eventlog: Repost initialisation events when eventlog restarts

If startEventlog is called after the program has already started running
then quite a few useful events are missing from the eventlog because
they are only posted when the program starts. This patch adds a
mechanism to declare that an event should be reposted everytime the
startEventlog function is called.

Now in EventLog.c there is a global list of functions called
`eventlog_header_funcs` which stores a list of functions which should be
called everytime the eventlog starts.

When calling `postInitEvent`, the event will not only be immediately
posted to the eventlog but also added to the global list.

When startEventLog is called, the list is traversed and the events
reposted.

1 files changed, 4 insertions, 1 deletions

diff --git a/rts/Trace.h b/rts/Trace.h
index a4b4cc173b..a1817e8b17 100644
--- a/rts/Trace.h
+++ b/rts/Trace.h
@@ -108,6 +108,8 @@ void traceEnd (void);
 void traceSchedEvent_ (Capability *cap, EventTypeNum tag,
                        StgTSO *tso, StgWord info1, StgWord info2);
 
+#define traceInitEvent(event) postInitEvent(event)
+
 /*
  * Record a GC event
  */
@@ -337,6 +339,7 @@ void flushTrace(void);
 #else /* !TRACING */
 
 #define traceSchedEvent(cap, tag, tso, other) /* nothing */
+#define traceInitEvent(event) /* nothing */
 #define traceSchedEvent2(cap, tag, tso, other, info) /* nothing */
 #define traceGcEvent(cap, tag) /* nothing */
 #define traceGcEventAtT(cap, ts, tag) /* nothing */
@@ -360,7 +363,7 @@ void flushTrace(void);
 #define traceCapEvent(cap, tag) /* nothing */
 #define traceCapsetEvent(tag, capset, info) /* nothing */
 #define traceWallClockTime_() /* nothing */
-#define traceOSProcessInfo_() /* nothing */
+#define traceOSProcessInfo_()  /* nothing */
 #define traceSparkCounters_(cap, counters, remaining) /* nothing */
 #define traceTaskCreate_(taskID, cap) /* nothing */
 #define traceTaskMigrate_(taskID, cap, new_cap) /* nothing */