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base / threading / platform_thread_ref.h [blame]
// Copyright 2021 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// WARNING: *DO NOT* use this class directly. base::PlatformThreadRef is a
// low-level platform-specific abstraction to the OS's threading interface.
// Instead, consider using a message-loop driven base::Thread, see
// base/threading/thread.h.
#ifndef BASE_THREADING_PLATFORM_THREAD_REF_H_
#define BASE_THREADING_PLATFORM_THREAD_REF_H_
#include <iosfwd>
#include "base/base_export.h"
#include "build/build_config.h"
#if BUILDFLAG(IS_WIN)
#include "base/win/windows_types.h"
#elif BUILDFLAG(IS_POSIX) || BUILDFLAG(IS_FUCHSIA)
#include <pthread.h>
#endif
namespace base {
// Used for thread checking and debugging.
// Meant to be as fast as possible.
// These are produced by PlatformThread::CurrentRef(), and used to later
// check if we are on the same thread or not by using ==. These are safe
// to copy between threads, but can't be copied to another process as they
// have no meaning there. Also, the internal identifier can be re-used
// after a thread dies, so a PlatformThreadRef cannot be reliably used
// to distinguish a new thread from an old, dead thread.
class PlatformThreadRef {
public:
#if BUILDFLAG(IS_WIN)
using RefType = DWORD;
#elif BUILDFLAG(IS_POSIX) || BUILDFLAG(IS_FUCHSIA)
using RefType = pthread_t;
#endif
constexpr PlatformThreadRef() = default;
explicit constexpr PlatformThreadRef(RefType id) : id_(id) {}
bool operator==(PlatformThreadRef other) const { return id_ == other.id_; }
bool operator!=(PlatformThreadRef other) const { return id_ != other.id_; }
bool is_null() const { return id_ == 0; }
private:
friend BASE_EXPORT std::ostream& operator<<(std::ostream& os,
const PlatformThreadRef& ref);
RefType id_ = 0;
};
BASE_EXPORT std::ostream& operator<<(std::ostream& os,
const PlatformThreadRef& ref);
} // namespace base
#endif // BASE_THREADING_PLATFORM_THREAD_REF_H_