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//
// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2022
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
#pragma once
#include "td/utils/port/config.h"
#include "td/utils/common.h"
#include "td/utils/Status.h"
#if TD_PORT_POSIX
#include <pthread.h>
#endif
#if TD_PORT_WINDOWS
union winlock_t {
struct {
long volatile readerCount;
long volatile writerCount;
};
SRWLOCK rwlock;
};
#endif
#include <memory>
namespace td {
class RwMutex {
public:
RwMutex() {
init();
}
RwMutex(const RwMutex &) = delete;
RwMutex &operator=(const RwMutex &) = delete;
RwMutex(RwMutex &&other) noexcept {
init();
other.clear();
}
RwMutex &operator=(RwMutex &&other) noexcept {
other.clear();
return *this;
}
~RwMutex() {
clear();
}
bool empty() const {
return !is_valid_;
}
void init();
void clear();
struct ReadUnlock {
void operator()(RwMutex *ptr) {
ptr->unlock_read_unsafe();
}
};
struct WriteUnlock {
void operator()(RwMutex *ptr) {
ptr->unlock_write_unsafe();
}
};
using ReadLock = std::unique_ptr<RwMutex, ReadUnlock>;
using WriteLock = std::unique_ptr<RwMutex, WriteUnlock>;
Result<ReadLock> lock_read() TD_WARN_UNUSED_RESULT {
lock_read_unsafe();
return ReadLock(this);
}
Result<WriteLock> lock_write() TD_WARN_UNUSED_RESULT {
lock_write_unsafe();
return WriteLock(this);
}
void lock_read_unsafe();
void lock_write_unsafe();
void unlock_read_unsafe();
void unlock_write_unsafe();
private:
bool is_valid_ = false;
#if TD_PORT_POSIX
pthread_rwlock_t mutex_;
#elif TD_PORT_WINDOWS
winlock_t mutex_;
#endif
};
void InitializeLock(winlock_t&);
void AcquireLockShared(winlock_t&);
void AcquireLockExclusive(winlock_t&);
void ReleaseLockShared(winlock_t&);
void ReleaseLockExclusive(winlock_t&);
inline void RwMutex::init() {
CHECK(empty());
is_valid_ = true;
#if TD_PORT_POSIX
pthread_rwlock_init(&mutex_, nullptr);
#elif TD_PORT_WINDOWS
InitializeLock(mutex_);
#endif
}
inline void RwMutex::clear() {
if (is_valid_) {
#if TD_PORT_POSIX
pthread_rwlock_destroy(&mutex_);
#endif
is_valid_ = false;
}
}
inline void RwMutex::lock_read_unsafe() {
CHECK(!empty());
// TODO error handling
#if TD_PORT_POSIX
pthread_rwlock_rdlock(&mutex_);
#elif TD_PORT_WINDOWS
AcquireLockShared(mutex_);
#endif
}
inline void RwMutex::lock_write_unsafe() {
CHECK(!empty());
#if TD_PORT_POSIX
pthread_rwlock_wrlock(&mutex_);
#elif TD_PORT_WINDOWS
AcquireLockExclusive(mutex_);
#endif
}
inline void RwMutex::unlock_read_unsafe() {
CHECK(!empty());
#if TD_PORT_POSIX
pthread_rwlock_unlock(&mutex_);
#elif TD_PORT_WINDOWS
ReleaseLockShared(mutex_);
#endif
}
inline void RwMutex::unlock_write_unsafe() {
CHECK(!empty());
#if TD_PORT_POSIX
pthread_rwlock_unlock(&mutex_);
#elif TD_PORT_WINDOWS
ReleaseLockExclusive(mutex_);
#endif
}
} // namespace td
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