bzr commit into mysql-6.0-maria branch (serg:2707) Bug#40990

[Sergei Golubchik]

#At file:///usr/home/serg/Abk/mysql/6.0-maria/

 2707 Sergei Golubchik	2008-12-22
      Bug#40990 Maria: failure of maria.test & maria_notemebedded in deadlock
detection
      detect a case when a blocker has removed itself and signalled after the condition
timed out
      but before it (cond_wait) acquired the mutex back
modified:
  include/waiting_threads.h
  mysys/waiting_threads.c

=== modified file 'include/waiting_threads.h'
--- a/include/waiting_threads.h	2008-11-04 13:09:32 +0000
+++ b/include/waiting_threads.h	2008-12-22 18:04:24 +0000
@@ -182,6 +182,7 @@ typedef struct st_wt_thd {
 } WT_THD;
 
 #define WT_TIMEOUT              ETIMEDOUT
+#define WT_FREE_TO_GO           1
 #define WT_OK                   0
 #define WT_DEADLOCK             -1
 #define WT_DEPTH_EXCEEDED       -2

=== modified file 'mysys/waiting_threads.c'
--- a/mysys/waiting_threads.c	2008-11-10 19:11:27 +0000
+++ b/mysys/waiting_threads.c	2008-12-22 18:04:24 +0000
@@ -613,7 +613,16 @@ static int deadlock(WT_THD *thd, WT_THD 
   if (ret == WT_DEADLOCK && depth)
     change_victim(blocker, &arg);
   if (arg.rc)
+  {
+    /* special return code if there's nobody to wait for */
+    if (depth == 0 && ret == WT_OK && arg.rc->owners.elements == 0)
+    {
+      DBUG_ASSERT(thd == blocker);
+      DBUG_ASSERT(arg.rc == thd->waiting_for);
+      ret= WT_FREE_TO_GO;
+    }
     rc_unlock(arg.rc);
+  }
   /* notify the victim, if appropriate */
   if (ret == WT_DEADLOCK && arg.victim != thd)
   {
@@ -888,7 +897,10 @@ int wt_thd_cond_timedwait(WT_THD *thd, p
     ret= pthread_cond_timedwait(&rc->cond, mutex, &timeout);
   if (ret == WT_TIMEOUT)
   {
-    if (deadlock(thd, thd, 0, *thd->deadlock_search_depth_long))
+    int r= deadlock(thd, thd, 0, *thd->deadlock_search_depth_long);
+    if (r == WT_FREE_TO_GO)
+      ret= WT_OK;
+    else if (r != WT_OK)
       ret= WT_DEADLOCK;
     else if (*thd->timeout_long > *thd->timeout_short)
     {