Import qlogger framework

Merge most parts of the qlogger framework from

git://gitorious.org/qtplayground/qlogger.git

The categorized logging feature is a replacement for qDebug, qWarning and
friends. With logging statements in an app/library, a developer can
turn on the statements they care about and turn off the ones they don't.

Most work for this was done by Wolfgang Beck and Lincoln Ramsay.

Task-number: QTBUG-25694
Change-Id: Ib0cdfbbf3694f86ad9ec553b2ea36f09a477cded
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

8 files changed, 1134 insertions, 2 deletions

diff --git a/src/corelib/doc/snippets/qloggingcategory/main.cpp b/src/corelib/doc/snippets/qloggingcategory/main.cpp
new file mode 100644
index 0000000000..d6d9ae0ff3
--- /dev/null
+++ b/src/corelib/doc/snippets/qloggingcategory/main.cpp
@@ -0,0 +1,113 @@
+/****************************************************************************
+**
+** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the examples 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 <QCoreApplication>
+#include <QLoggingCategory>
+
+//![1]
+// in a header
+Q_DECLARE_LOGGING_CATEGORY(QT_DRIVER_USB)
+
+// in one source file
+Q_LOGGING_CATEGORY(QT_DRIVER_USB, "qt.driver.usb")
+//![1]
+
+
+// Completely made up example, inspired by en.wikipedia.org/wiki/USB :)
+struct UsbEntry {
+    int id;
+    int classtype;
+};
+
+QDebug operator<<(QDebug &dbg, const UsbEntry &entry)
+{
+    dbg.nospace() << "" << entry.id << " (" << entry.classtype << ")";
+    return dbg.space();
+}
+
+QList<UsbEntry> usbEntries() {
+    QList<UsbEntry> entries;
+    return entries;
+}
+
+void main(int argc, char *argv[])
+{
+    QCoreApplication a(argc, argv);
+
+//![2]
+    // don't run the expensive code if the string won't print
+    if (QT_DRIVER_USB().isEnabled<QtDebugMsg>()) {
+        QStringList items;
+        foreach (const UsbEntry &entry, usbEntries())
+            items << QString("%1 (%2)").arg(entry.id, entry.classtype);
+        qCDebug(QT_DRIVER_USB) << "devices: " << items;
+    }
+//![2]
+
+//![3]
+    // usbEntries() will only be called if QT_DRIVER_USB category is enabled
+    qCDebug(QT_DRIVER_USB) << "devices: " << usbEntries();
+//![3]
+
+    {
+//![10]
+    QLoggingCategory category("qt.driver.usb");
+    qCDebug(category) << "a debug message";
+//![10]
+    }
+
+    {
+//![11]
+    QLoggingCategory category("qt.driver.usb");
+    qCWarning(category) << "a warning message";
+//![11]
+    }
+
+    {
+//![12]
+    QLoggingCategory category("qt.driver.usb");
+    qCCritical(category) << "a critical message";
+//![12]
+    }
+}
+
+//![20]
+void myCategoryFilter(QLoggingCategory *);
+//![20]
diff --git a/src/corelib/global/qlogging.cpp b/src/corelib/global/qlogging.cpp
index 5aaa0716f1..1cd11ad667 100644
--- a/src/corelib/global/qlogging.cpp
+++ b/src/corelib/global/qlogging.cpp
@@ -49,6 +49,8 @@
 #ifndef QT_BOOTSTRAPPED
 #include "qcoreapplication.h"
 #include "qthread.h"
+#include "qloggingcategory.h"
+#include "private/qloggingregistry_p.h"
 #endif
 #ifdef Q_OS_WIN
 #include <qt_windows.h>
@@ -920,6 +922,14 @@ static void qDefaultMsgHandler(QtMsgType type, const char *buf)
 
 static void qt_message_print(QtMsgType msgType, const QMessageLogContext &context, const QString &message)
 {
+#ifndef QT_BOOTSTRAPPED
+    // qDebug, qWarning, ... macros do not check whether category is enabled
+    if (!context.category || (strcmp(context.category, "default") == 0)) {
+        if (!QLoggingCategory::defaultCategory().isEnabled(msgType))
+            return;
+    }
+#endif
+
     if (!msgHandler)
         msgHandler = qDefaultMsgHandler;
     if (!messageHandler)
@@ -1151,6 +1161,7 @@ void qSetMessagePattern(const QString &pattern)
         qMessagePattern()->setPattern(pattern);
 }
 
+
 /*!
