From 507c3cd40af25c14dafbfce8bacf9985a854a029 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Niil=20=C3=96hlin?= <niil.ohlin@izettle.com>
Date: Thu, 26 Mar 2020 13:44:51 +0100
Subject: [PATCH 1/4] Remove warnings

---
 Flow/Callbacker.swift                 | 24 ++++++++-------
 Flow/Disposable.swift                 | 34 ++++++++++++---------
 Flow/Future+Combiners.swift           | 14 ++++++---
 Flow/Future.swift                     | 16 +++++-----
 Flow/FutureQueue.swift                | 43 ++++++++++++++------------
 Flow/Locking.swift                    | 44 ++++++++++++---------------
 Flow/OrderedCallbacker.swift          | 30 ++++++++++--------
 Flow/Signal+Construction.swift        | 24 +++++++++------
 Flow/Signal+Scheduling.swift          | 29 ++++++++++--------
 Flow/Signal+Transforms.swift          | 18 ++++++++---
 FlowTests/FutureSchedulingTests.swift |  4 ++-
 FlowTests/SignalProviderTests.swift   | 28 +++++++++++------
 12 files changed, 178 insertions(+), 130 deletions(-)

diff --git a/Flow/Callbacker.swift b/Flow/Callbacker.swift
index 01966e2..a581fc4 100644
--- a/Flow/Callbacker.swift
+++ b/Flow/Callbacker.swift
@@ -21,20 +21,22 @@ public final class Callbacker<Value> {
 
     private var callbacks = Callbacks.none
     private var _mutex = pthread_mutex_t()
-    private var mutex: PThreadMutex { return PThreadMutex(&_mutex) }
+    private func withMutex<T>(_ body: (PThreadMutex) throws -> T) rethrows -> T {
+        try withUnsafeMutablePointer(to: &_mutex, body)
+    }
 
     public init() {
-        mutex.initialize()
+        withMutex { $0.initialize() }
     }
 
     deinit {
-        mutex.deinitialize()
+        withMutex { $0.deinitialize() }
     }
 
     /// - Returns: True if no callbacks has been registered.
     public var isEmpty: Bool {
-        mutex.lock()
-        defer { mutex.unlock() }
+        withMutex { $0.lock() }
+        defer { withMutex { $0.unlock() } }
 
         switch callbacks {
         case .none: return true
@@ -46,8 +48,8 @@ public final class Callbacker<Value> {
     /// Register a callback to be called when `callAll` is executed.
     /// - Returns: A `Disposable` to be disposed to unregister the callback.
     public func addCallback(_ callback: @escaping (Value) -> Void) -> Disposable {
-        mutex.lock()
-        defer { mutex.unlock() }
+        withMutex { $0.lock() }
+        defer { withMutex { $0.unlock() } }
 
         let key = generateKey()
 
@@ -63,8 +65,8 @@ public final class Callbacker<Value> {
         }
 
         return NoLockKeyDisposer(key) { key in
-            self.mutex.lock()
-            defer { self.mutex.unlock() }
+            self.withMutex { $0.lock() }
+            defer { self.withMutex { $0.unlock() } }
 
             switch self.callbacks {
             case .single(let singleKey, _) where singleKey == key:
@@ -82,9 +84,9 @@ public final class Callbacker<Value> {
 
     /// Will call all registered callbacks with `value`
     public func callAll(with value: Value) {
-        mutex.lock()
+        withMutex { $0.lock() }
         let callbacks = self.callbacks
-        mutex.unlock()
+        withMutex { $0.unlock() }
 
         switch callbacks {
         case .none: break
diff --git a/Flow/Disposable.swift b/Flow/Disposable.swift
index 9b3bcc3..5fa4b42 100644
--- a/Flow/Disposable.swift
+++ b/Flow/Disposable.swift
@@ -29,24 +29,26 @@ public struct NilDisposer: Disposable {
 public final class Disposer: Disposable {
     private var disposer: (() -> ())?
     private var _mutex = pthread_mutex_t()
-    private var mutex: PThreadMutex { return PThreadMutex(&_mutex) }
+    private func withMutex<T>(_ body: (PThreadMutex) throws -> T) rethrows -> T {
+        try withUnsafeMutablePointer(to: &_mutex, body)
+    }
 
     /// Pass a closure to be called when being disposed
     public init(_ disposer: @escaping () -> () = {}) {
         self.disposer = disposer
-        mutex.initialize()
+        withMutex { $0.initialize() }
     }
 
     deinit {
         dispose()
-        mutex.deinitialize()
+        withMutex { $0.deinitialize() }
     }
 
     public func dispose() {
-        mutex.lock()
+        withMutex { $0.lock() }
         let disposer = self.disposer
         self.disposer = nil
-        mutex.unlock()
+        withMutex { $0.unlock() }
         disposer?()
     }
 }
@@ -59,48 +61,50 @@ public final class Disposer: Disposable {
 public final class DisposeBag: Disposable {
     private var disposables: [Disposable]
     private var _mutex = pthread_mutex_t()
-    private var mutex: PThreadMutex { return PThreadMutex(&_mutex) }
+    private func withMutex<T>(_ body: (PThreadMutex) throws -> T) rethrows -> T {
+        try withUnsafeMutablePointer(to: &_mutex, body)
+    }
 
     /// Create an empty instance
     public init() {
         self.disposables = []
-        mutex.initialize()
+        withMutex { $0.initialize() }
     }
 
     /// Create an instance already containing `disposables`
     public init<S: Sequence>(_ disposables: S) where S.Iterator.Element == Disposable {
         self.disposables = Array(disposables)
-        mutex.initialize()
+        withMutex { $0.initialize() }
     }
 
     /// Create an instance already containing `disposables`
     public init(_ disposables: Disposable...) {
         self.disposables = disposables
-        mutex.initialize()
+        withMutex { $0.initialize() }
     }
 
     deinit {
         dispose()
-        mutex.deinitialize()
+        withMutex { $0.deinitialize() }
     }
 
     /// Returns true if there is currently no disposables to dispose.
     public var isEmpty: Bool {
-        return mutex.protect { disposables.isEmpty }
+        return withMutex { $0.protect { disposables.isEmpty } }
     }
 
     public func dispose() {
-        mutex.lock()
+        withMutex { $0.lock() }
         let disposables = self.disposables // make sure to make a copy in the case any call to dispose will recursivaly call us back.
         self.disposables = []
-        mutex.unlock()
+        withMutex { $0.unlock() }
         for disposable in disposables { disposable.dispose() }
     }
 
     /// Add `disposable` to `self`
     public func add(_ disposable: Disposable) {
-        mutex.lock()
-        defer { mutex.unlock() }
+        withMutex { $0.lock() }
+        defer { withMutex { $0.unlock() } }
         disposables.append(disposable)
     }
 }
diff --git a/Flow/Future+Combiners.swift b/Flow/Future+Combiners.swift
index 26dcc41..1d39dd5 100644
--- a/Flow/Future+Combiners.swift
+++ b/Flow/Future+Combiners.swift
@@ -65,9 +65,9 @@ public func join<T>(_ futures: [Future<T>], cancelNonCompleted: Bool = true) ->
     var results = [T?](repeating: nil, count: futures.count)
     let mutex = Mutex()
     func onValue(_ i: Int, _ val: T) {
-        mutex.protect {
-            results[i] = val
-        }
+        mutex.lock()
+        results[i] = val
+        mutex.unlock()
     }
 
     var future = futures.first!.onValue(on: .none) { onValue(0, $0) }
@@ -220,7 +220,9 @@ public final class SingleTaskPerformer<Value> {
 
         mutex.unlock() // unlock while calling out as we might either recurs or always might execute at once.
         let singleFuture = function().always(on: .none) {
-            self.mutex.protect { self.future = nil }
+            self.mutex.lock()
+            self.future = nil
+            self.mutex.unlock()
         }
         mutex.lock()
 
@@ -233,7 +235,9 @@ public final class SingleTaskPerformer<Value> {
     }
 
     public var isPerforming: Bool {
-        return mutex.protect { self.future != nil }
+        mutex.lock()
+        defer { mutex.unlock() }
+        return self.future != nil
     }
 }
 
diff --git a/Flow/Future.swift b/Flow/Future.swift
index 19fad38..26a0b80 100644
--- a/Flow/Future.swift
+++ b/Flow/Future.swift
@@ -107,7 +107,7 @@ public final class Future<Value> {
                 try onResult(completion, Mover(shouldClone: true))
             }
         }
-        mutex.initialize()
+        withMutex { $0.initialize() }
 
         scheduler.async {
             do {
@@ -143,13 +143,13 @@ public final class Future<Value> {
 
         state = .completed(result)
         clone = { Future(result: result) }
-        mutex.initialize()
+        withMutex { $0.initialize() }
     }
 
     deinit {
         OSAtomicDecrement32(&futureUnitTestAliveCount)
         memPrint("Future deinit", futureUnitTestAliveCount)
-        mutex.deinitialize()
+        withMutex { $0.deinitialize() }
     }
 }
 
