Merge {DS-DRR improvements:code cleanup} into MWL#128+DS-MRR tree

1 files changed, 67 insertions, 134 deletions

diff --git a/sql/multi_range_read.cc b/sql/multi_range_read.cc
index a6a75c1d06e..d70d3243903 100644
--- a/sql/multi_range_read.cc
+++ b/sql/multi_range_read.cc
@@ -282,8 +282,20 @@ scan_it_again:
   DBUG_RETURN(result);
 }
 
+/****************************************************************************
+ * Mrr_*_reader classes (building blocks for DS-MRR)
+ ***************************************************************************/
 
-/***** MRR_impl classes ****************************************************/
+int Mrr_simple_index_reader::init(handler *h_arg, RANGE_SEQ_IF *seq_funcs, 
+                                  void *seq_init_param, uint n_ranges,
+                                  uint mode, Buffer_manager *buf_manager_arg)
+{
+  HANDLER_BUFFER no_buffer = {NULL, NULL, NULL};
+  h= h_arg;
+  res= 0;
+  return h->handler::multi_range_read_init(seq_funcs, seq_init_param, n_ranges,
+                                           mode, &no_buffer);
+}
 
 int Mrr_simple_index_reader::get_next(char **range_info)
 {
@@ -297,44 +309,35 @@ int Mrr_simple_index_reader::get_next(char **range_info)
   return res;
 }
 
-int Mrr_simple_index_reader::init(handler *h_arg, RANGE_SEQ_IF *seq_funcs, 
-                                  void *seq_init_param, uint n_ranges,
-                                  uint mode, Buffer_manager *buf_manager_arg)
-{
-  HANDLER_BUFFER no_buffer = {NULL, NULL, NULL};
-  h= h_arg;
-  res= 0;
-  return h->handler::multi_range_read_init(seq_funcs, seq_init_param, n_ranges,
-                                           mode, &no_buffer);
-}
 
 /**
-  DS-MRR/CPK: multi_range_read_next() function
-  
-  @param range_info  OUT  identifier of range that the returned record belongs to
+  @brief Get next index record
+
+  @param range_info  OUT identifier of range that the returned record belongs to
   
   @note
-    This function walks over key buffer and does index reads, i.e. it produces
-    {current_record, range_id} pairs.
-
-    The function has the same call contract like multi_range_read_next()'s.
-
     We actually iterate over nested sequences:
-    - a disjoint sequence of index ranges
-      - each range has multiple records
-        - each record goes into multiple identical ranges.
+    - an ordered sequence of groups of identical keys
+      - each key group has key value, which has multiple matching records 
+        - thus, each record matches all members of the key group
 
   @retval 0                   OK, next record was successfully read
   @retval HA_ERR_END_OF_FILE  End of records
   @retval Other               Some other error
 */
 
-int Mrr_ordered_index_reader::get_next(char **range_info_arg)
+int Mrr_ordered_index_reader::get_next(char **range_info)
 {
   DBUG_ENTER("Mrr_ordered_index_reader::get_next");
   
-  if (!know_key_tuple_params) /* We're in startup phase */
+  if (!know_key_tuple_params)
+  {
+    /* 
+      We're at the very start, haven't filled the buffer or even know what
+      will be there. Force the caller to call refill_buffer():
+    */
     DBUG_RETURN(HA_ERR_END_OF_FILE);
+  }
 
   while (1)
   {
@@ -355,24 +358,8 @@ int Mrr_ordered_index_reader::get_next(char **range_info_arg)
       {
         if (key_buffer->is_empty())
         {
-          /*if (auto_refill)
-          {
-            int res;
-            if ((res= refill_buffer()))
-              DBUG_RETURN(res);
-            if (key_buffer->is_empty())
-            {
-              index_scan_eof= TRUE;
-              DBUG_RETURN(HA_ERR_END_OF_FILE);
-            }
-          }
-          else
-          */
-          {
-            /* Buffer refills are managed by somebody else for us */
-            index_scan_eof= TRUE;
-            DBUG_RETURN(HA_ERR_END_OF_FILE);
-          }
+          index_scan_eof= TRUE;
+          DBUG_RETURN(HA_ERR_END_OF_FILE);
         }
       }
       scanning_key_val_iter= TRUE;
@@ -390,24 +377,21 @@ int Mrr_ordered_index_reader::get_next(char **range_info_arg)
     /* Go get another (record, range_id) combination */
   } /* while */
 
