qt5base-lts/src/dbus/qdbuspendingreply.cpp
Lars Knoll abd1b7f306 Cleanup QDBusPendingReply
Remove the limitation of max 8 arguments and clean up the
template code.

This required a bit of special work to ensure
QDBusPendingReply<void> works the same way
as QDBusPendingReply<>.

Change-Id: I8e822b2f97f0712746b917056ea8f3d5c219c7f6
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
2020-09-23 19:30:10 +02:00

287 lines
10 KiB
C++

/****************************************************************************
**
** Copyright (C) 2016 The Qt Company Ltd.
** Copyright (C) 2016 Intel Corporation.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the QtDBus 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 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 "qdbuspendingreply.h"
#include "qdbuspendingcall_p.h"
#include "qdbusmetatype.h"
#include <QtCore/private/qlocking_p.h>
#ifndef QT_NO_DBUS
/*!
\class QDBusPendingReply
\inmodule QtDBus
\since 4.5
\brief The QDBusPendingReply class contains the reply to an asynchronous method call.
The QDBusPendingReply is a template class with up to 8 template
parameters. Those parameters are the types that will be used to
extract the contents of the reply's data.
This class is similar in functionality to QDBusReply, but with two
important differences:
\list
\li QDBusReply accepts exactly one return type, whereas
QDBusPendingReply can have from 1 to 8 types
\li QDBusReply only works on already completed replies, whereas
QDBusPendingReply allows one to wait for replies from pending
calls
\endlist
Where with QDBusReply you would write:
\snippet code/src_qdbus_qdbusreply.cpp 0
with QDBusPendingReply, the equivalent code (including the blocking
wait for the reply) would be:
\snippet code/src_qdbus_qdbuspendingreply.cpp 0
For method calls that have more than one output argument, with
QDBusReply, you would write:
\snippet code/src_qdbus_qdbusreply.cpp 1
whereas with QDBusPendingReply, all of the output arguments should
be template parameters:
\snippet code/src_qdbus_qdbuspendingreply.cpp 2
QDBusPendingReply objects can be associated with
QDBusPendingCallWatcher objects, which emit signals when the reply
arrives.
\sa QDBusPendingCallWatcher, QDBusReply
*/
/*!
\fn template<typename... Types> QDBusPendingReply<Types...>::QDBusPendingReply()
Creates an empty QDBusPendingReply object. Without assigning a
QDBusPendingCall object to this reply, QDBusPendingReply cannot do
anything. All functions return their failure values.
*/
/*!
\fn template<typename... Types> QDBusPendingReply<Types...>::QDBusPendingReply(const QDBusPendingReply &other)
Creates a copy of the \a other QDBusPendingReply object. Just like
QDBusPendingCall and QDBusPendingCallWatcher, this QDBusPendingReply
object will share the same pending call reference. All copies
share the same return values.
*/
/*!
\fn template<typename... Types> QDBusPendingReply<Types...>::QDBusPendingReply(const QDBusPendingCall &call)
Creates a QDBusPendingReply object that will take its contents from
the \a call pending asynchronous call. This QDBusPendingReply object
will share the same pending call reference as \a call.
*/
/*!
\fn template<typename... Types> QDBusPendingReply<Types...>::QDBusPendingReply(const QDBusMessage &message)
Creates a QDBusPendingReply object that will take its contents from
the message \a message. In this case, this object will be already
in its finished state and the reply's contents will be accessible.
\sa isFinished()
*/
/*!
\fn template<typename... Types> QDBusPendingReply &QDBusPendingReply<Types...>::operator=(const QDBusPendingReply &other)
Makes a copy of \a other and drops the reference to the current
pending call. If the current reference is to an unfinished pending
call and this is the last reference, the pending call will be
canceled and there will be no way of retrieving the reply's
contents, when they arrive.
*/
/*!
\fn template<typename... Types> QDBusPendingReply &QDBusPendingReply<Types...>::operator=(const QDBusPendingCall &call)
Makes this object take its contents from the \a call pending call
and drops the reference to the current pending call. If the
current reference is to an unfinished pending call and this is the
last reference, the pending call will be canceled and there will
