/****************************************************************************

**

** Copyright (C) 2008-2010 Nokia Corporation and/or its subsidiary(-ies).

** All rights reserved.

** Contact: Nokia Corporation (developer.feedback@nokia.com)

**

** This file is part of the HbCore module of the UI Extensions for Mobile.

**

** GNU Lesser General Public License Usage

** This file may be used under the terms of the GNU Lesser General Public

** License version 2.1 as published by the Free Software Foundation and

** appearing in the file LICENSE.LGPL included in the packaging of this file.

** Please review the following information to ensure the GNU Lesser General

** Public License version 2.1 requirements will be met:

** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.

**

** In addition, as a special exception, Nokia gives you certain additional

** rights.  These rights are described in the Nokia Qt LGPL Exception

** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.

**

** If you have questions regarding the use of this file, please contact

** Nokia at developer.feedback@nokia.com.

**

****************************************************************************/

#include "hbpluginnamecache_p.h"

#include <hbdevicedialogplugin.h>

#include <hbdevicedialogtrace_p.h>

#include <QDir>

#include <QMutexLocker>

#include <QThread>

#include <QStringList>

/*

    \class HbPluginNameCache

    \brief HbPluginNameCache caches plugin file names by keys

    Searching for a correct plugin can be time consuming. This class maintains a cache of plugin

    file names and corresponding keys the pluging implements and speeds up the search. Keys are

    strings the plugin returns.

    The cache watches a set of directories for changes. On directory change, cache is cleared from

    all entries with that directory and the directory is re-scanned and cache updated.

    Directory is added into cache by addWatchPath() function and removed by removeWatchPath().

    A directory that does not change and need watching, eg. a directory on a rom drive, can be

    added into the cache by calling scanDirectory().

    Directory scans are performed by a worker thread.

    HbPluginNameCache constructor takes as parameter a function pointer which it uses to read keys

    from a plugin. Class user must implement this function for plugins to be cached. Optionally

    a pointer to plugin file name filter function can be provided. If none is provided, a default

    is used.

*/

// QPluginLoader is not re-entrant if two threads are accessing the same plugin. In Windows/Linux

// where indicator/device-dialog plugin managers run in application process cache thread cannot

// be enabled as there is a chance that application is using QPluginLoader. On Symbian, device

// dialog manager runs in separate process and we can ensure that indicator/device-dialog plugins

// are not accessed outside of the manager.

#if defined(Q_OS_SYMBIAN)

#define USE_NAME_CACHE_THREAD 1

#endif

// Thread that scans directories and keeps the cache current

class HbPluginNameCacheThread : public QThread

{

public:

    HbPluginNameCacheThread(HbPluginNameCache &nameCache,

        HbPluginNameCache::GetPluginKeys getPluginKeys,

        HbPluginNameCache::PluginFileNameFilter pluginFileNameFilter);

    void scanDirectory(const QString &path);

    void cancelScan(const QString &path);

    void stop();

    QMutex &lock(){return *mMutex;}

private:

    void doDirectoryScan(const QString &path);

    void run();

private: // data

    HbPluginNameCache::GetPluginKeys mGetPluginKeys; // function to get keys from a plugin

    HbPluginNameCache::PluginFileNameFilter mPluginFileNameFilter;

    bool mExit;

    QStringList mWorkQueue; // queue for directories to be scanned

    QString mCurrentScan;  // directory currently scanned

    HbPluginNameCache &mNameCache;

    static QMutex *mMutex;

};

// Share lock between all instances of the cache.

