Add a new traceMarker# primop for use in profiling output

In time-based profiling visualisations (e.g. heap profiles and ThreadScope)
it would be useful to be able to mark particular points in the execution and
have those points in time marked in the visualisation.

The traceMarker# primop currently emits an event into the eventlog. In
principle it could be extended to do something in the heap profiling too.

2 files changed, 25 insertions, 0 deletions

diff --git a/rts/eventlog/EventLog.c b/rts/eventlog/EventLog.c
index 81aaecb67d..ef6f69c6dd 100644
--- a/rts/eventlog/EventLog.c
+++ b/rts/eventlog/EventLog.c
@@ -80,6 +80,7 @@ char *EventDesc[] = {
   [EVENT_CREATE_SPARK_THREAD] = "Create spark thread",
   [EVENT_LOG_MSG]             = "Log message",
   [EVENT_USER_MSG]            = "User message",
+  [EVENT_USER_MARKER]         = "User marker",
   [EVENT_GC_IDLE]             = "GC idle",
   [EVENT_GC_WORK]             = "GC working",
   [EVENT_GC_DONE]             = "GC done",
@@ -369,6 +370,7 @@ initEventLogging(void)
 
         case EVENT_LOG_MSG:          // (msg)
         case EVENT_USER_MSG:         // (msg)
+        case EVENT_USER_MARKER:      // (markername)
         case EVENT_RTS_IDENTIFIER:   // (capset, str)
         case EVENT_PROGRAM_ARGS:     // (capset, strvec)
         case EVENT_PROGRAM_ENV:      // (capset, strvec)
@@ -1086,6 +1088,27 @@ void postEventStartup(EventCapNo n_caps)
     RELEASE_LOCK(&eventBufMutex);
 }
 
+void postUserMarker(Capability *cap, char *markername)
+{
+    EventsBuf *eb;
+    int size = strlen(markername);
+
+    eb = &capEventBuf[cap->no];
+
+    if (!hasRoomForVariableEvent(eb, size)){
+        printAndClearEventBuf(eb);
+
+        if (!hasRoomForVariableEvent(eb, size)){
+            // Event size exceeds buffer size, bail out:
+            return;
+        }
+    }
+
+    postEventHeader(eb, EVENT_USER_MARKER);
+    postPayloadSize(eb, size);
+    postBuf(eb, (StgWord8*) markername, size);
+}
+
 void postThreadLabel(Capability    *cap,
                      EventThreadID  id,
                      char          *label)
diff --git a/rts/eventlog/EventLog.h b/rts/eventlog/EventLog.h
index 5861f64757..85370e9843 100644
--- a/rts/eventlog/EventLog.h
+++ b/rts/eventlog/EventLog.h
@@ -49,6 +49,8 @@ void postUserMsg(Capability *cap, char *msg, va_list ap);
 
 void postCapMsg(Capability *cap, char *msg, va_list ap);
 
+void postUserMarker(Capability *cap, char *markername);
+
 void postEventStartup(EventCapNo n_caps);
 
 /*