singleapplication.cpp

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#include "singleapplication.h"
#include <QLocalSocket>
#include <utility>
#ifdef QT_DEBUG
#include "debughelper.h"
#endif
 
SingleApplication::SingleApplication(int &argc, char *argv[], QString uniqueKey)
    : QApplication(argc, argv), _uniqueKey(std::move(uniqueKey)) {
  sharedMemory.setKey(_uniqueKey);
  if (sharedMemory.attach()) {
    _isRunning = true;
  } else {
    _isRunning = false;
    // create shared memory.
    if (!sharedMemory.create(1)) {
#ifdef QT_DEBUG
      dbg() << "Unable to create single instance.";
#endif
      return;
    }
    // create local server and listen to incomming messages from other
    // instances.
    localServer.reset(new QLocalServer(this));
    connect(localServer.data(), &QLocalServer::newConnection, this,
            &SingleApplication::receiveMessage);
    localServer->listen(_uniqueKey);
  }
}
 
// public slots.
 
void SingleApplication::receiveMessage() {
  QLocalSocket *localSocket = localServer->nextPendingConnection();
  if (!localSocket->waitForReadyRead(timeout)) {
#ifdef QT_DEBUG
    dbg() << localSocket->errorString().toLatin1();
#endif
    return;
  }
  QByteArray byteArray = localSocket->readAll();
  QString message = QString::fromUtf8(byteArray.constData());
  emit messageAvailable(message);
  localSocket->disconnectFromServer();
}
 
// public functions.
bool SingleApplication::isRunning() { return _isRunning; }
 
bool SingleApplication::sendMessage(const QString &message) {
  if (!_isRunning)
    return false;
  QLocalSocket localSocket(this);
  localSocket.connectToServer(_uniqueKey, QIODevice::WriteOnly);
  if (!localSocket.waitForConnected(timeout)) {
#ifdef QT_DEBUG
    dbg() << localSocket.errorString().toLatin1();
#endif
    return false;
  }
  localSocket.write(message.toUtf8());
  if (!localSocket.waitForBytesWritten(timeout)) {
#ifdef QT_DEBUG
    dbg() << localSocket.errorString().toLatin1();
#endif
    return false;
  }
  localSocket.disconnectFromServer();
  return true;
}