@@ -327,18 +327,20 @@ func memPrint(_ str: String, _ count: Int32) {
 }
 
 private extension Future {
-    var mutex: PThreadMutex { return PThreadMutex(&_mutex) }
+    private func withMutex<T>(_ body: (PThreadMutex) throws -> T) rethrows -> T {
+        try withUnsafeMutablePointer(to: &_mutex, body)
+    }
 
     private var protectedState: State {
-        return mutex.protect { state }
+        return withMutex { $0.protect { state } }
     }
 
     func lock() {
-        mutex.lock()
+        withMutex { $0.lock() }
     }
 
     func unlock() {
-        mutex.unlock()
+        withMutex { $0.unlock() }
     }
 
     func completeWithResult(_ result: Result<Value>) {
diff --git a/Flow/FutureQueue.swift b/Flow/FutureQueue.swift
index 931f9e2..f058111 100644
--- a/Flow/FutureQueue.swift
+++ b/Flow/FutureQueue.swift
@@ -61,9 +61,9 @@ public extension FutureQueue {
         return Future { completion in
             let item = QueueItem<Output>(operation: operation, completion: completion)
 
-            self.mutex.protect {
-                self.items.append(item)
-            }
+            self.withMutex { $0.lock() }
+            self.items.append(item)
+            self.withMutex { $0.unlock() }
 
             self.executeNextItem()
 
@@ -119,7 +119,7 @@ public extension FutureQueue {
 public extension FutureQueue {
     /// Do we have any enqueued operations?
     var isEmpty: Bool {
-        return mutex.protect { items.isEmpty }
+        return withMutex { $0.protect { items.isEmpty } }
     }
 
     /// Returns a signal that will signal when `isEmpty` is changed.
@@ -164,19 +164,22 @@ public extension FutureQueue {
 
     /// The error passed to `abortQueuedExecutionWithError()` if called with `shouldCloseQueue` as true.
     var closedError: Error? {
-        return mutex.protect { _closedError }
+        return withMutex { $0.protect { _closedError } }
     }
 }
 
 private extension FutureQueue {
-    var mutex: PThreadMutex { return PThreadMutex(&_mutex) }
-    func lock() { mutex.lock() }
-    func unlock() { mutex.unlock() }
+    private func withMutex<T>(_ body: (PThreadMutex) throws -> T) rethrows -> T {
+        try withUnsafeMutablePointer(to: &_mutex, body)
+    }
+
+    func lock() { withMutex { $0.lock() } }
+    func unlock() { withMutex { $0.unlock() } }
 
     func removeItem(_ item: Executable) {
-        mutex.protect {
-            _ = items.firstIndex { $0 === item }.map { items.remove(at: $0) }
-        }
+        withMutex { $0.lock() }
+        _ = items.firstIndex { $0 === item }.map { items.remove(at: $0) }
+        withMutex { $0.unlock() }
     }
 
     func executeNextItem() {
@@ -188,9 +191,9 @@ private extension FutureQueue {
         unlock()
 
         item.execute(on: queueScheduler) {
-            self.mutex.protect {
-                self.concurrentCount -= 1
-            }
+            self.lock()
+            self.concurrentCount -= 1
+            self.unlock()
             self.removeItem(item)
             self.executeNextItem()
         }
@@ -215,25 +218,27 @@ private final class QueueItem<Output>: Executable {
     private weak var future: Future<Output>?
     private var hasBeenCancelled = false
     private var _mutex = pthread_mutex_t()
+    private func withMutex<T>(_ body: (PThreadMutex) throws -> T) rethrows -> T {
+        try withUnsafeMutablePointer(to: &_mutex, body)
+    }
 
     init(operation: @escaping () throws -> Future<Output>, completion: @escaping (Result<Output>) -> ()) {
         self.completion = completion
         self.operation = operation
-        mutex.initialize()
+        withMutex { $0.initialize() }
 
         OSAtomicIncrement32(&queueItemUnitTestAliveCount)
         memPrint("Queue Item init", queueItemUnitTestAliveCount)
     }
 
     deinit {
-        mutex.deinitialize()
+        withMutex { $0.deinitialize() }
         OSAtomicDecrement32(&queueItemUnitTestAliveCount)
         memPrint("Queue Item deinit", queueItemUnitTestAliveCount)
     }
 
-    private var mutex: PThreadMutex { return PThreadMutex(&_mutex) }
-    private func lock() { mutex.lock() }
-    private func unlock() { mutex.unlock() }
+    private func lock() { withMutex { $0.lock() } }
+    private func unlock() { withMutex { $0.unlock() } }
 
     private func complete(_ result: (Result<Output>)) {
         lock()
diff --git a/Flow/Locking.swift b/Flow/Locking.swift
index 416be1b..8ca8472 100644
--- a/Flow/Locking.swift
+++ b/Flow/Locking.swift
@@ -11,32 +11,26 @@ import Foundation
 /// A reference wrapper around a POSIX thread mutex
 public final class Mutex {
     private var _mutex = pthread_mutex_t()
-    private var mutex: PThreadMutex { return PThreadMutex(&_mutex) }
+    private func withMutex<T>(_ body: (PThreadMutex) throws -> T) rethrows -> T {
+        try withUnsafeMutablePointer(to: &_mutex, body)
+    }
 
     public init() {
-        mutex.initialize()
+        withMutex { $0.initialize() }
     }
 
     deinit {
-        mutex.deinitialize()
+        withMutex { $0.deinitialize() }
     }
 
     /// Attempt to acquire the lock, blocking a thread’s execution until the lock can be acquired.
     public func lock() {
-        mutex.lock()
+        withMutex { $0.lock() }
     }
 
     /// Releases a previously acquired lock.
     public func unlock() {
-        mutex.unlock()
-    }
-
-    /// Will lock `self`, call `block`, then unlock `self`
-    @discardableResult
-    public func protect<T>(_ block: () throws -> T) rethrows -> T {
-        mutex.lock()
-        defer { mutex.unlock() }
-        return try block()
+        withMutex { $0.unlock() }
     }
 }
 
@@ -87,16 +81,18 @@ final class StateAndCallback<Value, State>: Disposable {
     var val: State
     fileprivate var disposables = [Disposable]()
     private var _mutex = pthread_mutex_t()
-    fileprivate var mutex: PThreadMutex { return PThreadMutex(&_mutex) }
+    fileprivate func withMutex<T>(_ body: (PThreadMutex) throws -> T) rethrows -> T {
+        try withUnsafeMutablePointer(to: &_mutex, body)
+    }
 
     init(state: State, callback: @escaping (Value) -> ()) {
         val = state
         self.callback = callback
-        mutex.initialize()
+        withMutex { $0.initialize() }
     }
 
     deinit {
-        mutex.deinitialize()
+        withMutex { $0.deinitialize() }
         dispose()
     }
 
@@ -106,27 +102,27 @@ final class StateAndCallback<Value, State>: Disposable {
     }
 
     func lock() {
-        mutex.lock()
+        withMutex { $0.lock() }
     }
 
     func unlock() {
-        mutex.unlock()
+        withMutex { $0.unlock() }
     }
 
     @discardableResult
     func protect<T>(_ block: () throws -> T) rethrows -> T {
-        mutex.lock()
-        defer { mutex.unlock() }
+        withMutex { $0.lock() }
+        defer { withMutex { $0.unlock() } }
         return try block()
     }
 
     func dispose() {
-        mutex.lock()
+        withMutex { $0.lock() }
         let disposables = self.disposables // make sure to make a copy in the case any call to dispose will recursivaly call us back.
         callback = nil
         exclusiveQueue = []
         self.disposables = []
-        mutex.unlock()
+        withMutex { $0.unlock() }
         for disposable in disposables { disposable.dispose() }
     }
 
@@ -192,12 +188,12 @@ extension StateAndCallback where Value == () {
 
 func +=<Value, State>(bag: StateAndCallback<Value, State>, disposable: Disposable?) {
     guard let disposable = disposable else { return }
-    bag.mutex.lock()
+    bag.withMutex { $0.lock() }
     let hasBeenDisposed = bag.callback == nil
     if !hasBeenDisposed {
         bag.disposables.append(disposable)
     }
-    bag.mutex.unlock()
+    bag.withMutex { $0.unlock() }
     if hasBeenDisposed {
         disposable.dispose()
     }
diff --git a/Flow/OrderedCallbacker.swift b/Flow/OrderedCallbacker.swift
index 04e63ac..6c83100 100644
--- a/Flow/OrderedCallbacker.swift
+++ b/Flow/OrderedCallbacker.swift
@@ -15,19 +15,21 @@ import Foundation
 public final class OrderedCallbacker<OrderedValue, CallbackValue> {
     private var callbacks: [Key: (OrderedValue, (CallbackValue) -> Future<()>)] = [:]
     private var _mutex = pthread_mutex_t()
-    private var mutex: PThreadMutex { return PThreadMutex(&_mutex) }
+    private func withMutex<T>(_ body: (PThreadMutex) throws -> T) rethrows -> T {
+        try withUnsafeMutablePointer(to: &_mutex, body)
+    }
 
     public init() {
-        mutex.initialize()
+        withMutex { $0.initialize() }
     }
 
     deinit {
-        mutex.deinitialize()
+        withMutex { $0.deinitialize() }
     }
 
     /// - Returns: True if no callbacks has been registered.
     public var isEmpty: Bool {
-        return mutex.protect { callbacks.isEmpty }
+        return withMutex { $0.protect { callbacks.isEmpty } }
     }
 
