Core: Add a reaper that will asynchronously clean up QProcesses

Change-Id: Ic24dde261eac775d1a5854b8dbcbfeb002d0f729
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/plugins/coreplugin/reaper.cpp

@@ -0,0 +1,114 @@
+/****************************************************************************
+**
+** Copyright (C) 2016 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of Qt Creator.
+**
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3 as published by the Free Software
+** Foundation with exceptions as appearing in the file LICENSE.GPL3-EXCEPT
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-3.0.html.
+**
+****************************************************************************/
+
+#include "reaper.h"
+#include "reaper_p.h"
+
+#include <utils/algorithm.h>
+#include <utils/qtcassert.h>
+
+namespace Core {
+namespace Internal {
+
+static ReaperPrivate *d = nullptr;
+
+ProcessReaper::ProcessReaper(QProcess *p, int timeoutMs) : m_process(p)
+{
+    m_iterationTimer.setInterval(timeoutMs);
+    m_iterationTimer.setSingleShot(true);
+    connect(&m_iterationTimer, &QTimer::timeout, this, &ProcessReaper::nextIteration);
+
+    QTimer::singleShot(0, this, &ProcessReaper::nextIteration);
+    m_futureInterface.reportStarted();
+}
+
+void ProcessReaper::nextIteration()
+{
+    QProcess::ProcessState state = m_process->state();
+    if (state == QProcess::NotRunning || m_emergencyCounter > 5) {
+        delete m_process;
+        m_futureInterface.reportFinished();
+        return;
+    }
+
+    if (state == QProcess::Starting) {
+        if (m_lastState == QProcess::Starting)
+            m_process->kill();
+    } else if (state == QProcess::Running) {
+        if (m_lastState == QProcess::Running)
+            m_process->kill();
+        else
+            m_process->terminate();
+    }
+
+    m_lastState = state;
+    m_iterationTimer.start();
+
+    ++m_emergencyCounter;
+}
+
+ReaperPrivate::ReaperPrivate()
+{
+    d = this;
+}
+
+ReaperPrivate::~ReaperPrivate()
+{
+    d = nullptr;
+}
+
+} // namespace Internal
+
+namespace Reaper {
+
+void reap(QProcess *process, int timeoutMs)
+{
+    if (!process)
+        return;
+
+    QTC_ASSERT(Internal::d, return);
+
+    auto reaper = new Internal::ProcessReaper(process, timeoutMs);
+    QFuture<void> f = reaper->future();
+
+    Internal::d->m_synchronizer.addFuture(f);
+    auto watcher = new QFutureWatcher<void>();
+    watcher->setFuture(f);
+
+    QObject::connect(watcher, &QFutureWatcher<void>::finished, [watcher, reaper]() {
+        watcher->deleteLater();
+
+        const QList<QFuture<void>> futures = Utils::filtered(Internal::d->m_synchronizer.futures(),
+                                                             [reaper](const QFuture<void> &f) { return reaper->future() != f; });
+        for (const QFuture<void> &f : futures)
+            Internal::d->m_synchronizer.addFuture(f);
+
+        delete reaper;
+    });
+}
+
+} // namespace Reaper
+} // namespace Core
+