     Copies context information from \a logContext into this QMessageLogContext
     \internal
diff --git a/src/corelib/io/io.pri b/src/corelib/io/io.pri
index c00947dd97..b7fc1bc600 100644
--- a/src/corelib/io/io.pri
+++ b/src/corelib/io/io.pri
@@ -49,7 +49,10 @@ HEADERS +=  \
         io/qfilesystemmetadata_p.h \
         io/qfilesystemiterator_p.h \
         io/qfileselector.h \
-        io/qfileselector_p.h
+        io/qfileselector_p.h \
+        io/qloggingcategory.h \
+        io/qloggingcategory_p.h \
+        io/qloggingregistry_p.h
 
 SOURCES += \
         io/qabstractfileengine.cpp \
@@ -86,7 +89,9 @@ SOURCES += \
         io/qfilesystemwatcher_polling.cpp \
         io/qfilesystementry.cpp \
         io/qfilesystemengine.cpp \
-        io/qfileselector.cpp
+        io/qfileselector.cpp \
+        io/qloggingcategory.cpp \
+        io/qloggingregistry.cpp
 
 win32 {
         SOURCES += io/qsettings_win.cpp
diff --git a/src/corelib/io/qloggingcategory.cpp b/src/corelib/io/qloggingcategory.cpp
new file mode 100644
index 0000000000..562cf25964
--- /dev/null
+++ b/src/corelib/io/qloggingcategory.cpp
@@ -0,0 +1,352 @@
+/****************************************************************************
+**
+** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the QtCore module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** 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 Digia.  For licensing terms and
+** conditions see http://qt.digia.com/licensing.  For further information
+** use the contact form at http://qt.digia.com/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, 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, Digia gives you certain additional
+** rights.  These rights are described in the Digia 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.
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "qloggingcategory.h"
+#include "qloggingcategory_p.h"
+#include "qloggingregistry_p.h"
+
+QT_BEGIN_NAMESPACE
+
+const char qtDefaultCategoryName[] = "default";
+
+Q_GLOBAL_STATIC_WITH_ARGS(QLoggingCategory, qtDefaultCategory,
+                          (qtDefaultCategoryName))
+
+/*!
+    \class QLoggingCategory
+    \inmodule QtCore
+    \since 5.2
+
+    \brief A category, or 'area' in the logging infrastructure.
+
+    QLoggingCategory represents a certain logging category - identified
+    by a string - at runtime. Whether a category should be actually logged or
+    not can be checked with the \l isEnabled() methods.
+
+    \section1 Creating category objects
+
+    Qt provides the \l Q_LOGGING_CATEGORY(), Q_DECLARE_LOGGING_CATEGORY() macros
+    to conveniently create static QLoggingCategory objects on the heap:
+
+    \snippet qloggingcategory/main.cpp 1
+
+    \section1 Checking category configuration
+
+    QLoggingCategory provides two isEnabled methods, a template one and a
+    non-template one, for checking whether the current category is enabled.
+    The template version checks for the most common case that no special rules
+    are applied in inline code, and should be preferred:
+
+    \snippet qloggingcategory/main.cpp 2
+
+    Note that qCDebug() prevents arguments from being evaluated
+    if the string won't print, so calling isEnabled explicitly is not needed:
+    \l isEnabled().
+
+    \snippet qloggingcategory/main.cpp 3
+
+    \section1 Default configuration
+
+    In the default configuration \l isEnabled() will return true for all
+    \l QtMsgType types except QtDebugMsg: QtDebugMsg is only active by default
+    for the \c "default" category.