QMutex *HbPluginNameCacheThread::mMutex = 0;

HbPluginNameCacheThread::HbPluginNameCacheThread(HbPluginNameCache &nameCache,

    HbPluginNameCache::GetPluginKeys getPluginKeys,

    HbPluginNameCache::PluginFileNameFilter pluginFileNameFilter) :

    mGetPluginKeys(getPluginKeys), mPluginFileNameFilter(pluginFileNameFilter),

    mExit(false), mNameCache(nameCache)

{

    if (!mMutex) {

        mMutex = new QMutex();

    }

}

// Add directory to be scanned

void HbPluginNameCacheThread::scanDirectory(const QString &path)

{

    QMutexLocker lock(mMutex);

    if (!mWorkQueue.contains(path)) {

        mWorkQueue.append(path);

    }

#ifdef USE_NAME_CACHE_THREAD

    if (!isRunning()) {

        mExit = false;

        start(IdlePriority);

    }

#else

    mExit = false;

    lock.unlock();

    run();

#endif

}

// Cancel a directory scan request

void HbPluginNameCacheThread::cancelScan(const QString &path)

{

    QMutexLocker lock(mMutex);

    // If scan is waiting in a queue, remove it

    int i = mWorkQueue.indexOf(path);

    if (i >= 0) {

        mWorkQueue.removeAt(i);

    }

#ifdef USE_NAME_CACHE_THREAD

    // If thread is currently scanning the path, stop and wait for it to exit

    if (isRunning() && mCurrentScan == path) {

        mExit = true;

        lock.unlock();

        stop();

        // Restart scan thread if scan queue is not empty

        if (!mWorkQueue.isEmpty()) {

            scanDirectory(mWorkQueue.first());

        }

    }

#endif

}

// Stop thread and wait for it to exit

void HbPluginNameCacheThread::stop()

{

#ifdef USE_NAME_CACHE_THREAD

    QMutexLocker lock(mMutex);

    mExit = true;

    lock.unlock();

    const unsigned long time = 5000; // 5 s

    if (!wait(time)) {

        // Thread did not exit, terminate it

        TRACE("Thread didn't exit")

        terminate();

        wait();

    }

#endif

}

// Scan directory for plugins and keys they implement.

void HbPluginNameCacheThread::doDirectoryScan(const QString &path)

{

    TRACE_ENTRY_ARGS(path)

    QString fileNameFilter = mPluginFileNameFilter();

    QDir pluginDir(path, fileNameFilter, QDir::NoSort, QDir::Files | QDir::Readable);

    foreach (const QString &fileName, pluginDir.entryList()) {

        if (mExit) {

            break;

        }

        const QString absolutePath = pluginDir.absoluteFilePath(fileName);

        HbLockedPluginLoader *loader = new HbLockedPluginLoader(*mMutex, absolutePath);

        QObject *pluginInstance = loader->instance();

        if (pluginInstance) {

            // If plugin type is correct, plugin file name and keys are saved into a cache

            mNameCache.insert(mGetPluginKeys(pluginInstance), absolutePath);

        }

        loader->unload();

        delete loader;

        loader = 0;

    }

    TRACE_EXIT

}

// Plugin scan thread function

void HbPluginNameCacheThread::run()

{

    TRACE_ENTRY

    while(true) {

        mMutex->lock();

        if (mExit || mWorkQueue.isEmpty()) {

            break;

        }

        mCurrentScan = mWorkQueue.takeFirst();

        mMutex->unlock();

        doDirectoryScan(mCurrentScan);

        mCurrentScan.clear();

    }

    mMutex->unlock();

}

// Constructor

HbPluginNameCache::HbPluginNameCache(GetPluginKeys getPluginKeys,

    PluginFileNameFilter pluginFileNameFilter, QObject *parent) :

    QObject(parent)

{

    mThread = new HbPluginNameCacheThread(*this, getPluginKeys,

        pluginFileNameFilter ? pluginFileNameFilter:&HbPluginNameCache::pluginFileNameFilter);

    connect(&mWatcher, SIGNAL(directoryChanged(const QString&)), this, SLOT(directoryChanged(const QString&)));

}

// Destructor

HbPluginNameCache::~HbPluginNameCache()

{

    mThread->stop(); // ask thread to stop and wait

    delete mThread;

    mThread = 0;

}

// Add directory watch path

void HbPluginNameCache::addWatchPath(const QString &path)

