From 3ab93cf6eea1abba891a97da7cd3611d5082436f Mon Sep 17 00:00:00 2001
From: Ian Curtis <i.curtis@gmail.com>
Date: Tue, 2 Jan 2018 18:54:34 +0000
Subject: [PATCH] add asynchronous sending functions

---
 Src/Network/UDPSend.cpp | 52 +++++++++++++++++++++++++++++++++++++++--
 Src/Network/UDPSend.h   | 17 +++++++++++++-
 2 files changed, 66 insertions(+), 3 deletions(-)

diff --git a/Src/Network/UDPSend.cpp b/Src/Network/UDPSend.cpp
index c3dc35f..fa383ac 100644
--- a/Src/Network/UDPSend.cpp
+++ b/Src/Network/UDPSend.cpp
@@ -9,18 +9,66 @@ namespace SMUDP
 
 UDPSend::UDPSend()
 {
-	m_socket = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);		// create the socket
-	m_event = CreateEvent(NULL, FALSE, FALSE, NULL);
+	m_socket		= socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);		// create the socket
+	m_event			= CreateEvent(NULL, FALSE, FALSE, NULL);
+	m_exitEvent		= CreateEvent(NULL, FALSE, FALSE, NULL);
+	m_dataReady		= CreateEvent(NULL, FALSE, FALSE, NULL);			
+	m_sendComplete	= CreateEvent(NULL, FALSE, TRUE, NULL);			// start off ready
+
+	m_sendThread = std::thread(&UDPSend::SendThread, this);
 
 	WSAEventSelect(m_socket, m_event, FD_READ | FD_WRITE);
 }
 
 UDPSend::~UDPSend()
 {
+	SetEvent(m_exitEvent);		// trigger thread to exit
+	m_sendThread.join();		// block until thread has exited
+	CloseHandle(m_exitEvent);	// clean up the rest of the resources
+	CloseHandle(m_dataReady);
+	CloseHandle(m_sendComplete);
+
 	closesocket(m_socket);
 	CloseHandle(m_event);
 }
 
+bool UDPSend::SendAsync(const char* address, int port, int length, const void *data, int timeout)
+{
+	WaitForSingleObject(m_sendComplete, INFINITE);	// block until previous sends have completed, don't want overlapping
+
+	m_data.clear();
+	m_data.insert(m_data.end(), (UINT8*)data, (UINT8*)data + length);
+
+	m_address	= address;
+	m_port		= port;
+	m_timeout	= timeout;
+
+	SetEvent(m_dataReady);
+
+	return true;
+}
+
+void UDPSend::SendThread()
+{
+	HANDLE events[2];
+
+	events[0] = m_exitEvent;
+	events[1] = m_dataReady;
+
+	while (true) {
+
+		auto result = WaitForMultipleObjects(_countof(events), events, FALSE, INFINITE);
+
+		if (result == WAIT_OBJECT_0) {					// exit event triggered
+			break;	
+		}
+		else if (result == (WAIT_OBJECT_0 + 1)) {		// data ready
+			Send(m_address.c_str(), m_port, (int)m_data.size(), m_data.data(), m_timeout);
+			SetEvent(m_sendComplete);
+		}
+	}
+}
+
 bool UDPSend::Send(const char* ip, int port, int length, const void *data, int timeout)
 {
 	UINT8* pData = (UINT8*)data;
diff --git a/Src/Network/UDPSend.h b/Src/Network/UDPSend.h
index efcfae9..168e1d4 100644
--- a/Src/Network/UDPSend.h
+++ b/Src/Network/UDPSend.h
@@ -3,6 +3,8 @@
 
 #include "UDPPacket.h"
 #include "WinSockWrap.h"
+#include <vector>
+#include <thread>
 
 namespace SMUDP
 {
@@ -12,7 +14,8 @@ namespace SMUDP
 		UDPSend();
 		~UDPSend();
 
-		bool Send(const char* address, int port, int length, const void *data, int timeout);
+		bool Send(const char* address, int port, int length, const void *data, int timeout);		// blocking
+		bool SendAsync(const char* address, int port, int length, const void *data, int timeout);	// no blocking call
 
 	private:
 
@@ -23,6 +26,18 @@ namespace SMUDP
 		SOCKET m_socket;
 		HANDLE m_event;
 		WinSockWrap m_winsockWrap;
+
+		// async
+		void SendThread();
+
+		HANDLE m_exitEvent;
+		HANDLE m_dataReady;
+		HANDLE m_sendComplete;
+		int m_port;
+		int m_timeout;
+		std::string m_address;
+		std::vector<UINT8> m_data;
+		std::thread m_sendThread;
 	};
 }