Expose counters in javascript.

src/extensions/counters-extension.cc

Index: src/extensions/counters-extension.cc
diff --git a/src/extensions/counters-extension.cc b/src/extensions/counters-extension.cc
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+// Copyright 2010 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include "counters-extension.h"

[rossberg, 2012/07/18 12:23:39]

Can we perhaps call that "stats"?

+
+namespace v8 {
+namespace internal {
+
+const char* const CountersExtension::kSource =
+    "native function getV8Counters();";
+
+
+v8::Handle<v8::FunctionTemplate> CountersExtension::GetNativeFunction(
+    v8::Handle<v8::String> str) {
+  ASSERT(strcmp(*v8::String::AsciiValue(str), "getPerformanceCounters") == 0);
+  return v8::FunctionTemplate::New(CountersExtension::GetCounters);
+}
+
+
+v8::Handle<v8::Value> CountersExtension::GetCounters(
+    const v8::Arguments& args) {
+  Isolate* isolate = Isolate::Current();
+  Heap* heap = isolate->heap();
+  if (args.Length() > 0) {  // GC if first argument evaluates to true.
+    if (args[0]->IsBoolean() && args[0]->ToBoolean()->Value()) {
+      heap->CollectAllGarbage(Heap::kNoGCFlags, "counters extension");
+    }
+  }
+
+  Counters* counters = isolate->counters();
+  v8::Local<v8::Object> result = v8::Object::New();
+
+  StatsCounter* counter = NULL;
+
+#define STR(s) #s

[rossberg, 2012/07/18 12:23:39]

As discussed offline, you could get rid of this one.

+#define ADD_COUNTER(name, caption)                                             \
+  counter = counters->name();                                                  \
+  if (counter->Enabled())                                                      \
+    result->Set(v8::String::New(STR(name)),                                    \
+        v8::Number::New(static_cast<double>(*counter->GetInternalPointer())));

[rossberg, 2012/07/18 12:23:39]

Is the cast necessary? (here and below)

+
+  STATS_COUNTER_LIST_1(ADD_COUNTER)
+  STATS_COUNTER_LIST_2(ADD_COUNTER)
+#undef ADD_COUNTER
+#define ADD_COUNTER(name)                                                      \
+  counter = counters->count_of_##name();                                       \
+  if (counter->Enabled())                                                      \
+    result->Set(v8::String::New(STR(count_of_##name)),                         \
+        v8::Number::New(static_cast<double>(*counter->GetInternalPointer()))); \
+  counter = counters->size_of_##name();                                        \
+  if (counter->Enabled())                                                      \
+    result->Set(v8::String::New(STR(size_of_##name)),                          \
+        v8::Number::New(static_cast<double>(*counter->GetInternalPointer())));
+
+  INSTANCE_TYPE_LIST(ADD_COUNTER)
+#undef ADD_COUNTER
+#define ADD_COUNTER(name)                                                      \
+  result->Set(v8::String::New(STR(count_of_CODE_TYPE_##name)),                 \
+      v8::Number::New(static_cast<double>(                                     \
+          *counters->count_of_CODE_TYPE_##name()->GetInternalPointer())));     \
+  result->Set(v8::String::New(STR(size_of_CODE_TYPE_##name)),                  \
+        v8::Number::New(static_cast<double>(                                   \
+            *counters->size_of_CODE_TYPE_##name()->GetInternalPointer())));
+
+  CODE_KIND_LIST(ADD_COUNTER)
+#undef ADD_COUNTER
+#undef STR
+
+  return result;
+}
+
+
+void CountersExtension::Register() {
+  static CountersExtension counters_extension;
+  static v8::DeclareExtension declaration(&counters_extension);
+}
+
+} }  // namespace v8::internal