     /// Register a callback and orderedValue to be called when `callAll` is executed.
@@ -35,11 +37,13 @@ public final class OrderedCallbacker<OrderedValue, CallbackValue> {
     /// - Parameter orderedValue: The value used to order this callback
     /// - Returns: A `Disposable` to be disposed to unregister the callback.
     public func addCallback(_ callback: @escaping (CallbackValue) -> Future<()>, orderedBy orderedValue: OrderedValue) -> Disposable {
-        return mutex.protect {
-            let key = generateKey()
-            callbacks[key] = (orderedValue, callback)
-            return Disposer {
-                self.mutex.protect { self.callbacks[key] = nil }
+        return withMutex {
+            $0.protect {
+                let key = generateKey()
+                callbacks[key] = (orderedValue, callback)
+                return Disposer {
+                    self.withMutex { $0.protect { self.callbacks[key] = nil } }
+                }
             }
         }
     }
@@ -48,9 +52,11 @@ public final class OrderedCallbacker<OrderedValue, CallbackValue> {
     /// - Returns: A `Future` that will complete when all callbacks has been called.
     @discardableResult
     public func callAll(with value: CallbackValue, isOrderedBefore: (OrderedValue, OrderedValue) -> Bool) -> Future<()> {
-        return mutex.protect {
-            callbacks.values.sorted { isOrderedBefore($0.0, $1.0) }.map { $1 }
-        }.mapToFuture { $0(value) }.toVoid()
+        return withMutex {
+            $0.protect {
+                callbacks.values.sorted { isOrderedBefore($0.0, $1.0) }.map { $1 }
+            }.mapToFuture { $0(value) }.toVoid()
+        }
     }
 }
 
diff --git a/Flow/Signal+Construction.swift b/Flow/Signal+Construction.swift
index ee9697e..fc98885 100644
--- a/Flow/Signal+Construction.swift
+++ b/Flow/Signal+Construction.swift
@@ -113,27 +113,29 @@ private final class CallbackState<Value>: Disposable {
     let sharedKey: Key
 
     private var _mutex = pthread_mutex_t()
-    private var mutex: PThreadMutex { return PThreadMutex(&_mutex) }
+    private func withMutex<T>(_ body: (PThreadMutex) throws -> T) rethrows -> T {
+        try withUnsafeMutablePointer(to: &_mutex, body)
+    }
 
     init(shared: SharedState<Value>? = nil, getValue: (() -> Value)?, callback: @escaping (EventType<Value>) -> Void) {
         self.shared = shared
         self.sharedKey = shared == nil ? 0 : generateKey()
         self.getValue = getValue
         self.callback = callback
-        mutex.initialize()
+        withMutex { $0.initialize() }
     }
 
     deinit {
-        mutex.deinitialize()
+        withMutex { $0.deinitialize() }
         shared?.remove(key: sharedKey)
     }
 
     func lock() {
-        mutex.lock()
+        withMutex { $0.lock() }
     }
 
     func unlock() {
-        mutex.unlock()
+        withMutex { $0.unlock() }
     }
 
     // For efficiency `Self` could also also behave as a `NoLockKeyDisposer``, saving us an allocation for each listener.
@@ -293,7 +295,9 @@ private final class CallbackState<Value>: Disposable {
 final class SharedState<Value> {
     private let getValue: (() -> Value)?
     private var _mutex = pthread_mutex_t()
-    private var mutex: PThreadMutex { return PThreadMutex(&_mutex) }
+    private func withMutex<T>(_ body: (PThreadMutex) throws -> T) rethrows -> T {
+        try withUnsafeMutablePointer(to: &_mutex, body)
+    }
 
     typealias Callback = (EventType<Value>) -> Void
     var firstCallback: (key: Key, value: Callback)?
@@ -303,19 +307,19 @@ final class SharedState<Value> {
 
     init(getValue: (() -> Value)? = nil) {
         self.getValue = getValue
-        mutex.initialize()
+        withMutex { $0.initialize() }
     }
 
     deinit {
-        mutex.deinitialize()
+        withMutex { $0.deinitialize() }
     }
 
     func lock() {
-        mutex.lock()
+        withMutex { $0.lock() }
     }
 
     func unlock() {
-        mutex.unlock()
+        withMutex { $0.unlock() }
     }
 
     func remove(key: Key) {
diff --git a/Flow/Signal+Scheduling.swift b/Flow/Signal+Scheduling.swift
index 36bc088..14e959b 100644
--- a/Flow/Signal+Scheduling.swift
+++ b/Flow/Signal+Scheduling.swift
@@ -120,48 +120,51 @@ internal extension CoreSignal {
 private final class OnEventTypeDisposer<Value>: Disposable {
     private var disposable: Disposable?
     private var _mutex = pthread_mutex_t()
-    private var mutex: PThreadMutex { return PThreadMutex(&_mutex) }
+    private func withMutex<T>(_ body: (PThreadMutex) throws -> T) rethrows -> T {
+        try withUnsafeMutablePointer(to: &_mutex, body)
+    }
+
     private let scheduler: Scheduler
     private var callback: ((EventType<Value>) -> Void)?
 
     init(on scheduler: Scheduler, callback: @escaping (EventType<Value>) -> Void, onEventType: @escaping (@escaping (EventType<Value>) -> Void) -> Disposable) {
         self.scheduler = scheduler
         self.callback = callback
-        mutex.initialize()
+        withMutex { $0.initialize() }
 
         let disposable = onEventType { [weak self] in self?.handleEventType($0) }
 
-        mutex.lock()
+        withMutex { $0.lock() }
         if self.callback == nil {
             disposable.dispose()
         } else {
             self.disposable = disposable
         }
-        mutex.unlock()
+        withMutex { $0.unlock() }
     }
 
     deinit {
         dispose()
-        mutex.deinitialize()
+        withMutex { $0.deinitialize() }
     }
 
     public func dispose() {
-        mutex.lock()
+        withMutex { $0.lock() }
         let disposable = self.disposable
         self.disposable = nil
         callback = nil
-        mutex.unlock()
+        withMutex { $0.unlock() }
         disposable?.dispose()
     }
 
     func handleEventType(_ eventType: EventType<Value>) {
-        mutex.lock()
+        withMutex { $0.lock() }
 
         guard let callback = self.callback else {
-            return mutex.unlock()
+            return withMutex { $0.unlock() }
         }
 
-        mutex.unlock()
+        withMutex { $0.unlock() }
 
         if scheduler.isImmediate {
             validate(eventType: eventType)
@@ -176,14 +179,14 @@ private final class OnEventTypeDisposer<Value>: Disposable {
             scheduler.async { [weak self] in
                 guard let `self` = self else { return }
                 // At the time we are scheduled, we might already been disposed
-                self.mutex.lock()
+                self.withMutex { $0.lock() }
                 guard let callback = self.callback else {
-                    return self.mutex.unlock()
+                    return self.withMutex { $0.unlock() }
                 }
 
                 self.validate(eventType: eventType)
 
-                self.mutex.unlock()
+                self.withMutex { $0.unlock() }
                 callback(eventType)
                 if case .event(.end) = eventType {
                     self.dispose()
diff --git a/Flow/Signal+Transforms.swift b/Flow/Signal+Transforms.swift
index 8877b10..80359e3 100644
--- a/Flow/Signal+Transforms.swift
+++ b/Flow/Signal+Transforms.swift
@@ -741,14 +741,20 @@ private extension SignalProvider {
         let mutex = Mutex()
         var setter: ((T) -> ())?
         func setValue(_ value: T) {
-            let setValue = mutex.protect { setter ?? transform(signal.getter()!).setter! }
+            mutex.lock()
+            let setValue = setter ?? transform(signal.getter()!).setter!
+            mutex.unlock()
             setValue(value)
         }
 
         return CoreSignal(setValue: setValue, onEventType: { callback in
             let latestBag = DisposeBag()
             let bag = DisposeBag(latestBag)
-            bag += { mutex.protect { setter = nil } }
+            bag += {
+                mutex.lock()
+                setter = nil
+                mutex.unlock()
+            }
 
             bag += signal.onEventType(on: scheduler) { eventType in
                 switch eventType {
@@ -756,13 +762,17 @@ private extension SignalProvider {
                     callback(.initial(nil))
                 case .initial(let val?):
                     let signal = scheduler.sync { transform(val) }
-                    mutex.protect { setter = signal.setter }
+                    mutex.lock()
+                    setter = signal.setter
+                    mutex.unlock()
                     latestBag += signal.onEventType(callback)
                 case let .event(.value(val)):
                     let isFirstEvent = latestBag.isEmpty
                     latestBag.dispose()
                     let signal = transform(val)
-                    mutex.protect { setter = signal.setter }
+                    mutex.lock()
+                    setter = signal.setter
+                    mutex.unlock()
                     latestBag += signal.onEventType { eventType in
                         switch eventType {
                         case .initial(let val?) where KO.isReadable:
diff --git a/FlowTests/FutureSchedulingTests.swift b/FlowTests/FutureSchedulingTests.swift
index 17ecc64..16767ce 100644
--- a/FlowTests/FutureSchedulingTests.swift
+++ b/FlowTests/FutureSchedulingTests.swift
@@ -184,7 +184,9 @@ class FutureNewSchedulingTests: FutureTest {
                 var f = Future(v).delay(by: delay)
                 f = f.map(on: .concurrentBackground) { $0*2 }
                 return f/*assertValue(v*2)*/.assert(on: .main).always(on: .concurrentBackground) {
-                    mutex.protect { completeCount += 1 }
+                    mutex.lock()
+                    completeCount += 1
+                    mutex.unlock()
                 }
             }).onCancel { e.fulfill() }
 