+
+    \section1 Changing configuration
+
+    The default configuration can be changed by calling \l setEnabled(). However,
+    this only affects the current category object, not e.g. another object for the
+    same category name. Use either \l setFilterRules() or \l installFilter() to
+    configure categories globally.
+*/
+
+/*!
+    Constructs a QLoggingCategory object with the provided \a category name.
+    The object becomes the local identifier for the category.
+
+    If \a category is \c{0}, the category name is changed to \c{"default"}.
+*/
+QLoggingCategory::QLoggingCategory(const char *category)
+    : name(0),
+      enabledDebug(false),
+      enabledWarning(true),
+      enabledCritical(true)
+{
+    bool isDefaultCategory
+            = (category == 0) || (strcmp(category, qtDefaultCategoryName) == 0);
+
+    if (isDefaultCategory) {
+        // normalize default category names, so that we can just do
+        // pointer comparison in QLoggingRegistry::updateCategory
+        name = qtDefaultCategoryName;
+        enabledDebug = true;
+    } else {
+        name = category;
+    }
+
+    if (QLoggingRegistry *reg = QLoggingRegistry::instance())
+        reg->registerCategory(this);}
+
+/*!
+    Destructs a QLoggingCategory object
+*/
+QLoggingCategory::~QLoggingCategory()
+{
+    if (QLoggingRegistry *reg = QLoggingRegistry::instance())
+        reg->unregisterCategory(this);
+}
+
+/*!
+   \fn const char *QLoggingCategory::categoryName() const
+
+    Returns the name of the category.
+*/
+
+/*!
+    \fn bool QLoggingCategory::isEnabled() const
+
+    Returns true if a message of the template \c QtMsgType argument should be
+    shown. Returns false otherwise.
+
+    \note The qCDebug, qCWarning, qCCritical macros already do this check before
+    executing any code. However, calling this method may be useful to avoid
+    expensive generation of data that is only used for debug output.
+*/
+
+/*!
+    Returns true if a message of type \a msgtype for the category should be
+    shown. Returns false otherwise.
+
+    \note The templated, inline version of this method, \l isEnabled(), is
+    optimized for the common case that no configuration is set, and should
+    generally be preferred.
+*/
+bool QLoggingCategory::isEnabled(QtMsgType msgtype) const
+{
+    switch (msgtype) {
+    case QtDebugMsg: return enabledDebug;
+    case QtWarningMsg: return enabledWarning;
+    case QtCriticalMsg: return enabledCritical;
+    case QtFatalMsg: return true;
+    default: break;
+    }
+    return false;
+}
+
+/*!
+    Changes the type \a type for the category to \a enable.
+
+    Changes only affect the current QLoggingCategory object, and won't
+    change e.g. the settings of another objects for the same category name.
+
+    \note QtFatalMsg cannot be changed. It will always return true.
+*/
+void QLoggingCategory::setEnabled(QtMsgType type, bool enable)
+{
+    switch (type) {
+    case QtDebugMsg: enabledDebug = enable; break;
+    case QtWarningMsg: enabledWarning = enable; break;
+    case QtCriticalMsg: enabledCritical = enable; break;
+    case QtFatalMsg:
+    default: break;
+    }
+}
+
+/*!
+    \fn QLoggingCategory &QLoggingCategory::operator()()
+
+    Returns the object itself. This allows both a QLoggingCategory variable, and
+    a factory method returning a QLoggingCategory, to be used in qCDebug(),
+    qCWarning(), qCCritial() macros.
+ */
+
+/*!
+    Returns the category "default" that is used e.g. by qDebug(), qWarning(),
+    qCritical(), qFatal().
+ */
+QLoggingCategory &QLoggingCategory::defaultCategory()
+{
+    return *qtDefaultCategory();
+}
+
+/*!
+    \typedef QLoggingCategory::CategoryFilter
+
+    This is a typedef for a pointer to a function with the following
+    signature:
+
+    \snippet qloggingcategory/main.cpp 20
+
+    A function with this signature can be installed with \l installFilter().
+*/
+
+/*!
+    Installs a function \a filter that is used to determine which categories
+    and message types should be enabled. Returns a pointer to the previous
+    installed filter.
