Add a new Q_GLOBAL_STATIC implementation

Unlike the previous implementation, this implementation is locked:
only one initialisation is ever run at the same time. It is
exception-safe, meaning that a throwing constructor will restart the
process.

Also, start using the thread-safe behaviour that GCC has offered for a
long time and C++11 requires.

Change-Id: I20db44f57d258923df64c0051358fd0d9a5ccd51
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>
Reviewed-by: David Faure (KDE) <faure@kde.org>
Reviewed-by: Jędrzej Nowacki <jedrzej.nowacki@digia.com>

2 files changed, 226 insertions, 0 deletions

diff --git a/tests/auto/corelib/global/qglobalstatic/qglobalstatic.pro b/tests/auto/corelib/global/qglobalstatic/qglobalstatic.pro
new file mode 100644
index 0000000000..21cab8f67d
--- /dev/null
+++ b/tests/auto/corelib/global/qglobalstatic/qglobalstatic.pro
@@ -0,0 +1,12 @@
+QT       += testlib core-private
+
+QT       -= gui
+
+TARGET = tst_qglobalstatic
+CONFIG   += console
+CONFIG   -= app_bundle
+CONFIG   += exceptions
+
+SOURCES += tst_qglobalstatic.cpp
+DEFINES += SRCDIR=\\\"$$PWD/\\\"
+DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0
diff --git a/tests/auto/corelib/global/qglobalstatic/tst_qglobalstatic.cpp b/tests/auto/corelib/global/qglobalstatic/tst_qglobalstatic.cpp
new file mode 100644
index 0000000000..b9aa70fe80
--- /dev/null
+++ b/tests/auto/corelib/global/qglobalstatic/tst_qglobalstatic.cpp
@@ -0,0 +1,214 @@
+/****************************************************************************
+**
+** Copyright (C) 2011 Thiago Macieira <thiago@kde.org>
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the QtCore module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:BSD$
+** You may use this file under the terms of the BSD license as follows:
+**
+** "Redistribution and use in source and binary forms, with or without
+** modification, are permitted provided that the following conditions are
+** met:
+**   * Redistributions of source code must retain the above copyright
+**     notice, this list of conditions and the following disclaimer.
+**   * Redistributions in binary form must reproduce the above copyright
+**     notice, this list of conditions and the following disclaimer in
+**     the documentation and/or other materials provided with the
+**     distribution.
+**   * Neither the name of Digia Plc and its Subsidiary(-ies) nor the names
+**     of its contributors may be used to endorse or promote products derived
+**     from this software without specific prior written permission.
+**
+**
+** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include <QtCore/QThread>
+#include <QtTest/QtTest>
+
+class tst_QGlobalStatic : public QObject
+{
+    Q_OBJECT
+
+private Q_SLOTS:
+    void beforeInitialization();
+    void api();
+    void constVolatile();
+    void exception();
+    void threadStressTest();
+    void afterDestruction();
+};
+
+Q_GLOBAL_STATIC_WITH_ARGS(const int, constInt, (42))
+Q_GLOBAL_STATIC_WITH_ARGS(volatile int, volatileInt, (-47))
+
+void otherFunction()
+{
+    // never called
+    constInt();
+    volatileInt();
+}
+
+// do not initialize the following Q_GLOBAL_STATIC
+Q_GLOBAL_STATIC(int, checkedBeforeInitialization)
+void tst_QGlobalStatic::beforeInitialization()
+{
+    QVERIFY(!checkedBeforeInitialization.exists());
+    QVERIFY(!checkedBeforeInitialization.isDestroyed());
+}
+
+struct Type {
+    int i;
+};
+
+Q_GLOBAL_STATIC(Type, checkedAfterInitialization)
+void tst_QGlobalStatic::api()
+{
+    // check the API
+    QVERIFY((Type *)checkedAfterInitialization);
+    QVERIFY(checkedAfterInitialization());
+    *checkedAfterInitialization = Type();
+    *checkedAfterInitialization() = Type();
+
+    checkedAfterInitialization()->i = 47;
+    checkedAfterInitialization->i = 42;
