Initial GetSample implementation.

test/cctest/test-sampler-api.cc

+// Copyright 2014 the V8 project authors. All rights reserved.

[Benedikt Meurer, 2014/08/27 04:17:23]

Nit: Use new short copyright header.

[gholap, 2014/08/27 21:48:09]

Done.

+// 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.
+//
+// Tests the public sampling API in include/v8-sampler.h
+
+#include "include/v8.h"
+#include "include/v8-sampler.h"
+
+#include "src/v8.h"
+
+#include "src/base/platform/platform.h"
+
+#include "test/cctest/cctest.h"
+
+using v8::Local;
+using v8::Script;
+
+using v8::internal::Isolate;
+
+namespace SamplerTester {

[Benedikt Meurer, 2014/08/27 04:17:23]

Use an anonymous namespace instead.

[gholap, 2014/08/27 21:48:09]

Done.

+  // sampler thread waits on this semaphore.
+  v8::base::Semaphore* SamplerSemaphore = new v8::base::Semaphore(0);
+
+  // V8 thread (the JavaScript code) waits on this semaphore.
+  v8::base::Semaphore* V8Semaphore = new v8::base::Semaphore(0);
+
+  // The JavaScript calls this function when an full stack depth.
+  void SignalAndWaitForSampler(
+    const v8::FunctionCallbackInfo<v8::Value>& args) {
+    // Tell the sampler that it can take a sample now.
+    SamplerSemaphore->Signal();
+
+    // Wait for the sampler to finish collecting a sample.
+    V8Semaphore->Wait();
+  }
+}
+
+
+// A thread which collects samples from v8.
+class SamplerThread : public v8::base::Thread {

[Benedikt Meurer, 2014/08/27 04:17:23]

Nit: Mark as V8_FINAL.

[gholap, 2014/08/27 21:48:09]

Done.

+ public:
+  explicit SamplerThread(v8::Isolate* isolate);
+  virtual ~SamplerThread() {}
+  int sampleStackSize;
+
+  virtual void Run();
+  void Stop();
+
+ private:
+  v8::Isolate* isolate_;
+};
+
+static const int kSamplerThreadStackSize = 64 * 1024;

[Benedikt Meurer, 2014/08/27 04:17:24]

There should be no need to manually override specify the stack size for the
sampler thread.

[gholap, 2014/08/27 21:48:09]

Done.

+
+SamplerThread::SamplerThread(v8::Isolate* isolate)

[Benedikt Meurer, 2014/08/27 04:17:23]

Nit: Inline method definition into declaration above.

[gholap, 2014/08/27 21:48:09]

Done.

+    : Thread(v8::base::Thread::Options("sampler-api-tester",
+                                       kSamplerThreadStackSize)),
+      sampleStackSize(0),
+      isolate_(isolate) {
+}
+
+
+void SamplerThread::Stop() {

[Benedikt Meurer, 2014/08/27 04:17:23]

Nit: Remove this method, there's no advantage over using Join() directly.

[gholap, 2014/08/27 21:48:09]

Done.

+  Join();
+}
+
+
+void SamplerThread::Run() {

[Benedikt Meurer, 2014/08/27 04:17:23]

Nit: Inline method definition into declaration above.

[gholap, 2014/08/27 21:48:09]

Done.

+  v8::Sample sample;
+
+  // Wait for JS to reach full stack depth.
+  SamplerTester::SamplerSemaphore->Wait();
+
+  v8::Sample* sample_ptr = &sample;

[Benedikt Meurer, 2014/08/27 04:17:23]

Replace with something like:

v8::Sample sample;
CHECK_NOT_NULL(v8::Sampler::GetSample(isolate_, &sample));
CHECK_EQ(8, sample.frames_count);

[gholap, 2014/08/27 21:48:09]

Changed the API so that sample.frames_count is zero in case of failure in sample
collection.

+  sample_ptr = v8::Sampler::GetSample(isolate_, sample_ptr);
+  CHECK_NE(NULL, sample_ptr);
+  sampleStackSize = sample_ptr->frames_count;
+
+  // Tell JS that sample collection is done.
+  SamplerTester::V8Semaphore->Signal();
+}
+
+
+// A JavaScript program with stack depth 8.
+// When at the bottom of the recursion,
+// The JavaScript code calls into C++ test code,
+// waiting for the sampler to take a sample.
+static const char* sampler_api_test_source = "function func(count) {\n"
+"  if (count == 1) {\n"
+"    SignalAndWaitForSampler();\n"
+"  }\n"
+"  else return func(count - 1);\n"
+"}\n"
+"func(7);\n";
+
+
+// TODO(gholap): Right now, we are just checking whether GetSample
+//               gets samples and whether the stack depth is reasonable.
+//               After implementing code event listener API, add tests
+//               to further verify the correctness of collected samples.
+TEST(StackDepthIsConsistent) {
+  v8::Isolate* isolate = CcTest::isolate();
+  v8::HandleScope scope(isolate);
+  v8::Handle<v8::ObjectTemplate> global = v8::ObjectTemplate::New(isolate);
+  global->Set(
+    v8::String::NewFromUtf8(isolate, "SignalAndWaitForSampler"),
+    v8::FunctionTemplate::New(isolate, SamplerTester::SignalAndWaitForSampler));
+
+  LocalContext env(isolate, NULL, global);
+  Local<v8::Script> script = v8::Script::Compile(
+    v8::String::NewFromUtf8(isolate, sampler_api_test_source));
+  SamplerThread* sampler = new SamplerThread(isolate);

[Benedikt Meurer, 2014/08/27 04:17:23]

You leak the SamplerThread in this method. Just allocate it on the stack, i.e.

SamplerThread sampler(isolate);
sampler.Start();
script->Run();
sampler.Join();

[gholap, 2014/08/27 21:48:09]

Oops. Damn :(
Done.

+
+  sampler->Start();
+  script->Run();
+  sampler->Stop();
+
+  CHECK_EQ(8, sampler->sampleStackSize);

[Benedikt Meurer, 2014/08/27 04:17:23]

Remove this CHECK_EQ here.

[gholap, 2014/08/27 21:48:09]

Yes, removed all CHECK_* logic from the Run method and put it here instead.

+}