Port QThreadPool to the new property system

Ported all properties, except activeThreadCount. Marking it dirty may
cause a re-evaluation of properties depending on it, which may reault in
a deadlock in case of trying to read activeThreadCount property which is
being marked as dirty.

Task-number: QTBUG-85520
Change-Id: Id073b0895c89a9e6b05b57ad520db994e550a1c9
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

src/corelib/thread/qthreadpool.cpp

@@ -163,7 +163,7 @@ void QThreadPoolThread::registerThreadInactive()
 /*
     \internal
 */
-QThreadPoolPrivate:: QThreadPoolPrivate()
+QThreadPoolPrivate::QThreadPoolPrivate()
 { }
 
 bool QThreadPoolPrivate::tryStart(QRunnable *task)
@@ -223,10 +223,8 @@ void QThreadPoolPrivate::enqueueTask(QRunnable *runnable, int priority)
 
 int QThreadPoolPrivate::activeThreadCount() const
 {
-    return (allThreads.count()
-            - expiredThreads.count()
-            - waitingThreads.count()
-            + reservedThreads);
+    return int(allThreads.count() - expiredThreads.count() - waitingThreads.count()
+               + reservedThreads);
 }
 
 void QThreadPoolPrivate::tryToStartMoreThreads()
@@ -605,11 +603,15 @@ int QThreadPool::expiryTimeout() const
 void QThreadPool::setExpiryTimeout(int expiryTimeout)
 {
     Q_D(QThreadPool);
-    if (d->expiryTimeout == expiryTimeout)
-        return;
     d->expiryTimeout = expiryTimeout;
 }
 
+QBindable<int> QThreadPool::bindableExpiryTimeout()
+{
+    Q_D(QThreadPool);
+    return &d->expiryTimeout;
+}
+
 /*! \property QThreadPool::maxThreadCount
 
     \brief the maximum number of threads used by the thread pool.
@@ -631,11 +633,18 @@ void QThreadPool::setMaxThreadCount(int maxThreadCount)
     Q_D(QThreadPool);
     QMutexLocker locker(&d->mutex);
 
-    if (maxThreadCount == d->maxThreadCount)
-        return;
-
+    const auto maxThreadCountChanged = maxThreadCount != d->maxThreadCount;
+    // Rewrite the value in any case, to make sure the binding is cleared.
     d->maxThreadCount = maxThreadCount;
-    d->tryToStartMoreThreads();
+
+    if (maxThreadCountChanged)
+        d->tryToStartMoreThreads();
+}
+
+QBindable<int> QThreadPool::bindableMaxThreadCount()
+{
+    Q_D(QThreadPool);
+    return &d->maxThreadCount;
 }
 
 /*! \property QThreadPool::activeThreadCount
@@ -698,6 +707,12 @@ uint QThreadPool::stackSize() const
     return d->stackSize;
 }
 
+QBindable<uint> QThreadPool::bindableStackSize()
+{
+    Q_D(QThreadPool);
+    return &d->stackSize;
+}
+
 /*!
     Releases a thread previously reserved by a call to reserveThread().
 

src/corelib/thread/qthreadpool.h

@@ -56,10 +56,10 @@ class Q_CORE_EXPORT QThreadPool : public QObject
 {
     Q_OBJECT
     Q_DECLARE_PRIVATE(QThreadPool)
-    Q_PROPERTY(int expiryTimeout READ expiryTimeout WRITE setExpiryTimeout)
-    Q_PROPERTY(int maxThreadCount READ maxThreadCount WRITE setMaxThreadCount)
+    Q_PROPERTY(int expiryTimeout READ expiryTimeout WRITE setExpiryTimeout BINDABLE bindableExpiryTimeout)
+    Q_PROPERTY(int maxThreadCount READ maxThreadCount WRITE setMaxThreadCount BINDABLE bindableMaxThreadCount)
     Q_PROPERTY(int activeThreadCount READ activeThreadCount)
-    Q_PROPERTY(uint stackSize READ stackSize WRITE setStackSize)
+    Q_PROPERTY(uint stackSize READ stackSize WRITE setStackSize BINDABLE bindableStackSize)
     friend class QFutureInterfaceBase;
 
 public:
@@ -76,14 +76,17 @@ public:
 
     int expiryTimeout() const;
     void setExpiryTimeout(int expiryTimeout);
+    QBindable<int> bindableExpiryTimeout();
 
     int maxThreadCount() const;
     void setMaxThreadCount(int maxThreadCount);
+    QBindable<int> bindableMaxThreadCount();
 
     int activeThreadCount() const;
 
     void setStackSize(uint stackSize);
     uint stackSize() const;
+    QBindable<uint> bindableStackSize();
 
     void reserveThread();
     void releaseThread();

src/corelib/thread/qthreadpool_p.h

@@ -58,6 +58,7 @@
 #include "QtCore/qset.h"
 #include "QtCore/qqueue.h"
 #include "private/qobject_p.h"
+#include "private/qproperty_p.h"
 
 QT_REQUIRE_CONFIG(thread);
 
