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/****************************************************************************
**
** Copyright (C) 2016 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of Qt for Python.
**
** $QT_BEGIN_LICENSE:LGPL$
** 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 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 Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 3 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL3 included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 3 requirements
** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 2.0 or (at your option) the GNU General
** Public license version 3 or any later version approved by the KDE Free
** Qt Foundation. The licenses are as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
** 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-2.0.html and
** https://www.gnu.org/licenses/gpl-3.0.html.
**
** $QT_END_LICENSE$
**
****************************************************************************/

#include "globalreceiverv2.h"
#include "dynamicqmetaobject_p.h"
#include "pysideweakref.h"
#include "signalmanager.h"

#include <autodecref.h>
#include <gilstate.h>

#include <QtCore/QMetaMethod>
#include <QtCore/QSet>

#define RECEIVER_DESTROYED_SLOT_NAME "__receiverDestroyed__(QObject*)"

namespace
{
    static int DESTROY_SIGNAL_ID = 0;
    static int DESTROY_SLOT_ID = 0;
}

namespace PySide
{
class DynamicSlotDataV2
{
    Q_DISABLE_COPY(DynamicSlotDataV2)
    public:
        DynamicSlotDataV2(PyObject *callback, GlobalReceiverV2 *parent);
        ~DynamicSlotDataV2();

        int addSlot(const char *signature);
        int id(const char *signature) const;
        PyObject *callback();
        QByteArray hash() const;
        void notify();

        static void onCallbackDestroyed(void *data);
        static QByteArray hash(PyObject *callback);


    private:
        bool m_isMethod;
        PyObject *m_callback;
        PyObject *m_pythonSelf;
        PyObject *m_pyClass;
        PyObject *m_weakRef;
        QMap<QByteArray, int> m_signatures;
        GlobalReceiverV2 *m_parent;
        QByteArray m_hash;
};

}

using namespace PySide;

DynamicSlotDataV2::DynamicSlotDataV2(PyObject *callback, GlobalReceiverV2 *parent)
    : m_pythonSelf(0), m_pyClass(0), m_weakRef(0), m_parent(parent)
{
    Shiboken::GilState gil;

    m_isMethod = PyMethod_Check(callback);
    if (m_isMethod) {
        //Can not store calback pointe because this will be destroyed at the end of the scope
        //To avoid increment intance reference keep the callback information
        m_callback = PyMethod_GET_FUNCTION(callback);
#ifndef IS_PY3K
        m_pyClass = PyMethod_GET_CLASS(callback);
#endif
        m_pythonSelf = PyMethod_GET_SELF(callback);

        //monitor class from method lifetime
        m_weakRef = WeakRef::create(m_pythonSelf, DynamicSlotDataV2::onCallbackDestroyed, this);

        m_hash = QByteArray::number((qlonglong)PyObject_Hash(m_callback))
                 + QByteArray::number((qlonglong)PyObject_Hash(m_pythonSelf));

    } else {
        m_callback = callback;
        Py_INCREF(m_callback);

        m_hash = QByteArray::number((qlonglong)PyObject_Hash(m_callback));
    }
}

QByteArray DynamicSlotDataV2::hash() const
{
    return m_hash;
}

QByteArray DynamicSlotDataV2::hash(PyObject *callback)
{
    Shiboken::GilState gil;
    if (PyMethod_Check(callback)) {
        return  QByteArray::number((qlonglong)PyObject_Hash(PyMethod_GET_FUNCTION(callback)))
              + QByteArray::number((qlonglong)PyObject_Hash(PyMethod_GET_SELF(callback)));
    }
    return QByteArray::number(qlonglong(PyObject_Hash(callback)));
}

PyObject *DynamicSlotDataV2::callback()
{
    PyObject *callback = m_callback;

    //create a callback based on method data
    if (m_isMethod)
#ifdef IS_PY3K
        callback = PyMethod_New(m_callback, m_pythonSelf);
#else
        callback = PyMethod_New(m_callback, m_pythonSelf, m_pyClass);
#endif
    else
        Py_INCREF(callback);

    return callback;
}

int DynamicSlotDataV2::id(const char *signature) const
{
    const auto it = m_signatures.constFind(signature);
    return it != m_signatures.cend() ? it.value() : -1;
}

int DynamicSlotDataV2::addSlot(const char *signature)
{
    int index = id(signature);
    if (index == -1)
        index = m_signatures[signature] = m_parent->metaObjectBuilder().addSlot(signature);
    return index;
}

void DynamicSlotDataV2::onCallbackDestroyed(void *data)
{
    auto self = reinterpret_cast<DynamicSlotDataV2 *>(data);
    self->m_weakRef = 0;
    Py_BEGIN_ALLOW_THREADS
    delete self->m_parent;
    Py_END_ALLOW_THREADS
}

DynamicSlotDataV2::~DynamicSlotDataV2()
{
    Shiboken::GilState gil;

    Py_XDECREF(m_weakRef);
    m_weakRef = 0;

    if (!m_isMethod)
       Py_DECREF(m_callback);
}

GlobalReceiverV2::GlobalReceiverV2(PyObject *callback, SharedMap map) :
    QObject(nullptr),
    m_metaObject(GLOBAL_RECEIVER_CLASS_NAME, &QObject::staticMetaObject),
    m_sharedMap(std::move(map))
{
    m_data = new DynamicSlotDataV2(callback, this);
    m_metaObject.addSlot(RECEIVER_DESTROYED_SLOT_NAME);
    m_metaObject.update();
    m_refs.append(NULL);


    if (DESTROY_SIGNAL_ID == 0)
        DESTROY_SIGNAL_ID = QObject::staticMetaObject.indexOfSignal("destroyed(QObject*)");

    if (DESTROY_SLOT_ID == 0)
        DESTROY_SLOT_ID = m_metaObject.indexOfMethod(QMetaMethod::Slot, RECEIVER_DESTROYED_SLOT_NAME);


