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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>
#include <math.h>
namespace ContextProvider {
QHash<QPair<ServiceBackend*,QString>, PropertyPrivate*> PropertyPrivate::propertyPrivateMap;
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)
{
}
PropertyPrivate::~PropertyPrivate()
{
}
/// Increase the reference count by one. Property calls this.
void PropertyPrivate::ref()
{
refCount++;
if (refCount == 1) {
// Increase the reference count of serviceBackend to ensure it
// stays alive
serviceBackend->ref();
// Associate the property to the service backend
serviceBackend->addProperty(key, this);
}
}
/// Decrease the reference count by one. Property calls this. If the
/// reference count goes to zero, schedule the PropertyPrivate
/// instance to be deleted.
void PropertyPrivate::unref()
{
refCount--;
if (refCount == 0) {
// Remove the property from the service backend
serviceBackend->removeProperty(key);
// Now serviceBackend can be deleted if nobody else needs it.
serviceBackend->unref();
// For now, remove the PropertyPrivate from the instance
// map. If this is changed, we need to check carefully what
// happens if a new ServiceBackend is created with the same
// memory address as a previous ServiceBackend (which was
// destructed), and having the old PropertyPrivate store the
// ServiceBackend pointer to that memory address.
QPair<ServiceBackend*, QString> key = propertyPrivateMap.key(this);
if (key.second != "")
propertyPrivateMap.remove(key);
else
contextCritical() << "PropertyPrivate couldn't find itself in the instance store";
deleteLater(); // "delete this" would be probably unsafe
}
}
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()) {
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;
}
}
void PropertyPrivate::emitValue()
{
// No difference between intention and emitted value, nothing happens
if (emittedTimestamp == timestamp && emittedValue == value
&& emittedValue.isNull() == value.isNull())
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;
}
emit valueChanged(values, timestamp);
}
void PropertyPrivate::setSubscribed()
{
if (subscribed == false) {
subscribed = true;
emit firstSubscriberAppeared(key);
}
}
void PropertyPrivate::setUnsubscribed()
{
if (subscribed == true) {
subscribed = false;
emit lastSubscriberDisappeared(key);
}
}
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();
}
}
quint64 PropertyPrivate::currentTimestamp()
{
struct timespec time;
clock_gettime(CLOCK_MONOTONIC, &time);
quint64 toReturn = time.tv_nsec;
toReturn += ((quint64)pow(10,9) * time.tv_sec);
return toReturn;
}
} // end namespace
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