锁-读写锁-Swift

实现一 pthread_mutex_t：

ReadWriteLock/Sources/ReadWriteLock at main · SomeRandomiOSDev/ReadWriteLock · GitHub

https://swiftpackageindex.com/reers/reerkit/1.0.39/documentation/reerkit/readwritelock/ 

//
//  Copyright © 2022 reers.
//
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//  of this software and associated documentation files (the "Software"), to deal
//  in the Software without restriction, including without limitation the rights
//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
//  copies of the Software, and to permit persons to whom the Software is
//  furnished to do so, subject to the following conditions:
//
//  The above copyright notice and this permission notice shall be included in
//  all copies or substantial portions of the Software.
//
//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
//  THE SOFTWARE.#if canImport(Darwin)
import Darwin/// ReerKit: Represents a reader-writer lock. Note that this implementation is not recursive.
public final class ReadWriteLock {private var readMutex = pthread_mutex_t()private var writeMutex = pthread_mutex_t()private var readCount: UInt = 0public init() {pthread_mutex_init(&readMutex, nil)pthread_mutex_init(&writeMutex, nil)}deinit {pthread_mutex_destroy(&readMutex)pthread_mutex_destroy(&writeMutex)}public func readLock() {pthread_mutex_lock(&readMutex)defer { pthread_mutex_unlock(&readMutex) }if readCount == 0 {pthread_mutex_lock(&writeMutex)}readCount += 1}/// ReerKit: Returns true if the lock was succesfully locked and false if the lock was already locked.@discardableResultpublic func tryReadLock() -> Bool {pthread_mutex_lock(&readMutex)defer { pthread_mutex_unlock(&readMutex) }let success = (readCount == 0)? pthread_mutex_trylock(&writeMutex) == 0: trueif success {readCount += 1}return success}public func readUnlock() {pthread_mutex_lock(&readMutex)defer { pthread_mutex_unlock(&readMutex) }if readCount > 0 {readCount -= 1if readCount == 0 {pthread_mutex_unlock(&writeMutex)}}}public func writeLock() {pthread_mutex_lock(&writeMutex)}/// ReerKit: Returns true if the lock was succesfully locked and false if the lock was already locked.@discardableResultpublic func tryWriteLock() -> Bool {return pthread_mutex_trylock(&writeMutex) == 0}public func writeUnlock() {pthread_mutex_unlock(&writeMutex)}public func readAround<Result>(_ execute: () throws -> Result) rethrows -> Result {readLock()defer { readUnlock() }return try execute()}public func writeAround<Result>(_ execute: () throws -> Result) rethrows -> Result {writeLock()defer { writeUnlock() }return try execute()}
}#endif

实现二 NSLock：

class ReadWriteLockTT {private let readLock = NSLock()private let writeLock = NSLock()private var readersCount = 0func read() {readLock.lock()readersCount += 1if readersCount == 1 {writeLock.lock()}readLock.unlock()}func readUnlock() {readLock.lock()readersCount -= 1if readersCount == 0 {writeLock.unlock()}readLock.unlock()}func write() {writeLock.lock()}func writeUnlock() {writeLock.unlock()}func test() {let rwLock = ReadWriteLockTT()//        // 模拟多个读操作线程
//        DispatchQueue.concurrentPerform(iterations: 100) { _ in
//            rwLock.read()
//            // 这里执行读取共享资源的代码逻辑
//            print("执行读取操作")
//            rwLock.readUnlock()
//        }
//
//        // 模拟写操作线程
//        DispatchQueue.global().async {
//            rwLock.write()
//            // 这里执行写入共享资源的代码逻辑
//            print("执行写入操作")
//            rwLock.writeUnlock()
//        }var value = 0// 读线程DispatchQueue.global().async {for _ in 0..<20000 {
//                rwLock.read { value in
//                    print("Read value: \(value)")
//                }rwLock.read()// 这里执行读取共享资源的代码逻辑print("执行读取操作==\(value)")rwLock.readUnlock()}}// 写线程DispatchQueue.global().async {for i in 1...5 {sleep(1)  // 模拟写操作的延迟
//                rwLock.write(value: i)rwLock.write()// 这里执行写入共享资源的代码逻辑value += 1print("执行写入操作==\(value)")rwLock.writeUnlock()//                print("Written value: \(i)")}}DispatchQueue.global().asyncAfter(deadline: .now() + 200.0) {print("打印完成")}sleep(200)}
}

实现三 pthread_rwlock_t ：

swift-design-patterns/Concurrency Design Patterns/ReadWriteLock/ReadWriteLock.md at main · eleev/swift-design-patterns · GitHub

import Foundationclass ReadWriteLock {private var rwlock = pthread_rwlock_t()init() {pthread_rwlock_init(&rwlock, nil)}deinit {pthread_rwlock_destroy(&rwlock)}func read<T>(_ closure: () -> T) -> T {pthread_rwlock_rdlock(&rwlock)defer { pthread_rwlock_unlock(&rwlock) }return closure()}func write(_ closure: () -> Void) {pthread_rwlock_wrlock(&rwlock)defer { pthread_rwlock_unlock(&rwlock) }closure()}
}let readWriteLock = ReadWriteLock()// Reading data with a read lock
let data = readWriteLock.read { () -> Data in// Read shared data herereturn sharedData
}// Writing data with a write lock
readWriteLock.write {// Modify shared data heresharedData = newData
}

实现四 NSRecursiveLock 递归锁：

TODO: