Fix for CONC-196: Avoid unnecessary extra loops in alloc_root() funct…

…ion.

Added performance test which requires employees database.

libmariadb/my_alloc.c

@@ -23,10 +23,12 @@
 
 void init_alloc_root(MEM_ROOT *mem_root, size_t block_size, size_t pre_alloc_size)
 {
-  mem_root->free=mem_root->used=0;
+  mem_root->free= mem_root->used= mem_root->pre_alloc= 0;
   mem_root->min_malloc=32;
-  mem_root->block_size=block_size-MALLOC_OVERHEAD-sizeof(USED_MEM)-8;
+  mem_root->block_size= (block_size-MALLOC_OVERHEAD-sizeof(USED_MEM)+8);
   mem_root->error_handler=0;
+  mem_root->block_num= 4;
+  mem_root->first_block_usage= 0;
 #if !(defined(HAVE_purify) && defined(EXTRA_DEBUG))
   if (pre_alloc_size)
   {
@@ -60,30 +62,40 @@ gptr alloc_root(MEM_ROOT *mem_root, size_t Size)
 #else
   size_t get_size,max_left;
   gptr point;
-  reg1 USED_MEM *next;
+  reg1 USED_MEM *next= 0;
   reg2 USED_MEM **prev;
 
   Size= ALIGN_SIZE(Size);
-  prev= &mem_root->free;
   max_left=0;
-  for (next= *prev ; next && next->left < Size ; next= next->next)
+
+  if ((*(prev= &mem_root->free)))
   {
-    if (next->left > max_left)
-      max_left=next->left;
-    prev= &next->next;
+    if ((*prev)->left < Size &&
+        mem_root->first_block_usage++ >= 16 &&
+        (*prev)->left < 4096)
+    {
+      next= *prev;
+      *prev= next->next;
+      next->next= mem_root->used;
+      mem_root->used= next;
+      mem_root->first_block_usage= 0;
+    }
+    for (next= *prev; next && next->left < Size; next= next->next)
+      prev= &next->next;
   }
+
   if (! next)
   {						/* Time to alloc new block */
-    get_size= Size+ALIGN_SIZE(sizeof(USED_MEM));
-    if (max_left*4 < mem_root->block_size && get_size < mem_root->block_size)
-      get_size=mem_root->block_size;		/* Normal alloc */
+    get_size= MAX(Size+ALIGN_SIZE(sizeof(USED_MEM)),
+              (mem_root->block_size & ~1) * (mem_root->block_num >> 2));
 
-    if (!(next = (USED_MEM*) my_malloc(get_size,MYF(MY_WME | MY_ZEROFILL))))
+    if (!(next = (USED_MEM*) my_malloc(get_size,MYF(MY_WME))))
     {
       if (mem_root->error_handler)
 	(*mem_root->error_handler)();
       return((gptr) 0);				/* purecov: inspected */
     }
+    mem_root->block_num++;
     next->next= *prev;
     next->size= get_size;
     next->left= get_size-ALIGN_SIZE(sizeof(USED_MEM));
@@ -95,6 +107,7 @@ gptr alloc_root(MEM_ROOT *mem_root, size_t Size)
     *prev=next->next;				/* Remove block from list */
     next->next=mem_root->used;
     mem_root->used=next;
+    mem_root->first_block_usage= 0;
   }
   return(point);
 #endif

unittest/libmariadb/CMakeLists.txt

@@ -21,7 +21,7 @@ INCLUDE_DIRECTORIES(${CMAKE_SOURCE_DIR}/include
                     ${CMAKE_SOURCE_DIR}/unittest/mytap)
 ADD_DEFINITIONS(-DLIBMARIADB)
 
-SET(API_TESTS "async" "basic-t" "fetch" "charset" "logs" "cursor" "errors" "view" "ps" "ps_bugs" 
+SET(API_TESTS "performance" "async" "basic-t" "fetch" "charset" "logs" "cursor" "errors" "view" "ps" "ps_bugs" 
               "sp" "result" "connection" "misc" "ps_new" "sqlite3" "thread" "dyncol") 
 
 # Get finger print from server certificate 

unittest/libmariadb/performance.c

@@ -0,0 +1,94 @@
+/*
+Copyright (c) 2016 MariaDB Corporation AB
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published
+by the Free Software Foundation; version 2 of the License.
+
+This program is distributed in the hope that it will be useful, but
+WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+for more details.
+
+You should have received a copy of the GNU General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA
+*/
+
+
+/**
+  Some basic tests of the client API.
+*/
+
+#include "my_test.h"
+#include "ma_common.h"
+
+void show_time(struct timeval t1)
+{
+  struct timeval t2;
+  double elapsed;
+  gettimeofday(&t2, NULL);
+  elapsed = ((t2.tv_sec - t1.tv_sec)* 1000.0 + (t2.tv_usec - t1.tv_usec) / 1000.0) / 1000;
+  diag("elapsed: %5.2f", elapsed);
+}
+
+static int perf1(MYSQL *mysql)
+{
+  int rc;
+  MYSQL_STMT *stmt;
+  struct timeval t1;
+  char *stmtstr= "SELECT s.emp_no, s.salary, e.emp_no, e.first_name, e.last_name, e.gender FROM salaries s, employees e WHERE s.emp_no = e.emp_no";
+
+  rc= mysql_select_db(mysql, "employees");
+  if (rc)
+  {
+    diag("Employees database not installed");
+    return SKIP;
+  }
+
+  stmt= mysql_stmt_init(mysql);
+
+  diag("prepare");
+  gettimeofday(&t1, NULL);
+  rc= mysql_stmt_prepare(stmt, stmtstr, strlen(stmtstr));
+  check_stmt_rc(rc, stmt);
+  show_time(t1);
+
+  diag("execute");
+  gettimeofday(&t1, NULL);
+  rc= mysql_stmt_execute(stmt);
+  check_stmt_rc(rc, stmt);
+  show_time(t1);
+
+  diag("store");
+  gettimeofday(&t1, NULL);
+  rc= mysql_stmt_store_result(stmt);
+  check_stmt_rc(rc, stmt);
+  show_time(t1);
+
+  diag("fetch");
+  gettimeofday(&t1, NULL);
+  while (!mysql_stmt_fetch(stmt));
+  show_time(t1);
+
+  mysql_stmt_close(stmt);
+  return OK;
+}
+
+struct my_tests_st my_tests[] = {
+  {"perf1", perf1, TEST_CONNECTION_NEW, 0,  NULL,  NULL},
+  {NULL, NULL, 0, 0, NULL, NULL}
+};
+
+
+int main(int argc, char **argv)
+{
+  if (argc > 1)
+    get_options(argc, argv);
+
+  get_envvars();
+
+  run_tests(my_tests);
+
+  return(exit_status());
+}