chromium/base/sequence_token.h

// Copyright 2016 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef BASE_SEQUENCE_TOKEN_H_
#define BASE_SEQUENCE_TOKEN_H_

// TODO: Remove this unused include once no other file indirectly depends on it.
#include "base/auto_reset.h"
#include "base/base_export.h"

namespace base {
namespace internal {

// A token that identifies a series of sequenced work items (i.e. tasks, native
// message handlers, code blocks running outside or a `RunLoop`, etc. that are
// mutually exclusive).
class BASE_EXPORT SequenceToken { … };

// A token that identifies a task.
//
// This is used by ThreadCheckerImpl to determine whether calls to
// CalledOnValidThread() come from the same task and hence are deterministically
// single-threaded (vs. calls coming from different sequenced or parallel tasks,
// which may or may not run on the same thread).
class BASE_EXPORT TaskToken { … };

// Returns true if a thread checker bound in a different task than the current
// one but on the same sequence and thread may return true from
// `CalledOnValidSequence()`.
bool BASE_EXPORT CurrentTaskIsThreadBound();

// Identifies a scope in which a task runs.
class BASE_EXPORT [[maybe_unused, nodiscard]] TaskScope { … };

}  // namespace internal

// Returns true if the current task is run synchronously by `RunOrPostTask()`.
bool BASE_EXPORT CurrentTaskIsRunningSynchronously();

}  // namespace base

#endif  // BASE_SEQUENCE_TOKEN_H_