Fix segfault with STM; fixes #8035. Patch from errge.
[ghc.git] / rts / Timer.c
index 05d1fec..aa4b8d8 100644 (file)
  * on platform-specific services to install and run the timers.
  *
  */
+
+#include "PosixSource.h"
 #include "Rts.h"
-#include "RtsFlags.h"
+
+#include "Timer.h"
 #include "Proftimer.h"
-#include "Storage.h"
 #include "Schedule.h"
-#include "Timer.h"
 #include "Ticker.h"
 #include "Capability.h"
 #include "RtsSignals.h"
 /* ticks left before next pre-emptive context switch */
 static int ticks_to_ctxt_switch = 0;
 
-#if defined(THREADED_RTS)
 /* idle ticks left before we perform a GC */
 static int ticks_to_gc = 0;
-#endif
 
 /*
  * Function: handle_tick()
@@ -47,12 +46,11 @@ handle_tick(int unused STG_UNUSED)
       ticks_to_ctxt_switch--;
       if (ticks_to_ctxt_switch <= 0) {
          ticks_to_ctxt_switch = RtsFlags.ConcFlags.ctxtSwitchTicks;
-         context_switch = 1;   /* schedule a context switch */
+          contextSwitchAllCapabilities(); /* schedule a context switch */
       }
   }
 
-#if defined(THREADED_RTS)
-  /* 
+  /*
    * If we've been inactive for idleGCDelayTime (set by +RTS
    * -I), tell the scheduler to wake up and do a GC, to check
    * for threads that are deadlocked.
@@ -64,32 +62,74 @@ handle_tick(int unused STG_UNUSED)
                     RtsFlags.MiscFlags.tickInterval;
       break;
   case ACTIVITY_MAYBE_NO:
-      if (ticks_to_gc == 0) break; /* 0 ==> no idle GC */
-      ticks_to_gc--;
       if (ticks_to_gc == 0) {
-         ticks_to_gc = RtsFlags.GcFlags.idleGCDelayTime /
-                        RtsFlags.MiscFlags.tickInterval;
-         recent_activity = ACTIVITY_INACTIVE;
-         blackholes_need_checking = rtsTrue;
-         /* hack: re-use the blackholes_need_checking flag */
-         wakeUpRts();
+          if (RtsFlags.GcFlags.doIdleGC) {
+              recent_activity = ACTIVITY_INACTIVE;
+#ifdef THREADED_RTS
+              wakeUpRts();
+              // The scheduler will call stopTimer() when it has done
+              // the GC.
+#endif
+          } else {
+              recent_activity = ACTIVITY_DONE_GC;
+              // disable timer signals (see #1623, #5991)
+              // but only if we're not profiling
+#ifndef PROFILING
+              stopTimer();
+#endif
+          }
+      } else {
+          ticks_to_gc--;
       }
       break;
   default:
       break;
   }
-#endif
+}
+
+// This global counter is used to allow multiple threads to stop the
+// timer temporarily with a stopTimer()/startTimer() pair.  If 
+//      timer_enabled  == 0          timer is enabled
+//      timer_disabled == N, N > 0   timer is disabled by N threads
+// When timer_enabled makes a transition to 0, we enable the timer,
+// and when it makes a transition to non-0 we disable it.
+
+static StgWord timer_disabled;
+
+void
+initTimer(void)
+{
+    initProfTimer();
+    if (RtsFlags.MiscFlags.tickInterval != 0) {
+        initTicker(RtsFlags.MiscFlags.tickInterval, handle_tick);
+    }
+    timer_disabled = 1;
 }
 
 void
 startTimer(void)
 {
-  initProfTimer();
-  startTicker(RtsFlags.MiscFlags.tickInterval, handle_tick);
+    if (atomic_dec(&timer_disabled) == 0) {
+        if (RtsFlags.MiscFlags.tickInterval != 0) {
+            startTicker();
+        }
+    }
 }
 
 void
 stopTimer(void)
 {
-  stopTicker();
+    if (atomic_inc(&timer_disabled) == 1) {
+        if (RtsFlags.MiscFlags.tickInterval != 0) {
+            stopTicker();
+        }
+    }
+}
+
+void
+exitTimer (rtsBool wait)
+{
+    if (RtsFlags.MiscFlags.tickInterval != 0) {
+        exitTicker(wait);
+    }
 }