-  memcpy(range_info_arg, cur_range_info, sizeof(void*));
+  memcpy(range_info, cur_range_info, sizeof(void*));
   DBUG_RETURN(0);
 }
 
 
 /**
-  DS-MRR/CPK: Fill the buffer with (lookup_tuple, range_id) pairs and sort
-  
-  Enumerate the input range (=key) sequence, fill the key buffer with 
-  (lookup_key, range_id) pairs and sort it.
-
-  When this function returns, either
-   - key buffer is non-empty, or
-   - key buffer is empty and source range sequence is exhausted
-  
+  Fill the buffer with (lookup_tuple, range_id) pairs and sort
+ 
   @note
-    dsmrr_eof is set to indicate whether we've exhausted the list of ranges 
-    we're scanning.
+    We don't know lookup_tuple before we get the first key from
+    mrr_funcs.get_next(). Not knowing tuple length means we can't setup the
+    key buffer (in particular, which part of the buffer space it should occupy
+    when we have both key and rowid buffers).  This problem is solved by having 
+    know_key_tuple_params variabe, and buf_manager, which we ask to set/reset
+    buffers for us.
 */
 
 int Mrr_ordered_index_reader::refill_buffer()
@@ -427,23 +411,7 @@ int Mrr_ordered_index_reader::refill_buffer()
                               is_mrr_assoc? (uchar**)&range_info_ptr : NULL,
                               sizeof(uchar*));
   }
-#if 0
 
-  if (know_key_tuple_params)
-  {
-    if (do_rndpos_scan && rowid_buffer.is_empty())
-    {
-      /*
-        We're using two buffers and both of them are empty now. Restore the
-        original sizes
-      */
-      rowid_buffer.set_buffer_space(full_buf, rowid_buffer_end);
-      key_buffer= &backward_key_buf;
-      key_buffer->set_buffer_space(rowid_buffer_end, full_buf_end);
-    }
-  }
-  is all of the ifdef-ed stuff is handled above?
-#endif
   while ((!know_key_tuple_params || key_buffer->can_write()) && 
          !(res= mrr_funcs.next(mrr_iter, &cur_range)))
   {
@@ -478,7 +446,7 @@ int Mrr_ordered_index_reader::refill_buffer()
     key_buffer->write();
   }
 
-  no_more_keys= test(res);
+  bool no_more_keys= test(res);
   scanning_key_val_iter= FALSE;
   index_scan_eof= FALSE;
 
@@ -522,15 +490,8 @@ int Mrr_ordered_rndpos_reader::init(handler *h_arg,
   h= h_arg;
   index_reader= index_reader_arg;
   rowid_buffer= buf;
-  is_mrr_assoc=    !test(mode & HA_MRR_NO_ASSOCIATION);
-  //rowid_buff_elem_size= h->ref_length;
-  //if (!(mode & HA_MRR_NO_ASSOCIATION))
-  //  rowid_buff_elem_size += sizeof(char*);
-
+  is_mrr_assoc= !test(mode & HA_MRR_NO_ASSOCIATION);
   index_reader_exhausted= FALSE;
-  ///int res= index_reader->refill_buffer();
-  ///if (res && res!=HA_ERR_END_OF_FILE)
-  ///  return res;
   return 0;
 }
 
