CreateIoCompletionPort

iocp.c

#include <WINSOCK2.H>
#include <stdio.h>

#define PORT 5150
#define MSGSIZE 1024
#pragma comment(lib, "ws2_32.lib")

typedef enum {
    RECV_POSTED
} OPERATION_TYPE;

typedef struct {
    WSAOVERLAPPED overlap;
    WSABUF Buffer;
    char szMessage[MSGSIZE];
    DWORD NumberOfBytesRecvd;
    DWORD Flags;
    OPERATION_TYPE OperationType;
} PER_IO_OPERATION_DATA, * LPPER_IO_OPERATION_DATA;

DWORD WINAPI WorkerThread(LPVOID);

int main() {
    WSADATA wsaData;
    SOCKET sListen, sClient;
    SOCKADDR_IN local, client;
    DWORD i, dwThreadId;
    int iaddrSize = sizeof(SOCKADDR_IN);
    HANDLE CompletionPort = INVALID_HANDLE_VALUE;
    SYSTEM_INFO systeminfo;
    LPPER_IO_OPERATION_DATA lpPerIOData = NULL;
    WSAStartup(0x0202, &wsaData);
    CompletionPort = CreateIoCompletionPort(INVALID_HANDLE_VALUE, NULL, 0, 0);

    // Create worker thread
    GetSystemInfo(&systeminfo);
    for (i = 0; i < systeminfo.dwNumberOfProcessors; i++) {
        CreateThread(NULL, 0, WorkerThread, CompletionPort, 0, &dwThreadId);
    }
    // Create listening socket
    sListen = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);

    // Bind
    local.sin_addr.S_un.S_addr = htonl(INADDR_ANY);
    local.sin_family = AF_INET;
    local.sin_port = htons(PORT);
    bind(sListen, (struct sockaddr*)&local, sizeof(SOCKADDR_IN));

    // Listen
    listen(sListen, 3);

    while (TRUE) {
        // Accept a connection
        sClient = accept(sListen, (struct sockaddr*)&client, &iaddrSize);
        printf("Accepted client:%s:%d\n", inet_ntoa(client.sin_addr), ntohs(client.sin_port));
        // Associate the newly arrived client socket with completion port
        CreateIoCompletionPort((HANDLE)sClient, CompletionPort, (DWORD)sClient, 0);
        // Launch an asynchronous operation for new arrived connection
        lpPerIOData = (LPPER_IO_OPERATION_DATA)HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, sizeof(PER_IO_OPERATION_DATA));
        lpPerIOData->Buffer.len = MSGSIZE;
        lpPerIOData->Buffer.buf = lpPerIOData->szMessage;
        lpPerIOData->OperationType = RECV_POSTED;
        WSARecv(sClient, &lpPerIOData->Buffer, 1, &lpPerIOData->NumberOfBytesRecvd, &lpPerIOData->Flags, &lpPerIOData->overlap, NULL);
    }
    PostQueuedCompletionStatus(CompletionPort, 0xFFFFFFFF, 0, NULL);
    CloseHandle(CompletionPort);
    closesocket(sListen);
    WSACleanup();
    return 0;
}

DWORD WINAPI WorkerThread(LPVOID CompletionPortID)
{
    HANDLE CompletionPort = (HANDLE)CompletionPortID;
    DWORD dwBytesTransferred;
    SOCKET sClient;
    LPPER_IO_OPERATION_DATA lpPerIOData = NULL;
    while (TRUE) {
        GetQueuedCompletionStatus(CompletionPort, &dwBytesTransferred, &sClient, (LPOVERLAPPED*)&lpPerIOData, INFINITE);

        if (dwBytesTransferred == 0xFFFFFFFF) {
            return 0;
        }
        if (lpPerIOData->OperationType == RECV_POSTED) {
            if (dwBytesTransferred == 0) {
                // Connection was closed by client
                closesocket(sClient);
                HeapFree(GetProcessHeap(), 0, lpPerIOData);
            }
            else {
                lpPerIOData->szMessage[dwBytesTransferred] = '\0';
                send(sClient, lpPerIOData->szMessage, dwBytesTransferred, 0);
                // Launch another asynchronous operation for sClient
                memset(lpPerIOData, 0, sizeof(PER_IO_OPERATION_DATA));
                lpPerIOData->Buffer.len = MSGSIZE;
                lpPerIOData->Buffer.buf = lpPerIOData->szMessage;
                lpPerIOData->OperationType = RECV_POSTED;
                WSARecv(sClient, &lpPerIOData->Buffer, 1, &lpPerIOData->NumberOfBytesRecvd, &lpPerIOData->Flags, &lpPerIOData->overlap, NULL);
            }
        }
    }
    return 0;
}