+
+    Every QLoggingCategory object created is passed to the filter, and the
+    filter is free to change the respective category configuration with
+    \l setEnabled().
+
+    An alternative way of configuring the default filter is via
+    \l setFilterRules().
+ */
+QLoggingCategory::CategoryFilter
+QLoggingCategory::installFilter(QLoggingCategory::CategoryFilter filter)
+{
+    return QLoggingRegistry::instance()->installFilter(filter);
+}
+
+
+/*!
+    Configures which categories and message types should be enabled through a
+    a set of \a rules.
+
+    Each line in \a rules must have the format
+
+    \code
+    <category>[.<type>] = true|false
+    \endcode
+
+    where \c <category> is the name of the category, potentially with \c{*} as a
+    wildcard symbol at the start and/or the end. The optional \c <type> must
+    be either \c debug, \c warning, or \c critical.
+
+    The rules might be ignored if a custom category filter is installed with
+    \l installFilter().
+*/
+void QLoggingCategory::setFilterRules(const QString &rules)
+{
+    QLoggingRegistry::instance()->rulesParser.setRules(rules);
+}
+
+/*!
+    \macro qCDebug(category)
+    \relates QLoggingCategory
+    \since 5.2
+
+    Returns an output stream for debug messages in the logging category
+    \a category.
+
+    The macro expands to code that first checks whether
+    \l QLoggingCategory::isEnabled() evaluates for debug output to \c{true}.
+    If so, the stream arguments are processed and sent to the message handler.
+
+    Example:
+
+    \snippet qloggingcategory/main.cpp 10
+
+    \note Arguments are not processed if debug output for the category is not
+    enabled, so do not rely on any side effects.
+
+    \sa qDebug()
+*/
+
+/*!
+    \macro qCWarning(category)
+    \relates QLoggingCategory
+    \since 5.2
+
+    Returns an output stream for warning messages in the logging category
+    \a category.
+
+    The macro expands to code that first checks whether
+    \l QLoggingCategory::isEnabled() evaluates for warning output to \c{true}.
+    If so, the stream arguments are processed and sent to the message handler.
+
+    Example:
+
+    \snippet qloggingcategory/main.cpp 11
+
+    \note Arguments are not processed if warning output for the category is not
+    enabled, so do not rely on any side effects.
+
+    \sa qWarning()
+*/
+
+/*!
+    \macro qCCritical(category)
+    \relates QLoggingCategory
+    \since 5.2
+
+    Returns an output stream for critical messages in the logging category
+    \a category.
+
+    The macro expands to code that first checks whether
+    \l QLoggingCategory::isEnabled() evaluates for critical output to \c{true}.
+    If so, the stream arguments are processed and sent to the message handler.
+
+    Example:
+
+    \snippet qloggingcategory/main.cpp 12
+
+    \note Arguments are not processed if critical output for the category is not
+    enabled, so do not reply on any side effects.
+
+    \sa qCritical()
+*/
+
+/*!
+    \macro Q_DECLARE_LOGGING_CATEGORY(name)
+    \relates QLoggingCategory
+    \since 5.2
+
+    Declares a logging category \a name. The macro can be used to declare
+    a common logging category shared in different parts of the program.
+
+    This macro must be used outside of a class or method.
+*/
+
+/*!
+    \macro Q_LOGGING_CATEGORY(name, string)
+    \relates QLoggingCategory
+    \since 5.2
+
+    Defines a logging category \a name, and makes it configurable under the
+    \a string identifier.
+
+    Only one translation unit in a library or executable can define a category
+    with a specific name.
+
+    This macro must be used outside of a class or method.
+*/
+
+QT_END_NAMESPACE
diff --git a/src/corelib/io/qloggingcategory.h b/src/corelib/io/qloggingcategory.h
new file mode 100644
index 0000000000..90111c96fa
--- /dev/null
+++ b/src/corelib/io/qloggingcategory.h
@@ -0,0 +1,138 @@
+/****************************************************************************
+**
+** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the QtCore module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** 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 Digia.  For licensing terms and
+** conditions see http://qt.digia.com/licensing.  For further information
+** use the contact form at http://qt.digia.com/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, 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, Digia gives you certain additional
+** rights.  These rights are described in the Digia 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.
