Bug 1637642 - Add telemetry for weak marking phases r=sfink

Differential Revision: https://phabricator.services.mozilla.com/D75149

js/src/gc/Statistics.cpp

@@ -1065,6 +1065,8 @@ void Statistics::sendGCTelemetry() {
   TimeDuration prepareTotal = SumPhase(PhaseKind::PREPARE, phaseTimes);
   TimeDuration markTotal = SumPhase(PhaseKind::MARK, phaseTimes);
   TimeDuration markRootsTotal = SumPhase(PhaseKind::MARK_ROOTS, phaseTimes);
+  TimeDuration markWeakTotal = phaseTimes[Phase::SWEEP_MARK_WEAK] +
+                               phaseTimes[Phase::SWEEP_MARK_GRAY_WEAK];
   size_t markCount = gc->marker.getMarkCount();
   double markRate = markCount / t(markTotal);
   runtime->addTelemetry(JS_TELEMETRY_GC_PREPARE_MS, t(prepareTotal));
@@ -1078,6 +1080,7 @@ void Statistics::sendGCTelemetry() {
   runtime->addTelemetry(JS_TELEMETRY_GC_MARK_ROOTS_MS, t(markRootsTotal));
   runtime->addTelemetry(JS_TELEMETRY_GC_MARK_GRAY_MS,
                         t(phaseTimes[Phase::SWEEP_MARK_GRAY]));
+  runtime->addTelemetry(JS_TELEMETRY_GC_MARK_WEAK_MS, t(markWeakTotal));
   runtime->addTelemetry(JS_TELEMETRY_GC_NON_INCREMENTAL, nonincremental());
   if (nonincremental()) {
     runtime->addTelemetry(JS_TELEMETRY_GC_NON_INCREMENTAL_REASON,

js/src/jsfriendapi.h

@@ -154,6 +154,7 @@ enum {
   JS_TELEMETRY_GC_COMPACT_MS,
   JS_TELEMETRY_GC_MARK_ROOTS_MS,
   JS_TELEMETRY_GC_MARK_GRAY_MS,
+  JS_TELEMETRY_GC_MARK_WEAK_MS,
   JS_TELEMETRY_GC_SLICE_MS,
   JS_TELEMETRY_GC_SLOW_PHASE,
   JS_TELEMETRY_GC_SLOW_TASK,

js/xpconnect/src/XPCJSRuntime.cpp

@@ -2621,6 +2621,9 @@ static void AccumulateTelemetryCallback(int id, uint32_t sample,
     case JS_TELEMETRY_GC_MARK_GRAY_MS:
       Telemetry::Accumulate(Telemetry::GC_MARK_GRAY_MS, sample);
       break;
+    case JS_TELEMETRY_GC_MARK_WEAK_MS:
+      Telemetry::Accumulate(Telemetry::GC_MARK_WEAK_MS, sample);
+      break;
     case JS_TELEMETRY_GC_SLICE_MS:
       Telemetry::Accumulate(Telemetry::GC_SLICE_MS, sample);
       break;

toolkit/components/telemetry/Histograms.json

@@ -773,6 +773,18 @@
     "n_buckets": 50,
     "description": "Time spent marking gray GC objects (ms)"
   },
+  "GC_MARK_WEAK_MS": {
+    "record_in_processes": ["main", "content"],
+    "products": ["firefox"],
+    "alert_emails": ["dev-telemetry-gc-alerts@mozilla.org", "jcoppeard@mozilla.com"],
+    "expires_in_version": "never",
+    "releaseChannelCollection": "opt-out",
+    "kind": "exponential",
+    "high": 10000,
+    "n_buckets": 50,
+    "description": "Time spent marking GC objects held live through weakmaps (ms)",
+    "bug_numbers": [1637642]
+  },
   "GC_SLICE_MS": {
     "record_in_processes": ["main", "content"],
     "products": ["firefox", "fennec", "geckoview"],