platform_thread_internal_posix.h

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// Copyright 2015 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.

#ifndef BASE_THREADING_PLATFORM_THREAD_INTERNAL_POSIX_H_

#define BASE_THREADING_PLATFORM_THREAD_INTERNAL_POSIX_H_

#include "base/base_export.h"

#include "base/optional.h"

#include "base/threading/platform_thread.h"

#include "build/build_config.h"

namespace base {

namespace internal {

struct ThreadPriorityToNiceValuePair {

  ThreadPriority priority;

  int nice_value;

};

// The elements must be listed in the order of increasing priority (lowest

// priority first), that is, in the order of decreasing nice values (highest

// nice value first).

BASE_EXPORT extern

const ThreadPriorityToNiceValuePair kThreadPriorityToNiceValueMap[4];

// Returns the nice value matching |priority| based on the platform-specific

// implementation of kThreadPriorityToNiceValueMap.

int ThreadPriorityToNiceValue(ThreadPriority priority);

// Returns the ThreadPrioirty matching |nice_value| based on the platform-

// specific implementation of kThreadPriorityToNiceValueMap.

BASE_EXPORT ThreadPriority NiceValueToThreadPriority(int nice_value);

// If non-nullopt, this return value will be used as the platform-specific

// result of CanIncreaseThreadPriority().

Optional<bool> CanIncreaseCurrentThreadPriorityForPlatform(

    ThreadPriority priority);

// Allows platform specific tweaks to the generic POSIX solution for

// SetCurrentThreadPriority(). Returns true if the platform-specific

// implementation handled this |priority| change, false if the generic

// implementation should instead proceed.

bool SetCurrentThreadPriorityForPlatform(ThreadPriority priority);

// If non-null, this return value will be used as the platform-specific result

// of CanIncreaseThreadPriority().

Optional<ThreadPriority> GetCurrentThreadPriorityForPlatform();

#if defined(OS_LINUX)

// Current thread id is cached in thread local storage for performance reasons.

// In some rare cases it's important to clear that cache explicitly (e.g. after

// going through clone() syscall which does not call pthread_atfork()

// handlers).

BASE_EXPORT void ClearTidCache();

#endif  // defined(OS_LINUX)

}  // namespace internal

}  // namespace base

#endif  // BASE_THREADING_PLATFORM_THREAD_INTERNAL_POSIX_H_