// Copyright 2013 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef FLUTTER_RUNTIME_SKIA_CONCURRENT_EXECUTOR_H_
#define FLUTTER_RUNTIME_SKIA_CONCURRENT_EXECUTOR_H_

#include "flutter/fml/closure.h"
#include "flutter/fml/macros.h"
#include "third_party/skia/include/core/SkExecutor.h"

namespace flutter {

//------------------------------------------------------------------------------
/// @brief      An interface used by Skia to schedule work on engine managed
///             threads (usually workers in a concurrent message loop).
///
///             Skia may decide that certain workloads don't have thread
///             affinity and may be performed on a background thread. However,
///             Skia does not manage its own threads. So, it delegates the
///             scheduling of this work to the engine via this interface. The
///             engine has a dedicated pool of threads it uses for scheduling
///             background tasks that have no thread affinity. This thread
///             worker pool is held next to the process global Dart VM instance.
///             The Skia executor is wired up there as well.
///
class SkiaConcurrentExecutor : public SkExecutor {
 public:
  //----------------------------------------------------------------------------
  /// The callback invoked by the executor to schedule the given task onto an
  /// engine managed background thread.
  ///
  using OnWorkCallback = std::function<void(fml::closure work)>;

  //----------------------------------------------------------------------------
  /// @brief      Create a new instance of the executor.
  ///
  /// @param[in]  on_work  The work callback.
  ///
  SkiaConcurrentExecutor(const OnWorkCallback& on_work);

  // |SkExecutor|
  ~SkiaConcurrentExecutor() override;

  // |SkExecutor|
  void add(fml::closure work) override;

 private:
  OnWorkCallback on_work_;

  FML_DISALLOW_COPY_AND_ASSIGN(SkiaConcurrentExecutor);
};

}  // namespace flutter

#endif  // FLUTTER_RUNTIME_SKIA_CONCURRENT_EXECUTOR_H_