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// Copyright (C) 2016 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
// Qt-Security score:significant reason:default
#ifndef QREADWRITELOCK_H
#define QREADWRITELOCK_H
#include <QtCore/qglobal.h>
#include <QtCore/qdeadlinetimer.h>
#include <QtCore/qtsan_impl.h>
QT_BEGIN_NAMESPACE
#if QT_CONFIG(thread)
class QReadWriteLockPrivate;
class QBasicReadWriteLock
{
public:
constexpr QBasicReadWriteLock() = default;
void lockForRead()
{
tryLockForReadInternal(QDeadlineTimer::Forever, 0);
}
bool tryLockForRead()
{
return tryLockForReadInternal(QDeadlineTimer(), QtTsan::TryLock);
}
bool tryLockForRead(QDeadlineTimer timeout)
{
return tryLockForReadInternal(timeout, QtTsan::TryLock);
}
void lockForWrite()
{
tryLockForWriteInternal(QDeadlineTimer::Forever, 0);
}
bool tryLockForWrite()
{
return tryLockForWriteInternal(QDeadlineTimer(), QtTsan::TryLock);
}
bool tryLockForWrite(QDeadlineTimer timeout)
{
return tryLockForWriteInternal(timeout, QtTsan::TryLock);
}
void unlock()
{
QReadWriteLockPrivate *d = d_ptr.loadRelaxed();
unsigned flags = describeLockForTSan(d);
quintptr u = quintptr(d);
Q_ASSERT_X(u, "QReadWriteLock::unlock()", "Cannot unlock an unlocked lock");
QtTsan::mutexPreUnlock(this, flags);
if (u > StateMask || !d_ptr.testAndSetRelease(d, nullptr, d))
contendedUnlock(d);
QtTsan::mutexPostUnlock(this, flags);
}
// std::shared_mutex API:
void lock() { lockForWrite(); }
void lock_shared() { lockForRead(); }
bool try_lock() { return tryLockForWrite(); }
bool try_lock_shared() { return tryLockForRead(); }
void unlock_shared() { unlock(); }
protected:
static constexpr quintptr StateLockedForRead = 0x1;
static constexpr quintptr StateLockedForWrite = 0x2;
static constexpr quintptr StateMask = StateLockedForRead | StateLockedForWrite;
static constexpr quintptr Counter = 0x10;
Q_ALWAYS_INLINE bool fastTryLockForRead(QReadWriteLockPrivate *&d)
{
if (d == nullptr) {
auto dummyValue = reinterpret_cast<QReadWriteLockPrivate *>(StateLockedForRead);
return d_ptr.testAndSetAcquire(nullptr, dummyValue, d);
} else if (quintptr u = quintptr(d), v = u + Counter; u & StateLockedForRead) {
return d_ptr.testAndSetAcquire(d, reinterpret_cast<QReadWriteLockPrivate *>(v), d);
}
return false;
}
Q_ALWAYS_INLINE bool tryLockForReadInternal(QDeadlineTimer timeout, unsigned tsanFlags)
{
tsanFlags |= QtTsan::ReadLock;
QtTsan::mutexPreLock(this, tsanFlags);
QReadWriteLockPrivate *d = d_ptr.loadRelaxed();
bool locked = fastTryLockForRead(d);
if (!locked)
locked = contendedTryLockForRead(timeout, d);
if (!locked)
tsanFlags |= QtTsan::TryLockFailed;
QtTsan::mutexPostLock(this, tsanFlags, 0);
return locked;
}
Q_ALWAYS_INLINE bool fastTryLockForWrite(QReadWriteLockPrivate *&d)
{
auto dummyValue = reinterpret_cast<QReadWriteLockPrivate *>(StateLockedForWrite);
if (d == nullptr)
return d_ptr.testAndSetAcquire(nullptr, dummyValue, d);
return false;
}
Q_ALWAYS_INLINE bool tryLockForWriteInternal(QDeadlineTimer timeout, unsigned tsanFlags)
{
QtTsan::mutexPreLock(this, tsanFlags);
QReadWriteLockPrivate *d = d_ptr.loadRelaxed();
bool locked = fastTryLockForWrite(d);
if (!locked)
locked = contendedTryLockForWrite(timeout, d);
if (!locked)
tsanFlags |= QtTsan::TryLockFailed;
QtTsan::mutexPostLock(this, tsanFlags, 0);
return locked;
}
