From b4c894e3e0b8726177a99b14b263ef09f9c19ff6 Mon Sep 17 00:00:00 2001
From: Yi Wang <yiw@uber.com>
Date: Wed, 20 Feb 2019 11:35:42 -0800
Subject: [PATCH 1/2] Update ConcurrentSequenceExecutor to use
 AutoReleasingSemaphore

Fixes #29
---
 Sources/Concurrency/AutoReleasingSemaphore.swift          | 2 ++
 .../Concurrency/Executor/ConcurrentSequenceExecutor.swift | 8 ++++++--
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/Sources/Concurrency/AutoReleasingSemaphore.swift b/Sources/Concurrency/AutoReleasingSemaphore.swift
index 67b7db6..34a1c20 100644
--- a/Sources/Concurrency/AutoReleasingSemaphore.swift
+++ b/Sources/Concurrency/AutoReleasingSemaphore.swift
@@ -38,6 +38,7 @@ public class AutoReleasingSemaphore {
     /// in dispatch_semaphore_wait(_:_:).
     /// - returns: This function returns non-zero if a thread is woken.
     /// Otherwise, zero is returned.
+    @discardableResult
     public func signal() -> Int {
         let newValue = waitingCount.decrementAndGet()
         if newValue < 0 {
@@ -65,6 +66,7 @@ public class AutoReleasingSemaphore {
     /// - parameter timeout: The amount of time in seconds to wait
     /// before returning with failure.
     /// - returns: The waiting result.
+    @discardableResult
     public func wait(timeout: TimeInterval) -> DispatchTimeoutResult {
         waitingCount.incrementAndGet()
         return semaphore.wait(timeout: DispatchTime.now() + timeout)
diff --git a/Sources/Concurrency/Executor/ConcurrentSequenceExecutor.swift b/Sources/Concurrency/Executor/ConcurrentSequenceExecutor.swift
index ef27fa1..5a8cb12 100644
--- a/Sources/Concurrency/Executor/ConcurrentSequenceExecutor.swift
+++ b/Sources/Concurrency/Executor/ConcurrentSequenceExecutor.swift
@@ -39,7 +39,7 @@ public class ConcurrentSequenceExecutor: SequenceExecutor {
     public init(name: String, qos: DispatchQoS = .userInitiated, shouldTrackTaskId: Bool = false, maxConcurrentTasks: Int? = nil) {
         taskQueue = DispatchQueue(label: "Executor.taskQueue-\(name)", qos: qos, attributes: .concurrent)
         if let maxConcurrentTasks = maxConcurrentTasks {
-            taskSemaphore = DispatchSemaphore(value: maxConcurrentTasks)
+            taskSemaphore = AutoReleasingSemaphore(value: maxConcurrentTasks)
         } else {
             taskSemaphore = nil
         }
@@ -63,10 +63,14 @@ public class ConcurrentSequenceExecutor: SequenceExecutor {
         return handle
     }
 
+    deinit {
+        print("deinit")
+    }
+
     // MARK: - Private
 
     private let taskQueue: DispatchQueue
-    private let taskSemaphore: DispatchSemaphore?
+    private let taskSemaphore: AutoReleasingSemaphore?
     private let shouldTrackTaskId: Bool
 
     private func execute<SequenceResultType>(_ task: Task, with sequenceHandle: SynchronizedSequenceExecutionHandle<SequenceResultType>, _ execution: @escaping (Task, Any) -> SequenceExecution<SequenceResultType>) {

From 90fb4f4ff0e0afa3ad693a006906fd8a1e749bd1 Mon Sep 17 00:00:00 2001
From: Yi Wang <yiw@uber.com>
Date: Wed, 20 Feb 2019 12:47:55 -0800
Subject: [PATCH 2/2] Remove debugging code

---
 Sources/Concurrency/Executor/ConcurrentSequenceExecutor.swift | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/Sources/Concurrency/Executor/ConcurrentSequenceExecutor.swift b/Sources/Concurrency/Executor/ConcurrentSequenceExecutor.swift
index 5a8cb12..35f6570 100644
--- a/Sources/Concurrency/Executor/ConcurrentSequenceExecutor.swift
+++ b/Sources/Concurrency/Executor/ConcurrentSequenceExecutor.swift
@@ -63,10 +63,6 @@ public class ConcurrentSequenceExecutor: SequenceExecutor {
         return handle
     }
 
-    deinit {
-        print("deinit")
-    }
-
     // MARK: - Private
 
     private let taskQueue: DispatchQueue