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/*
* Copyright (C) 2008 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 "infobackend.h"
#include "infoxmlbackend.h"
#include "infocdbbackend.h"
#include <QMutex>
#include <QDebug>
#include <QCoreApplication>
#include <QMutexLocker>
/*!
\class InfoBackend
\brief An abstract (pure virtual) singleton class that represents the actual
registry backend.
This class is not exported in the public API. It provides a list methods that need
to be implemented by a concrete registry backend implementation. The InfoBackend instance
is a singleton that is created on first access. This class (the instance of it) is
used by ContextRegistryInfo and ContextPropertyInfo classes.
*/
InfoBackend* InfoBackend::backendInstance = NULL;
/// Constructs the object. The \a connectCount is 0 on start.
InfoBackend::InfoBackend(QObject *parent) : QObject(parent)
{
connectCount = 0;
}
/// Returns the actual singleton instance, creates it on first access. Mutex-protected.
/// ContextRegistryInfo and ContextPropertyInfo use this method to access the backend.
/// The optional \a backendName specifies the backend to force, ie: 'xml' or 'cdb'.
InfoBackend* InfoBackend::instance(const QString &backendName)
{
static QMutex mutex;
QMutexLocker locker(&mutex);
if (!backendInstance)
{
// Backend instance doesn't exist -> create it
if (backendName == "xml")
backendInstance = new InfoXmlBackend;
else if (backendName == "cdb")
backendInstance = new InfoCdbBackend;
else {
if (InfoCdbBackend::databaseExists())
backendInstance = new InfoCdbBackend;
else
backendInstance = new InfoXmlBackend;
}
// Move the backend to the main thread
backendInstance->moveToThread(QCoreApplication::instance()->thread());
// We must ensure that:
// 1) QFileSystemWatcher is deleted before QCoreApplication.
// 2) libcontextsubscriber can be unloaded successfully
// (QCoreApplication cannot have a post routine that is inside a library
// that has been unloaded.)
// For 1), we add a post routine to QCoreApplication for deleting the
// QFileSystemWathcer, for 2) we remove the post routine and delete the
// QFileSystemWatcher when the library is unloaded.
qAddPostRoutine(destroyInstance);
}
return backendInstance;
}
/// Given the \a currentKeys list of keys and the \a oldKeys list of keys,
/// emit a signal containing the new keys (keys that are in \a currentKeys
/// but are no in \a oldKeys). To be removed in future.
void InfoBackend::checkAndEmitKeysAdded(const QStringList ¤tKeys,
const QStringList &oldKeys)
{
QStringList addedKeys;
Q_FOREACH (QString key, currentKeys) {
if (! oldKeys.contains(key))
addedKeys << key;
}
if (addedKeys.size() > 0)
Q_EMIT keysAdded(addedKeys);
}
/// Given the \a currentKeys list of keys and the \a oldKeys list of keys,
/// emit a signal containing the removed keys (keys that are in \a oldKeys
/// but are no in \a currentKeys). To be removed in future.
void InfoBackend::checkAndEmitKeysRemoved(const QStringList ¤tKeys,
const QStringList &oldKeys)
{
QStringList removedKeys;
Q_FOREACH (QString key, oldKeys) {
if (! currentKeys.contains(key))
removedKeys << key;
}
if (removedKeys.size() > 0)
Q_EMIT keysRemoved(removedKeys);
}
/// Given the \a currentKeys list of keys and the \a oldKeys list of keys,
/// emit a keyChanged signal containing the union of those two lists.
void InfoBackend::checkAndEmitKeyChanged(const QStringList ¤tKeys,
const QStringList &oldKeys)
{
Q_FOREACH(QString key, oldKeys) {
Q_EMIT keyChanged(key);
}
Q_FOREACH(QString key, currentKeys) {
if (! oldKeys.contains(key))
Q_EMIT keyChanged(key);
}
}
/* Protected */
/// Called each time we have a signal connection. Increases the connect count.
void InfoBackend::connectNotify(const char *signal)
{
QObject::connectNotify(signal);
connectCount++;
}
/// Called each time we have a signal disconnection. Decreases the connect count.
void InfoBackend::disconnectNotify(const char *signal)
{
QObject::disconnectNotify(signal);
connectCount--;
}
/* Private */
/// Called before the application is destroyed. Deletes the backend instance.
/// This is to ensure that the QFileSystemWatcher in backends gets deleted
/// before the application terminates (otherwise weird issues follow).
void InfoBackend::destroyInstance()
{
delete backendInstance;
backendInstance = 0;
}
/// This will be called when the library is unloaded.
void __attribute__((destructor)) library_dtor()
{
// It seems to be ok to call qRemovePostRoutine even if QCoreApplication
// doesn't exist any more.
qRemovePostRoutine(InfoBackend::destroyInstance);
InfoBackend::destroyInstance();
}
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