diff --git a/FlowTests/SignalProviderTests.swift b/FlowTests/SignalProviderTests.swift
index dcc2e31..590f856 100644
--- a/FlowTests/SignalProviderTests.swift
+++ b/FlowTests/SignalProviderTests.swift
@@ -1718,13 +1718,19 @@ class SignalProviderTests: XCTestCase {
             _ = Signal(callbacker: callbacker).start(with: 1).take(first: 2).onEvent(on: .concurrentBackground) { event in
                 switch event {
                 case .value(let val):
-                    mutex.protect { result.append(val) }
+                    mutex.lock()
+                    result.append(val)
+                    mutex.unlock()
                     backgroundQueue.async {
                         callbacker.callAll(with: val + 1)
                     }
-                    mutex.protect { result.append(val*10) }
+                    mutex.lock()
+                    result.append(val*10)
+                    mutex.unlock()
                 case .end:
-                    XCTAssertEqual(mutex.protect { result }, [1, 10, 2, 20])
+                    mutex.lock()
+                    XCTAssertEqual(result, [1, 10, 2, 20])
+                    mutex.unlock()
                 }
             }
         }
@@ -2718,13 +2724,15 @@ final class SimulatedTimer {
 
     func schedule(at time: TimeInterval, execute work: @escaping () -> ()) -> Disposable {
         let key = UUID()
-        mutex.protect {
-            assert(time >= self.time)
-            scheduledWork[key] = (time, work)
-        }
+        mutex.lock()
+        assert(time >= self.time)
+        scheduledWork[key] = (time, work)
+        mutex.unlock()
 
         return Disposer {
-            self.mutex.protect { self.scheduledWork[key] = nil }
+            self.mutex.lock()
+            self.scheduledWork[key] = nil
+            self.mutex.unlock()
         }
     }
 
@@ -2748,7 +2756,9 @@ final class SimulatedTimer {
         //print("call", next)
         next.value.work()
 
-        mutex.protect { count -= 1 }
+        mutex.lock()
+        count -= 1
+        mutex.unlock()
         mainQueue.async { self.release() }
     }
 }

From 3aa11bcac843dc022b8c1884833620502c177fbd Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Niil=20=C3=96hlin?= <niil.ohlin@izettle.com>
Date: Mon, 30 Mar 2020 11:40:18 +0200
Subject: [PATCH 2/4] create extension for pthread_mutex_t

---
 Flow/Callbacker.swift          | 23 ++++++--------
 Flow/Disposable.swift          | 35 ++++++++++-----------
 Flow/Future.swift              | 18 +++++------
 Flow/FutureQueue.swift         | 35 ++++++++++-----------
 Flow/Locking.swift             | 56 ++++++++++++++++++++++------------
 Flow/OrderedCallbacker.swift   | 37 +++++++++++-----------
 Flow/Signal+Construction.swift | 22 +++++--------
 Flow/Signal+Scheduling.swift   | 27 ++++++++--------
 8 files changed, 124 insertions(+), 129 deletions(-)

diff --git a/Flow/Callbacker.swift b/Flow/Callbacker.swift
index a581fc4..c29209c 100644
--- a/Flow/Callbacker.swift
+++ b/Flow/Callbacker.swift
@@ -21,22 +21,19 @@ public final class Callbacker<Value> {
 
     private var callbacks = Callbacks.none
     private var _mutex = pthread_mutex_t()
-    private func withMutex<T>(_ body: (PThreadMutex) throws -> T) rethrows -> T {
-        try withUnsafeMutablePointer(to: &_mutex, body)
-    }
 
     public init() {
-        withMutex { $0.initialize() }
+        _mutex.initialize()
     }
 
     deinit {
-        withMutex { $0.deinitialize() }
+        _mutex.deinitialize()
     }
 
     /// - Returns: True if no callbacks has been registered.
     public var isEmpty: Bool {
-        withMutex { $0.lock() }
-        defer { withMutex { $0.unlock() } }
+        _mutex.lock()
+        defer { _mutex.unlock() }
 
         switch callbacks {
         case .none: return true
@@ -48,8 +45,8 @@ public final class Callbacker<Value> {
     /// Register a callback to be called when `callAll` is executed.
     /// - Returns: A `Disposable` to be disposed to unregister the callback.
     public func addCallback(_ callback: @escaping (Value) -> Void) -> Disposable {
-        withMutex { $0.lock() }
-        defer { withMutex { $0.unlock() } }
+        _mutex.lock()
+        defer { _mutex.unlock() }
 
         let key = generateKey()
 
@@ -65,8 +62,8 @@ public final class Callbacker<Value> {
         }
 
         return NoLockKeyDisposer(key) { key in
-            self.withMutex { $0.lock() }
-            defer { self.withMutex { $0.unlock() } }
+            self._mutex.lock()
+            defer { self._mutex.unlock() }
 
             switch self.callbacks {
             case .single(let singleKey, _) where singleKey == key:
@@ -84,9 +81,9 @@ public final class Callbacker<Value> {
 
     /// Will call all registered callbacks with `value`
     public func callAll(with value: Value) {
-        withMutex { $0.lock() }
+        _mutex.lock()
         let callbacks = self.callbacks
-        withMutex { $0.unlock() }
+        _mutex.unlock()
 
         switch callbacks {
         case .none: break
diff --git a/Flow/Disposable.swift b/Flow/Disposable.swift
index 5fa4b42..71c4149 100644
--- a/Flow/Disposable.swift
+++ b/Flow/Disposable.swift
@@ -29,26 +29,23 @@ public struct NilDisposer: Disposable {
 public final class Disposer: Disposable {
     private var disposer: (() -> ())?
     private var _mutex = pthread_mutex_t()
-    private func withMutex<T>(_ body: (PThreadMutex) throws -> T) rethrows -> T {
-        try withUnsafeMutablePointer(to: &_mutex, body)
-    }
 
     /// Pass a closure to be called when being disposed
     public init(_ disposer: @escaping () -> () = {}) {
         self.disposer = disposer
-        withMutex { $0.initialize() }
+        _mutex.initialize()
     }
 
     deinit {
         dispose()
-        withMutex { $0.deinitialize() }
+        _mutex.deinitialize()
     }
 
     public func dispose() {
-        withMutex { $0.lock() }
+        _mutex.lock()
         let disposer = self.disposer
         self.disposer = nil
-        withMutex { $0.unlock() }
+        _mutex.unlock()
         disposer?()
     }
 }
@@ -61,50 +58,50 @@ public final class Disposer: Disposable {
 public final class DisposeBag: Disposable {
     private var disposables: [Disposable]
     private var _mutex = pthread_mutex_t()
-    private func withMutex<T>(_ body: (PThreadMutex) throws -> T) rethrows -> T {
-        try withUnsafeMutablePointer(to: &_mutex, body)
-    }
 
     /// Create an empty instance
     public init() {
         self.disposables = []
-        withMutex { $0.initialize() }
+        _mutex.initialize()
     }
 
     /// Create an instance already containing `disposables`
     public init<S: Sequence>(_ disposables: S) where S.Iterator.Element == Disposable {
         self.disposables = Array(disposables)
-        withMutex { $0.initialize() }
+        _mutex.initialize()
     }
 
     /// Create an instance already containing `disposables`
     public init(_ disposables: Disposable...) {
         self.disposables = disposables
-        withMutex { $0.initialize() }
+        _mutex.initialize()
     }
 
     deinit {
         dispose()
-        withMutex { $0.deinitialize() }
+        _mutex.deinitialize()
     }
 
     /// Returns true if there is currently no disposables to dispose.
     public var isEmpty: Bool {
-        return withMutex { $0.protect { disposables.isEmpty } }
+        _mutex.lock()
+        let isEmpty = disposables.isEmpty
+        _mutex.unlock()
+        return isEmpty
     }
 
     public func dispose() {
-        withMutex { $0.lock() }
+        _mutex.lock()
         let disposables = self.disposables // make sure to make a copy in the case any call to dispose will recursivaly call us back.
         self.disposables = []
-        withMutex { $0.unlock() }
+        _mutex.unlock()
         for disposable in disposables { disposable.dispose() }
     }
 
     /// Add `disposable` to `self`
     public func add(_ disposable: Disposable) {
-        withMutex { $0.lock() }
-        defer { withMutex { $0.unlock() } }
+        _mutex.lock()
+        defer { _mutex.unlock() }
         disposables.append(disposable)
     }
 }
diff --git a/Flow/Future.swift b/Flow/Future.swift
index 26a0b80..ce6d755 100644
--- a/Flow/Future.swift
+++ b/Flow/Future.swift
@@ -107,7 +107,7 @@ public final class Future<Value> {
                 try onResult(completion, Mover(shouldClone: true))
             }
         }
-        withMutex { $0.initialize() }
+        _mutex.initialize()
 
         scheduler.async {
             do {
@@ -143,13 +143,13 @@ public final class Future<Value> {
 
         state = .completed(result)
         clone = { Future(result: result) }
-        withMutex { $0.initialize() }
+        _mutex.initialize()
     }
 
     deinit {
         OSAtomicDecrement32(&futureUnitTestAliveCount)
         memPrint("Future deinit", futureUnitTestAliveCount)
-        withMutex { $0.deinitialize() }
+        _mutex.deinitialize()
     }
 }
 
