【QT】Qt Application Manager启动应用源码分析

Qt Application Manager启动应用源码分析

• Qt Application Manager（以下简称QTAM）是QT推出的一款应用管理程序，可以把它简单理解成Android的Launcher+SystemUI。但是，QTAM又集成了Wayland功能，并且自身实现了一套Compositor。QTAM以多进程启动情况下（默认），其地位相当于 Launcher+SystemUI+Compositor。
• 关于QTAM的基本介绍可以参考《Qt Application Manager简介》

启用应用

• QTAM作为一款应用管理程序，适用于嵌入式端（如车载）应用。利用QT开发的应用程序只需要简单适配一下QTAM的规范，可以大幅度减少开发一套应用管理程序的成本。同时QTAM支持QML方式。应用管理最基本的功能，是应用的启动。下面基于QTAM 6.2.2版本进行分析。
  

• 启动应用的接口ApplicationManager:: startApplication，该接口可以以C++或QML的形式调用（下述摘取了部分源码）

// src\manager-lib\applicationmanager.h
class ApplicationManager : public QAbstractListModel
{Q_OBJECTQ_CLASSINFO("D-Bus Interface", "io.qt.ApplicationManager")Q_CLASSINFO("AM-QmlType", "QtApplicationManager.SystemUI/ApplicationManager 2.0 SINGLETON")public:// 通过C++和QML互相调用的方式，QML端也可以调用到该接口。// 关于QML调用C++，网上文章比较多可自行百度。Q_SCRIPTABLE bool startApplication(const QString &id, const QString &documentUrl = QString());
}// src\manager-lib\applicationmanager.cpp
bool ApplicationManager::startApplication(const QString &id, const QString &documentUrl)
{try {return startApplicationInternal(id, documentUrl);} catch (const Exception &e) {qCWarning(LogSystem) << e.what();return false;}
}// src\manager-lib\applicationmanager.cpp
bool ApplicationManager::startApplicationInternal(const QString &appId, const QString &documentUrl,const QString &documentMimeType,const QString &debugWrapperSpecification,const QVector<int> &stdioRedirections)  Q_DECL_NOEXCEPT_EXPR(false)
{// 根据appid，获取到应用信息。appid唯一标识应用Application *app = fromId(appId);// 获取应用的RunTime，Runtime可以理解为应用运行时。QTAM提供多种Runtime，比如NativeRuntime、QML Runtime等。AbstractRuntime *runtime = app->currentRuntime();auto runtimeManager = runtime ? runtime->manager() : RuntimeFactory::instance()->manager(app->runtimeName());if (!runtimeManager)throw Exception("No RuntimeManager found for runtime: %1").arg(app->runtimeName());// 判断QtAM运行的是多进程模式，还是单进程模式（默认为多进程模式，即每个应用以单独的进程启动）bool inProcess = runtimeManager->inProcess();// 判断当前rimtime的状态。 应用的状态为 StartingUp-> Running -> ShuttingDown -> NotRunning// 第一次启动时，这里为NotRunningif (runtime) {switch (runtime->state()) {case Am::StartingUp:case Am::Running:if (!debugWrapperCommand.isEmpty()) {throw Exception("Application %1 is already running - cannot start with debug-wrapper: %2").arg(app->id(), debugWrapperSpecification);}// documentUrl为应用入口。比如一个QML文件。if (!documentUrl.isNull())runtime->openDocument(documentUrl, documentMimeType);else if (!app->documentUrl().isNull())runtime->openDocument(app->documentUrl(), documentMimeType);// 激活AppemitActivated(app);return true;case Am::ShuttingDown:return false;case Am::NotRunning:break;}}// container指应用运行上下文（Context）AbstractContainer *container = nullptr;QString containerId;// 如果是多进程模式if (!inProcess) {if (d->containerSelectionConfig.isEmpty()) {// 默认使用ProcessContainercontainerId = qSL("process");} else {// check config filefor (const auto &it : qAsConst(d->containerSelectionConfig)) {const QString &key = it.first;const QString &value = it.second;bool hasAsterisk = key.contains(qL1C('*'));if ((hasAsterisk && key.length() == 1)|| (!hasAsterisk && key == app->id())|| QRegularExpression(QRegularExpression::wildcardToRegularExpression(key)).match(app->id()).hasMatch()) {containerId = value;break;}}}if (d->containerSelectionFunction.isCallable()) {QJSValueList args = { QJSValue(app->id()), QJSValue(containerId) };containerId = d->containerSelectionFunction.call(args).toString();}if (!ContainerFactory::instance()->manager(containerId))throw Exception("No ContainerManager found for container: %1").arg(containerId);}bool attachRuntime = false;if (!runtime) {if (!inProcess) {// 快启动模式，可以理解为预先启动几个（有上限）的Runtime+Contianer，预先加载了一些资源。if (QuickLauncher::instance()) {// 该情况比较特殊，不考虑。}if (!container) {// 创建Containercontainer = ContainerFactory::instance()->create(containerId, app, stdioRedirections,debugEnvironmentVariables, debugWrapperCommand);} else {container->setApplication(app);}if (!container) {qCCritical(LogSystem) << "ERROR: Couldn't create Container for Application (" << app->id() <<")!";return false;}if (runtime)attachRuntime = true;}if (!runtime)runtime = RuntimeFactory::instance()->create(container, app);if (runtime)emit internalSignals.newRuntimeCreated(runtime);}if (!runtime) {qCCritical(LogSystem) << "ERROR: Couldn't create Runtime for Application (" << app->id() <<")!";return false;}// 绑定信号与槽。监听应用状态变化。connect(runtime, &AbstractRuntime::stateChanged, this, [this, app](Am::RunState newRuntimeState) {app->setRunState(newRuntimeState);emit applicationRunStateChanged(app->id(), newRuntimeState);emitDataChanged(app, QVector<int> { IsRunning, IsStartingUp, IsShuttingDown });});// 加载应用入口。if (!documentUrl.isNull())runtime->openDocument(documentUrl, documentMimeType);else if (!app->documentUrl().isNull())runtime->openDocument(app->documentUrl(), documentMimeType);if (inProcess) {// 如果是单进程模式（以线程方式启动应用）bool ok = runtime->start();if (ok)emitActivated(app);elseruntime->deleteLater();return ok;} else {// We can only start the app when both the container and the windowmanager are ready.// Using a state-machine would be one option, but then we would need that state-machine// object plus the per-app state. Relying on 2 lambdas is the easier choice for now.// 多进程模式下，QTAM需要完成了Compositor初始化，才可以启动应用。auto doStartInContainer = [this, app, attachRuntime, runtime]() -> bool {// 首次启动应用默认走 runtime->start()bool successfullyStarted = attachRuntime ? runtime->attachApplicationToQuickLauncher(app): runtime->start();if (successfullyStarted)emitActivated(app);elseruntime->deleteLater(); // ~Runtime() will clean app->nonAliased()->m_runtimereturn successfullyStarted;};auto tryStartInContainer = [container, doStartInContainer]() -> bool {if (container->isReady()) {// Since the container is already ready, start the app immediatelyreturn doStartInContainer();} else {// We postpone the starting of the application to a later point in time,// since the container is not ready yet
#  if defined(Q_CC_MSVC)qApp->connect(container, &AbstractContainer::ready, doStartInContainer); // MSVC cannot distinguish between static and non-static overloads in lambdas
# elseconnect(container, &AbstractContainer::ready, doStartInContainer);
#endifreturn true;}};if (isWindowManagerCompositorReady()) {return tryStartInContainer();} else {connect(this, &ApplicationManager::windowManagerCompositorReadyChanged, tryStartInContainer);return true;}}
}