@@ -553,7 +514,6 @@ int Mrr_ordered_rndpos_reader::init(handler *h_arg,
   @retval other  Error
 */
 
-
 int Mrr_ordered_rndpos_reader::refill_buffer()
 {
   int res;
@@ -562,7 +522,7 @@ int Mrr_ordered_rndpos_reader::refill_buffer()
   if (index_reader_exhausted)
     DBUG_RETURN(HA_ERR_END_OF_FILE);
 
-  while ((res= refill2() == HA_ERR_END_OF_FILE))
+  while ((res= refill_from_key_buffer() == HA_ERR_END_OF_FILE))
   {
     if ((res= index_reader->refill_buffer()))
     {
@@ -575,13 +535,23 @@ int Mrr_ordered_rndpos_reader::refill_buffer()
 }
 
 
-/* This one refills without calling index_reader->refill_buffer(). */
-int Mrr_ordered_rndpos_reader::refill2()
+void Mrr_index_reader::position()
+{
+  h->position(h->get_table()->record[0]);
+}
+
+
+/* 
+  @brief Try to refill the rowid buffer without calling
+  index_reader->refill_buffer(). 
+*/
+
+int Mrr_ordered_rndpos_reader::refill_from_key_buffer()
 {
   char *range_info;
   uchar **range_info_ptr= (uchar**)&range_info;
   int res;
-  DBUG_ENTER("Mrr_ordered_rndpos_reader::refill2");
+  DBUG_ENTER("Mrr_ordered_rndpos_reader::refill_from_key_buffer");
 
   DBUG_ASSERT(rowid_buffer->is_empty());
   index_rowid= index_reader->get_rowid_ptr();
@@ -600,7 +570,7 @@ int Mrr_ordered_rndpos_reader::refill2()
       break;
 
     /* Put rowid, or {rowid, range_id} pair into the buffer */
-    index_reader->h->position(index_reader->h->get_table()->record[0]);
+    index_reader->position();
 
     rowid_buffer->write();
   }
@@ -615,10 +585,12 @@ int Mrr_ordered_rndpos_reader::refill2()
 }
 
 
-/**
-  DS-MRR implementation: multi_range_read_next() function.
+/*
+  Get the next record+range_id using ordered array of rowid+range_id pairds
 
-  Calling convention is like multi_range_read_next() has.
+  @note
+    Since we have sorted rowids, we try not to make multiple rnd_pos() calls
+    with the same rowid value.
 */
 
 int Mrr_ordered_rndpos_reader::get_next(char **range_info)
@@ -652,31 +624,6 @@ int Mrr_ordered_rndpos_reader::get_next(char **range_info)
 
   while (1)
   {
-#if 0      
-    if (rowid_buffer->is_empty()) /* We're out of rowids */
-    {
-      /* First, finish off the sorted keys we have */ 
-      if (!index_reader->eof())
-      {
-        res= refill_buffer();
-        if (res && res != HA_ERR_END_OF_FILE)
-          return res;
-      }
-
-      if (rowid_buffer->is_empty())
-      {
-        /*
-          Ok neither index_reader nor us have any records. Refill index
-          reader, then refill us.
-        */
-        // TODO: if key buffer is empty, too, redistribute the buffer space.
-        if ((res= index_reader->refill_buffer()) ||
-            (res= refill_buffer()))
-          return res;
-      }
-    }
-#endif
-   
     last_identical_rowid= NULL;
 
     /* Return eof if there are no rowids in the buffer after re-fill attempt */
@@ -724,13 +671,8 @@ int Mrr_ordered_rndpos_reader::get_next(char **range_info)
 }
 
 
-
-
-/************ MRR_impl classes end *********************************************/
-
-
 /****************************************************************************
- * DS-MRR implementation 
+ * Top-level DS-MRR implementation functions (the ones called by storage engine)
  ***************************************************************************/
 
