Fix race condition allowing to run multiple instances at the same time (closes #286968)

src/qtsingleapp/qtsinglecoreapplication.cpp

@@ -0,0 +1,155 @@
+/****************************************************************************
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+** Copyright (c) 2009 Nokia Corporation and/or its subsidiary(-ies).
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+** General Public License version 2.1 as published by the Free Software
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+****************************************************************************/
+
+
+#include "qtsinglecoreapplication.h"
+#include "qtlocalpeer.h"
+
+/*!
+    \class QtSingleCoreApplication qtsinglecoreapplication.h
+    \brief A variant of the QtSingleApplication class for non-GUI applications.
+
+    This class is a variant of QtSingleApplication suited for use in
+    console (non-GUI) applications. It is an extension of
+    QCoreApplication (instead of QApplication). It does not require
+    the QtGui library.
+
+    The API and usage is identical to QtSingleApplication, except that
+    functions relating to the "activation window" are not present, for
+    obvious reasons. Please refer to the QtSingleApplication
+    documentation for explanation of the usage.
+
+    A QtSingleCoreApplication instance can communicate to a
+    QtSingleApplication instance if they share the same application
+    id. Hence, this class can be used to create a light-weight
+    command-line tool that sends commands to a GUI application.
+
+    \sa QtSingleApplication
+*/
+
+/*!
+    Creates a QtSingleCoreApplication object. The application identifier
+    will be QCoreApplication::applicationFilePath(). \a argc and \a
+    argv are passed on to the QCoreAppliation constructor.
+*/
+
+QtSingleCoreApplication::QtSingleCoreApplication(int &argc, char **argv)
+    : QCoreApplication(argc, argv)
+{
+    peer = new QtLocalPeer(this);
+    connect(peer, SIGNAL(messageReceived(const QString&)), SIGNAL(messageReceived(const QString&)));
+}
+
+
+/*!
+    Creates a QtSingleCoreApplication object with the application
+    identifier \a appId. \a argc and \a argv are passed on to the
+    QCoreAppliation constructor.
+*/
+QtSingleCoreApplication::QtSingleCoreApplication(const QString &appId, int &argc, char **argv)
+    : QCoreApplication(argc, argv)
+{
+    peer = new QtLocalPeer(this, appId);
+    connect(peer, SIGNAL(messageReceived(const QString&)), SIGNAL(messageReceived(const QString&)));
+}
+
+
+/*!
+    Returns true if another instance of this application is running;
+    otherwise false.
+
+    This function does not find instances of this application that are
+    being run by a different user (on Windows: that are running in
+    another session).
+
+    \sa sendMessage()
+*/
+
+bool QtSingleCoreApplication::isRunning()
+{
+    return peer->isClient();
+}
+
+
+/*!
+    Tries to send the text \a message to the currently running
+    instance. The QtSingleCoreApplication object in the running instance
+    will emit the messageReceived() signal when it receives the
+    message.
+
+    This function returns true if the message has been sent to, and
+    processed by, the current instance. If there is no instance
+    currently running, or if the running instance fails to process the
+    message within \a timeout milliseconds, this function return false.
+
+    \sa isRunning(), messageReceived()
+*/
+
+bool QtSingleCoreApplication::sendMessage(const QString &message, int timeout)
+{
+    return peer->sendMessage(message, timeout);
+}
+
+
+/*!
+    Returns the application identifier. Two processes with the same
+    identifier will be regarded as instances of the same application.
+*/
+
+QString QtSingleCoreApplication::id() const
+{
+    return peer->applicationId();
+}
+
+
+/*!
+    \fn void QtSingleCoreApplication::messageReceived(const QString& message)
+
+    This signal is emitted when the current instance receives a \a
+    message from another instance of this application.
+
+    \sa sendMessage()
+*/