271 lines
8.5 KiB
C++
271 lines
8.5 KiB
C++
// The MIT License (MIT)
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//
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// Copyright (c) Itay Grudev 2015 - 2020
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in
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// all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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// THE SOFTWARE.
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//
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// W A R N I N G !!!
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// -----------------
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//
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// This is a modified version of SingleApplication,
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// The original version is at:
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//
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// https://github.com/itay-grudev/SingleApplication
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//
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//
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#include <cstdlib>
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#include <limits>
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#include <QtGlobal>
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#include <QCoreApplication>
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#include <QThread>
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#include <QSharedMemory>
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#include <QLocalSocket>
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#include <QByteArray>
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#include <QElapsedTimer>
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#include <QtDebug>
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#include "singlecoreapplication.h"
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#include "singlecoreapplication_p.h"
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/**
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* @brief Constructor. Checks and fires up LocalServer or closes the program if another instance already exists
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* @param argc
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* @param argv
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* @param allowSecondary Whether to enable secondary instance support
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* @param options Optional flags to toggle specific behaviour
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* @param timeout Maximum time blocking functions are allowed during app load
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*/
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SingleCoreApplication::SingleCoreApplication(int &argc, char *argv[], bool allowSecondary, Options options, int timeout)
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: app_t(argc, argv),
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d_ptr(new SingleCoreApplicationPrivate(this)) {
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Q_D(SingleCoreApplication);
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// Store the current mode of the program
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d->options_ = options;
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// Generating an application ID used for identifying the shared memory block and QLocalServer
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d->genBlockServerName();
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// To mitigate QSharedMemory issues with large amount of processes attempting to attach at the same time
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d->randomSleep();
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#ifdef Q_OS_UNIX
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// By explicitly attaching it and then deleting it we make sure that the memory is deleted even after the process has crashed on Unix.
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d->memory_ = new QSharedMemory(d->blockServerName_);
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d->memory_->attach();
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delete d->memory_;
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#endif
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// Guarantee thread safe behaviour with a shared memory block.
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d->memory_ = new QSharedMemory(d->blockServerName_);
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// Create a shared memory block
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if (d->memory_->create(sizeof(InstancesInfo))) {
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// Initialize the shared memory block
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if (!d->memory_->lock()) {
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qCritical() << "SingleCoreApplication: Unable to lock memory block after create.";
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abortSafely();
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}
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d->initializeMemoryBlock();
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}
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else {
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if (d->memory_->error() == QSharedMemory::AlreadyExists) {
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// Attempt to attach to the memory segment
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if (!d->memory_->attach()) {
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qCritical() << "SingleCoreApplication: Unable to attach to shared memory block.";
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abortSafely();
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}
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if (!d->memory_->lock()) {
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qCritical() << "SingleCoreApplication: Unable to lock memory block after attach.";
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abortSafely();
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}
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}
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else {
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qCritical() << "SingleCoreApplication: Unable to create block.";
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abortSafely();
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}
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}
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InstancesInfo *inst = static_cast<InstancesInfo*>(d->memory_->data());
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QElapsedTimer time;
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time.start();
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// Make sure the shared memory block is initialised and in consistent state
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forever {
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// If the shared memory block's checksum is valid continue
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if (d->blockChecksum() == inst->checksum) break;
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// If more than 5s have elapsed, assume the primary instance crashed and assume it's position
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if (time.elapsed() > 5000) {
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qWarning() << "SingleCoreApplication: Shared memory block has been in an inconsistent state from more than 5s. Assuming primary instance failure.";
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d->initializeMemoryBlock();
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}
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// Otherwise wait for a random period and try again.
