task-handle.h

Go to the documentation of this file.

// Copyright 2020 the V8 project 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 V8_HEAP_CPPGC_TASK_HANDLE_H_
#define V8_HEAP_CPPGC_TASK_HANDLE_H_
 
#include <memory>
 
#include "src/base/logging.h"
 
namespace cppgc {
namespace internal {
 
// A handle that is used for cancelling individual tasks.
struct SingleThreadedHandle {
  struct NonEmptyTag {};
 
  // Default construction results in empty handle.
  SingleThreadedHandle() = default;
 
  explicit SingleThreadedHandle(NonEmptyTag)
      : is_cancelled_(std::make_shared<bool>(false)) {}
 
  void Cancel() {
    DCHECK(is_cancelled_);
    *is_cancelled_ = true;
  }
 
  void CancelIfNonEmpty() {
    if (is_cancelled_) {
      *is_cancelled_ = true;
    }
  }
 
  bool IsCanceled() const {
    DCHECK(is_cancelled_);
    return *is_cancelled_;
  }
 
  // A handle is active if it is non-empty and not cancelled.
  explicit operator bool() const {
    return is_cancelled_.get() && !*is_cancelled_.get();
  }
 
 private:
  std::shared_ptr<bool> is_cancelled_;
};
 
}  // namespace internal
}  // namespace cppgc
 
#endif  // V8_HEAP_CPPGC_TASK_HANDLE_H_