Emit the task-tracking events

Based on initial patches by Mikolaj Konarski <mikolaj@well-typed.com>

Use the new task tracing functions traceTaskCreate/Migrate/Delete.
There are two key places. One is for worker tasks which have a
relatively simple life cycle. Worker tasks are created and deleted by
the RTS. The other case is bound tasks which are either created by the
RTS, or appear as foreign C threads making calls into the RTS. For bound
threads we do the tracing in rts_lock/unlock, which actually covers both
threads coming in from outside, and also bound threads made by the RTS.

1 files changed, 15 insertions, 0 deletions

diff --git a/rts/RtsAPI.c b/rts/RtsAPI.c
index 0463f15ad8..c0896f7c6a 100644
--- a/rts/RtsAPI.c
+++ b/rts/RtsAPI.c
@@ -553,6 +553,14 @@ rts_lock (void)
 
     cap = NULL;
     waitForReturnCapability(&cap, task);
+
+    if (task->incall->prev_stack == NULL) {
+      // This is a new outermost call from C into Haskell land.
+      // Until the corresponding call to rts_unlock, this task
+      // is doing work on behalf of the RTS.
+      traceTaskCreate(task, cap);
+    }
+
     return (Capability *)cap;
 }
 
@@ -586,4 +594,11 @@ rts_unlock (Capability *cap)
     // Finally, we can release the Task to the free list.
     boundTaskExiting(task);
     RELEASE_LOCK(&cap->lock);
+
+    if (task->incall == NULL) {
+      // This is the end of an outermost call from C into Haskell land.
+      // From here on, the task goes back to C land and we should not count
+      // it as doing work on behalf of the RTS.
+      traceTaskDelete(task);
+    }
 }