Bug 1391633: Integrate use counters in the JavaScript engine; r=jonco, r=froydnj, data-review=francois

MozReview-Commit-ID: 1KOo0Zz0ccG

--HG--
extra : rebase_source : 1bdd89205a3d96f6d8314fc0cf08423b5c141cb6
extra : histedit_source : a000151b02c6423c967a72054b22679b08e25df9

dom/base/UseCounters.conf

@@ -90,3 +90,7 @@ method DataTransfer.mozSetDataAt
 method DataTransfer.mozGetDataAt
 attribute DataTransfer.mozUserCancelled
 attribute DataTransfer.mozSourceNode
+
+// JavaScript feature usage
+custom JS_asmjs uses asm.js
+custom JS_wasm uses WebAssembly

js/src/jsfriendapi.cpp

@@ -657,6 +657,12 @@ JS_SetAccumulateTelemetryCallback(JSContext* cx, JSAccumulateTelemetryDataCallba
     cx->runtime()->setTelemetryCallback(cx->runtime(), callback);
 }
 
+JS_FRIEND_API(void)
+JS_SetSetUseCounterCallback(JSContext* cx, JSSetUseCounterCallback callback)
+{
+    cx->runtime()->setUseCounterCallback(cx->runtime(), callback);
+}
+
 JS_FRIEND_API(JSObject*)
 JS_CloneObject(JSContext* cx, HandleObject obj, HandleObject protoArg)
 {

js/src/jsfriendapi.h

@@ -172,6 +172,24 @@ typedef void
 extern JS_FRIEND_API(void)
 JS_SetAccumulateTelemetryCallback(JSContext* cx, JSAccumulateTelemetryDataCallback callback);
 
+/*
+ * Use counter names passed to the accumulate use counter callback.
+ *
+ * It's OK to for these enum values to change as they will be mapped to a
+ * fixed member of the mozilla::UseCounter enum by the callback.
+ */
+
+enum class JSUseCounter {
+    ASMJS,
+    WASM
+};
+
+typedef void
+(*JSSetUseCounterCallback)(JSObject* obj, JSUseCounter counter);
+
+extern JS_FRIEND_API(void)
+JS_SetSetUseCounterCallback(JSContext* cx, JSSetUseCounterCallback callback);
+
 extern JS_FRIEND_API(bool)
 JS_GetIsSecureContext(JSCompartment* compartment);
 

js/src/vm/Runtime.cpp

@@ -444,6 +444,19 @@ JSRuntime::setTelemetryCallback(JSRuntime* rt, JSAccumulateTelemetryDataCallback
     rt->telemetryCallback = callback;
 }
 
+void
+JSRuntime::setUseCounter(JSObject* obj, JSUseCounter counter)
+{
+    if (useCounterCallback)
+        (*useCounterCallback)(obj, counter);
+}
+
+void
+JSRuntime::setUseCounterCallback(JSRuntime* rt, JSSetUseCounterCallback callback)
+{
+    rt->useCounterCallback = callback;
+}
+
 void
 JSRuntime::addSizeOfIncludingThis(mozilla::MallocSizeOf mallocSizeOf, JS::RuntimeSizes* rtSizes)
 {

js/src/vm/Runtime.h

@@ -455,6 +455,10 @@ struct JSRuntime : public js::MallocProvider<JSRuntime>
 
     /* Call this to accumulate telemetry data. */
     js::ActiveThreadData<JSAccumulateTelemetryDataCallback> telemetryCallback;
+
+    /* Call this to accumulate use counter data. */
+    js::ActiveThreadData<JSSetUseCounterCallback> useCounterCallback;
+
   public:
     // Accumulates data for Firefox telemetry. |id| is the ID of a JS_TELEMETRY_*
     // histogram. |key| provides an additional key to identify the histogram.
@@ -463,6 +467,13 @@ struct JSRuntime : public js::MallocProvider<JSRuntime>
 
     void setTelemetryCallback(JSRuntime* rt, JSAccumulateTelemetryDataCallback callback);
 
+    // Sets the use counter for a specific feature, measuring the presence or
+    // absence of usage of a feature on a specific web page and document which
+    // the passed JSObject belongs to.
+    void setUseCounter(JSObject* obj, JSUseCounter counter);
+
+    void setUseCounterCallback(JSRuntime* rt, JSSetUseCounterCallback callback);
+
   public:
     js::UnprotectedData<js::OffThreadPromiseRuntimeState> offThreadPromiseState;
 

js/src/wasm/WasmModule.cpp

@@ -1206,5 +1206,8 @@ Module::instantiate(JSContext* cx,
     uint32_t mode = uint32_t(metadata().isAsmJS() ? Telemetry::ASMJS : Telemetry::WASM);
     cx->runtime()->addTelemetry(JS_TELEMETRY_AOT_USAGE, mode);
 
+    JSUseCounter useCounter = metadata().isAsmJS() ? JSUseCounter::ASMJS : JSUseCounter::WASM;
+    cx->runtime()->setUseCounter(instance, useCounter);
+
     return true;
 }

js/xpconnect/src/XPCJSRuntime.cpp

@@ -2663,6 +2663,21 @@ AccumulateTelemetryCallback(int id, uint32_t sample, const char* key)
     }
 }
 
+static void
+SetUseCounterCallback(JSObject* obj, JSUseCounter counter)
+{
+    switch (counter) {
+      case JSUseCounter::ASMJS:
+        SetDocumentAndPageUseCounter(nullptr, obj, eUseCounter_custom_JS_asmjs);
+        break;
+      case JSUseCounter::WASM:
+        SetDocumentAndPageUseCounter(nullptr, obj, eUseCounter_custom_JS_wasm);
+        break;
+      default:
+        MOZ_ASSERT_UNREACHABLE("Unexpected JSUseCounter id");
+    }
+}
+
 static void
 CompartmentNameCallback(JSContext* cx, JSCompartment* comp,
                         char* buf, size_t bufsize)
@@ -2865,6 +2880,7 @@ XPCJSRuntime::Initialize(JSContext* cx)
     JS_SetWrapObjectCallbacks(cx, &WrapObjectCallbacks);
     js::SetPreserveWrapperCallback(cx, PreserveWrapper);
     JS_SetAccumulateTelemetryCallback(cx, AccumulateTelemetryCallback);
+    JS_SetSetUseCounterCallback(cx, SetUseCounterCallback);
     js::SetWindowProxyClass(cx, &OuterWindowProxyClass);
     js::SetXrayJitInfo(&gXrayJitInfo);
     JS::SetProcessLargeAllocationFailureCallback(OnLargeAllocationFailureCallback);