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#include "qt-local-peer.h"
#include <QCoreApplication>
#include <QDataStream>
#include <QTime>

#if defined(Q_OS_UNIX)
#include <sys/types.h>
#include <time.h>
#include <unistd.h>
#endif

namespace QtLP_Private {
#include "qt-locked-file.cpp"
#include "qt-locked-file-unix.cpp"
}

const char* QtLocalPeer::ack = "ack";

QtLocalPeer::QtLocalPeer(QObject* parent, const QString &appId)
    : QObject(parent), id(appId) {
    QString prefix = id;
    if(id.isEmpty()) {
        id = QCoreApplication::applicationFilePath();
#if defined(Q_OS_WIN)
        id = id.toLower();
#endif
        prefix = id.section(QLatin1Char('/'), -1); //完整路径按‘/’分隔后取最后一个字段
    }
    prefix.remove(QRegExp("[^a-zA-Z]")); //去掉名称中的非字母
    prefix.truncate(6); //取前六位

    QByteArray idc = id.toUtf8();
    quint16 idNum = qChecksum(idc.constData(), idc.size());
    socketName = QLatin1String("qtsingleapp-") + prefix
                 + QLatin1Char('-') + QString::number(idNum, 16);

#if defined(Q_OS_WIN)
    if(!pProcessIdToSessionId) {
        QLibrary lib("kernel32");
        pProcessIdToSessionId = (PProcessIdToSessionId)lib.resolve("ProcessIdToSessionId");
    }
    if(pProcessIdToSessionId) {
        DWORD sessionId = 0;
        pProcessIdToSessionId(GetCurrentProcessId(), &sessionId);
        socketName += QLatin1Char('-') + QString::number(sessionId, 16);
    }
#else
    socketName += QLatin1Char('-') + QString::number(::getuid(), 16);
#endif

    server = new QLocalServer(this);
    QString lockName = QDir(QDir::tempPath()).absolutePath()
                       + QLatin1Char('/') + socketName
                       + QLatin1String("-lockfile"); //tmp目录下的锁文件
    lockFile.setFileName(lockName);
    lockFile.open(QIODevice::ReadWrite);
}



bool QtLocalPeer::isClient() {
    if(lockFile.isLocked())
        return false;

    if(!lockFile.lock(QtLP_Private::QtLockedFile::WriteLock, false))
        return true;

    //由于文件锁的存在，仅当本进程第一次启动时能执行到此并使server进行监听和关联槽函数
    bool res = server->listen(socketName);
#if defined(Q_OS_UNIX) && (QT_VERSION >= QT_VERSION_CHECK(4,5,0))
    // ### Workaround
    if(!res && server->serverError() == QAbstractSocket::AddressInUseError) {
        QFile::remove(QDir::cleanPath(QDir::tempPath()) + QLatin1Char('/') + socketName);
        res = server->listen(socketName);
    }
#endif
    if(!res)
        qWarning("QtSingleCoreApplication: listen on local socket failed, %s", qPrintable(server->errorString()));
    QObject::connect(server, &QLocalServer::newConnection, this, &QtLocalPeer::receiveConnection);
    return false;
}


bool QtLocalPeer::sendMessage(const QString &message, int timeout) {
    if(!isClient())
        return false;

    QLocalSocket socket;
    bool connOk = false;
    for(int i = 0; i < 2; i++) {
        // Try twice, in case the other instance is just starting up
        socket.connectToServer(socketName);
        connOk = socket.waitForConnected(timeout / 2);
        if(connOk || i)
            break;
        int ms = 250;
#if defined(Q_OS_WIN)
        Sleep(DWORD(ms));
#else
        struct timespec ts = { ms / 1000, (ms % 1000) * 1000 * 1000 };
        nanosleep(&ts, NULL);
#endif
    }
    if(!connOk)
        return false;

    QByteArray uMsg(message.toUtf8());
    QDataStream ds(&socket);
    ds.writeBytes(uMsg.constData(), uMsg.size());
    bool res = socket.waitForBytesWritten(timeout);
    if(res) {
        res &= socket.waitForReadyRead(timeout);   // wait for ack
        if(res)
            res &= (socket.read(qstrlen(ack)) == ack);
    }
    return res;
}

/**
 * @brief QtLocalPeer::receiveConnection 当新进程启动时，会尝试连接此进程server,server接收到newConnection信号并触发此槽函数
 */
void QtLocalPeer::receiveConnection() {
    QLocalSocket* socket = server->nextPendingConnection(); //获取新进程的socket
    if(!socket)
        return;

    while(true) {
        if(socket->state() == QLocalSocket::UnconnectedState) {
            qWarning("QtLocalPeer: Peer disconnected");
            delete socket;
            return;
        }
        if(socket->bytesAvailable() >= qint64(sizeof(quint32)))
            break;
        socket->waitForReadyRead();
    }

    QDataStream ds(socket);
    QByteArray uMsg;
    quint32 remaining;
    ds >> remaining;
    uMsg.resize(remaining);
    int got = 0;
    char* uMsgBuf = uMsg.data();
    do {
        got = ds.readRawData(uMsgBuf, remaining);
        remaining -= got;
        uMsgBuf += got;
    } while(remaining && got >= 0 && socket->waitForReadyRead(2000));
    if(got < 0) {
        qWarning("QtLocalPeer: Message reception failed %s", socket->errorString().toLatin1().constData());
        delete socket;
        return;
    }
    QString message(QString::fromUtf8(uMsg));
    socket->write(ack, qstrlen(ack));
    socket->waitForBytesWritten(1000);
    socket->waitForDisconnected(1000); // make sure client reads ack
    delete socket;
    Q_EMIT messageReceived(message); //获取新进程的启动信息并作为信号发送给前端
}