系统优化随记

时间：2018-04-22 12:49:58 阅读：205 评论：0 收藏：0 [点我收藏+]

源起

手头的项目使用TCP协议传输实时非压缩视频流，需要很大的带宽，但我们的程序只能达到400Mb，使用iperf工具测试却可以达到700Mb以上。

优化过程

优化数据发送流程

由于项目采用QT作为底层库，初步怀疑QT封装socket操作导致效率降低，写了一个简单的测试程序用于验证。

#ifndef TCPSERVER_H
#define TCPSERVER_H

#include <QObject>
#include <QThread>
class QTcpServer;
class QTcpSocket;


class tcpserver : public QObject
{
    Q_OBJECT
public:
    explicit tcpserver(QObject *parent = 0);

signals:
    void transmit();

public slots:
    void handleNewConnection();
    void onSocketRead();
    void onSocketWritten(qint64 bytes);
    void onSocketConnected();
    void onSocketDisconnected();
    void doTransmit();

private:
    //socket
    QTcpSocket *mSocket;
    QTcpServer *mTcpServer;
    QThread *mThread;
    QByteArray *mData;
    qintptr mSD;
};

#endif // TCPSERVER_H

#include "tcpserver.h"
#include <QTcpSocket>
#include <QTcpServer>
#include <unistd.h>
#include <QThreadPool>

class TransmitThread : public QRunnable
{
public:
    TransmitThread(QTcpSocket *sock) {mSocket = sock;}
    void run(){
        QByteArray dataBuff(900*1024,‘H‘);
        qintptr sd = mSocket->socketDescriptor();
            while (true) {
                int sent = ::write(sd,dataBuff.data(),dataBuff.size());
//                if(sent != dataBuff.size()){
//                     qInfo() << "sent" << sent << "/" <<dataBuff.size();
//                }
                if(sent < 0){
                    QThread::msleep(5);
                }
            }

//        while (true) {
//            if (mSocket->bytesToWrite() > 1000000) continue;
//            int sent = mSocket->write(dataBuff);
//            qInfo() << "sent" << sent << "/" <<dataBuff.size();
//            QThread::sleep(1);
//            mSocket->waitForBytesWritten();
//        }
    }
private:
    QTcpSocket *mSocket;
};
tcpserver::tcpserver(QObject *parent) : QObject(parent)
{
    mData = new QByteArray(900*1024,‘H‘);
    mTcpServer = new QTcpServer();
    mSocket = nullptr;
    connect(mTcpServer, &QTcpServer::newConnection, this, &tcpserver::handleNewConnection);
//    connect(this, SIGNAL(transmit()), this, SLOT(doTransmit()));
    mTcpServer->listen(QHostAddress::Any, 5001);
    mThread = new QThread;
    moveToThread(mThread);
    mTcpServer->moveToThread(mThread);
    mThread->start();
}

void tcpserver::handleNewConnection()
{
    QTcpSocket *newSocket = mTcpServer->nextPendingConnection();

    if (nullptr != mSocket && (mSocket->state() == QAbstractSocket::ConnectedState
        || mSocket->state() == QAbstractSocket::ConnectingState )) {
        //reject new connection.
        qInfo() << "reject new connection";
        newSocket->disconnectFromHost();
        delete newSocket;
        return;
    }

    qInfo() << newSocket->peerAddress().toString().split(":").last() << " connected!";
    if (nullptr != mSocket) {
        delete mSocket;
        mSocket = nullptr;
    }

    mSocket = newSocket;
    mSD = mSocket->socketDescriptor();
    connect(mSocket, &QTcpSocket::connected, this, &tcpserver::onSocketConnected);
    connect(mSocket, &QTcpSocket::disconnected, this, &tcpserver::onSocketDisconnected);
    connect(mSocket, &QTcpSocket::readyRead, this, &tcpserver::onSocketRead);
    connect(mSocket, &QTcpSocket::bytesWritten, this, &tcpserver::onSocketWritten);
    emit transmit();
    TransmitThread * th = new TransmitThread(mSocket);
    QThreadPool::globalInstance()->start(th);
}

void tcpserver::onSocketRead()
{
    QByteArray buffer = mSocket->readAll();
    qInfo() << "received:" << buffer;
}

void tcpserver::onSocketWritten(qint64 bytes)
{
    Q_UNUSED(bytes);
    emit transmit();
}

void tcpserver::onSocketConnected()
{
    qInfo() << "tcp onSocketConnected!";
    emit transmit();
}

void tcpserver::onSocketDisconnected()
{
    qInfo() << "tcp onSocketDisconnected!";
}

void tcpserver::doTransmit()
{
//    int sent = mSocket->write(*mData);

//    while (true) {
//        int sent = ::write(mSD,mData->data(),mData->size());
//        if(sent != mData->size()){
//             qInfo() << "sent" << sent << "/" <<mData->size();
//        }
//    }
    while (true) {
        if (mSocket->bytesToWrite() > 1000000) continue;
        int sent = mSocket->write(*mData);
        qInfo() << "sent" << sent << "/" <<mData->size();
        mSocket->waitForBytesWritten();
    }
}