be no way of retrieving the reply's contents, when they arrive.
*/
/*!
\fn template<typename... Types> QDBusPendingReply &QDBusPendingReply<Types...>::operator=(const QDBusMessage &message)
Makes this object take its contents from the \a message message
and drops the reference to the current pending call. If the
current reference is to an unfinished pending call and this is the
last reference, the pending call will be canceled and there will
be no way of retrieving the reply's contents, when they arrive.
After this function is finished, the QDBusPendingReply object will
be in its "finished" state and the \a message contents will be
accessible.
\sa isFinished()
*/
/*!
\enum QDBusPendingReply::anonymous
\value Count The number of arguments the reply is expected to have
*/
/*!
\fn template<typename... Types> int QDBusPendingReply<Types...>::count() const
Return the number of arguments the reply is supposed to have. This
number matches the number of non-void template parameters in this
class.
If the reply arrives with a different number of arguments (or with
different types), it will be transformed into an error reply
indicating a bad signature.
*/
/*!
\fn template<typename... Types> QVariant QDBusPendingReply<Types...>::argumentAt(int index) const
Returns the argument at position \a index in the reply's
contents. If the reply doesn't have that many elements, this
function's return value is undefined (will probably cause an
assertion failure), so it is important to verify that the
processing is finished and the reply is valid.
If the reply does not contain an argument at position \a index or if the
reply was an error, this function returns an invalid QVariant. Since D-Bus
messages can never contain invalid QVariants, this return can be used to
detect an error condition.
*/
/*!
\fn template<typename... Types> T1 QDBusPendingReply<Types...>::value() const
Returns the first argument in this reply, cast to type \c T1 (the
first template parameter of this class). This is equivalent to
calling argumentAt<0>().
This function is provided as a convenience, matching the
QDBusReply::value() function.
Note that, if the reply hasn't arrived, this function causes the
calling thread to block until the reply is processed.
If the reply is an error reply, this function returns a default-constructed
\c T1 object, which may be indistinguishable from a valid value. To
reliably determine whether the message was an error, use isError().
*/
/*!
\fn template<typename... Types> QDBusPendingReply<Types...>::operator T1() const
Returns the first argument in this reply, cast to type \c T1 (the
first template parameter of this class). This is equivalent to
calling argumentAt<0>().
This function is provided as a convenience, matching the
QDBusReply::value() function.
Note that, if the reply hasn't arrived, this function causes the
calling thread to block until the reply is processed.
If the reply is an error reply, this function returns a default-constructed
\c T1 object, which may be indistinguishable from a valid value. To
reliably determine whether the message was an error, use isError().
*/
/*!
\fn template<typename... Types> void QDBusPendingReply<Types...>::waitForFinished()
Suspends the execution of the calling thread until the reply is
received and processed. After this function returns, isFinished()
should return true, indicating the reply's contents are ready to
be processed.
\sa QDBusPendingCallWatcher::waitForFinished()
*/
QDBusPendingReplyBase::QDBusPendingReplyBase()
: QDBusPendingCall(nullptr) // initialize base class empty
{
}
QDBusPendingReplyBase::~QDBusPendingReplyBase()
{
}
void QDBusPendingReplyBase::assign(const QDBusPendingCall &other)
{
QDBusPendingCall::operator=(other);
}
void QDBusPendingReplyBase::assign(const QDBusMessage &message)
{
d = new QDBusPendingCallPrivate(QDBusMessage(), nullptr); // drops the reference to the old one
d->replyMessage = message;
}
QVariant QDBusPendingReplyBase::argumentAt(int index) const
{
if (!d)
return QVariant();
d->waitForFinished(); // bypasses "const"
return d->replyMessage.arguments().value(index);
}
void QDBusPendingReplyBase::setMetaTypes(int count, const int *types)
{
Q_ASSERT(d);
const auto locker = qt_scoped_lock(d->mutex);
d->setMetaTypes(count, types);
d->checkReceivedSignature();
}
#endif // QT_NO_DBUS