@@ -327,20 +327,18 @@ func memPrint(_ str: String, _ count: Int32) {
 }
 
 private extension Future {
-    private func withMutex<T>(_ body: (PThreadMutex) throws -> T) rethrows -> T {
-        try withUnsafeMutablePointer(to: &_mutex, body)
-    }
-
     private var protectedState: State {
-        return withMutex { $0.protect { state } }
+        _mutex.lock()
+        defer { _mutex.unlock() }
+        return state
     }
 
     func lock() {
-        withMutex { $0.lock() }
+        _mutex.lock()
     }
 
     func unlock() {
-        withMutex { $0.unlock() }
+        _mutex.unlock()
     }
 
     func completeWithResult(_ result: Result<Value>) {
diff --git a/Flow/FutureQueue.swift b/Flow/FutureQueue.swift
index f058111..eb5b6ff 100644
--- a/Flow/FutureQueue.swift
+++ b/Flow/FutureQueue.swift
@@ -61,9 +61,9 @@ public extension FutureQueue {
         return Future { completion in
             let item = QueueItem<Output>(operation: operation, completion: completion)
 
-            self.withMutex { $0.lock() }
+            self._mutex.lock()
             self.items.append(item)
-            self.withMutex { $0.unlock() }
+            self._mutex.unlock()
 
             self.executeNextItem()
 
@@ -119,7 +119,9 @@ public extension FutureQueue {
 public extension FutureQueue {
     /// Do we have any enqueued operations?
     var isEmpty: Bool {
-        return withMutex { $0.protect { items.isEmpty } }
+        _mutex.lock()
+        defer { _mutex.unlock() }
+        return items.isEmpty
     }
 
     /// Returns a signal that will signal when `isEmpty` is changed.
@@ -164,22 +166,20 @@ public extension FutureQueue {
 
     /// The error passed to `abortQueuedExecutionWithError()` if called with `shouldCloseQueue` as true.
     var closedError: Error? {
-        return withMutex { $0.protect { _closedError } }
+        _mutex.lock()
+        defer { _mutex.unlock() }
+        return _closedError
     }
 }
 
 private extension FutureQueue {
-    private func withMutex<T>(_ body: (PThreadMutex) throws -> T) rethrows -> T {
-        try withUnsafeMutablePointer(to: &_mutex, body)
-    }
-
-    func lock() { withMutex { $0.lock() } }
-    func unlock() { withMutex { $0.unlock() } }
+    func lock() { _mutex.lock() }
+    func unlock() { _mutex.unlock() }
 
     func removeItem(_ item: Executable) {
-        withMutex { $0.lock() }
+        _mutex.lock()
         _ = items.firstIndex { $0 === item }.map { items.remove(at: $0) }
-        withMutex { $0.unlock() }
+        _mutex.unlock()
     }
 
     func executeNextItem() {
@@ -218,27 +218,24 @@ private final class QueueItem<Output>: Executable {
     private weak var future: Future<Output>?
     private var hasBeenCancelled = false
     private var _mutex = pthread_mutex_t()
-    private func withMutex<T>(_ body: (PThreadMutex) throws -> T) rethrows -> T {
-        try withUnsafeMutablePointer(to: &_mutex, body)
-    }
 
     init(operation: @escaping () throws -> Future<Output>, completion: @escaping (Result<Output>) -> ()) {
         self.completion = completion
         self.operation = operation
-        withMutex { $0.initialize() }
+        _mutex.initialize()
 
         OSAtomicIncrement32(&queueItemUnitTestAliveCount)
         memPrint("Queue Item init", queueItemUnitTestAliveCount)
     }
 
     deinit {
-        withMutex { $0.deinitialize() }
+        _mutex.deinitialize()
         OSAtomicDecrement32(&queueItemUnitTestAliveCount)
         memPrint("Queue Item deinit", queueItemUnitTestAliveCount)
     }
 
-    private func lock() { withMutex { $0.lock() } }
-    private func unlock() { withMutex { $0.unlock() } }
+    private func lock() { _mutex.lock() }
+    private func unlock() { _mutex.unlock() }
 
     private func complete(_ result: (Result<Output>)) {
         lock()
diff --git a/Flow/Locking.swift b/Flow/Locking.swift
index 8ca8472..874badf 100644
--- a/Flow/Locking.swift
+++ b/Flow/Locking.swift
@@ -11,26 +11,45 @@ import Foundation
 /// A reference wrapper around a POSIX thread mutex
 public final class Mutex {
     private var _mutex = pthread_mutex_t()
-    private func withMutex<T>(_ body: (PThreadMutex) throws -> T) rethrows -> T {
-        try withUnsafeMutablePointer(to: &_mutex, body)
-    }
 
     public init() {
-        withMutex { $0.initialize() }
+        _mutex.initialize()
     }
 
     deinit {
-        withMutex { $0.deinitialize() }
+        _mutex.deinitialize()
     }
 
     /// Attempt to acquire the lock, blocking a thread’s execution until the lock can be acquired.
     public func lock() {
-        withMutex { $0.lock() }
+        _mutex.lock()
     }
 
     /// Releases a previously acquired lock.
     public func unlock() {
-        withMutex { $0.unlock() }
+        _mutex.unlock()
+    }
+}
+
+extension pthread_mutex_t {
+    mutating func withPointer<T>(_ body: (PThreadMutex) throws -> T) rethrows -> T {
+        try withUnsafeMutablePointer(to: &self, body)
+    }
+    
+    mutating func initialize() {
+        withPointer { $0.initialize() }
+    }
+
+    mutating func deinitialize() {
+        withPointer { $0.deinitialize() }
+    }
+
+    mutating func lock() {
+        withPointer { $0.lock() }
+    }
+
+    mutating func unlock() {
+        withPointer { $0.unlock() }
     }
 }
 
@@ -81,18 +100,15 @@ final class StateAndCallback<Value, State>: Disposable {
     var val: State
     fileprivate var disposables = [Disposable]()
     private var _mutex = pthread_mutex_t()
-    fileprivate func withMutex<T>(_ body: (PThreadMutex) throws -> T) rethrows -> T {
-        try withUnsafeMutablePointer(to: &_mutex, body)
-    }
 
     init(state: State, callback: @escaping (Value) -> ()) {
         val = state
         self.callback = callback
-        withMutex { $0.initialize() }
+        _mutex.initialize()
     }
 
     deinit {
-        withMutex { $0.deinitialize() }
+        _mutex.deinitialize()
         dispose()
     }
 
@@ -102,27 +118,27 @@ final class StateAndCallback<Value, State>: Disposable {
     }
 
     func lock() {
-        withMutex { $0.lock() }
+        _mutex.lock()
     }
 
     func unlock() {
-        withMutex { $0.unlock() }
+        _mutex.unlock()
     }
 
     @discardableResult
     func protect<T>(_ block: () throws -> T) rethrows -> T {
-        withMutex { $0.lock() }
-        defer { withMutex { $0.unlock() } }
+        _mutex.lock()
+        defer { _mutex.unlock() }
         return try block()
     }
 
     func dispose() {
-        withMutex { $0.lock() }
+        _mutex.lock()
         let disposables = self.disposables // make sure to make a copy in the case any call to dispose will recursivaly call us back.
         callback = nil
         exclusiveQueue = []
         self.disposables = []
-        withMutex { $0.unlock() }
+        _mutex.unlock()
         for disposable in disposables { disposable.dispose() }
     }
 
@@ -188,12 +204,12 @@ extension StateAndCallback where Value == () {
 
 func +=<Value, State>(bag: StateAndCallback<Value, State>, disposable: Disposable?) {
     guard let disposable = disposable else { return }
-    bag.withMutex { $0.lock() }
+    bag.lock()
     let hasBeenDisposed = bag.callback == nil
     if !hasBeenDisposed {
         bag.disposables.append(disposable)
     }
-    bag.withMutex { $0.unlock() }
+    bag.unlock()
     if hasBeenDisposed {
         disposable.dispose()
     }
diff --git a/Flow/OrderedCallbacker.swift b/Flow/OrderedCallbacker.swift
index 6c83100..3d557ab 100644
--- a/Flow/OrderedCallbacker.swift
+++ b/Flow/OrderedCallbacker.swift
@@ -15,21 +15,21 @@ import Foundation
 public final class OrderedCallbacker<OrderedValue, CallbackValue> {
     private var callbacks: [Key: (OrderedValue, (CallbackValue) -> Future<()>)] = [:]
     private var _mutex = pthread_mutex_t()
-    private func withMutex<T>(_ body: (PThreadMutex) throws -> T) rethrows -> T {
-        try withUnsafeMutablePointer(to: &_mutex, body)
-    }
 
     public init() {
-        withMutex { $0.initialize() }
+        _mutex.initialize()
     }
 
     deinit {
-        withMutex { $0.deinitialize() }
+        _mutex.deinitialize()
     }
 
     /// - Returns: True if no callbacks has been registered.
     public var isEmpty: Bool {
-        return withMutex { $0.protect { callbacks.isEmpty } }
+        _mutex.lock()
+        let isEmpty = callbacks.isEmpty
+        _mutex.unlock()
+        return isEmpty
     }
 
     /// Register a callback and orderedValue to be called when `callAll` is executed.
@@ -37,14 +37,14 @@ public final class OrderedCallbacker<OrderedValue, CallbackValue> {
     /// - Parameter orderedValue: The value used to order this callback
     /// - Returns: A `Disposable` to be disposed to unregister the callback.
     public func addCallback(_ callback: @escaping (CallbackValue) -> Future<()>, orderedBy orderedValue: OrderedValue) -> Disposable {
-        return withMutex {
-            $0.protect {
-                let key = generateKey()
-                callbacks[key] = (orderedValue, callback)
-                return Disposer {
-                    self.withMutex { $0.protect { self.callbacks[key] = nil } }
-                }
-            }
+        _mutex.lock()
+        defer { _mutex.unlock() }
+        let key = generateKey()
+        callbacks[key] = (orderedValue, callback)
+        return Disposer {
+            self._mutex.lock()
+            self.callbacks[key] = nil
+            self._mutex.unlock()
         }
     }
 