Q_CORE_EXPORT bool contendedTryLockForRead(QDeadlineTimer timeout, void *dd);
Q_CORE_EXPORT bool contendedTryLockForWrite(QDeadlineTimer timeout, void *dd);
Q_CORE_EXPORT void contendedUnlock(void *dd);
#if QT_CORE_REMOVED_SINCE(6, 12)
Q_CORE_EXPORT bool isContendedLockForRead(const void *dd) Q_DECL_PURE_FUNCTION;
#endif
static Q_CORE_EXPORT quintptr describeLockInternal(void *dd) noexcept Q_DECL_PURE_FUNCTION;
static uint describeLockForTSan(QReadWriteLockPrivate *d, uint flags = 0) noexcept
{
if constexpr (QtTsan::IsEnabled) {
if (describeLockInternal(d) & StateLockedForRead)
flags |= QtTsan::ReadLock;
}
return flags;
}
constexpr QBasicReadWriteLock(QReadWriteLockPrivate *d) noexcept : d_ptr(d)
{}
Q_DISABLE_COPY(QBasicReadWriteLock)
QAtomicPointer<QReadWriteLockPrivate> d_ptr = { nullptr };
friend class QReadWriteLockPrivate;
};
class QT6_ONLY(Q_CORE_EXPORT) QReadWriteLock : public QBasicReadWriteLock
{
public:
enum RecursionMode { NonRecursive, Recursive };
QT_CORE_INLINE_SINCE(6, 6)
explicit QReadWriteLock(RecursionMode recursionMode = NonRecursive);
QT_CORE_INLINE_SINCE(6, 6)
~QReadWriteLock();
#if QT_CORE_REMOVED_SINCE(6, 11) || defined(Q_QDOC)
// was: QT_CORE_INLINE_SINCE(6, 6)
void lockForRead();
bool tryLockForRead();
#endif
QT_CORE_INLINE_SINCE(6, 6)
bool tryLockForRead(int timeout);
#if QT_CORE_REMOVED_SINCE(6, 11) || defined(Q_QDOC)
bool tryLockForRead(QDeadlineTimer timeout = {});
#endif
using QBasicReadWriteLock::tryLockForRead;
#if QT_CORE_REMOVED_SINCE(6, 11) || defined(Q_QDOC)
// was: QT_CORE_INLINE_SINCE(6, 6)
void lockForWrite();
bool tryLockForWrite();
#endif
QT_CORE_INLINE_SINCE(6, 6)
bool tryLockForWrite(int timeout);
#if QT_CORE_REMOVED_SINCE(6, 11) || defined(Q_QDOC)
bool tryLockForWrite(QDeadlineTimer timeout = {});
#endif
using QBasicReadWriteLock::tryLockForWrite;
#if QT_CORE_REMOVED_SINCE(6, 11) || defined(Q_QDOC)
void unlock();
#endif
private:
#if QT_CORE_REMOVED_SINCE(6, 12)
static QReadWriteLockPrivate *initRecursive();
static void destroyRecursive(QReadWriteLockPrivate *);
#endif
QT7_ONLY(Q_CORE_EXPORT) static void *initRecursiveHelper();
QT7_ONLY(Q_CORE_EXPORT) static void destroyRecursiveHelper(void *) noexcept;
static QReadWriteLockPrivate *initRecursiveInline()
{
auto d = static_cast<QReadWriteLockPrivate *>(initRecursiveHelper());
Q_PRESUME(quintptr(d) > StateMask);
#ifdef QT_BUILDING_UNDER_TSAN
unsigned flags = __tsan_mutex_write_reentrant | __tsan_mutex_read_reentrant;
# if (defined(Q_CC_GNU_ONLY) && Q_CC_GNU >= 1200) || (defined(Q_CC_CLANG) && Q_CC_CLANG >= 1200)
flags |= __tsan_mutex_not_static;
# endif
__tsan_mutex_create(d, flags);
#endif
return d;
}
static void destroyRecursiveInline(QReadWriteLockPrivate *d)
{
#ifdef QT_BUILDING_UNDER_TSAN
unsigned flags = 0;
__tsan_mutex_destroy(d, flags);
#endif
destroyRecursiveHelper(d);
}
};
#if QT_CORE_INLINE_IMPL_SINCE(6, 6)
QReadWriteLock::QReadWriteLock(RecursionMode recursionMode)
: QBasicReadWriteLock(recursionMode == Recursive ? initRecursiveInline() : nullptr)
{
}
QReadWriteLock::~QReadWriteLock()
{
if (auto d = d_ptr.loadAcquire())
destroyRecursiveInline(d);
}
bool QReadWriteLock::tryLockForRead(int timeout)
{
return tryLockForRead(QDeadlineTimer(timeout));
}
bool QReadWriteLock::tryLockForWrite(int timeout)
{
return tryLockForWrite(QDeadlineTimer(timeout));
}
#endif // inline since 6.6
