Merge commit '7621e2f8dec938cf48181c8b10afc9b01f444e68' into beta

submodules/SSignalKit/SwiftSignalKit/Source/QueueLocalObject.swift

@@ -0,0 +1,58 @@
+import Foundation
+
+public final class QueueLocalObject<T: AnyObject> {
+    public let queue: Queue
+    private var valueRef: Unmanaged<T>?
+    
+    public init(queue: Queue, generate: @escaping () -> T) {
+        self.queue = queue
+        
+        self.queue.async {
+            let value = generate()
+            self.valueRef = Unmanaged.passRetained(value)
+        }
+    }
+    
+    deinit {
+        let valueRef = self.valueRef
+        self.queue.async {
+            valueRef?.release()
+        }
+    }
+    
+    public func unsafeGet() -> T? {
+        assert(self.queue.isCurrent())
+        return self.valueRef?.takeUnretainedValue()
+    }
+    
+    public func with(_ f: @escaping (T) -> Void) {
+        self.queue.async {
+            if let valueRef = self.valueRef {
+                let value = valueRef.takeUnretainedValue()
+                f(value)
+            }
+        }
+    }
+    
+    public func syncWith<R>(_ f: @escaping (T) -> R) -> R {
+        var result: R?
+        self.queue.sync {
+            if let valueRef = self.valueRef {
+                let value = valueRef.takeUnretainedValue()
+                result = f(value)
+            }
+        }
+        return result!
+    }
+    
+    public func signalWith<R, E>(_ f: @escaping (T, Subscriber<R, E>) -> Disposable) -> Signal<R, E> {
+        return Signal { [weak self] subscriber in
+            if let strongSelf = self, let valueRef = strongSelf.valueRef {
+                let value = valueRef.takeUnretainedValue()
+                return f(value, subscriber)
+            } else {
+                return EmptyDisposable
+            }
+        } |> runOn(self.queue)
+    }
+}