85 lines
3.3 KiB
C
85 lines
3.3 KiB
C
|
// Copyright 2019 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_SCOPED_THREAD_PRIORITY_H_
|
||
|
|
#define BASE_THREADING_SCOPED_THREAD_PRIORITY_H_
|
||
|
|
|
||
|
|
#include "base/base_export.h"
|
||
|
|
#include "base/compiler_specific.h"
|
||
|
|
#include "base/location.h"
|
||
|
|
#include "base/macros.h"
|
||
|
|
#include "base/optional.h"
|
||
|
|
#include "build/build_config.h"
|
||
|
|
|
||
|
|
namespace base {
|
||
|
|
|
||
|
|
class Location;
|
||
|
|
enum class ThreadPriority : int;
|
||
|
|
|
||
|
|
// INTERNAL_SCOPED_THREAD_PRIORITY_APPEND_LINE(name) produces an identifier by
|
||
|
|
// appending the current line number to |name|. This is used to avoid name
|
||
|
|
// collisions from variables defined inside a macro.
|
||
|
|
#define INTERNAL_SCOPED_THREAD_PRIORITY_CONCAT(a, b) a##b
|
||
|
|
// CONCAT1 provides extra level of indirection so that __LINE__ macro expands.
|
||
|
|
#define INTERNAL_SCOPED_THREAD_PRIORITY_CONCAT1(a, b) \
|
||
|
|
INTERNAL_SCOPED_THREAD_PRIORITY_CONCAT(a, b)
|
||
|
|
#define INTERNAL_SCOPED_THREAD_PRIORITY_APPEND_LINE(name) \
|
||
|
|
INTERNAL_SCOPED_THREAD_PRIORITY_CONCAT1(name, __LINE__)
|
||
|
|
|
||
|
|
// All code that may load a DLL on a background thread must be surrounded by a
|
||
|
|
// scope that starts with this macro.
|
||
|
|
//
|
||
|
|
// Example:
|
||
|
|
// Foo();
|
||
|
|
// {
|
||
|
|
// SCOPED_MAY_LOAD_LIBRARY_AT_BACKGROUND_PRIORITY();
|
||
|
|
// LoadMyDll();
|
||
|
|
// }
|
||
|
|
// Bar();
|
||
|
|
//
|
||
|
|
// The macro raises the thread priority to NORMAL for the scope when first
|
||
|
|
// encountered. On Windows, loading a DLL on a background thread can lead to a
|
||
|
|
// priority inversion on the loader lock and cause huge janks.
|
||
|
|
#define SCOPED_MAY_LOAD_LIBRARY_AT_BACKGROUND_PRIORITY() \
|
||
|
|
base::internal::ScopedMayLoadLibraryAtBackgroundPriority \
|
||
|
|
INTERNAL_SCOPED_THREAD_PRIORITY_APPEND_LINE( \
|
||
|
|
scoped_may_load_library_at_background_priority)(FROM_HERE); \
|
||
|
|
{ \
|
||
|
|
/* Thread-safe static local variable initialization ensures that */ \
|
||
|
|
/* OnScopeFirstEntered() is only invoked the first time that this is */ \
|
||
|
|
/* encountered. */ \
|
||
|
|
static bool INTERNAL_SCOPED_THREAD_PRIORITY_APPEND_LINE(invoke_once) = \
|
||
|
|
INTERNAL_SCOPED_THREAD_PRIORITY_APPEND_LINE( \
|
||
|
|
scoped_may_load_library_at_background_priority) \
|
||
|
|
.OnScopeFirstEntered(); \
|
||
|
|
ALLOW_UNUSED_LOCAL( \
|
||
|
|
INTERNAL_SCOPED_THREAD_PRIORITY_APPEND_LINE(invoke_once)); \
|
||
|
|
}
|
||
|
|
|
||
|
|
namespace internal {
|
||
|
|
|
||
|
|
class BASE_EXPORT ScopedMayLoadLibraryAtBackgroundPriority {
|
||
|
|
public:
|
||
|
|
explicit ScopedMayLoadLibraryAtBackgroundPriority(const Location& from_here);
|
||
|
|
~ScopedMayLoadLibraryAtBackgroundPriority();
|
||
|
|
|
||
|
|
// The SCOPED_MAY_LOAD_LIBRARY_AT_BACKGROUND_PRIORITY() macro invokes this the
|
||
|
|
// first time that it is encountered.
|
||
|
|
bool OnScopeFirstEntered();
|
||
|
|
|
||
|
|
private:
|
||
|
|
#if defined(OS_WIN)
|
||
|
|
// The original priority when invoking OnScopeFirstEntered().
|
||
|
|
base::Optional<ThreadPriority> original_thread_priority_;
|
||
|
|
#endif
|
||
|
|
|
||
|
|
DISALLOW_COPY_AND_ASSIGN(ScopedMayLoadLibraryAtBackgroundPriority);
|
||
|
|
};
|
||
|
|
|
||
|
|
} // namespace internal
|
||
|
|
|
||
|
|
} // namespace base
|
||
|
|
|
||
|
|
#endif // BASE_THREADING_SCOPED_THREAD_PRIORITY_H_
|