temporary commit to pull Monty's changes

include/my_global.h:
  added dbug_volatile
mysys/mf_iocache2.c:
  some debugging code to investigate failed assert in my_b_append_tell()
sql/item_func.cc:
  fixed logging bug in DO RELEASE_LOCK()

include/my_global.h

@@ -51,6 +51,16 @@
 #endif
 #endif /* _WIN32... */
 
+/* sometimes we want to make sure that the variable is not put into
+   a register in debugging mode so we can see its value in the core
+*/
+
+#ifndef DBUG_OFF
+#define dbug_volatile volatile
+#else
+#define dbug_volatile
+#endif
+
 /*
   The macros below are borrowed from include/linux/compiler.h in the
   Linux kernel. Use them to indicate the likelyhood of the truthfulness

mysys/mf_iocache2.c

@@ -27,7 +27,10 @@
 
 my_off_t my_b_append_tell(IO_CACHE* info)
 {
-  my_off_t res; 
+  /* prevent optimizer from putting res in a register when debugging
+     we need this to be able to see the value of res when the assert fails
+  */
+  dbug_volatile my_off_t res; 
 /* we need to lock the append buffer mutex to keep flush_io_cache()
    from messing with the variables that we need in order to provide the
    answer to the question.
@@ -35,8 +38,11 @@ my_off_t my_b_append_tell(IO_CACHE* info)
 #ifdef THREAD
   pthread_mutex_lock(&info->append_buffer_lock);
 #endif
+  /* save the value of my_tell in res so we can see it when studying
+     coredump
+  */
   DBUG_ASSERT(info->end_of_file - (info->append_read_pos-info->write_buffer)
-	      == my_tell(info->file,MYF(0)));
+	      == (res=my_tell(info->file,MYF(0))));
   res = info->end_of_file + (info->write_pos-info->append_read_pos);
 #ifdef THREAD
   pthread_mutex_unlock(&info->append_buffer_lock);

sql/item_func.cc

@@ -1418,16 +1418,19 @@ void item_user_lock_release(ULL *ull)
   if (mysql_bin_log.is_open())
   {
     THD *thd = current_thd;
+    uint save_query_length;
     char buf[256];
     String tmp(buf,sizeof(buf));
     tmp.length(0);
     tmp.append("DO RELEASE_LOCK(\"");
     tmp.append(ull->key,ull->key_length);
     tmp.append("\")");
+    save_query_length=thd->query_length;
     thd->query_length=tmp.length();
     Query_log_event qev(thd,tmp.ptr());
     qev.error_code=0; // this query is always safe to run on slave
     mysql_bin_log.write(&qev);
+    thd->query_length=save_query_length;
   }
   if (--ull->count)
     pthread_cond_signal(&ull->cond);