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QLOGGINGCATEGORY_H
+#define QLOGGINGCATEGORY_H
+
+#include <QtCore/qglobal.h>
+#include <QtCore/qdebug.h>
+
+QT_BEGIN_NAMESPACE
+
+class Q_CORE_EXPORT QLoggingCategory
+{
+    Q_DISABLE_COPY(QLoggingCategory)
+public:
+    explicit QLoggingCategory(const char *category);
+    ~QLoggingCategory();
+
+    template <QtMsgType T>
+    bool isEnabled() const
+    {
+        return isEnabled(T);
+    }
+
+    bool isEnabled(QtMsgType type) const;
+    void setEnabled(QtMsgType type, bool enable);
+
+    const char *categoryName() const { return name; }
+
+    // allows usage of both factory method and variable in qCX macros
+    QLoggingCategory &operator()() { return *this; }
+
+    static QLoggingCategory &defaultCategory();
+
+    typedef void (*CategoryFilter)(QLoggingCategory*);
+    static CategoryFilter installFilter(CategoryFilter);
+
+    static void setFilterRules(const QString &rules);
+
+private:
+    const char *name;
+
+    bool enabledDebug;
+    bool enabledWarning;
+    bool enabledCritical;
+
+    friend class QLoggingRegistry;
+};
+
+template <>
+inline bool QLoggingCategory::isEnabled<QtDebugMsg>() const
+{
+    return enabledDebug;
+}
+
+template <>
+inline bool QLoggingCategory::isEnabled<QtWarningMsg>() const
+{
+    return enabledWarning;
+}
+
+template <>
+inline bool QLoggingCategory::isEnabled<QtCriticalMsg>() const
+{
+    return enabledCritical;
+}
+
+#define Q_DECLARE_LOGGING_CATEGORY(name) \
+    extern QLoggingCategory &name();
+
+// relies on QLoggingCategory(QString) being thread safe!
+#define Q_LOGGING_CATEGORY(name, string) \
+    QLoggingCategory &name() \
+    { \
+        static QLoggingCategory category(string); \
+        return category; \
+    }
+
+#define qCDebug(category) \
+    for (bool enabled = category().isEnabled<QtDebugMsg>(); enabled; enabled = false) \
+        QMessageLogger(__FILE__, __LINE__, Q_FUNC_INFO, category().categoryName()).debug()
+#define qCWarning(category) \
+    for (bool enabled = category().isEnabled<QtWarningMsg>(); enabled; enabled = false) \
+        QMessageLogger(__FILE__, __LINE__, Q_FUNC_INFO, category().categoryName()).warning()
+#define qCCritical(category) \
+    for (bool enabled = category().isEnabled<QtCriticalMsg>(); enabled; enabled = false) \
+        QMessageLogger(__FILE__, __LINE__, Q_FUNC_INFO, category().categoryName()).critical()
+
+#if defined(QT_NO_DEBUG_OUTPUT)
+#  undef qCDebug
+#  define qCDebug(category) QT_NO_QDEBUG_MACRO()
+#endif
+#if defined(QT_NO_WARNING_OUTPUT)
+#  undef qCWarning
+#  define qCWarning(category) QT_NO_QWARNING_MACRO()
+#endif
+
+QT_END_NAMESPACE
+
+#endif // QLOGGINGCATEGORY_H
diff --git a/src/corelib/io/qloggingcategory_p.h b/src/corelib/io/qloggingcategory_p.h
new file mode 100644
index 0000000000..7802f017fd
--- /dev/null
+++ b/src/corelib/io/qloggingcategory_p.h
@@ -0,0 +1,66 @@
+/****************************************************************************
+**
+** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the QtCore module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** 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 Digia.  For licensing terms and
+** conditions see http://qt.digia.com/licensing.  For further information
+** use the contact form at http://qt.digia.com/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, 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, Digia gives you certain additional
+** rights.  These rights are described in the Digia 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.
