Patch: pthreads error checking

[Tom Tromey <tromey@cygnus.com>]

The last missed patch.  This one adds some error checking to the
pthreads thread implementation.  It also makes things a bit slower,
which is unfortunate.

Re-reading this, it occurs to me that this patch is actually flawed.
pthread_mutex_trylock doesn't actually tell us if the thread holds the
lock, just whether the thread *can* hold the lock.  The lock might be
unheld.  I'll write a better patch shortly.

1999-09-01  Tom Tromey  <tromey@cygnus.com>

	* posix-threads.cc (_Jv_CondWait): Call _Jv_PthreadCheckMonitor.
	* include/posix-threads.h (_Jv_PthreadCheckMonitor): New
	function.
	(_Jv_CondNotify): Use it.
	(_Jv_CondNotifyAll): Likewise.

Tom

Index: posix-threads.cc
===================================================================
RCS file: /cvs/java/libgcj/libjava/posix-threads.cc,v
retrieving revision 1.5
retrieving revision 1.6
diff -u -r1.5 -r1.6
--- posix-threads.cc	1999/08/25 00:46:23	1.5
+++ posix-threads.cc	1999/09/01 18:29:38	1.6
@@ -75,6 +75,9 @@
 _Jv_CondWait (_Jv_ConditionVariable_t *cv, _Jv_Mutex_t *mu,
 	      jlong millis, jint nanos)
 {
+  if (_Jv_PthreadCheckMonitor (mu))
+    return 1;
+
   int r;
   pthread_mutex_t *pmu;
 #ifdef HAVE_RECURSIVE_MUTEX
@@ -82,6 +85,7 @@
 #else
   pmu = &mu->mutex2;
 #endif
+
   if (millis == 0 && nanos == 0)
     r = pthread_cond_wait (cv, pmu);
   else
@@ -96,6 +100,7 @@
       if (r && errno == ETIMEDOUT)
 	r = 0;
     }
+
   return r;
 }
 
Index: include/posix-threads.h
===================================================================
RCS file: /cvs/java/libgcj/libjava/include/posix-threads.h,v
retrieving revision 1.1
retrieving revision 1.2
diff -u -r1.1 -r1.2
--- posix-threads.h	1999/04/07 14:52:35	1.1
+++ posix-threads.h	1999/09/01 18:29:39	1.2
@@ -65,6 +65,25 @@
 typedef void _Jv_ThreadStartFunc (java::lang::Thread *);
 
 
+// This is a convenience function used only by the pthreads thread
+// implementation.  This is slow, but that's too bad -- we need to do
+// the checks for correctness.  It might be nice to be able to compile
+// this out.
+inline int _Jv_PthreadCheckMonitor (_Jv_Mutex_t *mu)
+{
+  pthread_mutex_t *pmu;
+#ifdef HAVE_RECURSIVE_MUTEX
+  pmu = mu;
+#else
+  pmu = &mu->mutex2;
+#endif
+  // See if the mutex is locked by this thread.
+  if (pthread_mutex_trylock (pmu))
+    return 1;
+  pthread_mutex_unlock (pmu);
+  return 0;
+}
+
 //
 // Condition variables.
 //
@@ -94,17 +113,15 @@
 		  jlong millis, jint nanos);
 
 inline int
-_Jv_CondNotify (_Jv_ConditionVariable_t *cv, _Jv_Mutex_t *)
+_Jv_CondNotify (_Jv_ConditionVariable_t *cv, _Jv_Mutex_t *mu)
 {
-  // FIXME: check to see if mutex is held by current thread.
-  return pthread_cond_signal (cv);
+  return _Jv_PthreadCheckMonitor (mu) || pthread_cond_signal (cv);
 }
 
 inline int
-_Jv_CondNotifyAll (_Jv_ConditionVariable_t *cv, _Jv_Mutex_t *)
+_Jv_CondNotifyAll (_Jv_ConditionVariable_t *cv, _Jv_Mutex_t *mu)
 {
-  // FIXME: check to see if mutex is held by current thread.
-  return pthread_cond_broadcast (cv);
+  return _Jv_PthreadCheckMonitor (mu) || pthread_cond_broadcast (cv);
 }