Provide a counter for thrown JavaScript errors per context

This will be used as a data source for an
UMA histogram.

LOG=N
BUG=chromium:546603
R=jochen@chromium.org,yangguo@chromium.org

Review URL: https://codereview.chromium.org/1413503007

Cr-Commit-Position: refs/heads/master@{#31851}

src/bootstrapper.cc

@@ -370,6 +370,9 @@ static void SetObjectPrototype(Handle<JSObject> object, Handle<Object> proto) {
 
 
 void Bootstrapper::DetachGlobal(Handle<Context> env) {
+  env->GetIsolate()->counters()->errors_thrown_per_context()->AddSample(
+    env->GetErrorsThrown());
+
   Factory* factory = env->GetIsolate()->factory();
   Handle<JSGlobalProxy> global_proxy(JSGlobalProxy::cast(env->global_proxy()));
   global_proxy->set_native_context(*factory->null_value());
@@ -3171,6 +3174,9 @@ Genesis::Genesis(Isolate* isolate,
       if (!ConfigureGlobalObjects(global_proxy_template)) return;
     }
     isolate->counters()->contexts_created_from_scratch()->Increment();
+    // Re-initialize the counter because it got incremented during snapshot
+    // creation.
+    isolate->native_context()->set_errors_thrown(Smi::FromInt(0));
   }
 
   // Install experimental natives. Do not include them into the

src/contexts.cc

@@ -577,5 +577,16 @@ bool Context::IsBootstrappingOrGlobalObject(Isolate* isolate, Object* object) {
 }
 #endif
 
+
+void Context::IncrementErrorsThrown() {
+  DCHECK(IsNativeContext());
+
+  int previous_value = errors_thrown()->value();
+  set_errors_thrown(Smi::FromInt(previous_value + 1));
+}
+
+
+int Context::GetErrorsThrown() { return errors_thrown()->value(); }
+
 }  // namespace internal
 }  // namespace v8

src/contexts.h

@@ -186,6 +186,7 @@ enum BindingFlags {
   V(DATA_VIEW_FUN_INDEX, JSFunction, data_view_fun)                            \
   V(ERROR_MESSAGE_FOR_CODE_GEN_FROM_STRINGS_INDEX, Object,                     \
     error_message_for_code_gen_from_strings)                                   \
+  V(ERRORS_THROWN_INDEX, Smi, errors_thrown)                                   \
   V(EXTRAS_EXPORTS_OBJECT_INDEX, JSObject, extras_binding_object)              \
   V(EXTRAS_UTILS_OBJECT_INDEX, JSObject, extras_utils_object)                  \
   V(FAST_ALIASED_ARGUMENTS_MAP_INDEX, Map, fast_aliased_arguments_map)         \
@@ -396,6 +397,9 @@ class Context: public FixedArray {
     THROWN_OBJECT_INDEX = MIN_CONTEXT_SLOTS,
   };
 
+  void IncrementErrorsThrown();
+  int GetErrorsThrown();
+
   // Direct slot access.
   inline JSFunction* closure();
   inline void set_closure(JSFunction* closure);

src/counters.h

@@ -483,7 +483,8 @@ double AggregatedMemoryHistogram<Histogram>::Aggregate(double current_ms,
   HR(gc_idle_time_limit_overshot, V8.GCIdleTimeLimit.Overshot, 0, 10000, 101) \
   HR(gc_idle_time_limit_undershot, V8.GCIdleTimeLimit.Undershot, 0, 10000,    \
      101)                                                                     \
-  HR(code_cache_reject_reason, V8.CodeCacheRejectReason, 1, 6, 6)
+  HR(code_cache_reject_reason, V8.CodeCacheRejectReason, 1, 6, 6)             \
+  HR(errors_thrown_per_context, V8.ErrorsThrownPerContext, 0, 200, 20)
 
 #define HISTOGRAM_TIMER_LIST(HT)                                              \
   /* Garbage collection timers. */                                            \

src/factory.cc

@@ -727,6 +727,7 @@ Handle<Context> Factory::NewNativeContext() {
   array->set_map_no_write_barrier(*native_context_map());
   Handle<Context> context = Handle<Context>::cast(array);
   context->set_js_array_maps(*undefined_value());
+  context->set_errors_thrown(Smi::FromInt(0));
   DCHECK(context->IsNativeContext());
   return context;
 }

src/runtime/runtime-internal.cc

@@ -307,6 +307,7 @@ RUNTIME_FUNCTION(Runtime_FormatMessageString) {
   ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
       isolate, result,
       MessageTemplate::FormatMessage(template_index, arg0, arg1, arg2));
+  isolate->native_context()->IncrementErrorsThrown();
   return *result;
 }