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QLOGGINGCATEGORY_P_H
+#define QLOGGINGCATEGORY_P_H
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists for the convenience
+// of a number of Qt sources files.  This header file may change from
+// version to version without notice, or even be removed.
+//
+// We mean it.
+//
+
+#include <QtCore/qglobal.h>
+
+QT_BEGIN_NAMESPACE
+
+// unique pointer to default category
+// (allows to compare for pointers instead of strings)
+extern const char qtDefaultCategoryName[];
+
+QT_END_NAMESPACE
+
+#endif // QLOGGINGCATEGORY_P_H
diff --git a/src/corelib/io/qloggingregistry.cpp b/src/corelib/io/qloggingregistry.cpp
new file mode 100644
index 0000000000..a82e6f65f4
--- /dev/null
+++ b/src/corelib/io/qloggingregistry.cpp
@@ -0,0 +1,312 @@
+/****************************************************************************
+**
+** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the QtCore module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** 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 Digia.  For licensing terms and
+** conditions see http://qt.digia.com/licensing.  For further information
+** use the contact form at http://qt.digia.com/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, 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, Digia gives you certain additional
+** rights.  These rights are described in the Digia 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.
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "qloggingregistry_p.h"
+#include "qloggingcategory_p.h"
+
+QT_BEGIN_NAMESPACE
+
+Q_GLOBAL_STATIC(QLoggingRegistry, qtLoggingRegistry)
+
+/*!
+    \internal
+    Constructs a logging rule with default values.
+*/
+QLoggingRule::QLoggingRule() :
+    flags(Invalid),
+    enabled(false)
+{
+}
+
+/*!
+    \internal
+    Constructs a logging rule.
+*/
+QLoggingRule::QLoggingRule(const QString &pattern, bool enabled) :
+    pattern(pattern),
+    flags(Invalid),
+    enabled(enabled)
+{
+    parse();
+}
+
+/*!
+    \internal
+    Return value 1 means filter passed, 0 means filter doesn't influence this
+    category, -1 means category doesn't pass this filter.
+ */
+int QLoggingRule::pass(const QString &categoryName, QtMsgType msgType) const
+{
+    QString fullCategory = categoryName;
+    switch (msgType) {
+    case QtDebugMsg:
+        fullCategory += QLatin1String(".debug");
+        break;
+    case QtWarningMsg:
+        fullCategory += QLatin1String(".warning");
+        break;
+    case QtCriticalMsg:
+        fullCategory += QLatin1String(".critical");
+        break;
+    default:
+        break;
+    }
+
+    if (flags == FullText) {
+        // can be
+        //   qtproject.org.debug = true
+        // or
+        //   qtproject.org = true
+        if (pattern == categoryName
+                || pattern == fullCategory)
+            return (enabled ? 1 : -1);
+    }
+
+    int idx = 0;
+    if (flags == MidFilter) {
+        // e.g. *.qtproject*
+        idx = fullCategory.indexOf(pattern);
+        if (idx >= 0)
+            return (enabled ? 1 : -1);
+    } else {
+        idx = fullCategory.indexOf(pattern);
+        if (flags == LeftFilter) {
+            // e.g. org.qtproject.*
+            if (idx == 0)
+                return (enabled ? 1 : -1);
+        } else if (flags == RightFilter) {
+            // e.g. *.qtproject
+            if (idx == (fullCategory.count() - pattern.count()))
+                return (enabled ? 1 : -1);
+        }
+    }
+    return 0;
+}
+
+/*!
+    \internal
+    Parses the category and checks which kind of wildcard the filter can contain.
+    Allowed is f.ex.:
+             org.qtproject.logging FullText
+             org.qtproject.*       LeftFilter
+             *.qtproject           RightFilter
+             *.qtproject*          MidFilter
+ */
+void QLoggingRule::parse()
+{
+    int index = pattern.indexOf(QLatin1Char('*'));
+    if (index < 0) {
+        flags = FullText;
+    } else {
+        flags = Invalid;
+        if (index == 0) {
+            flags |= RightFilter;
+            pattern = pattern.remove(0, 1);
+            index = pattern.indexOf(QLatin1Char('*'));
+        }
+        if (index == (pattern.length() - 1)) {
+            flags |= LeftFilter;
+            pattern = pattern.remove(pattern.length() - 1, 1);
+        }
+    }
+}
+
+/*!
+    \internal
+    Creates a new QLoggingRules object.
+*/
+QLoggingRulesParser::QLoggingRulesParser(QLoggingRegistry *registry)  :
+    registry(registry)
+{
+}
+
+/*!
+    \internal
+    Sets logging rules string.
+*/
+void QLoggingRulesParser::setRules(const QString &content)
+{
+    QString content_ = content;
+    QTextStream stream(&content_, QIODevice::ReadOnly);
+    parseRules(stream);
+}
+
+/*!
+    \internal
+    Parses rules out of a QTextStream.
+*/
+void QLoggingRulesParser::parseRules(QTextStream &stream)
+{
+    QVector<QLoggingRule> rules;
+
+    while (!stream.atEnd()) {
+        QString line = stream.readLine();
+
+        // Remove all whitespace from line
+        line = line.simplified();
+        line.remove(QLatin1Char(' '));
+
+        const QStringList pair = line.split(QLatin1Char('='));
+        if (pair.count() == 2) {
+            const QString pattern = pair.at(0);
+            bool enabled = (QString::compare(pair.at(1),
+                                             QLatin1String("true"),
+                                             Qt::CaseInsensitive) == 0);
+            rules.append(QLoggingRule(pattern, enabled));
+        }
+    }
+
+    registry->setRules(rules);
+}
+
+/*!
+    \internal
+    QLoggingPrivate constructor
+ */
+QLoggingRegistry::QLoggingRegistry()
+    : rulesParser(this),
+      categoryFilter(defaultCategoryFilter)
+{
+}
+
+/*!
+    \internal
+    Registers a category object.
+
+    This method might be called concurrently for the same category object.
+*/
+void QLoggingRegistry::registerCategory(QLoggingCategory *cat)
+{
+    QMutexLocker locker(&registryMutex);
+
+    if (!categories.contains(cat)) {
+        categories.append(cat);
+        (*categoryFilter)(cat);
+    }
+}
+
+/*!
+    \internal
+    Unregisters a category object.
+*/
+void QLoggingRegistry::unregisterCategory(QLoggingCategory *cat)
+{
+    QMutexLocker locker(&registryMutex);
+
+    categories.removeOne(cat);
+}
+
+/*!
+    \internal
+    Activates a new set of logging rules for the default filter.
+*/
+void QLoggingRegistry::setRules(const QVector<QLoggingRule> &rules_)
+{
+    QMutexLocker locker(&registryMutex);
+
+    rules = rules_;
+
+    if (categoryFilter != defaultCategoryFilter)
+        return;
+
+    foreach (QLoggingCategory *cat, categories)
+        (*categoryFilter)(cat);
+}
+
+/*!
+    \internal
+    Installs a custom filter rule.
+*/
+QLoggingCategory::CategoryFilter
+QLoggingRegistry::installFilter(QLoggingCategory::CategoryFilter filter)
+{
+    QMutexLocker locker(&registryMutex);
+
+    if (filter == 0)
+        filter = defaultCategoryFilter;
+
+    QLoggingCategory::CategoryFilter old = categoryFilter;
+    categoryFilter = filter;
+
+    foreach (QLoggingCategory *cat, categories)
+        (*categoryFilter)(cat);
+
+    return old;
+}
+
+QLoggingRegistry *QLoggingRegistry::instance()
+{
+    return qtLoggingRegistry();
+}
+
+/*!
+    \internal
+    Updates category settings according to rules.
