// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "gin/public/v8_platform.h"

#include <algorithm>

#include "base/bind.h"
#include "base/debug/stack_trace.h"
#include "base/location.h"
#include "base/sys_info.h"
#include "base/task_scheduler/post_task.h"
#include "base/task_scheduler/task_scheduler.h"
#include "base/trace_event/trace_event.h"
#include "gin/per_isolate_data.h"

namespace gin {

namespace {

constexpr base::TaskTraits kBackgroundThreadTaskTraits = {
    base::TaskPriority::USER_VISIBLE};

base::LazyInstance<V8Platform>::Leaky g_v8_platform = LAZY_INSTANCE_INITIALIZER;

void RunWithLocker(v8::Isolate* isolate, v8::Task* task) {
  v8::Locker lock(isolate);
  task->Run();
}

class IdleTaskWithLocker : public v8::IdleTask {
 public:
  IdleTaskWithLocker(v8::Isolate* isolate, v8::IdleTask* task)
      : isolate_(isolate), task_(task) {}

  ~IdleTaskWithLocker() override = default;

  // v8::IdleTask implementation.
  void Run(double deadline_in_seconds) override {
    v8::Locker lock(isolate_);
    task_->Run(deadline_in_seconds);
  }

 private:
  v8::Isolate* isolate_;
  std::unique_ptr<v8::IdleTask> task_;

  DISALLOW_COPY_AND_ASSIGN(IdleTaskWithLocker);
};

void PrintStackTrace() {
  base::debug::StackTrace trace;
  trace.Print();
}

class ConvertableToTraceFormatWrapper final
    : public base::trace_event::ConvertableToTraceFormat {
 public:
  explicit ConvertableToTraceFormatWrapper(
      std::unique_ptr<v8::ConvertableToTraceFormat>& inner)
      : inner_(std::move(inner)) {}
  ~ConvertableToTraceFormatWrapper() override = default;
  void AppendAsTraceFormat(std::string* out) const final {
    inner_->AppendAsTraceFormat(out);
  }

 private:
  std::unique_ptr<v8::ConvertableToTraceFormat> inner_;

  DISALLOW_COPY_AND_ASSIGN(ConvertableToTraceFormatWrapper);
};

class EnabledStateObserverImpl final
    : public base::trace_event::TraceLog::EnabledStateObserver {
 public:
  EnabledStateObserverImpl() = default;

  void OnTraceLogEnabled() final {
    base::AutoLock lock(mutex_);
    for (auto* o : observers_) {
      o->OnTraceEnabled();
    }
  }

  void OnTraceLogDisabled() final {
    base::AutoLock lock(mutex_);
    for (auto* o : observers_) {
      o->OnTraceDisabled();
    }
  }

  void AddObserver(v8::TracingController::TraceStateObserver* observer) {
    {
      base::AutoLock lock(mutex_);
      DCHECK(!observers_.count(observer));
      if (observers_.empty()) {
        base::trace_event::TraceLog::GetInstance()->AddEnabledStateObserver(
            this);
      }
      observers_.insert(observer);
    }
    // Fire the observer if recording is already in progress.
    if (base::trace_event::TraceLog::GetInstance()->IsEnabled())
      observer->OnTraceEnabled();
  }

  void RemoveObserver(v8::TracingController::TraceStateObserver* observer) {
    base::AutoLock lock(mutex_);
    DCHECK(observers_.count(observer) == 1);
    observers_.erase(observer);
    if (observers_.empty()) {
      base::trace_event::TraceLog::GetInstance()->RemoveEnabledStateObserver(
          this);
    }
  }

 private:
  base::Lock mutex_;
  std::unordered_set<v8::TracingController::TraceStateObserver*> observers_;

  DISALLOW_COPY_AND_ASSIGN(EnabledStateObserverImpl);
};

base::LazyInstance<EnabledStateObserverImpl>::Leaky g_trace_state_dispatcher =
    LAZY_INSTANCE_INITIALIZER;

}  // namespace

class V8Platform::TracingControllerImpl : public v8::TracingController {
 public:
  TracingControllerImpl() = default;
  ~TracingControllerImpl() override = default;