@@ -173,11 +174,17 @@ public:
     QList<QueuePage *> queue;
     QWaitCondition noActiveThreads;
 
-    int expiryTimeout = 30000;
-    int maxThreadCount = QThread::idealThreadCount();
+    Q_OBJECT_BINDABLE_PROPERTY_WITH_ARGS(QThreadPoolPrivate, int, expiryTimeout, 30000)
+
+    void setMaxThreadCount(int count) { q_func()->setMaxThreadCount(count); }
+    Q_OBJECT_COMPAT_PROPERTY_WITH_ARGS(QThreadPoolPrivate, int, maxThreadCount,
+                                       &QThreadPoolPrivate::setMaxThreadCount,
+                                       QThread::idealThreadCount())
+
     int reservedThreads = 0;
     int activeThreads = 0;
-    uint stackSize = 0;
+
+    Q_OBJECT_BINDABLE_PROPERTY_WITH_ARGS(QThreadPoolPrivate, uint, stackSize, 0)
 };
 
 QT_END_NAMESPACE

tests/auto/corelib/thread/qthreadpool/tst_qthreadpool.cpp

@@ -104,8 +104,23 @@ private slots:
     void stressTest();
     void takeAllAndIncreaseMaxThreadCount();
     void waitForDoneAfterTake();
+    void bindings();
 
 private:
+    class WaitingTask : public QRunnable
+    {
+    public:
+        QSemaphore waitForStarted, waitToFinish;
+
+        WaitingTask() { setAutoDelete(false); }
+
+        void run() override
+        {
+            waitForStarted.release();
+            waitToFinish.acquire();
+        }
+    };
+
     QMutex m_functionTestMutex;
 };
 
@@ -471,20 +486,6 @@ void tst_QThreadPool::setMaxThreadCount()
 
 void tst_QThreadPool::setMaxThreadCountStartsAndStopsThreads()
 {
-    class WaitingTask : public QRunnable
-    {
-    public:
-        QSemaphore waitForStarted, waitToFinish;
-
-        WaitingTask() { setAutoDelete(false); }
-
-        void run() override
-        {
-            waitForStarted.release();
-            waitToFinish.acquire();
-        }
-    };
-
     QThreadPool threadPool;
     threadPool.setMaxThreadCount(1);
 
@@ -1305,5 +1306,68 @@ void tst_QThreadPool::waitForDoneAfterTake()
 
 }
 
+void tst_QThreadPool::bindings()
+{
+    {
+        QThreadPool pool;
+
+        // expiryTimeout property
+        QProperty<int> expiryTimeout;
+        pool.bindableExpiryTimeout().setBinding(Qt::makePropertyBinding(expiryTimeout));
+        expiryTimeout = 1000;
+        QCOMPARE(pool.expiryTimeout(), 1000);
+
+        QProperty<int> expiryTimeoutObserver;
+        expiryTimeoutObserver.setBinding(pool.bindableExpiryTimeout().makeBinding());
+        pool.setExpiryTimeout(100);
+        QCOMPARE(expiryTimeoutObserver, 100);
+
+        // stackSize property
+        QProperty<uint> stackSize;
+        pool.bindableStackSize().setBinding(Qt::makePropertyBinding(stackSize));
+        stackSize = 1000;
+        QCOMPARE(pool.stackSize(), 1000);
+
+        QProperty<uint> stackSizeObserver;
+        stackSizeObserver.setBinding(pool.bindableStackSize().makeBinding());
+        pool.setStackSize(100);
+        QCOMPARE(stackSizeObserver, 100);
+    }
+
+    // maxThreadCount property
+    {
+        // Make sure changing the max thread count via binding starts new threads
+        QThreadPool pool;
+        WaitingTask task;
+
+        pool.setMaxThreadCount(1);
+        pool.start(&task);
+        pool.start(&task);
+        QVERIFY(task.waitForStarted.tryAcquire(1, 1000));
+
+        // thread limit is 1, cannot start more tasks
+        QVERIFY(!task.waitForStarted.tryAcquire(1, 1000));
+        QCOMPARE(pool.activeThreadCount(), 1);
+
+        QProperty<int> maxThreadCount;
+        pool.bindableMaxThreadCount().setBinding(Qt::makePropertyBinding(maxThreadCount));
+
+        maxThreadCount = 2;
+        QCOMPARE(pool.maxThreadCount(), 2);
+
+        // increasing thread count should allow starting more tasks
+        QVERIFY(task.waitForStarted.tryAcquire(1, 1000));
+        QCOMPARE(pool.activeThreadCount(), 2);
+
+        task.waitToFinish.release(2);
+        pool.waitForDone();
+
+        QProperty<int> maxThreadCountObserver;
+        maxThreadCountObserver.setBinding(pool.bindableMaxThreadCount().makeBinding());
+        pool.setMaxThreadCount(10);
+        QCOMPARE(maxThreadCountObserver, 10);
+    }
+}
+
 QTEST_MAIN(tst_QThreadPool);
 #include "tst_qthreadpool.moc"