+    QCOMPARE(checkedAfterInitialization()->i, 42);
+    checkedAfterInitialization()->i = 47;
+    QCOMPARE(checkedAfterInitialization->i, 47);
+
+    QVERIFY(checkedAfterInitialization.exists());
+    QVERIFY(!checkedAfterInitialization.isDestroyed());
+}
+
+void tst_QGlobalStatic::constVolatile()
+{
+    QCOMPARE(*constInt(), 42);
+    QCOMPARE((int)*volatileInt(), -47);
+    QCOMPARE(*constInt(), 42);
+    QCOMPARE((int)*volatileInt(), -47);
+}
+
+struct ThrowingType
+{
+    static QBasicAtomicInt constructedCount;
+    static QBasicAtomicInt destructedCount;
+    ThrowingType(QBasicAtomicInt &throwControl)
+    {
+        constructedCount.ref();
+        if (throwControl.fetchAndAddRelaxed(-1) != 0)
+            throw 0;
+    }
+    ~ThrowingType() { destructedCount.ref(); }
+};
+QBasicAtomicInt ThrowingType::constructedCount = Q_BASIC_ATOMIC_INITIALIZER(0);
+QBasicAtomicInt ThrowingType::destructedCount = Q_BASIC_ATOMIC_INITIALIZER(0);
+
+QBasicAtomicInt exceptionControlVar = Q_BASIC_ATOMIC_INITIALIZER(1);
+Q_GLOBAL_STATIC_WITH_ARGS(ThrowingType, exceptionGS, (exceptionControlVar))
+void tst_QGlobalStatic::exception()
+{
+    if (exceptionControlVar.load() != 1)
+        QSKIP("This test cannot be run more than once");
+    ThrowingType::constructedCount.store(0);
+    ThrowingType::destructedCount.store(0);
+
+    bool exceptionCaught = false;
+    try {
+        exceptionGS();
+    } catch (int) {
+        exceptionCaught = true;
+    }
+    QCOMPARE(ThrowingType::constructedCount.load(), 1);
+    QVERIFY(exceptionCaught);
+
+    exceptionGS();
+    QCOMPARE(ThrowingType::constructedCount.load(), 2);
+}
+
+QBasicAtomicInt threadStressTestControlVar = Q_BASIC_ATOMIC_INITIALIZER(5);
+Q_GLOBAL_STATIC_WITH_ARGS(ThrowingType, threadStressTestGS, (threadStressTestControlVar))
+
+
+void tst_QGlobalStatic::threadStressTest()
+{
+    class ThreadStressTestThread: public QThread
+    {
+    public:
+        QReadWriteLock *lock;
+        void run()
+        {
+            QReadLocker l(lock);
+            //usleep(qrand() * 200 / RAND_MAX);
+            // thundering herd
+            try {
+                threadStressTestGS();
+            } catch (int) {
+            }
+        }
+    };
+
+    ThrowingType::constructedCount.store(0);
+    ThrowingType::destructedCount.store(0);
+    int expectedConstructionCount = threadStressTestControlVar.load() + 1;
+    if (expectedConstructionCount <= 0)
+        QSKIP("This test cannot be run more than once");
+
+    const int numThreads = 200;
+    ThreadStressTestThread threads[numThreads];
+    QReadWriteLock lock;
+    lock.lockForWrite();
+    for (int i = 0; i < numThreads; ++i) {
+        threads[i].lock = &lock;
+        threads[i].start();
+    }
+
+    // wait for all threads
+    // release the herd
+    lock.unlock();
+
+    for (int i = 0; i < numThreads; ++i)
+        threads[i].wait();
+
+    QCOMPARE(ThrowingType::constructedCount.loadAcquire(), expectedConstructionCount);
+    QCOMPARE(ThrowingType::destructedCount.loadAcquire(), 0);
+}
+
+Q_GLOBAL_STATIC(int, checkedAfterDestruction)
+void tst_QGlobalStatic::afterDestruction()
+{
+    // this test will not produce results now
+    // it will simply run some code on destruction (after the global statics have been deleted)
+    // if that fails, this will cause a crash
+
+    // static destruction is LIFO: so we must add our exit-time code before the
+    // global static is used for the first time
+    static struct RunAtExit {
+        ~RunAtExit() {
+            int *ptr = checkedAfterDestruction();
+            if (ptr)
+                qFatal("Global static is not null as was expected");
+        }
+    } runAtExit;
+    (void) runAtExit;
+
+    *checkedAfterDestruction = 42;
+}
+
+QTEST_APPLESS_MAIN(tst_QGlobalStatic);
+
+#include "tst_qglobalstatic.moc"