Cherry pick dynamic array changes from commit:

commit 85fd3d901311688e18ffce92ffc78129e5625791
Author: Monty <monty@mariadb.org>
Date:   Fri Aug 29 14:07:43 2014 +0300

    my_alloc.c
    - Changed 0x%lx -> %p
    array.c:
    - Static (preallocated) buffer can now be anywhere
    my_sys.h
    - Define MY_INIT_BUFFER_USED
    sql_delete.cc & sql_lex.cc
    - Use memroot when allocating classes (avoids call to current_thd)
    sql_explain.h:
    - Use preallocated buffers
    sql_explain.cc:
    - Use preallocated buffers and memroot
    sql_select.cc:
    - Use multi_alloc_root() instead of many alloc_root()
    - Update calls to Explain

1 files changed, 22 insertions, 19 deletions

diff --git a/mysys/array.c b/mysys/array.c
index a8c5d181638..35a41f2222c 100644
--- a/mysys/array.c
+++ b/mysys/array.c
@@ -35,7 +35,6 @@
     init_alloc eilements.
     Array is usable even if space allocation failed, hence, the
     function never returns TRUE.
-    Static buffers must begin immediately after the array structure.
 
   RETURN VALUE
     FALSE	Ok
@@ -57,8 +56,12 @@ my_bool init_dynamic_array2(DYNAMIC_ARRAY *array, uint element_size,
   array->alloc_increment=alloc_increment;
   array->size_of_element=element_size;
   array->malloc_flags= my_flags;
+  DBUG_ASSERT((my_flags & MY_INIT_BUFFER_USED) == 0);
   if ((array->buffer= init_buffer))
+  {
+    array->malloc_flags|= MY_INIT_BUFFER_USED; 
     DBUG_RETURN(FALSE);
+  }
   /* 
     Since the dynamic array is usable even if allocation fails here malloc
     should not throw an error
@@ -124,10 +127,10 @@ void *alloc_dynamic(DYNAMIC_ARRAY *array)
   if (array->elements == array->max_element)
   {
     char *new_ptr;
-    if (array->buffer == (uchar *)(array + 1))
+    if (array->malloc_flags & MY_INIT_BUFFER_USED)
     {
       /*
-        In this senerio, the buffer is statically preallocated,
+        In this scenario, the buffer is statically preallocated,
         so we have to create an all-new malloc since we overflowed
       */
       if (!(new_ptr= (char *) my_malloc((array->max_element+
@@ -137,6 +140,7 @@ void *alloc_dynamic(DYNAMIC_ARRAY *array)
         DBUG_RETURN(0);
       memcpy(new_ptr, array->buffer,
              array->elements * array->size_of_element);
+      array->malloc_flags&= ~MY_INIT_BUFFER_USED;
     }
     else if (!(new_ptr=(char*)
                my_realloc(array->buffer,(array->max_element+
@@ -231,7 +235,7 @@ my_bool allocate_dynamic(DYNAMIC_ARRAY *array, uint max_elements)
     uchar *new_ptr;
     size= (max_elements + array->alloc_increment)/array->alloc_increment;
     size*= array->alloc_increment;
-    if (array->buffer == (uchar *)(array + 1))
+    if (array->malloc_flags & MY_INIT_BUFFER_USED)
     {
        /*
          In this senerio, the buffer is statically preallocated,
@@ -243,7 +247,8 @@ my_bool allocate_dynamic(DYNAMIC_ARRAY *array, uint max_elements)
          DBUG_RETURN(0);
        memcpy(new_ptr, array->buffer,
               array->elements * array->size_of_element);
-     }
+       array->malloc_flags&= ~MY_INIT_BUFFER_USED;
+    }
     else if (!(new_ptr= (uchar*) my_realloc(array->buffer,size*
                                             array->size_of_element,
                                             MYF(MY_WME | MY_ALLOW_ZERO_PTR |
@@ -293,15 +298,11 @@ void delete_dynamic(DYNAMIC_ARRAY *array)
   /*
     Just mark as empty if we are using a static buffer
   */
-  if (array->buffer == (uchar *)(array + 1))
-    array->elements= 0;
-  else
-  if (array->buffer)
-  {
+  if (!(array->malloc_flags & MY_INIT_BUFFER_USED) && array->buffer)
     my_free(array->buffer);
-    array->buffer=0;
-    array->elements=array->max_element=0;
-  }
+
+  array->buffer= 0;
+  array->elements= array->max_element= 0;
 }
 
 /*
@@ -350,24 +351,25 @@ void delete_dynamic_with_callback(DYNAMIC_ARRAY *array, FREE_FUNC f) {
 
 void freeze_size(DYNAMIC_ARRAY *array)
 {
-  uint elements=MY_MAX(array->elements,1);
+  uint elements;
 
   /*
     Do nothing if we are using a static buffer
   */
-  if (array->buffer == (uchar *)(array + 1))
+  if (array->malloc_flags & MY_INIT_BUFFER_USED)
     return;
 
-  if (array->buffer && array->max_element != elements)
+  elements= MY_MAX(array->elements, 1);
+  if (array->buffer && array->max_element > elements)
   {
     array->buffer=(uchar*) my_realloc(array->buffer,
-                                     elements*array->size_of_element,
+                                      elements*array->size_of_element,
                                       MYF(MY_WME | array->malloc_flags));
-    array->max_element=elements;
+    array->max_element= elements;
   }
 }
 
-
+#ifdef NOT_USED
 /*
   Get the index of a dynamic element
 
@@ -391,3 +393,4 @@ int get_index_dynamic(DYNAMIC_ARRAY *array, void* element)
   return ret;
 
 }
+#endif