@@ -52,11 +52,10 @@ public final class OrderedCallbacker<OrderedValue, CallbackValue> {
     /// - Returns: A `Future` that will complete when all callbacks has been called.
     @discardableResult
     public func callAll(with value: CallbackValue, isOrderedBefore: (OrderedValue, OrderedValue) -> Bool) -> Future<()> {
-        return withMutex {
-            $0.protect {
-                callbacks.values.sorted { isOrderedBefore($0.0, $1.0) }.map { $1 }
-            }.mapToFuture { $0(value) }.toVoid()
-        }
+        _mutex.lock()
+        let sortedCallbacks = callbacks.values.sorted { isOrderedBefore($0.0, $1.0) }.map { $1 }
+        _mutex.unlock()
+        return sortedCallbacks.mapToFuture { $0(value) }.toVoid()
     }
 }
 
diff --git a/Flow/Signal+Construction.swift b/Flow/Signal+Construction.swift
index fc98885..7230f4e 100644
--- a/Flow/Signal+Construction.swift
+++ b/Flow/Signal+Construction.swift
@@ -113,29 +113,26 @@ private final class CallbackState<Value>: Disposable {
     let sharedKey: Key
 
     private var _mutex = pthread_mutex_t()
-    private func withMutex<T>(_ body: (PThreadMutex) throws -> T) rethrows -> T {
-        try withUnsafeMutablePointer(to: &_mutex, body)
-    }
 
     init(shared: SharedState<Value>? = nil, getValue: (() -> Value)?, callback: @escaping (EventType<Value>) -> Void) {
         self.shared = shared
         self.sharedKey = shared == nil ? 0 : generateKey()
         self.getValue = getValue
         self.callback = callback
-        withMutex { $0.initialize() }
+        _mutex.initialize()
     }
 
     deinit {
-        withMutex { $0.deinitialize() }
+        _mutex.deinitialize()
         shared?.remove(key: sharedKey)
     }
 
     func lock() {
-        withMutex { $0.lock() }
+        _mutex.lock()
     }
 
     func unlock() {
-        withMutex { $0.unlock() }
+        _mutex.unlock()
     }
 
     // For efficiency `Self` could also also behave as a `NoLockKeyDisposer``, saving us an allocation for each listener.
@@ -295,9 +292,6 @@ private final class CallbackState<Value>: Disposable {
 final class SharedState<Value> {
     private let getValue: (() -> Value)?
     private var _mutex = pthread_mutex_t()
-    private func withMutex<T>(_ body: (PThreadMutex) throws -> T) rethrows -> T {
-        try withUnsafeMutablePointer(to: &_mutex, body)
-    }
 
     typealias Callback = (EventType<Value>) -> Void
     var firstCallback: (key: Key, value: Callback)?
@@ -307,19 +301,19 @@ final class SharedState<Value> {
 
     init(getValue: (() -> Value)? = nil) {
         self.getValue = getValue
-        withMutex { $0.initialize() }
+        _mutex.initialize()
     }
 
     deinit {
-        withMutex { $0.deinitialize() }
+        _mutex.deinitialize()
     }
 
     func lock() {
-        withMutex { $0.lock() }
+        _mutex.lock()
     }
 
     func unlock() {
-        withMutex { $0.unlock() }
+        _mutex.unlock()
     }
 
     func remove(key: Key) {
diff --git a/Flow/Signal+Scheduling.swift b/Flow/Signal+Scheduling.swift
index 14e959b..2209a7d 100644
--- a/Flow/Signal+Scheduling.swift
+++ b/Flow/Signal+Scheduling.swift
@@ -120,9 +120,6 @@ internal extension CoreSignal {
 private final class OnEventTypeDisposer<Value>: Disposable {
     private var disposable: Disposable?
     private var _mutex = pthread_mutex_t()
-    private func withMutex<T>(_ body: (PThreadMutex) throws -> T) rethrows -> T {
-        try withUnsafeMutablePointer(to: &_mutex, body)
-    }
 
     private let scheduler: Scheduler
     private var callback: ((EventType<Value>) -> Void)?
@@ -130,41 +127,41 @@ private final class OnEventTypeDisposer<Value>: Disposable {
     init(on scheduler: Scheduler, callback: @escaping (EventType<Value>) -> Void, onEventType: @escaping (@escaping (EventType<Value>) -> Void) -> Disposable) {
         self.scheduler = scheduler
         self.callback = callback
-        withMutex { $0.initialize() }
+        _mutex.initialize()
 
         let disposable = onEventType { [weak self] in self?.handleEventType($0) }
 
-        withMutex { $0.lock() }
+        _mutex.lock()
         if self.callback == nil {
             disposable.dispose()
         } else {
             self.disposable = disposable
         }
-        withMutex { $0.unlock() }
+        _mutex.unlock()
     }
 
     deinit {
         dispose()
-        withMutex { $0.deinitialize() }
+        _mutex.deinitialize()
     }
 
     public func dispose() {
-        withMutex { $0.lock() }
+        _mutex.lock()
         let disposable = self.disposable
         self.disposable = nil
         callback = nil
-        withMutex { $0.unlock() }
+        _mutex.unlock()
         disposable?.dispose()
     }
 
     func handleEventType(_ eventType: EventType<Value>) {
-        withMutex { $0.lock() }
+        _mutex.lock()
 
         guard let callback = self.callback else {
-            return withMutex { $0.unlock() }
+            return _mutex.unlock()
         }
 
-        withMutex { $0.unlock() }
+        _mutex.unlock()
 
         if scheduler.isImmediate {
             validate(eventType: eventType)
@@ -179,14 +176,14 @@ private final class OnEventTypeDisposer<Value>: Disposable {
             scheduler.async { [weak self] in
                 guard let `self` = self else { return }
                 // At the time we are scheduled, we might already been disposed
-                self.withMutex { $0.lock() }
+                self._mutex.lock()
                 guard let callback = self.callback else {
-                    return self.withMutex { $0.unlock() }
+                    return self._mutex.unlock()
                 }
 
                 self.validate(eventType: eventType)
 
-                self.withMutex { $0.unlock() }
+                self._mutex.unlock()
                 callback(eventType)
                 if case .event(.end) = eventType {
                     self.dispose()

From bfbf94bdb4e6b1edeb1d9e63967a7137d943f51b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Niil=20=C3=96hlin?= <niil.ohlin@izettle.com>
Date: Mon, 30 Mar 2020 12:46:10 +0200
Subject: [PATCH 3/4] rename _mutex to mutex

---
 Flow/Callbacker.swift          | 22 +++++++++++-----------
 Flow/Disposable.swift          | 32 ++++++++++++++++----------------
 Flow/Future.swift              | 16 ++++++++--------
 Flow/FutureQueue.swift         | 32 ++++++++++++++++----------------
 Flow/Locking.swift             | 30 +++++++++++++++---------------
 Flow/OrderedCallbacker.swift   | 22 +++++++++++-----------
 Flow/Signal+Construction.swift | 20 ++++++++++----------
 Flow/Signal+Scheduling.swift   | 26 +++++++++++++-------------
 8 files changed, 100 insertions(+), 100 deletions(-)

diff --git a/Flow/Callbacker.swift b/Flow/Callbacker.swift
index c29209c..99bfccf 100644
--- a/Flow/Callbacker.swift
+++ b/Flow/Callbacker.swift
@@ -20,20 +20,20 @@ public final class Callbacker<Value> {
     }
 
     private var callbacks = Callbacks.none
-    private var _mutex = pthread_mutex_t()
+    private var mutex = pthread_mutex_t()
 
     public init() {
-        _mutex.initialize()
+        mutex.initialize()
     }
 
     deinit {
-        _mutex.deinitialize()
+        mutex.deinitialize()
     }
 
     /// - Returns: True if no callbacks has been registered.
     public var isEmpty: Bool {
-        _mutex.lock()
-        defer { _mutex.unlock() }
+        mutex.lock()
+        defer { mutex.unlock() }
 
         switch callbacks {
         case .none: return true
@@ -45,8 +45,8 @@ public final class Callbacker<Value> {
     /// Register a callback to be called when `callAll` is executed.
     /// - Returns: A `Disposable` to be disposed to unregister the callback.
     public func addCallback(_ callback: @escaping (Value) -> Void) -> Disposable {
-        _mutex.lock()
-        defer { _mutex.unlock() }
+        mutex.lock()
+        defer { mutex.unlock() }
 
         let key = generateKey()
 
@@ -62,8 +62,8 @@ public final class Callbacker<Value> {
         }
 
         return NoLockKeyDisposer(key) { key in
-            self._mutex.lock()
-            defer { self._mutex.unlock() }
+            self.mutex.lock()
+            defer { self.mutex.unlock() }
 
             switch self.callbacks {
             case .single(let singleKey, _) where singleKey == key:
@@ -81,9 +81,9 @@ public final class Callbacker<Value> {
 
