use qcoro for async ssh control

using coroutines allows use async io without having to deal with
multithreading

Author: lievenhey

CMakeLists.txt

@@ -23,7 +23,7 @@ if(NOT CMAKE_BUILD_TYPE)
     )
 endif()
 
-set(CMAKE_CXX_STANDARD 17)
+set(CMAKE_CXX_STANDARD 20)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
 
 option(APPIMAGE_BUILD "configure build for bundling in an appimage" OFF)
@@ -58,6 +58,13 @@ find_package(
     REQUIRED
 )
 
+find_package(
+    QCoro${QT_MAJOR_VERSION}
+    COMPONENTS Core
+    REQUIRED
+)
+qcoro_enable_coroutines()
+
 find_package(LibElf REQUIRED)
 find_package(ElfUtils REQUIRED)
 find_package(ECM 1.0.0 NO_MODULE REQUIRED)

src/CMakeLists.txt

@@ -120,6 +120,7 @@ target_link_libraries(
     models
     PrefixTickLabels
     KDAB::kddockwidgets
+    QCoro::Core
 )
 
 if(KFArchive_FOUND)

src/recordhost.cpp

@@ -11,6 +11,9 @@
 #include <QProcess>
 #include <QStandardPaths>
 #include <QThread>
+#include <QTimer>
+
+#include <QCoroCore>
 
 #include <KShell>
 #include <KUser>
@@ -282,13 +285,17 @@ void RecordHost::setCurrentWorkingDirectory(const QString& cwd)
             emit currentWorkingDirectoryChanged(cwd);
         }
     } else {
-        if (!m_remoteDevice->checkIfDirectoryExists(cwd)) {
-            emit errorOccurred(tr("Working directory folder cannot be found: %1").arg(cwd));
-        } else {
-            emit errorOccurred({});
-            m_cwd = cwd;
-            emit currentWorkingDirectoryChanged(m_cwd);
-        }
+        QTimer::singleShot(0, this, [this, cwd]() -> QCoro::Task<void> {
+            bool exists = co_await m_remoteDevice->checkIfDirectoryExists(cwd);
+            if (!exists) {
+                emit errorOccurred(tr("Working directory folder cannot be found: %1").arg(cwd));
+            } else {
+                emit errorOccurred({});
+                m_cwd = cwd;
+                emit currentWorkingDirectoryChanged(m_cwd);
+            }
+            co_return;
+        });
     }
 }
 
@@ -324,12 +331,17 @@ void RecordHost::setClientApplication(const QString& clientApplication)
     } else {
         if (!m_remoteDevice->isConnected()) {
             emit errorOccurred(tr("Hotspot is not connected to the remote device"));
-        } else if (!m_remoteDevice->checkIfFileExists(clientApplication)) {
-            emit errorOccurred(tr("Application file cannot be found: %1").arg(clientApplication));
         } else {
-            emit errorOccurred({});
-            m_clientApplication = clientApplication;
-            emit clientApplicationChanged(m_clientApplication);
+            QTimer::singleShot(0, this, [this, clientApplication]() -> QCoro::Task<void> {
+                bool exists = co_await m_remoteDevice->checkIfFileExists(clientApplication);
+                if (!exists) {
+                    emit errorOccurred(tr("Application file cannot be found: %1").arg(clientApplication));
+                } else {
+                    emit errorOccurred({});
+                    m_clientApplication = clientApplication;
+                    emit clientApplicationChanged(m_clientApplication);
+                }
+            });
         }
     }
 }

src/remotedevice.cpp

@@ -11,6 +11,8 @@
 #include <QStandardPaths>
 #include <QThread>
 
+#include <QCoroProcess>
+
 #include <KSharedConfig>
 
 #include "settings.h"
@@ -74,6 +76,10 @@ RemoteDevice::~RemoteDevice()
 {
     if (m_connection) {
         disconnect();
+        QTimer::singleShot(0, this, [connection = m_connection.release()]() -> QCoro::Task<void> {
+            co_await qCoro(connection).waitForFinished();
+            delete connection;
+        });
     }
 }
 
@@ -122,34 +128,36 @@ bool RemoteDevice::isConnected() const
 
 bool RemoteDevice::checkIfProgramExists(const QString& program) const
 {
+    Q_ASSERT(QThread::currentThread() != thread());
+    // this is only used to check if perf is installed and is run in a background thread
     auto ssh = sshProcess({QStringLiteral("command"), program});
     ssh->start();
     ssh->waitForFinished();
     auto exitCode = ssh->exitCode();
-    ssh->deleteLater();
     // 128 -> not found
     // perf will return 1 and display the help message
     return exitCode != 128;
 }
 
-bool RemoteDevice::checkIfDirectoryExists(const QString& directory) const
+QCoro::Task<bool> RemoteDevice::checkIfDirectoryExists(const QString& directory) const
 {
-    auto ssh = sshProcess({QStringLiteral("test"), QStringLiteral("-d"), directory});
-    ssh->start();
-    ssh->waitForFinished();
-    auto exitCode = ssh->exitCode();
-    ssh->deleteLater();
-    return exitCode == 0;
+    auto _ssh = sshProcess({QStringLiteral("test"), QStringLiteral("-d"), directory});
+    auto ssh = qCoro(_ssh.get());
+    co_await ssh.start();
+    co_await ssh.waitForFinished();
+    auto exitCode = _ssh->exitCode();
+    co_return exitCode == 0;
 }
 
-bool RemoteDevice::checkIfFileExists(const QString& file) const
+QCoro::Task<bool> RemoteDevice::checkIfFileExists(const QString& file) const
 {
-    auto ssh = sshProcess({QStringLiteral("test"), QStringLiteral("-f"), file});
-    ssh->start();
-    ssh->waitForFinished();
-    auto exitCode = ssh->exitCode();
-    ssh->deleteLater();
-    return exitCode == 0;
+    auto _ssh = sshProcess({QStringLiteral("test"), QStringLiteral("-f"), file});
+
+    auto ssh = qCoro(_ssh.get());
+    co_await ssh.start();
+    co_await ssh.waitForFinished();
+    auto exitCode = _ssh->exitCode();
+    co_return exitCode == 0;
 }
 
 QByteArray RemoteDevice::getProgramOutput(const QStringList& args) const

src/remotedevice.h

@@ -12,6 +12,8 @@
 #include <QFileSystemWatcher>
 #include <QTemporaryDir>
 
+#include <QCoroTask>
+
 #include <KConfigGroup>
 
 #include <memory>
@@ -31,8 +33,8 @@ class RemoteDevice : public QObject
     bool isConnected() const;
 
     bool checkIfProgramExists(const QString& program) const;
-    bool checkIfDirectoryExists(const QString& directory) const;
-    bool checkIfFileExists(const QString& file) const;
+    QCoro::Task<bool> checkIfDirectoryExists(const QString& directory) const;
+    QCoro::Task<bool> checkIfFileExists(const QString& file) const;
     QByteArray getProgramOutput(const QStringList& args) const;
 
     std::unique_ptr<QProcess> runPerf(const QString& cdw, const QStringList& perfOptions) const;

tests/integrationtests/CMakeLists.txt

@@ -22,6 +22,7 @@ ecm_add_test(
     KF${QT_MAJOR_VERSION}::WindowSystem
     KF${QT_MAJOR_VERSION}::KIOCore
     KF${QT_MAJOR_VERSION}::Parts
+    QCoro::Core
     TEST_NAME
     tst_perfparser
 )