text: // Copyright (c) 2014 GitHub, Inc.
  // Use of this source code is governed by the MIT license that can be
  // found in the LICENSE file.
  
  #include <set>
  #include <string>
  
  #include "atom/common/native_mate_converters/callback.h"
  #include "atom/common/native_mate_converters/file_path_converter.h"
  #include "atom/common/native_mate_converters/value_converter.h"
  #include "atom/common/promise_util.h"
  #include "base/bind.h"
  #include "base/files/file_util.h"
  #include "content/public/browser/tracing_controller.h"
  #include "native_mate/dictionary.h"
  
  #include "atom/common/node_includes.h"
  
  using content::TracingController;
  
  namespace mate {
  
  template <>
  struct Converter<base::trace_event::TraceConfig> {
    static bool FromV8(v8::Isolate* isolate,
                       v8::Local<v8::Value> val,
                       base::trace_event::TraceConfig* out) {
      // (alexeykuzmin): A combination of "categoryFilter" and "traceOptions"
      // has to be checked first because none of the fields
      // in the `memory_dump_config` dict below are mandatory
      // and we cannot check the config format.
      Dictionary options;
      if (ConvertFromV8(isolate, val, &options)) {
        std::string category_filter, trace_options;
        if (options.Get("categoryFilter", &category_filter) &&
            options.Get("traceOptions", &trace_options)) {
          *out = base::trace_event::TraceConfig(category_filter, trace_options);
          return true;
        }
      }
  
      base::DictionaryValue memory_dump_config;
      if (ConvertFromV8(isolate, val, &memory_dump_config)) {
        *out = base::trace_event::TraceConfig(memory_dump_config);
        return true;
      }
  
      return false;
    }
  };
  
  }  // namespace mate
  
  namespace {
  
  using CompletionCallback = base::Callback<void(const base::FilePath&)>;
  
  scoped_refptr<TracingController::TraceDataEndpoint> GetTraceDataEndpoint(
      const base::FilePath& path,
      const CompletionCallback& callback) {
    base::FilePath result_file_path = path;
    if (result_file_path.empty() && !base::CreateTemporaryFile(&result_file_path))
      LOG(ERROR) << "Creating temporary file failed";
  
    return TracingController::CreateFileEndpoint(
        result_file_path, base::Bind(callback, result_file_path));
  }
  
  void OnRecordingStopped(const atom::util::CopyablePromise& promise,
                          const base::FilePath& path) {
    promise.GetPromise().Resolve(path);
  }
  
  v8::Local<v8::Promise> StopRecording(v8::Isolate* isolate,
                                       const base::FilePath& path) {
    atom::util::Promise promise(isolate);
    v8::Local<v8::Promise> handle = promise.GetHandle();
  
    // TODO(zcbenz): Remove the use of CopyablePromise when the
    // CreateFileEndpoint API accepts OnceCallback.
    TracingController::GetInstance()->StopTracing(GetTraceDataEndpoint(
        path,
        base::Bind(&OnRecordingStopped, atom::util::CopyablePromise(promise))));
    return handle;
  }
  
  void OnCategoriesAvailable(atom::util::Promise promise,
                             const std::set<std::string>& categories) {
    promise.Resolve(categories);
  }
  
  v8::Local<v8::Promise> GetCategories(v8::Isolate* isolate) {
    atom::util::Promise promise(isolate);
    v8::Local<v8::Promise> handle = promise.GetHandle();
  
    // Note: This method always succeeds.
    TracingController::GetInstance()->GetCategories(
        base::BindOnce(&OnCategoriesAvailable, std::move(promise)));
    return handle;
  }
  
  void OnTracingStarted(atom::util::Promise promise) {
    promise.Resolve();
  }
  
  v8::Local<v8::Promise> StartTracing(
      v8::Isolate* isolate,
      const base::trace_event::TraceConfig& trace_config) {
    atom::util::Promise promise(isolate);
    v8::Local<v8::Promise> handle = promise.GetHandle();
  
    // Note: This method always succeeds.
    TracingController::GetInstance()->StartTracing(
        trace_config, base::BindOnce(&OnTracingStarted, std::move(promise)));
    return handle;
  }
  
  void OnTraceBufferUsageAvailable(atom::util::Promise promise,
                                   float percent_full,
                                   size_t approximate_count) {
    mate::Dictionary dict = mate::Dictionary::CreateEmpty(promise.isolate());
    dict.Set("percentage", percent_full);
    dict.Set("value", approximate_count);
  
    promise.Resolve(dict.GetHandle());
  }
  
  v8::Local<v8::Promise> GetTraceBufferUsage(v8::Isolate* isolate) {
    atom::util::Promise promise(isolate);
    v8::Local<v8::Promise> handle = promise.GetHandle();
  
    // Note: This method always succeeds.
    TracingController::GetInstance()->GetTraceBufferUsage(
        base::BindOnce(&OnTraceBufferUsageAvailable, std::move(promise)));
    return handle;
  }
  
  void Initialize(v8::Local<v8::Object> exports,
                  v8::Local<v8::Value> unused,
                  v8::Local<v8::Context> context,
                  void* priv) {
    mate::Dictionary dict(context->GetIsolate(), exports);
    dict.SetMethod("getCategories", &GetCategories);
    dict.SetMethod("startRecording", &StartTracing);
    dict.SetMethod("stopRecording", &StopRecording);
    dict.SetMethod("getTraceBufferUsage", &GetTraceBufferUsage);
  }
  
  }  // namespace
  
  NODE_BUILTIN_MODULE_CONTEXT_AWARE(atom_browser_content_tracing, Initialize)
  