rts: Introduce --eventlog-flush-interval flagwip/eventlog-flush-interval

This introduces a flag, --eventlog-flush-interval, which can be used to
set an upper bound on the amount of time for which an eventlog event
will remain enqueued. This can be useful in real-time monitoring
settings.

1 files changed, 13 insertions, 0 deletions

diff --git a/rts/Timer.c b/rts/Timer.c
index 97d87ad989..d60d09e726 100644
--- a/rts/Timer.c
+++ b/rts/Timer.c
@@ -24,6 +24,7 @@
 #include "Ticker.h"
 #include "Capability.h"
 #include "RtsSignals.h"
+#include "rts/EventLogWriter.h"
 
 // This global counter is used to allow multiple threads to stop the
 // timer temporarily with a stopTimer()/startTimer() pair.  If
@@ -37,6 +38,9 @@ static StgWord timer_disabled;
 /* ticks left before next pre-emptive context switch */
 static int ticks_to_ctxt_switch = 0;
 
+/* ticks left before next next forced eventlog flush */
+static int ticks_to_eventlog_flush = 0;
+
 
 /*
  Note [GC During Idle Time]
@@ -111,6 +115,15 @@ handle_tick(int unused STG_UNUSED)
       }
   }
 
+  if (eventLogStatus() == EVENTLOG_RUNNING
+      && RtsFlags.TraceFlags.eventlogFlushTicks > 0) {
+      ticks_to_eventlog_flush--;
+      if (ticks_to_eventlog_flush <= 0) {
+          ticks_to_eventlog_flush = RtsFlags.TraceFlags.eventlogFlushTicks;
+          flushEventLog(NULL);
+      }
+  }
+
   /*
    * If we've been inactive for idleGCDelayTime (set by +RTS
    * -I), tell the scheduler to wake up and do a GC, to check