• 上面的代码中，主要就是通过AppID获取应用对象（包含应用信息）、创建应用Runtime、创建应用Container（Context）、加载应用入口（比如QML文件）、调用RunTime启动应用。加载应用入口文件，实际上会调用QML引擎解析QML文件。这里主要关注RunTime如何将应用进程启动。
• 多进程默认情况下，走NativeRuntime。

// src\manager-lib\nativeruntime.cpp
bool NativeRuntime::start()
{// 首次启动时，状态为 Am::NotRunningswitch (state()) {case Am::StartingUp:case Am::Running:return true;case Am::ShuttingDown:return false;case Am::NotRunning:break;}// 初始化OpenGL配置if (m_app)openGLConfig = m_app->info()->openGLConfiguration();if (openGLConfig.isEmpty())openGLConfig = manager()->systemOpenGLConfiguration();if (!openGLConfig.isEmpty())uiConfig.insert(qSL("opengl"), openGLConfig);// 获取IconQString iconThemeName = manager()->iconThemeName();QStringList iconThemeSearchPaths = manager()->iconThemeSearchPaths();if (!iconThemeName.isEmpty())uiConfig.insert(qSL("iconThemeName"), iconThemeName);if (!iconThemeSearchPaths.isEmpty())uiConfig.insert(qSL("iconThemeSearchPaths"), iconThemeSearchPaths);QVariantMap config = {{ qSL("logging"), loggingConfig },{ qSL("baseDir"), QDir::currentPath() },{ qSL("runtimeConfiguration"), configuration() },{ qSL("securityToken"), qL1S(securityToken().toHex()) },{ qSL("dbus"), dbusConfig }};if (!m_startedViaLauncher && !m_isQuickLauncher)config.insert(qSL("systemProperties"), systemProperties());if (!uiConfig.isEmpty())config.insert(qSL("ui"), uiConfig);QMap<QString, QString> env = {{ qSL("QT_QPA_PLATFORM"), qSL("wayland") },{ qSL("QT_IM_MODULE"), QString() },     // Applications should use wayland text input{ qSL("QT_SCALE_FACTOR"), QString() },  // do not scale wayland clients{ qSL("AM_CONFIG"), QString::fromUtf8(QtYaml::yamlFromVariantDocuments({ config })) },{ qSL("QT_WAYLAND_SHELL_INTEGRATION"), qSL("xdg-shell")},};// 判断DLT（一种日志服务）是否开启。if (!Logging::isDltEnabled()) {// sadly we still need this, since we need to disable DLT as soon as possibleenv.insert(qSL("AM_NO_DLT_LOGGING"), qSL("1"));}// 获取环境变量（QT也有自己的一套环境变量）for (QMapIterator<QString, QVariant> it(configuration().value(qSL("environmentVariables")).toMap()); it.hasNext(); ) {it.next();if (!it.key().isEmpty())env.insert(it.key(), it.value().toString());}QStringList args;if (!m_startedViaLauncher) {args.append(variantToStringList(m_app->runtimeParameters().value(qSL("arguments"))));// 获取启动参数if (!m_document.isNull())args << qSL("--start-argument") << m_document;// 如果DLT没有开启的话if (!Logging::isDltEnabled())args << qSL("--no-dlt-logging");} else {if (m_isQuickLauncher)args << qSL("--quicklaunch");args << QString::fromLocal8Bit(ProcessTitle::placeholderArgument);    // must be last argument}emit signaler()->aboutToStart(this);// 调用Container，启动应用m_process = m_container->start(args, env, config);if (!m_process)return false;// 绑定信号，获得应用状态。QObject::connect(m_process, &AbstractContainerProcess::started,this, &NativeRuntime::onProcessStarted);QObject::connect(m_process, &AbstractContainerProcess::errorOccured,this, &NativeRuntime::onProcessError);QObject::connect(m_process, &AbstractContainerProcess::finished,this, &NativeRuntime::onProcessFinished);// 到此默认认为应用已经启动。通过上面的三个绑定信号操作，可以更新状态。setState(Am::StartingUp);return true;
}

