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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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// The above copyright notice and this permission notice shall be included in
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// 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:
