Add QFreeList as an internal class

This is a generic implementation of the lock-free free list found in
qabstracteventdispatcher.cpp. Use next() to get the next free entry in
the list, and release(id) when done with the id.

This version is templated and allows having a payload which can be
accessed using the id returned by next(). The payload is allocated and
deallocated automatically by the free list, but *NOT* when calling
next()/release(). Initialization should be done by code needing it after
next() returns. Likewise, cleanup should happen before calling
release(). It is possible to have use 'void' as the payload type, in
which case the free list only contains indexes to the next free entry.

Autotest included.

Change-Id: Ifd12a961d47f3d76593c45061f72e55c9b80a43b
Reviewed-on: http://codereview.qt.nokia.com/2160
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Olivier Goffart <olivier.goffart@nokia.com>

3 files changed, 186 insertions, 0 deletions

diff --git a/tests/auto/corelib.pro b/tests/auto/corelib.pro
index 95a16f67d9..7a655d6208 100644
--- a/tests/auto/corelib.pro
+++ b/tests/auto/corelib.pro
@@ -30,6 +30,7 @@ SUBDIRS=\
    qfileinfo \
    qfilesystemwatcher \
    qflags \
+   qfreelist \
    qfuture \
    qfuturewatcher \
    qgetputenv \
diff --git a/tests/auto/qfreelist/qfreelist.pro b/tests/auto/qfreelist/qfreelist.pro
new file mode 100644
index 0000000000..b7f2b3d38f
--- /dev/null
+++ b/tests/auto/qfreelist/qfreelist.pro
@@ -0,0 +1,6 @@
+load(qttest_p4)
+SOURCES  += tst_qfreelist.cpp
+QT += core-private
+QT -= gui
+
+!private_tests:SOURCES += $$QT_SOURCE_TREE/src/corelib/tools/qfreelist.cpp
diff --git a/tests/auto/qfreelist/tst_qfreelist.cpp b/tests/auto/qfreelist/tst_qfreelist.cpp
new file mode 100644
index 0000000000..139d76e64a
--- /dev/null
+++ b/tests/auto/qfreelist/tst_qfreelist.cpp
@@ -0,0 +1,179 @@
+/****************************************************************************
+**
+** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
+** All rights reserved.
+** Contact: Nokia Corporation (qt-info@nokia.com)
+**
+** This file is part of the test suite of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** GNU Lesser General Public License Usage
+** This file may be used under the terms of the GNU Lesser General Public
+** License version 2.1 as published by the Free Software Foundation and
+** appearing in the file LICENSE.LGPL included in the packaging of this
+** file. Please review the following information to ensure the GNU Lesser
+** General Public License version 2.1 requirements will be met:
+** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Nokia gives you certain additional
+** rights. These rights are described in the Nokia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU General
+** Public License version 3.0 as published by the Free Software Foundation
+** and appearing in the file LICENSE.GPL included in the packaging of this
+** file. Please review the following information to ensure the GNU General
+** Public License version 3.0 requirements will be met:
+** http://www.gnu.org/copyleft/gpl.html.
+**
+** Other Usage
+** Alternatively, this file may be used in accordance with the terms and
+** conditions contained in a signed written agreement between you and Nokia.
+**
+**
+**
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+
+#include <QtCore/QCoreApplication>
+#include <QtCore/QElapsedTimer>
+#include <QtCore/QList>
+#include <QtCore/QThread>
+#include <private/qfreelist_p.h>
+#include <QtTest/QtTest>
+
+//TESTED_CLASS=QFreeList
+//TESTED_FILES=corelib/tools/qfreelist_p.h
+
+class tst_QFreeList : public QObject
+{
+    Q_OBJECT
+
+private slots:
+    void basicTest();
+    void customized();
+    void threadedTest();
+};
+
+void tst_QFreeList::basicTest()
+{
+    {
+        QFreeList<void> voidFreeList;
+        int zero = voidFreeList.next();
+        int one  = voidFreeList.next();
+        int two = voidFreeList.next();
+        QCOMPARE(zero, 0);
+        QCOMPARE(one, 1);
+        QCOMPARE(two, 2);
+        voidFreeList[zero];
+        voidFreeList[one];
+        voidFreeList[two];
+        voidFreeList.at(zero);
+        voidFreeList.at(one);
+        voidFreeList.at(two);
+        voidFreeList.release(one);
+        int next = voidFreeList.next();
+        QCOMPARE(next, 1);
+        voidFreeList[next];
+        voidFreeList.at(next);
+    }
+
+    {
+        QFreeList<int> intFreeList;
+        int zero = intFreeList.next();
+        int one = intFreeList.next();
+        int two = intFreeList.next();
+        QCOMPARE(zero, 0);
+        QCOMPARE(one, 1);
+        QCOMPARE(two, 2);
+        intFreeList[zero] = zero;
+        intFreeList[one] = one;
+        intFreeList[two] = two;
+        QCOMPARE(intFreeList.at(zero), zero);
+        QCOMPARE(intFreeList.at(one), one);
+        QCOMPARE(intFreeList.at(two), two);
+        intFreeList.release(one);
+        int next = intFreeList.next();
+        QCOMPARE(next, 1);
+        QCOMPARE(intFreeList.at(next), one);
+        intFreeList[next] = -one;
+        QCOMPARE(intFreeList.at(next), -one);
+    }
+}
+
+struct CustomFreeListConstants : public QFreeListDefaultConstants
+{
+    enum {
+        InitialNextValue = 50,
+        BlockCount = 10
+    };
+
+    static const int Sizes[10];
+};
+
+const int CustomFreeListConstants::Sizes[10] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 16777216 - 1 - 2 - 3 - 4 - 5 - 6 - 7 - 8 - 9 };
+
+void tst_QFreeList::customized()
+{
+    QFreeList<void, CustomFreeListConstants> customFreeList;
+    int next = customFreeList.next();
+    QCOMPARE(next, int(CustomFreeListConstants::InitialNextValue));
+    customFreeList[next];
+    customFreeList.at(next);
+    customFreeList.release(next);
+}
+
+enum { TimeLimit = 3000 };
+
+class FreeListThread : public QThread
+{
+    static QFreeList<void> freelist;
+
+public:
+    inline FreeListThread() : QThread() { }
+    inline void run()
+    {
+        QElapsedTimer t;
+        t.start();
+        QList<int> needToRelease;
+        do {
+            int i = freelist.next();
+            int j = freelist.next();
+            int k = freelist.next();
+            int l = freelist.next();
+            freelist.release(k);
+            int n = freelist.next();
+            int m = freelist.next();
+            freelist.release(l);
+            freelist.release(m);
+            freelist.release(n);
+            freelist.release(j);
+            // freelist.release(i);
+            needToRelease << i;
+        } while (t.elapsed() < TimeLimit);
+
+        foreach (int x, needToRelease)
+            freelist.release(x);
+    }
+};
+
+QFreeList<void> FreeListThread::freelist;
+
+void tst_QFreeList::threadedTest()
+{
+    const int ThreadCount = QThread::idealThreadCount();
+    FreeListThread *threads = new FreeListThread[ThreadCount];
+    for (int i = 0; i < ThreadCount; ++i)
+        threads[i].start();
+    for (int i = 0; i < ThreadCount; ++i)
+        threads[i].wait();
+    delete [] threads;
+}
+
+QTEST_MAIN(tst_QFreeList)
+#include "tst_qfreelist.moc"