Scalable Servers with IO Completion Ports and How to Cook Them

// echo_server.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#define _WIN32_WINNT 0x0400 

#include <stdio.h>
#include <conio.h>
#include <time.h>
#include "INCLUDE/server_service.h"

#define BUFF_SIZE 8
#define MAX_CONNECTIONS 10
#define NO_THREADS 4
#define TIME_OUT 10
#define PORT 8080

//---------------------------------------------------------------------------------
struct Attachment {
	volatile time_t				tmLastActionTime;
	char						sString[BUFF_SIZE];
	DWORD						dwStringSize; // current string size

	Attachment() { Clear(); };

	bool Commit( DWORD dwBytesTransferred ) {
		DWORD dwSize = dwStringSize + dwBytesTransferred;
	
		if ( dwBytesTransferred <= 0 ) return false;
		if ( dwSize >= BUFF_SIZE ) return false;

		dwStringSize = dwSize;
		sString[dwStringSize] = 0;
		return true;
	};

	// as requested by the API of the framework
	void Clear() { memset(this, 0, sizeof(Attachment) ); };

	// as requested by the API of the framework
	void ResetTime( bool toZero ) { 
		if (toZero) tmLastActionTime = 0;
		else {
			time_t	lLastActionTime;
			time(&lLastActionTime); 
			tmLastActionTime = lLastActionTime;
		}
	};

	// as requested by the API of the framework
	long GetTimeElapsed() {
		time_t tmCurrentTime;

		if (0 == tmLastActionTime) return 0;

		time(&tmCurrentTime);
		return (tmCurrentTime - tmLastActionTime);
	};
};

//---------------------------------------------------------------------------------
typedef ClientSocket<Attachment> MyCSocket;
typedef ServerSocket<Attachment> MySSocket;
typedef IOCPSimple<Attachment> MyIOCPSimple;
typedef ISockEvent<Attachment> MyISockEvent;
typedef ServerService<Attachment> MyServerService;
//---------------------------------------------------------------------------------

class MyISockEventHandler: public MyISockEvent {
public:
	MyISockEventHandler() {};
	~MyISockEventHandler() {};

	// empty method, not used
	virtual void OnClose( MyCSocket *pSocket, MYOVERLAPPED *pOverlap, 
		MySSocket *pServerSocket, MyIOCPSimple *pHIocp ) {};

	// empty method, not used
	virtual void OnPending( MyCSocket *pSocket, MYOVERLAPPED *pOverlap, 
		MySSocket *pServerSocket, MyIOCPSimple *pHIocp ) {};

	virtual void OnAccept( MyCSocket *pSocket, MYOVERLAPPED *pOverlap, 
		MySSocket *pServerSocket, MyIOCPSimple *pHIocp ) {
		int nRet;
		DWORD dwSize;
		char *temp;

		dwSize = BUFF_SIZE - 1;
		temp = pSocket->GetAttachment()->sString;

		// initiate the reading with OnAccept
		nRet = pSocket->ReadFromSocket( temp, dwSize );
		pSocket->GetAttachment()->ResetTime( false );

		if ( nRet == SOCKET_ERROR ) {
			pServerSocket->Release( pSocket );
		}
	};

	virtual void OnReadFinalized( MyCSocket *pSocket, MYOVERLAPPED *pOverlap,
		DWORD dwBytesTransferred, MySSocket *pServerSocket, MyIOCPSimple *pHIocp ) {
		int nRet;
		DWORD dwSize, dwPos;
		char *temp;

		// finalize the filling of the buffer
		pSocket->GetAttachment()->Commit( dwBytesTransferred );

		dwSize = BUFF_SIZE - 1;
		dwPos = pSocket->GetAttachment()->dwStringSize;
		temp = pSocket->GetAttachment()->sString;

		nRet = pSocket->ReadFromSocket(	temp + dwPos, dwSize - dwPos );
		pSocket->GetAttachment()->ResetTime( false );

		if ( nRet == SOCKET_ERROR ) {
			pServerSocket->Release( pSocket );
		}
		else if ( nRet == RECV_BUFFER_EMPTY ) {
			// means that dwSize - dwPos == 0, so send the data 
			// back to the socket

			nRet = pSocket->WriteToSocket( temp, dwSize );
			if ( nRet == SOCKET_ERROR ) {
				pServerSocket->Release( pSocket );
			}
		}
	};

	virtual void OnWriteFinalized( MyCSocket *pSocket, MYOVERLAPPED *pOverlap,
		DWORD dwBytesTransferred, MySSocket *pServerSocket, MyIOCPSimple *pHIocp ) {
		char *temp = pSocket->GetAttachment()->sString;

		// clean the attachment
		pSocket->GetAttachment()->Clear();

		// and once again
		OnAccept(pSocket, NULL,pServerSocket, NULL);
	};
};

//---------------------------------------------------------------------------------
int main(int argc, char* argv[])
{
    int	nRet;
	MyServerService *sService;
	MyISockEventHandler *mSockHndl;
	WSAData	wsData;

	nRet = WSAStartup(MAKEWORD(2,2),&wsData);
	if ( nRet < 0 ) {
		Log::LogMessage(L"Can't load winsock.dll.\n");
		return -1;
	}

	try {
		Overlapped::Init( MAX_CONNECTIONS );
		mSockHndl = new MyISockEventHandler();

		sService = new MyServerService((MyISockEvent *) mSockHndl, PORT, 
			MAX_CONNECTIONS, NO_THREADS, TIME_OUT, false);
		sService->start();

		printf("hit <ENTER> to stop ...\n");
		while( !_kbhit() ) ::Sleep(100);
		
		delete sService;
		delete mSockHndl;
	}
	catch (const char *err) {
		printf("%s\n", err);
	}
	catch (const wchar_t *err) {
		wprintf(L"%ls\n", err);
	}

	WSACleanup();
	return 0;
}