Wrapper class with a simple API around a recursive pthread_mutex_t

ReentrantLock.swift

final class ReentrantLock {
    private var _lock: pthread_mutex_t
    
    init() {
        var attr = pthread_mutexattr_t()
        pthread_mutexattr_init(&attr)
        pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE)
        
        self._lock = pthread_mutex_t()
        pthread_mutex_init(&self._lock, &attr)
        
        pthread_mutexattr_destroy(&attr)
    }
    
    deinit {
        pthread_mutex_destroy(&self._lock)
    }
    
    func inLock(_ work: () throws -> Void) rethrows {
        defer { unlock() }
        lock()
        try work()
    }
    
    func inLock<ReturnType>(_ work: () throws -> ReturnType) rethrows -> ReturnType {
        defer { unlock() }
        lock()
        return try work()
    }
    
    func lock() {
        pthread_mutex_lock(&_lock)
    }
    
    func unlock() {
        pthread_mutex_unlock(&_lock)
    }
}