AsyncBridge: Add new wrapper class that bridges async sequences

This class encapsulates all the logic and operations required to
correctly bridge an async operation into a sync function.
In particular, it also makes it less easy to forget to check if the
io_service exited because it was stop()ped.

include/asynchronousBridge.h

@@ -0,0 +1,47 @@
+#ifndef ASYNCHRONOUS_BRIDGE_H
+#define ASYNCHRONOUS_BRIDGE_H
+
+#include <atomic>
+#include <boost/asio.hpp>
+
+namespace smo {
+
+class AsynchronousBridge
+{
+public:
+	AsynchronousBridge(boost::asio::io_service &io_service)
+	: io_service(io_service), isAsyncOperationComplete(false)
+	{}
+
+	void setAsyncOperationComplete(void)
+	{
+		/**		EXPLANATION:
+		 * This empty post()ed message is necessary to ensure that the thread
+		 * that's waiting on the io_service is signaled to wake up and check
+		 * the io_service's queue.
+		 */
+		isAsyncOperationComplete.store(true);
+		io_service.post([]{});
+	}
+
+	void waitForAsyncOperationCompleteOrIoServiceStopped(void)
+	{
+		for (;;)
+		{
+			io_service.run_one();
+			if (isAsyncOperationComplete.load() || io_service.stopped())
+				{ break; }
+		}
+	}
+
+	bool exitedBecauseIoServiceStopped(void) const
+		{ return io_service.stopped(); }
+
+private:
+	std::atomic<bool> isAsyncOperationComplete;
+	boost::asio::io_service &io_service;
+};
+
+} // namespace smo
+
+#endif // ASYNCHRONOUS_BRIDGE_H