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/*
* Copyright (C) 2021 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#pragma once
#include <atomic>
#include <utility>
#include <wtf/ThreadSafetyAnalysis.h>
namespace WTF {
class ThreadLikeAssertion;
WTF_EXPORT_PRIVATE bool isMainThread();
struct MainThreadLike {
constexpr operator uint32_t() const { return -3; }
};
inline constexpr MainThreadLike mainThreadLike;
struct CurrentThreadLike {
constexpr operator uint32_t() const { return static_cast<uint32_t>(-2); }
};
inline constexpr CurrentThreadLike currentThreadLike;
struct AnyThreadLike {
constexpr operator uint32_t() const { return static_cast<uint32_t>(-1); }
};
inline constexpr AnyThreadLike anyThreadLike;
struct NoneThreadLike {
constexpr operator uint32_t() const { return 0; }
};
inline constexpr NoneThreadLike noneThreadLike;
class ThreadLike {
public:
// Never returns 0.
WTF_EXPORT_PRIVATE static uint32_t currentSequence();
protected:
static constexpr uint32_t mainThreadID { 1 };
static std::atomic<uint32_t> s_uid;
static ThreadLikeAssertion createThreadLikeAssertion(uint32_t);
};
// A type to use for asserting that private member functions or private member variables
// of a class are accessed from correct threads.
// Supports run-time checking with assertion enabled builds.
// Supports compile-time declaration and checking.
// Example:
// struct MyClass {
// void doTask() { assertIsCurrent(m_ownerThread); doTaskImpl(); }
// template<typename> void doTaskCompileFailure() { doTaskImpl(); }
// private:
// void doTaskImpl() WTF_REQUIRES_CAPABILITY(m_ownerThread);
// int m_value WTF_GUARDED_BY_CAPABILITY(m_ownerThread) { 0 };
// NO_UNIQUE_ADDRESS ThreadLikeAssertion m_ownerThread;
// };
class WTF_CAPABILITY("is current") ThreadLikeAssertion {
public:
constexpr ThreadLikeAssertion(NoneThreadLike a)
: ThreadLikeAssertion(static_cast<uint32_t>(a))
{
}
constexpr ThreadLikeAssertion(AnyThreadLike a)
: ThreadLikeAssertion(static_cast<uint32_t>(a))
{
}
constexpr ThreadLikeAssertion(MainThreadLike a)
: ThreadLikeAssertion(static_cast<uint32_t>(a))
{
}
ThreadLikeAssertion(CurrentThreadLike = currentThreadLike);
ThreadLikeAssertion(ThreadLikeAssertion&&);
~ThreadLikeAssertion() { assertIsCurrent(*this); }
ThreadLikeAssertion(const ThreadLikeAssertion&) = default;
ThreadLikeAssertion& operator=(const ThreadLikeAssertion&) = default;
ThreadLikeAssertion& operator=(ThreadLikeAssertion&&);
void reset() { *this = currentThreadLike; }
bool isCurrent() const; // Public as used in API tests.
private:
constexpr ThreadLikeAssertion(uint32_t uid);
#if ASSERT_ENABLED
uint32_t m_uid;
#endif
friend void assertIsCurrent(const ThreadLikeAssertion&);
friend class ThreadLike;
};
inline ThreadLikeAssertion::ThreadLikeAssertion(CurrentThreadLike)
{
#if ASSERT_ENABLED
m_uid = isMainThread() ? mainThreadLike : ThreadLike::currentSequence();
#endif
}
inline ThreadLikeAssertion::ThreadLikeAssertion(ThreadLikeAssertion&& other)
{
*this = WTFMove(other);
}
inline ThreadLikeAssertion& ThreadLikeAssertion::operator=(ThreadLikeAssertion&& other)
{
#if ASSERT_ENABLED
m_uid = std::exchange(other.m_uid, anyThreadLike);
#else
UNUSED_PARAM(other);
#endif
return *this;
}
inline constexpr ThreadLikeAssertion::ThreadLikeAssertion(uint32_t uid)
#if ASSERT_ENABLED
: m_uid(uid)
#endif
{
#if !ASSERT_ENABLED
UNUSED_PARAM(uid);
#endif
}
inline bool ThreadLikeAssertion::isCurrent() const
{
#if ASSERT_ENABLED
if (m_uid == anyThreadLike)
return true;
if (m_uid == mainThreadLike)
return isMainThread();
return ThreadLike::currentSequence() == m_uid;
#else
return true;
#endif
}
inline void assertIsCurrent(const ThreadLikeAssertion& threadLikeAssertion) WTF_ASSERTS_ACQUIRED_CAPABILITY(threadLikeAssertion)
{
ASSERT_UNUSED(threadLikeAssertion, threadLikeAssertion.isCurrent());
}
inline ThreadLikeAssertion ThreadLike::createThreadLikeAssertion(uint32_t uid)
{
return ThreadLikeAssertion { uid };
}
// Type for globally named assertions for describing access requirements.
// Can be used, for example, to require that a variable is accessed only in
// a known named thread.
// Example:
// extern NamedAssertion& mainThread;
// inline void assertIsMainThread() WTF_ASSERTS_ACQUIRED_CAPABILITY(mainThread);
// void myTask() WTF_REQUIRES_CAPABILITY(mainThread) { printf("my task is running"); }
// void runner() {
// assertIsMainThread();
// myTask();
// }
// template<typename> runnerCompileFailure() {
// myTask();
// }
class WTF_CAPABILITY("is current") NamedAssertion { };
}
using WTF::anyThreadLike;
using WTF::AnyThreadLike;
using WTF::assertIsCurrent;
using WTF::currentThreadLike;
using WTF::CurrentThreadLike;
using WTF::mainThreadLike;
using WTF::MainThreadLike;
using WTF::NamedAssertion;
using WTF::noneThreadLike;
using WTF::NoneThreadLike;
using WTF::ThreadLike;
using WTF::ThreadLikeAssertion;
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