#if defined(Q_CC_MSVC)
#pragma warning( push )
#pragma warning( disable : 4312 ) // ignoring the warning from /Wp64
#endif
class QT6_ONLY(Q_CORE_EXPORT) QReadLocker
{
public:
Q_NODISCARD_CTOR
inline QReadLocker(QReadWriteLock *readWriteLock);
inline ~QReadLocker()
{ unlock(); }
inline void unlock()
{
if (q_val) {
if ((q_val & quintptr(1u)) == quintptr(1u)) {
q_val &= ~quintptr(1u);
readWriteLock()->unlock();
}
}
}
inline void relock()
{
if (q_val) {
if ((q_val & quintptr(1u)) == quintptr(0u)) {
readWriteLock()->lockForRead();
q_val |= quintptr(1u);
}
}
}
inline QReadWriteLock *readWriteLock() const
{ return reinterpret_cast<QReadWriteLock *>(q_val & ~quintptr(1u)); }
private:
Q_DISABLE_COPY(QReadLocker)
quintptr q_val;
};
inline QReadLocker::QReadLocker(QReadWriteLock *areadWriteLock)
: q_val(reinterpret_cast<quintptr>(areadWriteLock))
{
Q_ASSERT_X((q_val & quintptr(1u)) == quintptr(0),
"QReadLocker", "QReadWriteLock pointer is misaligned");
relock();
}
class QT6_ONLY(Q_CORE_EXPORT) QWriteLocker
{
public:
Q_NODISCARD_CTOR
inline QWriteLocker(QReadWriteLock *readWriteLock);
inline ~QWriteLocker()
{ unlock(); }
inline void unlock()
{
if (q_val) {
if ((q_val & quintptr(1u)) == quintptr(1u)) {
q_val &= ~quintptr(1u);
readWriteLock()->unlock();
}
}
}
inline void relock()
{
if (q_val) {
if ((q_val & quintptr(1u)) == quintptr(0u)) {
readWriteLock()->lockForWrite();
q_val |= quintptr(1u);
}
}
}
inline QReadWriteLock *readWriteLock() const
{ return reinterpret_cast<QReadWriteLock *>(q_val & ~quintptr(1u)); }
private:
Q_DISABLE_COPY(QWriteLocker)
quintptr q_val;
};
inline QWriteLocker::QWriteLocker(QReadWriteLock *areadWriteLock)
: q_val(reinterpret_cast<quintptr>(areadWriteLock))
{
Q_ASSERT_X((q_val & quintptr(1u)) == quintptr(0),
"QWriteLocker", "QReadWriteLock pointer is misaligned");
relock();
}
#if defined(Q_CC_MSVC)
#pragma warning( pop )
#endif
#else // QT_CONFIG(thread)
class QT6_ONLY(Q_CORE_EXPORT) QReadWriteLock
{
public:
enum RecursionMode { NonRecursive, Recursive };
inline explicit QReadWriteLock(RecursionMode = NonRecursive) noexcept { }
inline ~QReadWriteLock() { }
void lockForRead() noexcept { }
bool tryLockForRead() noexcept { return true; }
bool tryLockForRead(QDeadlineTimer) noexcept { return true; }
bool tryLockForRead(int timeout) noexcept { Q_UNUSED(timeout); return true; }
void lockForWrite() noexcept { }
bool tryLockForWrite() noexcept { return true; }
bool tryLockForWrite(QDeadlineTimer) noexcept { return true; }
bool tryLockForWrite(int timeout) noexcept { Q_UNUSED(timeout); return true; }
void unlock() noexcept { }
private:
Q_DISABLE_COPY(QReadWriteLock)
};
class QT6_ONLY(Q_CORE_EXPORT) QReadLocker
{
public:
Q_NODISCARD_CTOR
inline explicit QReadLocker(QReadWriteLock *) noexcept { }
inline ~QReadLocker() noexcept { }
void unlock() noexcept { }
void relock() noexcept { }
QReadWriteLock *readWriteLock() noexcept { return nullptr; }
private:
Q_DISABLE_COPY(QReadLocker)
};
class QT6_ONLY(Q_CORE_EXPORT) QWriteLocker
{
public:
Q_NODISCARD_CTOR
inline explicit QWriteLocker(QReadWriteLock *) noexcept { }
inline ~QWriteLocker() noexcept { }
void unlock() noexcept { }
void relock() noexcept { }
QReadWriteLock *readWriteLock() noexcept { return nullptr; }
private:
Q_DISABLE_COPY(QWriteLocker)
};
#endif // QT_CONFIG(thread)
QT_END_NAMESPACE
#endif // QREADWRITELOCK_H