     /// Will call all registered callbacks with `value`
     public func callAll(with value: Value) {
-        _mutex.lock()
+        mutex.lock()
         let callbacks = self.callbacks
-        _mutex.unlock()
+        mutex.unlock()
 
         switch callbacks {
         case .none: break
diff --git a/Flow/Disposable.swift b/Flow/Disposable.swift
index 71c4149..5949b22 100644
--- a/Flow/Disposable.swift
+++ b/Flow/Disposable.swift
@@ -28,24 +28,24 @@ public struct NilDisposer: Disposable {
 /// - Note: Is thread safe and reentrant (dispose callback could call itself)
 public final class Disposer: Disposable {
     private var disposer: (() -> ())?
-    private var _mutex = pthread_mutex_t()
+    private var mutex = pthread_mutex_t()
 
     /// Pass a closure to be called when being disposed
     public init(_ disposer: @escaping () -> () = {}) {
         self.disposer = disposer
-        _mutex.initialize()
+        mutex.initialize()
     }
 
     deinit {
         dispose()
-        _mutex.deinitialize()
+        mutex.deinitialize()
     }
 
     public func dispose() {
-        _mutex.lock()
+        mutex.lock()
         let disposer = self.disposer
         self.disposer = nil
-        _mutex.unlock()
+        mutex.unlock()
         disposer?()
     }
 }
@@ -57,51 +57,51 @@ public final class Disposer: Disposable {
 /// - Note: New disposables could be added after a disposal.
 public final class DisposeBag: Disposable {
     private var disposables: [Disposable]
-    private var _mutex = pthread_mutex_t()
+    private var mutex = pthread_mutex_t()
 
     /// Create an empty instance
     public init() {
         self.disposables = []
-        _mutex.initialize()
+        mutex.initialize()
     }
 
     /// Create an instance already containing `disposables`
     public init<S: Sequence>(_ disposables: S) where S.Iterator.Element == Disposable {
         self.disposables = Array(disposables)
-        _mutex.initialize()
+        mutex.initialize()
     }
 
     /// Create an instance already containing `disposables`
     public init(_ disposables: Disposable...) {
         self.disposables = disposables
-        _mutex.initialize()
+        mutex.initialize()
     }
 
     deinit {
         dispose()
-        _mutex.deinitialize()
+        mutex.deinitialize()
     }
 
     /// Returns true if there is currently no disposables to dispose.
     public var isEmpty: Bool {
-        _mutex.lock()
+        mutex.lock()
         let isEmpty = disposables.isEmpty
-        _mutex.unlock()
+        mutex.unlock()
         return isEmpty
     }
 
     public func dispose() {
-        _mutex.lock()
+        mutex.lock()
         let disposables = self.disposables // make sure to make a copy in the case any call to dispose will recursivaly call us back.
         self.disposables = []
-        _mutex.unlock()
+        mutex.unlock()
         for disposable in disposables { disposable.dispose() }
     }
 
     /// Add `disposable` to `self`
     public func add(_ disposable: Disposable) {
-        _mutex.lock()
-        defer { _mutex.unlock() }
+        mutex.lock()
+        defer { mutex.unlock() }
         disposables.append(disposable)
     }
 }
diff --git a/Flow/Future.swift b/Flow/Future.swift
index ce6d755..82bf33f 100644
--- a/Flow/Future.swift
+++ b/Flow/Future.swift
@@ -57,7 +57,7 @@ public final class Future<Value> {
 
     private var state: State
     private let clone: () -> Future
-    private var _mutex = pthread_mutex_t()
+    private var mutex = pthread_mutex_t()
 
     /// Helper used to move external futures inside `Future.init`'s `onComplete` closure. Needed for repetition to work properly.
     public struct Mover {
@@ -107,7 +107,7 @@ public final class Future<Value> {
                 try onResult(completion, Mover(shouldClone: true))
             }
         }
-        _mutex.initialize()
+        mutex.initialize()
 
         scheduler.async {
             do {
@@ -143,13 +143,13 @@ public final class Future<Value> {
 
         state = .completed(result)
         clone = { Future(result: result) }
-        _mutex.initialize()
+        mutex.initialize()
     }
 
     deinit {
         OSAtomicDecrement32(&futureUnitTestAliveCount)
         memPrint("Future deinit", futureUnitTestAliveCount)
-        _mutex.deinitialize()
+        mutex.deinitialize()
     }
 }
 
@@ -328,17 +328,17 @@ func memPrint(_ str: String, _ count: Int32) {
 
 private extension Future {
     private var protectedState: State {
-        _mutex.lock()
-        defer { _mutex.unlock() }
+        mutex.lock()
+        defer { mutex.unlock() }
         return state
     }
 
     func lock() {
-        _mutex.lock()
+        mutex.lock()
     }
 
     func unlock() {
-        _mutex.unlock()
+        mutex.unlock()
     }
 
     func completeWithResult(_ result: Result<Value>) {
diff --git a/Flow/FutureQueue.swift b/Flow/FutureQueue.swift
index eb5b6ff..145ed53 100644
--- a/Flow/FutureQueue.swift
+++ b/Flow/FutureQueue.swift
@@ -18,7 +18,7 @@ public final class FutureQueue<Resource> {
     private let queueScheduler: Scheduler
     private var _closedError: Error?
     private let isEmptyCallbacker = Callbacker<Bool>()
-    private var _mutex = pthread_mutex_t()
+    private var mutex = pthread_mutex_t()
 
     // enqueued items.
     private var items: [Executable] = [] {
@@ -61,9 +61,9 @@ public extension FutureQueue {
         return Future { completion in
             let item = QueueItem<Output>(operation: operation, completion: completion)
 
-            self._mutex.lock()
+            self.mutex.lock()
             self.items.append(item)
-            self._mutex.unlock()
+            self.mutex.unlock()
 
             self.executeNextItem()
 
@@ -119,8 +119,8 @@ public extension FutureQueue {
 public extension FutureQueue {
     /// Do we have any enqueued operations?
     var isEmpty: Bool {
-        _mutex.lock()
-        defer { _mutex.unlock() }
+        mutex.lock()
+        defer { mutex.unlock() }
         return items.isEmpty
     }
 
@@ -166,20 +166,20 @@ public extension FutureQueue {
 
     /// The error passed to `abortQueuedExecutionWithError()` if called with `shouldCloseQueue` as true.
     var closedError: Error? {
-        _mutex.lock()
-        defer { _mutex.unlock() }
+        mutex.lock()
+        defer { mutex.unlock() }
         return _closedError
     }
 }
 
 private extension FutureQueue {
-    func lock() { _mutex.lock() }
-    func unlock() { _mutex.unlock() }
+    func lock() { mutex.lock() }
+    func unlock() { mutex.unlock() }
 
     func removeItem(_ item: Executable) {
-        _mutex.lock()
+        mutex.lock()
         _ = items.firstIndex { $0 === item }.map { items.remove(at: $0) }
-        _mutex.unlock()
+        mutex.unlock()
     }
 
     func executeNextItem() {
@@ -217,25 +217,25 @@ private final class QueueItem<Output>: Executable {
     private let completion: (Result<Output>) -> ()
     private weak var future: Future<Output>?
     private var hasBeenCancelled = false
-    private var _mutex = pthread_mutex_t()
+    private var mutex = pthread_mutex_t()
 
     init(operation: @escaping () throws -> Future<Output>, completion: @escaping (Result<Output>) -> ()) {
         self.completion = completion
         self.operation = operation
-        _mutex.initialize()
+        mutex.initialize()
 
         OSAtomicIncrement32(&queueItemUnitTestAliveCount)
         memPrint("Queue Item init", queueItemUnitTestAliveCount)
     }
 
     deinit {
-        _mutex.deinitialize()
+        mutex.deinitialize()
         OSAtomicDecrement32(&queueItemUnitTestAliveCount)
         memPrint("Queue Item deinit", queueItemUnitTestAliveCount)
     }
 
-    private func lock() { _mutex.lock() }
-    private func unlock() { _mutex.unlock() }
+    private func lock() { mutex.lock() }
+    private func unlock() { mutex.unlock() }
 
     private func complete(_ result: (Result<Output>)) {
         lock()
diff --git a/Flow/Locking.swift b/Flow/Locking.swift
index 874badf..24af83c 100644
--- a/Flow/Locking.swift
+++ b/Flow/Locking.swift
@@ -10,24 +10,24 @@ import Foundation
 
 /// A reference wrapper around a POSIX thread mutex
 public final class Mutex {
-    private var _mutex = pthread_mutex_t()
+    private var mutex = pthread_mutex_t()
 
     public init() {
-        _mutex.initialize()
+        mutex.initialize()
     }
 
     deinit {
-        _mutex.deinitialize()
+        mutex.deinitialize()
     }
 
     /// Attempt to acquire the lock, blocking a thread’s execution until the lock can be acquired.
     public func lock() {
-        _mutex.lock()
+        mutex.lock()
     }
 
     /// Releases a previously acquired lock.
     public func unlock() {
-        _mutex.unlock()
+        mutex.unlock()
     }
 }
 
@@ -35,7 +35,7 @@ extension pthread_mutex_t {
     mutating func withPointer<T>(_ body: (PThreadMutex) throws -> T) rethrows -> T {
         try withUnsafeMutablePointer(to: &self, body)
     }
-    
+
     mutating func initialize() {
         withPointer { $0.initialize() }
     }
@@ -99,16 +99,16 @@ final class StateAndCallback<Value, State>: Disposable {
     var callback: ((Value) -> ())?
     var val: State
     fileprivate var disposables = [Disposable]()
-    private var _mutex = pthread_mutex_t()
+    private var mutex = pthread_mutex_t()
 
     init(state: State, callback: @escaping (Value) -> ()) {
         val = state
         self.callback = callback
-        _mutex.initialize()
+        mutex.initialize()
     }
 
     deinit {
-        _mutex.deinitialize()
+        mutex.deinitialize()
         dispose()
     }
 
