Edit: /usr/include/oneapi/tbb/queuing_rw_mutex.h (6631B)
/*
Copyright (c) 2005-2021 Intel Corporation
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
#ifndef __TBB_queuing_rw_mutex_H
#define __TBB_queuing_rw_mutex_H
#include "detail/_config.h"
#include "detail/_namespace_injection.h"
#include "detail/_assert.h"
#include "detail/_mutex_common.h"
#include "profiling.h"
#include
#include
namespace tbb {
namespace detail {
namespace r1 {
struct queuing_rw_mutex_impl;
}
namespace d1 {
//! Queuing reader-writer mutex with local-only spinning.
/** Adapted from Krieger, Stumm, et al. pseudocode at
https://www.researchgate.net/publication/221083709_A_Fair_Fast_Scalable_Reader-Writer_Lock
@ingroup synchronization */
class queuing_rw_mutex {
friend r1::queuing_rw_mutex_impl;
public:
//! Construct unacquired mutex.
queuing_rw_mutex() noexcept {
create_itt_sync(this, "tbb::queuing_rw_mutex", "");
}
//! Destructor asserts if the mutex is acquired, i.e. q_tail is non-NULL
~queuing_rw_mutex() {
__TBB_ASSERT(q_tail.load(std::memory_order_relaxed) == nullptr, "destruction of an acquired mutex");
}
//! No Copy
queuing_rw_mutex(const queuing_rw_mutex&) = delete;
queuing_rw_mutex& operator=(const queuing_rw_mutex&) = delete;
//! The scoped locking pattern
/** It helps to avoid the common problem of forgetting to release lock.
It also nicely provides the "node" for queuing locks. */
class scoped_lock {
friend r1::queuing_rw_mutex_impl;
//! Initialize fields to mean "no lock held".
void initialize() {
my_mutex = nullptr;
my_internal_lock.store(0, std::memory_order_relaxed);
my_going.store(0, std::memory_order_relaxed);
#if TBB_USE_ASSERT
my_state = 0xFF; // Set to invalid state
my_next.store(reinterpret_cast(reinterpret_cast(-1)), std::memory_order_relaxed);
my_prev.store(reinterpret_cast(reinterpret_cast(-1)), std::memory_order_relaxed);
#endif /* TBB_USE_ASSERT */
}
public:
//! Construct lock that has not acquired a mutex.
/** Equivalent to zero-initialization of *this. */
scoped_lock() {initialize();}
//! Acquire lock on given mutex.
scoped_lock( queuing_rw_mutex& m, bool write=true ) {
initialize();
acquire(m,write);
}
//! Release lock (if lock is held).
~scoped_lock() {
if( my_mutex ) release();
}
//! No Copy
scoped_lock(const scoped_lock&) = delete;
scoped_lock& operator=(const scoped_lock&) = delete;
//! Acquire lock on given mutex.
void acquire( queuing_rw_mutex& m, bool write=true );
//! Acquire lock on given mutex if free (i.e. non-blocking)
bool try_acquire( queuing_rw_mutex& m, bool write=true );
//! Release lock.
void release();
//! Upgrade reader to become a writer.
/** Returns whether the upgrade happened without releasing and re-acquiring the lock */
bool upgrade_to_writer();
//! Downgrade writer to become a reader.
bool downgrade_to_reader();
bool is_writer() const;
private:
//! The pointer to the mutex owned, or NULL if not holding a mutex.
queuing_rw_mutex* my_mutex;
//! The 'pointer' to the previous and next competitors for a mutex
std::atomic my_prev;
std::atomic my_next;
using state_t = unsigned char ;
//! State of the request: reader, writer, active reader, other service states
std::atomic my_state;
//! The local spin-wait variable
/** Corresponds to "spin" in the pseudocode but inverted for the sake of zero-initialization */
std::atomic my_going;
//! A tiny internal lock
std::atomic my_internal_lock;
};
// Mutex traits
static constexpr bool is_rw_mutex = true;
static constexpr bool is_recursive_mutex = false;
static constexpr bool is_fair_mutex = true;
private:
//! The last competitor requesting the lock
std::atomic q_tail{nullptr};
};
#if TBB_USE_PROFILING_TOOLS
inline void set_name(queuing_rw_mutex& obj, const char* name) {
itt_set_sync_name(&obj, name);
}
#if (_WIN32||_WIN64)
inline void set_name(queuing_rw_mutex& obj, const wchar_t* name) {
itt_set_sync_name(&obj, name);
}
#endif //WIN
#else
inline void set_name(queuing_rw_mutex&, const char*) {}
#if (_WIN32||_WIN64)
inline void set_name(queuing_rw_mutex&, const wchar_t*) {}
#endif //WIN
#endif
} // namespace d1
namespace r1 {
TBB_EXPORT void acquire(d1::queuing_rw_mutex&, d1::queuing_rw_mutex::scoped_lock&, bool);
TBB_EXPORT bool try_acquire(d1::queuing_rw_mutex&, d1::queuing_rw_mutex::scoped_lock&, bool);
TBB_EXPORT void release(d1::queuing_rw_mutex::scoped_lock&);
TBB_EXPORT bool upgrade_to_writer(d1::queuing_rw_mutex::scoped_lock&);
TBB_EXPORT bool downgrade_to_reader(d1::queuing_rw_mutex::scoped_lock&);
TBB_EXPORT bool is_writer(const d1::queuing_rw_mutex::scoped_lock&);
} // namespace r1
namespace d1 {
inline void queuing_rw_mutex::scoped_lock::acquire(queuing_rw_mutex& m,bool write) {
r1::acquire(m, *this, write);
}
inline bool queuing_rw_mutex::scoped_lock::try_acquire(queuing_rw_mutex& m, bool write) {
return r1::try_acquire(m, *this, write);
}
inline void queuing_rw_mutex::scoped_lock::release() {
r1::release(*this);
}
inline bool queuing_rw_mutex::scoped_lock::upgrade_to_writer() {
return r1::upgrade_to_writer(*this);
}
inline bool queuing_rw_mutex::scoped_lock::downgrade_to_reader() {
return r1::downgrade_to_reader(*this);
}
inline bool queuing_rw_mutex::scoped_lock::is_writer() const {
return r1::is_writer(*this);
}
} // namespace d1
} // namespace detail
inline namespace v1 {
using detail::d1::queuing_rw_mutex;
} // namespace v1
namespace profiling {
using detail::d1::set_name;
}
} // namespace tbb
#endif /* __TBB_queuing_rw_mutex_H */