Bug 1157870 - Performance Groups should have a unique ID (low-level). r=jandem

--HG--
extra : transplant_source : .%DB%86%B6%B8%84%EB%94%EF%2B%12Of%28%ED%09U%5C%16%2A

js/src/jsapi.cpp

@@ -338,7 +338,7 @@ IterPerformanceStats(JSContext* cx,
             continue;
         }
 
-        if (!(*walker)(cx, group->data, closure)) {
+        if (!(*walker)(cx, group->data, group->uid, closure)) {
             // Issue in callback
             return false;
         }

js/src/jsapi.h

@@ -5448,6 +5448,9 @@ struct PerformanceGroup {
     // Performance data for this group.
     PerformanceData data;
 
+    // An id unique to this runtime.
+    const uint64_t uid;
+
     // `true` if an instance of `AutoStopwatch` is already monitoring
     // the performance of this performance group for this iteration
     // of the event loop, `false` otherwise.
@@ -5472,12 +5475,7 @@ struct PerformanceGroup {
         stopwatch_ = nullptr;
     }
 
-    explicit PerformanceGroup(void* key)
-      : stopwatch_(nullptr)
-      , iteration_(0)
-      , key_(key)
-      , refCount_(0)
-    { }
+    explicit PerformanceGroup(JSContext* cx, void* key);
     ~PerformanceGroup()
     {
         MOZ_ASSERT(refCount_ == 0);
@@ -5589,7 +5587,7 @@ extern JS_PUBLIC_API(PerformanceData*)
 GetPerformanceData(JSRuntime*);
 
 typedef bool
-(PerformanceStatsWalker)(JSContext* cx, const PerformanceData& stats, void* closure);
+(PerformanceStatsWalker)(JSContext* cx, const PerformanceData& stats, uint64_t uid, void* closure);
 
 /**
  * Extract the performance statistics.

js/src/vm/Runtime.cpp

@@ -955,7 +955,7 @@ js::PerformanceGroupHolder::getGroup(JSContext* cx)
         group_ = ptr->value();
         MOZ_ASSERT(group_);
     } else {
-        group_ = runtime_->new_<PerformanceGroup>(key);
+        group_ = runtime_->new_<PerformanceGroup>(cx, key);
         runtime_->stopwatch.groups_.add(ptr, key, group_);
     }
 
@@ -970,6 +970,15 @@ js::GetPerformanceData(JSRuntime* rt)
     return &rt->stopwatch.performance;
 }
 
+js::PerformanceGroup::PerformanceGroup(JSContext* cx, void* key)
+  : uid(cx->runtime()->stopwatch.uniqueId())
+  , stopwatch_(nullptr)
+  , iteration_(0)
+  , key_(key)
+  , refCount_(0)
+{
+}
+
 void
 JS_SetCurrentPerfGroupCallback(JSRuntime *rt, JSCurrentPerfGroupCallback cb)
 {

js/src/vm/Runtime.h

@@ -1517,6 +1517,7 @@ struct JSRuntime : public JS::shadow::Runtime,
           , currentPerfGroupCallback(nullptr)
           , isMonitoringJank_(false)
           , isMonitoringCPOW_(false)
+          , idCounter_(0)
         { }
 
         /**
@@ -1570,6 +1571,13 @@ struct JSRuntime : public JS::shadow::Runtime,
             return isMonitoringCPOW_;
         }
 
+        /**
+         * Return a identifier for a group, unique to the runtime.
+         */
+        uint64_t uniqueId() {
+            return idCounter_++;
+        }
+
         // Some systems have non-monotonic clocks. While we cannot
         // improve the precision, we can make sure that our measures
         // are monotonic nevertheless. We do this by storing the
@@ -1620,6 +1628,11 @@ struct JSRuntime : public JS::shadow::Runtime,
          */
         bool isMonitoringJank_;
         bool isMonitoringCPOW_;
+
+        /**
+         * A counter used to generate unique identifiers for groups.
+         */
+        uint64_t idCounter_;
     };
     Stopwatch stopwatch;
 };