@@ -118,27 +118,27 @@ final class StateAndCallback<Value, State>: Disposable {
     }
 
     func lock() {
-        _mutex.lock()
+        mutex.lock()
     }
 
     func unlock() {
-        _mutex.unlock()
+        mutex.unlock()
     }
 
     @discardableResult
     func protect<T>(_ block: () throws -> T) rethrows -> T {
-        _mutex.lock()
-        defer { _mutex.unlock() }
+        mutex.lock()
+        defer { mutex.unlock() }
         return try block()
     }
 
     func dispose() {
-        _mutex.lock()
+        mutex.lock()
         let disposables = self.disposables // make sure to make a copy in the case any call to dispose will recursivaly call us back.
         callback = nil
         exclusiveQueue = []
         self.disposables = []
-        _mutex.unlock()
+        mutex.unlock()
         for disposable in disposables { disposable.dispose() }
     }
 
diff --git a/Flow/OrderedCallbacker.swift b/Flow/OrderedCallbacker.swift
index 3d557ab..075db90 100644
--- a/Flow/OrderedCallbacker.swift
+++ b/Flow/OrderedCallbacker.swift
@@ -14,21 +14,21 @@ import Foundation
 /// - Note: Is thread safe.
 public final class OrderedCallbacker<OrderedValue, CallbackValue> {
     private var callbacks: [Key: (OrderedValue, (CallbackValue) -> Future<()>)] = [:]
-    private var _mutex = pthread_mutex_t()
+    private var mutex = pthread_mutex_t()
 
     public init() {
-        _mutex.initialize()
+        mutex.initialize()
     }
 
     deinit {
-        _mutex.deinitialize()
+        mutex.deinitialize()
     }
 
     /// - Returns: True if no callbacks has been registered.
     public var isEmpty: Bool {
-        _mutex.lock()
+        mutex.lock()
         let isEmpty = callbacks.isEmpty
-        _mutex.unlock()
+        mutex.unlock()
         return isEmpty
     }
 
@@ -37,14 +37,14 @@ public final class OrderedCallbacker<OrderedValue, CallbackValue> {
     /// - Parameter orderedValue: The value used to order this callback
     /// - Returns: A `Disposable` to be disposed to unregister the callback.
     public func addCallback(_ callback: @escaping (CallbackValue) -> Future<()>, orderedBy orderedValue: OrderedValue) -> Disposable {
-        _mutex.lock()
-        defer { _mutex.unlock() }
+        mutex.lock()
+        defer { mutex.unlock() }
         let key = generateKey()
         callbacks[key] = (orderedValue, callback)
         return Disposer {
-            self._mutex.lock()
+            self.mutex.lock()
             self.callbacks[key] = nil
-            self._mutex.unlock()
+            self.mutex.unlock()
         }
     }
 
@@ -52,9 +52,9 @@ public final class OrderedCallbacker<OrderedValue, CallbackValue> {
     /// - Returns: A `Future` that will complete when all callbacks has been called.
     @discardableResult
     public func callAll(with value: CallbackValue, isOrderedBefore: (OrderedValue, OrderedValue) -> Bool) -> Future<()> {
-        _mutex.lock()
+        mutex.lock()
         let sortedCallbacks = callbacks.values.sorted { isOrderedBefore($0.0, $1.0) }.map { $1 }
-        _mutex.unlock()
+        mutex.unlock()
         return sortedCallbacks.mapToFuture { $0(value) }.toVoid()
     }
 }
diff --git a/Flow/Signal+Construction.swift b/Flow/Signal+Construction.swift
index 7230f4e..0bdfc15 100644
--- a/Flow/Signal+Construction.swift
+++ b/Flow/Signal+Construction.swift
@@ -112,27 +112,27 @@ private final class CallbackState<Value>: Disposable {
     private var shared: SharedState<Value>?
     let sharedKey: Key
 
-    private var _mutex = pthread_mutex_t()
+    private var mutex = pthread_mutex_t()
 
     init(shared: SharedState<Value>? = nil, getValue: (() -> Value)?, callback: @escaping (EventType<Value>) -> Void) {
         self.shared = shared
         self.sharedKey = shared == nil ? 0 : generateKey()
         self.getValue = getValue
         self.callback = callback
-        _mutex.initialize()
+        mutex.initialize()
     }
 
     deinit {
-        _mutex.deinitialize()
+        mutex.deinitialize()
         shared?.remove(key: sharedKey)
     }
 
     func lock() {
-        _mutex.lock()
+        mutex.lock()
     }
 
     func unlock() {
-        _mutex.unlock()
+        mutex.unlock()
     }
 
     // For efficiency `Self` could also also behave as a `NoLockKeyDisposer``, saving us an allocation for each listener.
@@ -291,7 +291,7 @@ private final class CallbackState<Value>: Disposable {
 /// Helper to implement sharing of a single `onEvent` if more than one listner, see `SignalOption.shared`
 final class SharedState<Value> {
     private let getValue: (() -> Value)?
-    private var _mutex = pthread_mutex_t()
+    private var mutex = pthread_mutex_t()
 
     typealias Callback = (EventType<Value>) -> Void
     var firstCallback: (key: Key, value: Callback)?
@@ -301,19 +301,19 @@ final class SharedState<Value> {
 
     init(getValue: (() -> Value)? = nil) {
         self.getValue = getValue
-        _mutex.initialize()
+        mutex.initialize()
     }
 
     deinit {
-        _mutex.deinitialize()
+        mutex.deinitialize()
     }
 
     func lock() {
-        _mutex.lock()
+        mutex.lock()
     }
 
     func unlock() {
-        _mutex.unlock()
+        mutex.unlock()
     }
 
     func remove(key: Key) {
diff --git a/Flow/Signal+Scheduling.swift b/Flow/Signal+Scheduling.swift
index 2209a7d..6db5972 100644
--- a/Flow/Signal+Scheduling.swift
+++ b/Flow/Signal+Scheduling.swift
@@ -119,7 +119,7 @@ internal extension CoreSignal {
 // Using custom Disposable instead of DisposeBag for efficiency (less allocations)
 private final class OnEventTypeDisposer<Value>: Disposable {
     private var disposable: Disposable?
-    private var _mutex = pthread_mutex_t()
+    private var mutex = pthread_mutex_t()
 
     private let scheduler: Scheduler
     private var callback: ((EventType<Value>) -> Void)?
@@ -127,41 +127,41 @@ private final class OnEventTypeDisposer<Value>: Disposable {
     init(on scheduler: Scheduler, callback: @escaping (EventType<Value>) -> Void, onEventType: @escaping (@escaping (EventType<Value>) -> Void) -> Disposable) {
         self.scheduler = scheduler
         self.callback = callback
-        _mutex.initialize()
+        mutex.initialize()
 
         let disposable = onEventType { [weak self] in self?.handleEventType($0) }
 
-        _mutex.lock()
+        mutex.lock()
         if self.callback == nil {
             disposable.dispose()
         } else {
             self.disposable = disposable
         }
-        _mutex.unlock()
+        mutex.unlock()
     }
 
     deinit {
         dispose()
-        _mutex.deinitialize()
+        mutex.deinitialize()
     }
 
     public func dispose() {
-        _mutex.lock()
+        mutex.lock()
         let disposable = self.disposable
         self.disposable = nil
         callback = nil
-        _mutex.unlock()
+        mutex.unlock()
         disposable?.dispose()
     }
 
     func handleEventType(_ eventType: EventType<Value>) {
-        _mutex.lock()
+        mutex.lock()
 
         guard let callback = self.callback else {
-            return _mutex.unlock()
+            return mutex.unlock()
         }
 
-        _mutex.unlock()
+        mutex.unlock()
 
         if scheduler.isImmediate {
             validate(eventType: eventType)
@@ -176,14 +176,14 @@ private final class OnEventTypeDisposer<Value>: Disposable {
             scheduler.async { [weak self] in
                 guard let `self` = self else { return }
                 // At the time we are scheduled, we might already been disposed
-                self._mutex.lock()
+                self.mutex.lock()
                 guard let callback = self.callback else {
-                    return self._mutex.unlock()
+                    return self.mutex.unlock()
                 }
 
                 self.validate(eventType: eventType)
 
-                self._mutex.unlock()
+                self.mutex.unlock()
                 callback(eventType)
                 if case .event(.end) = eventType {
                     self.dispose()

From 797072b267fedd887d4549100e05390a8d625624 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Niil=20=C3=96hlin?= <niil.ohlin@izettle.com>
Date: Mon, 30 Mar 2020 14:49:40 +0200
Subject: [PATCH 4/4] Remove missing return statement

---
 Flow/Locking.swift | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Flow/Locking.swift b/Flow/Locking.swift
index 24af83c..4447da2 100644
--- a/Flow/Locking.swift
+++ b/Flow/Locking.swift
@@ -33,7 +33,7 @@ public final class Mutex {
 
 extension pthread_mutex_t {
     mutating func withPointer<T>(_ body: (PThreadMutex) throws -> T) rethrows -> T {
-        try withUnsafeMutablePointer(to: &self, body)
+        return try withUnsafeMutablePointer(to: &self, body)
     }
 
     mutating func initialize() {