Draft implementation for Chronos thread freeze guard.

chroprof/api.nim

@@ -7,11 +7,11 @@ export
 var profilerInstance {.threadvar.}: ProfilerState
 
 proc getMetrics*(): MetricsTotals =
-  ## Returns the `MetricsTotals` for the event loop running in the 
+  ## Returns the `MetricsTotals` for the event loop running in the
   ## current thread.
   result = profilerInstance.metrics
 
-template enableProfiling*(callback: EventCallback) =
+template enableProfiling*(callback: EventCallback, maxExecThreshold: Duration) =
   ## Enables profiling for the the event loop running in the current thread.
   ## The client may optionally supply a callback to be notified of `Future`
   ## events.
@@ -19,10 +19,14 @@ template enableProfiling*(callback: EventCallback) =
       proc(e: Event) {.nimcall, gcsafe, raises: [].} =
         profilerInstance.processEvent(e)
         callback(e)
+      ,
+      maxExecThreshold = maxExecThreshold
   )
 
-template enableProfiling*() =
+template enableProfiling*(maxExecThreshold: Duration) =
   attachMonitoring(
     proc(e: Event) {.nimcall, gcsafe, raises: [].} =
       profilerInstance.processEvent(e)
+    ,
+    maxExecThreshold = maxExecThreshold
   )

chroprof/collector.nim

@@ -1,4 +1,4 @@
-## Metrics collector which allows exporting Chronos profiling metrics to 
+## Metrics collector which allows exporting Chronos profiling metrics to
 ## Prometheus.
 
 import std/algorithm
@@ -173,7 +173,7 @@ when defined(metrics):
 
   var asyncProfilerInfo* {.global.}: ChronosProfilerInfo
 
-  proc enableProfilerMetrics*(k: int) =
+  proc enableProfilerMetrics*(k: int, maxExecThreshold: Duration) =
     assert threadId() == moduleInitThread,
       "You cannot call enableProfilerMetrics() from a thread other than" &
         " the one that initialized the metricscolletor module."
@@ -193,4 +193,6 @@ when defined(metrics):
         {.cast(gcsafe).}:
           if e.newState == ExtendedFutureState.Completed:
             asyncProfilerInfo.collect()
+      ,
+      maxExecThreshold = maxExecThreshold
     )

chroprof/profiler.nim

@@ -142,6 +142,10 @@ proc aggregatePartial(
   self.metrics.withValue(metrics.futureType, aggMetrics):
     let execTime = metrics.partialExecTime - metrics.partialChildrenExecOverlap
 
+    if execTime > threshold:
+      raiseAssert("Execution time of future is too high (" &
+        $metrics.futureType & ")" & $execTime)
+
     aggMetrics.callCount.inc()
     aggMetrics.execTime += execTime
     aggMetrics.execTimeMax = max(aggMetrics.execTimeMax, execTime)