick(READ_RECORD *info)
 {
   int tmp;
-  while ((tmp= info->select->quick->get_next()))
-  {
+  if ((tmp= info->select->quick->get_next()))
     tmp= rr_handle_error(info, tmp);
-    break;
-  }
   return tmp;
 }
 
@@ -427,16 +424,14 @@ static int rr_index_first(READ_RECORD *info)
   int tmp;
   // tell handler that we are doing an index scan
   if ((tmp = info->table->file->prepare_index_scan())) 
-  {
-    tmp= rr_handle_error(info, tmp);
-    return tmp;
-  }
+    goto err;
 
-  tmp= info->table->file->ha_index_first(info->record());
   info->read_record_func= rr_index;
-  if (tmp)
-    tmp= rr_handle_error(info, tmp);
-  return tmp;
+  if (!(tmp= info->table->file->ha_index_first(info->record())))
+    return tmp;
+
+err:
+  return rr_handle_error(info, tmp);
 }
 
 
@@ -455,9 +450,9 @@ static int rr_index_first(READ_RECORD *info)
 
 static int rr_index_last(READ_RECORD *info)
 {
-  int tmp= info->table->file->ha_index_last(info->record());
+  int tmp;
   info->read_record_func= rr_index_desc;
-  if (tmp)
+  if ((tmp= info->table->file->ha_index_last(info->record())))
     tmp= rr_handle_error(info, tmp);
   return tmp;
 }

sql/sql_join_cache.cc

@@ -2146,12 +2146,12 @@ enum_nested_loop_state JOIN_CACHE::join_records(bool skip_last)
 
   if (!join_tab->first_unmatched)
   {
-    bool pfs_batch_update= join_tab->pfs_batch_update(join);
-    if (pfs_batch_update)
+    DBUG_ASSERT(join_tab->cached_pfs_batch_update == join_tab->pfs_batch_update());
+    if (join_tab->cached_pfs_batch_update)
       join_tab->table->file->start_psi_batch_mode();
     /* Find all records from join_tab that match records from join buffer */
     rc= join_matching_records(skip_last);   
-    if (pfs_batch_update)
+    if (join_tab->cached_pfs_batch_update)
       join_tab->table->file->end_psi_batch_mode();
     if (rc != NESTED_LOOP_OK && rc != NESTED_LOOP_NO_MORE_ROWS)
       goto finish;
@@ -2321,7 +2321,8 @@ enum_nested_loop_state JOIN_CACHE::join_matching_records(bool skip_last)
   if ((rc= join_tab_execution_startup(join_tab)) < 0)
     goto finish2;
 
-  join_tab->build_range_rowid_filter_if_needed();
+  if (join_tab->need_to_build_rowid_filter)
+    join_tab->build_range_rowid_filter();
 
   /* Prepare to retrieve all records of the joined table */
   if (unlikely((error= join_tab_scan->open())))

sql/sql_select.h

@@ -423,6 +423,8 @@ typedef struct st_join_table {
   bool          cached_eq_ref_table,eq_ref_table;
   bool          shortcut_for_distinct;
   bool          sorted;
+  bool          cached_pfs_batch_update;
+
   /* 
     If it's not 0 the number stored this field indicates that the index
     scan has been chosen to access the table data and we expect to scan 
@@ -571,10 +573,11 @@ typedef struct st_join_table {
   Range_rowid_filter_cost_info *range_rowid_filter_info;
   /* Rowid filter to be used when joining this join table */
   Rowid_filter *rowid_filter;
-  /* Becomes true just after the used range filter has been built / filled */
-  bool is_rowid_filter_built;
+  /* True if the plan requires a rowid filter and it's not built yet */
+  bool need_to_build_rowid_filter;
 
-  void build_range_rowid_filter_if_needed();
+  void build_range_rowid_filter();
+  void clear_range_rowid_filter();
 
   void cleanup();
   inline bool is_using_loose_index_scan()
@@ -685,7 +688,7 @@ typedef struct st_join_table {
   double get_examined_rows();
   bool preread_init();
 
-  bool pfs_batch_update(JOIN *join);
+  bool pfs_batch_update();
 
   bool is_sjm_nest() { return MY_TEST(bush_children); }