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// The random sleep here limits the probability of a collision between two racing apps and allows the app to initialise faster
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if (!d->memory_->unlock()) {
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qDebug() << "SingleCoreApplication: Unable to unlock memory for random wait.";
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qDebug() << d->memory_->errorString();
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}
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d->randomSleep();
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if (!d->memory_->lock()) {
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qCritical() << "SingleCoreApplication: Unable to lock memory after random wait.";
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abortSafely();
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}
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}
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if (!inst->primary) {
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d->startPrimary();
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if (!d->memory_->unlock()) {
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qDebug() << "SingleCoreApplication: Unable to unlock memory after primary start.";
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qDebug() << d->memory_->errorString();
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}
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return;
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}
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// Check if another instance can be started
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if (allowSecondary) {
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d->startSecondary();
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if (d->options_ & Mode::SecondaryNotification) {
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d->connectToPrimary(timeout, SingleCoreApplicationPrivate::SecondaryInstance);
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}
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if (!d->memory_->unlock()) {
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qDebug() << "SingleCoreApplication: Unable to unlock memory after secondary start.";
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qDebug() << d->memory_->errorString();
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}
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return;
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}
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if (!d->memory_->unlock()) {
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qDebug() << "SingleCoreApplication: Unable to unlock memory at end of execution.";
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qDebug() << d->memory_->errorString();
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}
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d->connectToPrimary(timeout, SingleCoreApplicationPrivate::NewInstance);
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delete d;
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::exit(EXIT_SUCCESS);
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}
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SingleCoreApplication::~SingleCoreApplication() {
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Q_D(SingleCoreApplication);
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delete d;
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}
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/**
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* Checks if the current application instance is primary.
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* @return Returns true if the instance is primary, false otherwise.
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*/
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bool SingleCoreApplication::isPrimary() {
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Q_D(SingleCoreApplication);
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return d->server_ != nullptr;
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}
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/**
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* Checks if the current application instance is secondary.
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* @return Returns true if the instance is secondary, false otherwise.
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*/
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bool SingleCoreApplication::isSecondary() {
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Q_D(SingleCoreApplication);
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return d->server_ == nullptr;
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}
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/**
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* Allows you to identify an instance by returning unique consecutive instance ids.
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* It is reset when the first (primary) instance of your app starts and only incremented afterwards.
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* @return Returns a unique instance id.
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*/
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quint32 SingleCoreApplication::instanceId() {
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Q_D(SingleCoreApplication);
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return d->instanceNumber_;
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}
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/**
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* Returns the OS PID (Process Identifier) of the process running the primary instance.
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* Especially useful when SingleCoreApplication is coupled with OS. specific APIs.
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* @return Returns the primary instance PID.
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*/
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qint64 SingleCoreApplication::primaryPid() {
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Q_D(SingleCoreApplication);
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return d->primaryPid();
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}
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/**
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* Returns the username the primary instance is running as.
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* @return Returns the username the primary instance is running as.
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*/
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QString SingleCoreApplication::primaryUser() {
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Q_D(SingleCoreApplication);
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return d->primaryUser();
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}
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/**
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* Returns the username the current instance is running as.
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* @return Returns the username the current instance is running as.
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*/
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QString SingleCoreApplication::currentUser() {
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Q_D(SingleCoreApplication);
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return d->getUsername();
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}
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/**
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* Sends message to the Primary Instance.
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* @param message The message to send.
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* @param timeout the maximum timeout in milliseconds for blocking functions.
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* @return true if the message was sent successfully, false otherwise.
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*/
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bool SingleCoreApplication::sendMessage(const QByteArray &message, const int timeout) {
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Q_D(SingleCoreApplication);
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// Nobody to connect to
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if (isPrimary()) return false;
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// Make sure the socket is connected
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if (!d->connectToPrimary(timeout, SingleCoreApplicationPrivate::Reconnect)) {
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return false;
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}
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d->socket_->write(message);
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const bool dataWritten = d->socket_->waitForBytesWritten(timeout);
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d->socket_->flush();
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return dataWritten;
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}
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/**
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* Cleans up the shared memory block and exits with a failure.
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* This function halts program execution.
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*/
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void SingleCoreApplication::abortSafely() {
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Q_D(SingleCoreApplication);
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qCritical() << "SingleCoreApplication: " << d->memory_->error() << d->memory_->errorString();
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delete d;
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::exit(EXIT_FAILURE);
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}
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