  // TracingController implementation.
  const uint8_t* GetCategoryGroupEnabled(const char* name) override {
    return TRACE_EVENT_API_GET_CATEGORY_GROUP_ENABLED(name);
  }
  uint64_t AddTraceEvent(
      char phase,
      const uint8_t* category_enabled_flag,
      const char* name,
      const char* scope,
      uint64_t id,
      uint64_t bind_id,
      int32_t num_args,
      const char** arg_names,
      const uint8_t* arg_types,
      const uint64_t* arg_values,
      std::unique_ptr<v8::ConvertableToTraceFormat>* arg_convertables,
      unsigned int flags) override {
    std::unique_ptr<base::trace_event::ConvertableToTraceFormat>
        convertables[2];
    if (num_args > 0 && arg_types[0] == TRACE_VALUE_TYPE_CONVERTABLE) {
      convertables[0].reset(
          new ConvertableToTraceFormatWrapper(arg_convertables[0]));
    }
    if (num_args > 1 && arg_types[1] == TRACE_VALUE_TYPE_CONVERTABLE) {
      convertables[1].reset(
          new ConvertableToTraceFormatWrapper(arg_convertables[1]));
    }
    DCHECK_LE(num_args, 2);
    base::trace_event::TraceEventHandle handle =
        TRACE_EVENT_API_ADD_TRACE_EVENT_WITH_BIND_ID(
            phase, category_enabled_flag, name, scope, id, bind_id, num_args,
            arg_names, arg_types, (const long long unsigned int*)arg_values,
            convertables, flags);
    uint64_t result;
    memcpy(&result, &handle, sizeof(result));
    return result;
  }
  void UpdateTraceEventDuration(const uint8_t* category_enabled_flag,
                                const char* name,
                                uint64_t handle) override {
    base::trace_event::TraceEventHandle traceEventHandle;
    memcpy(&traceEventHandle, &handle, sizeof(handle));
    TRACE_EVENT_API_UPDATE_TRACE_EVENT_DURATION(category_enabled_flag, name,
                                                traceEventHandle);
  }
  void AddTraceStateObserver(TraceStateObserver* observer) override {
    g_trace_state_dispatcher.Get().AddObserver(observer);
  }
  void RemoveTraceStateObserver(TraceStateObserver* observer) override {
    g_trace_state_dispatcher.Get().RemoveObserver(observer);
  }

 private:
  DISALLOW_COPY_AND_ASSIGN(TracingControllerImpl);
};

// static
V8Platform* V8Platform::Get() { return g_v8_platform.Pointer(); }

V8Platform::V8Platform() : tracing_controller_(new TracingControllerImpl) {}

V8Platform::~V8Platform() {}

size_t V8Platform::NumberOfAvailableBackgroundThreads() {
  return std::max(1, base::TaskScheduler::GetInstance()
                         ->GetMaxConcurrentTasksWithTraitsDeprecated(
                             kBackgroundThreadTaskTraits));
}

void V8Platform::CallOnBackgroundThread(
    v8::Task* task,
    v8::Platform::ExpectedRuntime expected_runtime) {
  base::PostTaskWithTraits(FROM_HERE, kBackgroundThreadTaskTraits,
                           base::Bind(&v8::Task::Run, base::Owned(task)));
}

void V8Platform::CallOnForegroundThread(v8::Isolate* isolate, v8::Task* task) {
  PerIsolateData* data = PerIsolateData::From(isolate);
  if (data->access_mode() == IsolateHolder::kUseLocker) {
    data->task_runner()->PostTask(
        FROM_HERE, base::Bind(RunWithLocker, base::Unretained(isolate),
                              base::Owned(task)));
  } else {
    data->task_runner()->PostTask(
        FROM_HERE, base::Bind(&v8::Task::Run, base::Owned(task)));
  }
}

void V8Platform::CallDelayedOnForegroundThread(v8::Isolate* isolate,
                                               v8::Task* task,
                                               double delay_in_seconds) {
  PerIsolateData* data = PerIsolateData::From(isolate);
  if (data->access_mode() == IsolateHolder::kUseLocker) {
    data->task_runner()->PostDelayedTask(
        FROM_HERE,
        base::Bind(RunWithLocker, base::Unretained(isolate), base::Owned(task)),
        base::TimeDelta::FromSecondsD(delay_in_seconds));
  } else {
    data->task_runner()->PostDelayedTask(
        FROM_HERE, base::Bind(&v8::Task::Run, base::Owned(task)),
        base::TimeDelta::FromSecondsD(delay_in_seconds));
  }
}

void V8Platform::CallIdleOnForegroundThread(v8::Isolate* isolate,
                                            v8::IdleTask* task) {
  PerIsolateData* data = PerIsolateData::From(isolate);
  DCHECK(data->idle_task_runner());
  if (data->access_mode() == IsolateHolder::kUseLocker) {
    data->idle_task_runner()->PostIdleTask(
        new IdleTaskWithLocker(isolate, task));
  } else {
    data->idle_task_runner()->PostIdleTask(task);
  }
}

bool V8Platform::IdleTasksEnabled(v8::Isolate* isolate) {
  return PerIsolateData::From(isolate)->idle_task_runner() != nullptr;
}

double V8Platform::MonotonicallyIncreasingTime() {
  return base::TimeTicks::Now().ToInternalValue() /
      static_cast<double>(base::Time::kMicrosecondsPerSecond);
}

v8::TracingController* V8Platform::GetTracingController() {
  return tracing_controller_.get();
}

v8::Platform::StackTracePrinter V8Platform::GetStackTracePrinter() {
  return PrintStackTrace;
}

}  // namespace gin