+*/
+void QLoggingRegistry::defaultCategoryFilter(QLoggingCategory *cat)
+{
+    // QLoggingCategory() normalizes all "default" strings
+    // to qtDefaultCategoryName
+    bool debug = (cat->categoryName() == qtDefaultCategoryName);
+    bool warning = true;
+    bool critical = true;
+
+    QString categoryName = QLatin1String(cat->categoryName());
+    QLoggingRegistry *reg = QLoggingRegistry::instance();
+    foreach (const QLoggingRule &item, reg->rules) {
+        int filterpass = item.pass(categoryName, QtDebugMsg);
+        if (filterpass != 0)
+            debug = (filterpass > 0);
+        filterpass = item.pass(categoryName, QtWarningMsg);
+        if (filterpass != 0)
+            warning = (filterpass > 0);
+        filterpass = item.pass(categoryName, QtCriticalMsg);
+        if (filterpass != 0)
+            critical = (filterpass > 0);
+    }
+
+    cat->setEnabled(QtDebugMsg, debug);
+    cat->setEnabled(QtWarningMsg, warning);
+    cat->setEnabled(QtCriticalMsg, critical);
+}
+
+
+QT_END_NAMESPACE
diff --git a/src/corelib/io/qloggingregistry_p.h b/src/corelib/io/qloggingregistry_p.h
new file mode 100644
index 0000000000..cbf7aecc4f
--- /dev/null
+++ b/src/corelib/io/qloggingregistry_p.h
@@ -0,0 +1,135 @@
+/****************************************************************************
+**
+** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the QtCore module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** 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 Digia.  For licensing terms and
+** conditions see http://qt.digia.com/licensing.  For further information
+** use the contact form at http://qt.digia.com/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, 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, Digia gives you certain additional
+** rights.  These rights are described in the Digia 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.
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QLOGGINGREGISTRY_P_H
+#define QLOGGINGREGISTRY_P_H
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists for the convenience
+// of a number of Qt sources files.  This header file may change from
+// version to version without notice, or even be removed.
+//
+// We mean it.
+//
+
+#include <QtCore/qloggingcategory.h>
+#include <QtCore/qmap.h>
+#include <QtCore/qmutex.h>
+#include <QtCore/qstring.h>
+#include <QtCore/qtextstream.h>
+#include <QtCore/qvector.h>
+
+QT_BEGIN_NAMESPACE
+
+class QLoggingRule
+{
+public:
+    QLoggingRule();
+    QLoggingRule(const QString &pattern, bool enabled);
+    int pass(const QString &categoryName, QtMsgType type) const;
+
+    enum PatternFlag {
+        Invalid = 0x0,
+        FullText = 0x1,
+        LeftFilter = 0x2,
+        RightFilter = 0x4,
+        MidFilter = LeftFilter |  RightFilter
+    };
+    Q_DECLARE_FLAGS(PatternFlags, PatternFlag)
+
+    QString pattern;
+    PatternFlags flags;
+    bool enabled;
+
+private:
+    void parse();
+};
+
+Q_DECLARE_OPERATORS_FOR_FLAGS(QLoggingRule::PatternFlags)
+Q_DECLARE_TYPEINFO(QLoggingRule, Q_MOVABLE_TYPE);
+
+class QLoggingRulesParser
+{
+private:
+    explicit QLoggingRulesParser(class QLoggingRegistry *logging);
+
+public:
+    void setRules(const QString &content);
+
+private:
+    void parseRules(QTextStream &stream);
+    QLoggingRegistry *registry;
+
+    friend class QLoggingRegistry;
+};
+
+class QLoggingRegistry
+{
+public:
+    QLoggingRegistry();
+
+    void registerCategory(QLoggingCategory *category);
+    void unregisterCategory(QLoggingCategory *category);
+
+    void setRules(const QVector<QLoggingRule> &rules);
+
+    QLoggingCategory::CategoryFilter
+    installFilter(QLoggingCategory::CategoryFilter filter);
+
+    static QLoggingRegistry *instance();
+
+    QLoggingRulesParser rulesParser;
+
+private:
+    static void defaultCategoryFilter(QLoggingCategory *category);
+
+    QMutex registryMutex;
+    QVector<QLoggingRule> rules;
+    QList<QLoggingCategory*> categories;
+    QLoggingCategory::CategoryFilter categoryFilter;
+};
+
+QT_END_NAMESPACE
+
+#endif // QLOGGINGREGISTRY_P_H