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/*
* Copyright (C) 2008, 2009 Nokia Corporation.
*
* Contact: Marius Vollmer <marius.vollmer@nokia.com>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public License
* version 2.1 as published by the Free Software Foundation.
*
* This library is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA
*
*/
#include "propertyprivate.h"
#include "servicebackend.h"
#include "logging.h"
#include "sconnect.h"
#include "loggingfeatures.h"
#include <time.h>
namespace ContextProvider {
/*!
\class PropertyPrivate ContextProvider ContextProvider
\brief The private implementation of Property.
For each (ServiceBackend*, key) pair there exists only one
PropertyPrivate; multiple Property objects may share it.
*/
QHash<QPair<ServiceBackend*,QString>, PropertyPrivate*> PropertyPrivate::propertyPrivateMap;
/// Constructor. Register the PropertyPrivate to its ServiceBackend;
/// this will make the Property object appear on D-Bus.
PropertyPrivate::PropertyPrivate(ServiceBackend* serviceBackend, const QString &key, QObject *parent)
: QObject(parent), refCount(0), serviceBackend(serviceBackend),
key(key), value(QVariant()), timestamp(currentTimestamp()), subscribed(false),
emittedValue(value), emittedTimestamp(timestamp), overheard(false)
{
// Associate the property to the service backend
serviceBackend->addProperty(key, this);
}
/// Set value for the PropertyPrivate. Results in a valueChanged
/// signal emission, if 1) the value was different than the current
/// value of the PropertyPrivate, or 2) The provider has overheard
/// another provider setting a different value having a more recent
/// time stamp than our last emission.
void PropertyPrivate::setValue(const QVariant& v)
{
contextDebug() << F_PROPERTY << "Setting key:" << key << "to type:" << v.typeName();
// Always store the intention of the provider
timestamp = currentTimestamp();
value = v;
// The provider is setting a different value than it has previously.
if (value != emittedValue ||
value.isNull() != emittedValue.isNull() ||
value.type() != emittedValue.type()) {
emitValue();
return;
}
// The provider is setting the same value again. But it has
// overheard a different value after the emission of
// emittedValue. Thus, emit again.
if (overheard) {
emitValue();
return;
}
}
/// Emit the valueChanged signal and update the emittedValue and
/// emittedTimestamp. (If subscribed is false, no value is emitted.)
void PropertyPrivate::emitValue()
{
// No difference between intention and emitted value, nothing
// happens
if (emittedTimestamp == timestamp &&
emittedValue == value &&
emittedValue.isNull() == value.isNull() &&
emittedValue.type() == value.type())
return;
emittedValue = value;
emittedTimestamp = timestamp;
overheard = false;
// If nobody is subscribed to us, no D-Bus signal needs to be
// emitted. Note: The bookkeeping above must be done, though.
if (!subscribed) {
return;
}
QVariantList values;
if (value.isNull() == false) {
values << value;
}
Q_EMIT valueChanged(values, timestamp);
}
/// Set the PropertyPrivate to subscribed state. If it was in the
/// unsubscribed state, the firstSubscriberAppeared signal is
/// emitted. (Property transmits the signal forward.)
void PropertyPrivate::setSubscribed()
{
if (subscribed == false) {
subscribed = true;
Q_EMIT firstSubscriberAppeared(key);
}
}
/// Set the PropertyPrivate to unsubscribed state. If it was in the
/// subscribed state, the lastSubscriberDisappeared signal is
/// emitted. (Property transmits the signal forward.)
void PropertyPrivate::setUnsubscribed()
{
if (subscribed == true) {
subscribed = false;
Q_EMIT lastSubscriberDisappeared(key);
}
}
/// Called by PropertyAdaptor when it has overheard another provider
/// sending a value on D-Bus. Check if the value is different and more
/// recent than the value we've emitted last. If so, emit our value
/// again. This way we ensure that the client gets the correct time
/// stamp for our value.
void PropertyPrivate::updateOverheardValue(const QVariantList& v, const quint64& t)
{
contextDebug() << "Updating overheard value" << v << t;
QVariant overheardValue;
// Update the "overheard" value
if (v.size() == 0) {
overheardValue = QVariant();
}
else {
overheardValue = v[0];
}
if (t > emittedTimestamp && overheardValue != emittedValue){
// record that a different and more recent value than the one
// emitted has been overheard
overheard = true;
// emit the value because provider might have a more recent
// timestamp than t
emitValue();
}
}
#define NSECS_IN_SEC 1000000000ULL
/// Compute a unique time stamp for our value. The time stamp is based
/// on monotonic clock and its value is: seconds * 10e9 + nanoseconds.
quint64 PropertyPrivate::currentTimestamp()
{
struct timespec time;
clock_gettime(CLOCK_MONOTONIC, &time);
quint64 toReturn = time.tv_nsec;
toReturn += (NSECS_IN_SEC * time.tv_sec);
return toReturn;
}
} // end namespace
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