Merge commit '7621e2f8dec938cf48181c8b10afc9b01f444e68' into beta

submodules/SSignalKit/SwiftSignalKit/Source/Lock.swift

@@ -0,0 +1,34 @@
+import Foundation
+
+public final class Lock {
+    private var mutex = pthread_mutex_t()
+    
+    public init() {
+        pthread_mutex_init(&self.mutex, nil)
+    }
+    
+    deinit {
+        pthread_mutex_destroy(&self.mutex)
+    }
+    
+    public func locked(_ f: () -> ()) {
+        pthread_mutex_lock(&self.mutex)
+        f()
+        pthread_mutex_unlock(&self.mutex)
+    }
+    
+    public func throwingLocked(_ f: () throws -> Void) throws {
+        var error: Error?
+        pthread_mutex_lock(&self.mutex)
+        do {
+            try f()
+        } catch let e {
+            error = e
+        }
+        pthread_mutex_unlock(&self.mutex)
+        
+        if let error = error {
+            throw(error)
+        }
+    }
+}