From 583db88299bff9b95cd147e4340cf2f5227494d2 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sat, 22 Oct 2016 21:58:45 -0400
Subject: [PATCH] Added a dispatch queue-powered Apple implementation of the
 async task queue, removed any mention of skip_samples in the AY since it
 isn't implemented.

---
 Components/AY38910/AY38910.cpp |  6 ------
 Components/AY38910/AY38910.hpp |  1 -
 Concurrency/AsyncTaskQueue.cpp | 21 ++++++++++++++++++++-
 Concurrency/AsyncTaskQueue.hpp |  8 ++++++++
 4 files changed, 28 insertions(+), 8 deletions(-)

diff --git a/Components/AY38910/AY38910.cpp b/Components/AY38910/AY38910.cpp
index fc6c2fd3a..9e2aec75d 100644
--- a/Components/AY38910/AY38910.cpp
+++ b/Components/AY38910/AY38910.cpp
@@ -168,12 +168,6 @@ void AY38910::evaluate_output_volume()
 	);
 }
 
-void AY38910::skip_samples(unsigned int number_of_samples)
-{
-	// TODO
-//	printf("Skip %d\n", number_of_samples);
-}
-
 void AY38910::select_register(uint8_t r)
 {
 	_selected_register = r & 0xf;
diff --git a/Components/AY38910/AY38910.hpp b/Components/AY38910/AY38910.hpp
index 96d3724c1..82dc913af 100644
--- a/Components/AY38910/AY38910.hpp
+++ b/Components/AY38910/AY38910.hpp
@@ -49,7 +49,6 @@ class AY38910: public ::Outputs::Filter<AY38910> {
 
 		// to satisfy ::Outputs::Speaker (included via ::Outputs::Filter; not for public consumption
 		void get_samples(unsigned int number_of_samples, int16_t *target);
-		void skip_samples(unsigned int number_of_samples);
 
 	private:
 		int _selected_register;
diff --git a/Concurrency/AsyncTaskQueue.cpp b/Concurrency/AsyncTaskQueue.cpp
index 1aa544c5e..939cd016a 100644
--- a/Concurrency/AsyncTaskQueue.cpp
+++ b/Concurrency/AsyncTaskQueue.cpp
@@ -10,8 +10,14 @@
 
 using namespace Concurrency;
 
-AsyncTaskQueue::AsyncTaskQueue() : should_destruct_(false)
+AsyncTaskQueue::AsyncTaskQueue()
+#ifndef __APPLE__
+	: should_destruct_(false)
+#endif
 {
+#ifdef __APPLE__
+	serial_dispatch_queue_ = dispatch_queue_create("com.thomasharte.clocksignal.asyntaskqueue", DISPATCH_QUEUE_SERIAL);
+#else
 	thread_.reset(new std::thread([this]() {
 		while(!should_destruct_)
 		{
@@ -39,25 +45,37 @@ AsyncTaskQueue::AsyncTaskQueue() : should_destruct_(false)
 			}
 		}
 	}));
+#endif
 }
 
 AsyncTaskQueue::~AsyncTaskQueue()
 {
+#ifdef __APPLE__
+	dispatch_release(serial_dispatch_queue_);
+#else
 	should_destruct_ = true;
 	enqueue([](){});
 	thread_->join();
 	thread_.reset();
+#endif
 }
 
 void AsyncTaskQueue::enqueue(std::function<void(void)> function)
 {
+#ifdef __APPLE__
+	dispatch_async(serial_dispatch_queue_, ^{function();});
+#else
 	std::lock_guard<std::mutex> lock(queue_mutex_);
 	pending_tasks_.push_back(function);
 	processing_condition_.notify_all();
+#endif
 }
 
 void AsyncTaskQueue::flush()
 {
+#ifdef __APPLE__
+	dispatch_sync(serial_dispatch_queue_, ^{});
+#else
 	std::shared_ptr<std::mutex> flush_mutex(new std::mutex);
 	std::shared_ptr<std::condition_variable> flush_condition(new std::condition_variable);
 	std::unique_lock<std::mutex> lock(*flush_mutex);
@@ -66,4 +84,5 @@ void AsyncTaskQueue::flush()
 		flush_condition->notify_all();
 	});
 	flush_condition->wait(lock);
+#endif
 }
diff --git a/Concurrency/AsyncTaskQueue.hpp b/Concurrency/AsyncTaskQueue.hpp
index 77485265a..aa53dd954 100644
--- a/Concurrency/AsyncTaskQueue.hpp
+++ b/Concurrency/AsyncTaskQueue.hpp
@@ -14,6 +14,10 @@
 #include <list>
 #include <condition_variable>
 
+#ifdef __APPLE__
+#include <dispatch/dispatch.h>
+#endif
+
 namespace Concurrency {
 
 /*!
@@ -42,12 +46,16 @@ class AsyncTaskQueue {
 		void flush();
 
 	private:
+#ifdef __APPLE__
+		dispatch_queue_t serial_dispatch_queue_;
+#else
 		std::unique_ptr<std::thread> thread_;
 
 		std::mutex queue_mutex_;
 		std::list<std::function<void(void)>> pending_tasks_;
 		std::condition_variable processing_condition_;
 		std::atomic_bool should_destruct_;
+#endif
 };
 
 }