• Runtime调用Container启动应用，默认情况下走ProcessContainer，这里会调用QProcess创建出应用进程。

// src\manager-lib\processcontainer.cpp
AbstractContainerProcess *ProcessContainer::start(const QStringList &arguments,const QMap<QString, QString> &runtimeEnvironment,const QVariantMap &amConfig)
{// m_program 是 Appman 这个二进制程序。是QTAM提供的用来加载应用的程序。if (!QFile::exists(m_program)) {qCWarning(LogSystem) << "Program" << m_program << "not found";return nullptr;}// 创建HostProcess，通过它创建出进程。HostProcess *process = new HostProcess();process->setWorkingDirectory(m_baseDirectory);process->setProcessEnvironment(penv);process->setStopBeforeExec(configuration().value(qSL("stopBeforeExec")).toBool());process->setStdioRedirections(m_stdioRedirections);QString command = m_program;QStringList args = arguments;if (!m_debugWrapperCommand.isEmpty()) {auto cmd = DebugWrapper::substituteCommand(m_debugWrapperCommand, m_program, arguments);command = cmd.takeFirst();args = cmd;}qCDebug(LogSystem) << "Running command:" << command << "arguments:" << args;// 实际上，第一个参数是Appman这个二进程程序的路径。// 例如： /system/bin/Appman// 调用HostProcess启动应用process->start(command, args);m_process = process;setControlGroup(configuration().value(qSL("defaultControlGroup")).toString());return process;
}// src\manager-lib\processcontainer.cpp
void HostProcess::start(const QString &program, const QStringList &arguments)
{// 绑定各种状态信号connect(m_process, &QProcess::started, this, [this]() {// we to cache the pid in order to have it available after the process crashedm_pid = m_process->processId();emit started();});connect(m_process, &QProcess::errorOccurred, this, [this](QProcess::ProcessError error) {emit errorOccured(static_cast<Am::ProcessError>(error));});connect(m_process, static_cast<void (QProcess::*)(int,QProcess::ExitStatus)>(&QProcess::finished),this, [this](int exitCode, QProcess::ExitStatus exitStatus) {emit finished(exitCode, static_cast<Am::ExitStatus>(exitStatus));});connect(m_process, &QProcess::stateChanged,this, [this](QProcess::ProcessState newState) {emit stateChanged(static_cast<Am::RunState>(newState));});#if defined(Q_OS_UNIX)// make sure that the redirection fds do not have a close-on-exec flag, since we need them// in the child process.for (int fd : qAsConst(m_stdioRedirections)) {if (fd < 0)continue;int flags = fcntl(fd, F_GETFD);if (flags & FD_CLOEXEC)fcntl(fd, F_SETFD, flags & ~FD_CLOEXEC);}
#endif//  QProcess *m_process;//  调用QProcess的start函数，这个类会根据入参启动进程。//  参数Program是 Appman这个二进制程序。//  参数arguments作为入参，传给Appman这个二进制程序。//  到此应用进程就启动起来了。m_process->start(program, arguments);#if defined(Q_OS_UNIX)// we are forked now and the child process has received a copy of all redirected fds// now it's time to close our fds, since we don't need them anymore (plus we would block// the tty where they originated from)for (int fd : qAsConst(m_stdioRedirections)) {if (fd >= 0)::close(fd);}
#endif
}

• 上述代码中，实际上利用了QProcess这个，将Appman（二进制程序）和入参（比如应用的QML启动文件）作为参数。通过QProcess创建了新的进程，启动了应用程序。

从上述代码中，可以看出QTAM多进程模式下，是通过QProcess创建了子进程来加载AppMan（可以理解为Applauncher），根据入参（应用的QML文件）启动了应用。并且监听了QProcess的状态 ，用来设置对应的应用状态。

其实很多应用管理模块，启用应用的大概思路也是这样的。这种思路，在新规AppManager模块时可作为借鉴。