 /**
@@ -769,7 +711,7 @@ int DsMrr_impl::dsmrr_init(handler *h_arg, RANGE_SEQ_IF *seq_funcs,
   if ((mode & HA_MRR_USE_DEFAULT_IMPL) || (mode & HA_MRR_SORTED))
   {
     DBUG_ASSERT(h->inited == handler::INDEX);
-    Mrr_simple_index_reader *s= &strategy_factory.simple_index_reader;
+    Mrr_simple_index_reader *s= &reader_factory.simple_index_reader;
     res= s->init(h, seq_funcs, seq_init_param, n_ranges, mode, this);
     strategy= s;
     DBUG_RETURN(res);
@@ -786,10 +728,10 @@ int DsMrr_impl::dsmrr_init(handler *h_arg, RANGE_SEQ_IF *seq_funcs,
   if ((mode & HA_MRR_SINGLE_POINT) &&
       optimizer_flag(thd, OPTIMIZER_SWITCH_MRR_SORT_KEYS))
   {
-    index_strategy= ordered_idx_reader= &strategy_factory.ordered_index_reader;
+    index_strategy= ordered_idx_reader= &reader_factory.ordered_index_reader;
   }
   else
-    index_strategy= &strategy_factory.simple_index_reader;
+    index_strategy= &reader_factory.simple_index_reader;
 
   strategy= index_strategy;
   /*
@@ -807,7 +749,7 @@ int DsMrr_impl::dsmrr_init(handler *h_arg, RANGE_SEQ_IF *seq_funcs,
   Mrr_ordered_rndpos_reader *disk_strategy= NULL;
   if (!(keyno == table->s->primary_key && h_idx->primary_key_is_clustered()))
   {
-    strategy= disk_strategy= &strategy_factory.ordered_rndpos_reader;
+    strategy= disk_strategy= &reader_factory.ordered_rndpos_reader;
   }
 
   if (is_mrr_assoc)
@@ -818,8 +760,6 @@ int DsMrr_impl::dsmrr_init(handler *h_arg, RANGE_SEQ_IF *seq_funcs,
   
   if (strategy == index_strategy)
   {
-    ///if (ordered_idx_reader)
-    //  ordered_idx_reader->auto_refill= TRUE;
     /* Index strategy serves it all. We don't need two handlers, etc */
     /* Give the buffer to index strategy */
     if ((res= index_strategy->init(h, seq_funcs, seq_init_param, n_ranges,
@@ -838,9 +778,6 @@ int DsMrr_impl::dsmrr_init(handler *h_arg, RANGE_SEQ_IF *seq_funcs,
     if ((res= setup_two_handlers()))
       DBUG_RETURN(res);
 
-    ///if (ordered_idx_reader)
-    ///  ordered_idx_reader->auto_refill= FALSE;
-
     if ((res= index_strategy->init(h2, seq_funcs, seq_init_param, n_ranges, 
                                    mode, this)) || 
         (res= disk_strategy->init(h, index_strategy, mode, &rowid_buffer)))
@@ -960,8 +897,8 @@ int DsMrr_impl::setup_two_handlers()
       goto error;
   }
   DBUG_RETURN(0);
+
 error:
-  //close_second_handler(); -- caller does that
   DBUG_RETURN(res);
 }
 
@@ -1132,6 +1069,7 @@ void DsMrr_impl::reset_buffer_sizes()
   }
 }
 
+
 /**
   Take unused space from the key buffer and give it to the rowid buffer
 */
@@ -1144,14 +1082,9 @@ void DsMrr_impl::reallocate_buffer_space()
 }
 
 
-//////////////////////////////////////////////////////////////////////////////
-//////////////////////////////////////////////////////////////////////////////
-
 bool Key_value_records_iterator::init(Mrr_ordered_index_reader *owner_arg)
 {
   int res;
-  //h= h_arg;
-  //param= param_arg;
   owner= owner_arg;
 
   identical_key_it.init(owner->key_buffer);