}

GlobalReceiverV2::~GlobalReceiverV2()
{
    m_refs.clear();
    // Remove itself from map.
    m_sharedMap->remove(m_data->hash());
    // Suppress handling of destroyed() for objects whose last reference is contained inside
    // the callback object that will now be deleted. The reference could be a default argument,
    // a callback local variable, etc.
    // The signal has to be suppressed because it would lead to the following situation:
    // Callback is deleted, hence the last reference is decremented,
    // leading to the object being deleted, which emits destroyed(), which would try to invoke
    // the already deleted callback, and also try to delete the object again.
    DynamicSlotDataV2 *data = m_data;
    m_data = Q_NULLPTR;
    delete data;
}

int GlobalReceiverV2::addSlot(const char *signature)
{
    return m_data->addSlot(signature);
}

void GlobalReceiverV2::incRef(const QObject *link)
{
    if (link) {
        if (!m_refs.contains(link)) {
            bool connected;
            Py_BEGIN_ALLOW_THREADS
            connected = QMetaObject::connect(link, DESTROY_SIGNAL_ID, this, DESTROY_SLOT_ID);
            Py_END_ALLOW_THREADS
            if (connected)
                m_refs.append(link);
            else
                Q_ASSERT(false);
        } else {
            m_refs.append(link);
        }
    } else {
        m_refs.append(NULL);
    }
}

void GlobalReceiverV2::decRef(const QObject *link)
{
    if (m_refs.empty())
        return;


    m_refs.removeOne(link);
    if (link) {
        if (!m_refs.contains(link)) {
            bool result;
            Py_BEGIN_ALLOW_THREADS
            result = QMetaObject::disconnect(link, DESTROY_SIGNAL_ID, this, DESTROY_SLOT_ID);
            Py_END_ALLOW_THREADS
            Q_ASSERT(result);
            if (!result)
                return;
        }
    }

    if (m_refs.empty())
        Py_BEGIN_ALLOW_THREADS
        delete this;
        Py_END_ALLOW_THREADS

}

int GlobalReceiverV2::refCount(const QObject *link) const
{
    if (link)
        return m_refs.count(link);

    return m_refs.size();
}

void GlobalReceiverV2::notify()
{
#if QT_VERSION >= 0x050E00
    const QSet<const QObject *> objSet(m_refs.cbegin(), m_refs.cend());
#else
    const auto objSet = QSet<const QObject *>::fromList(m_refs);
#endif
    Py_BEGIN_ALLOW_THREADS
    for (const QObject *o : objSet) {
        QMetaObject::disconnect(o, DESTROY_SIGNAL_ID, this, DESTROY_SLOT_ID);
        QMetaObject::connect(o, DESTROY_SIGNAL_ID, this, DESTROY_SLOT_ID);
    }
    Py_END_ALLOW_THREADS
}

QByteArray GlobalReceiverV2::hash() const
{
    return m_data->hash();
}

QByteArray GlobalReceiverV2::hash(PyObject *callback)
{
    return DynamicSlotDataV2::hash(callback);
}

const QMetaObject *GlobalReceiverV2::metaObject() const
{
    return const_cast<GlobalReceiverV2 *>(this)->m_metaObject.update();
}

int GlobalReceiverV2::qt_metacall(QMetaObject::Call call, int id, void **args)
{
    Shiboken::GilState gil;
    Q_ASSERT(call == QMetaObject::InvokeMetaMethod);
    Q_ASSERT(id >= QObject::staticMetaObject.methodCount());

    QMetaMethod slot = metaObject()->method(id);
    Q_ASSERT(slot.methodType() == QMetaMethod::Slot);

    if (!m_data) {
        if (id != DESTROY_SLOT_ID) {
            const QByteArray message = "PySide2 Warning: Skipping callback call "
                + slot.methodSignature() + " because the callback object is being destructed.";
            PyErr_WarnEx(PyExc_RuntimeWarning, message.constData(), 0);
        }
        return -1;
    }

    if (id == DESTROY_SLOT_ID) {
        if (m_refs.empty())
            return -1;
        auto obj = *reinterpret_cast<QObject **>(args[1]);
        incRef(); //keep the object live (safe ref)
        m_refs.removeAll(obj); // remove all refs to this object
        decRef(); //remove the safe ref
    } else {
        bool isShortCuit = (strstr(slot.methodSignature(), "(") == 0);
        Shiboken::AutoDecRef callback(m_data->callback());
        SignalManager::callPythonMetaMethod(slot, args, callback, isShortCuit);
    }

    // SignalManager::callPythonMetaMethod might have failed, in that case we have to print the
    // error so it considered "handled".
    if (PyErr_Occurred()) {
        int reclimit = Py_GetRecursionLimit();
        // Inspired by Python's errors.c: PyErr_GivenExceptionMatches() function.
        // Temporarily bump the recursion limit, so that PyErr_Print will not raise a recursion
        // error again. Don't do it when the limit is already insanely high, to avoid overflow.
        if (reclimit < (1 << 30))
            Py_SetRecursionLimit(reclimit + 5);
        PyErr_Print();
        Py_SetRecursionLimit(reclimit);
    }

    return -1;
}