{

    TRACE_ENTRY_ARGS(path)

    QString dirPath = directoryPath(path);

    TRACE(dirPath)

    if (!dirPath.isEmpty()) {

        mWatcher.addPath(dirPath); // start watching

        directoryChanged(dirPath); // scan directory

    }

}

// Remove directory watch path

void HbPluginNameCache::removeWatchPath(const QString &path)

{

    TRACE_ENTRY_ARGS(path)

    QString dirPath = directoryPath(path);

    TRACE(dirPath)

    if (!dirPath.isEmpty()) {

#if defined(Q_OS_LINUX) || defined(Q_OS_MAC)

        const Qt::CaseSensitivity cs = Qt::CaseSensitive;

#else

        const Qt::CaseSensitivity cs = Qt::CaseInsensitive;

#endif // Q_OS_LINUX || Q_OS_MAC

        if (mWatcher.directories().contains(dirPath, cs)) {

            mWatcher.removePath(dirPath);

            mThread->cancelScan(dirPath);

            removePath(path);

        }

    }

}

// Scan directory directory for plugins

void HbPluginNameCache::scanDirectory(const QString &path)

{

    TRACE_ENTRY_ARGS(path)

    QString dirPath = directoryPath(path);

    TRACE(dirPath)

    if (!dirPath.isEmpty()) {

        mThread->scanDirectory(dirPath);

    }

}

// Find a plugin by a key. Returns plugin file path or an empty string

QString HbPluginNameCache::find(const QString &key)

{

    TRACE_ENTRY_ARGS(key)

    QMutexLocker(&mThread->lock());

    return mCache.value(key);

}

// Get directory part of a file name

QString HbPluginNameCache::directoryPath(const QString &path)

{

    // Use QString instead of QFileInfo to handle path to ensure that file system is not

    // accessed (performance). Assume path is a directory if it ends with '/', otherwise

    // it's a file.

    QChar slash('/');

    if (path.isEmpty() || path.endsWith(slash)) {

        return path;

    } else {

        int i = path.lastIndexOf(slash);

        return i != -1 ? path.left(i + 1) : QString();

    }

}

// Print cache contents

void HbPluginNameCache::print()

{

    TRACE_ENTRY

    QMutexLocker(&mThread->lock());

    QHash<QString, QString>::iterator i = mCache.begin();

    while (i != mCache.end()) {

        TRACE(i.key() << i.value())

        ++i;

    }

}

// Update cache with \a keys and \a filePath

void HbPluginNameCache::insert(const QStringList &keys, const QString &filePath)

{

    TRACE_ENTRY_ARGS("keys" << keys << "filePath" << filePath)

    QMutexLocker(&mThread->lock());

    for (int i = 0; i < keys.size(); ++i) {

        // New entry is added into a cache or existing one is updated

        mCache.insert(keys.at(i), filePath);

    }

}

// Remove a key from from a cache

void HbPluginNameCache::remove(const QString &key)

{

    TRACE_ENTRY_ARGS(key)

    QMutexLocker(&mThread->lock());

    mCache.remove(key);

}

// Remove all keys with a \a filePath

void HbPluginNameCache::removePath(const QString &filePath)

{

    TRACE_ENTRY_ARGS(filePath)

    QMutexLocker(&mThread->lock());

    QHash<QString, QString>::iterator i = mCache.begin();

    while (i != mCache.end()) {

#if defined(Q_OS_LINUX) || defined(Q_OS_MAC)

        const Qt::CaseSensitivity cs = Qt::CaseSensitive;

#else

        const Qt::CaseSensitivity cs = Qt::CaseInsensitive;

#endif // Q_OS_LINUX || Q_OS_MAC

        if (i.value().startsWith(filePath, cs)) {

            i = mCache.erase(i);

        } else {

            ++i;

        }

    }

}

// Generate filter for plugin file names

QString HbPluginNameCache::pluginFileNameFilter()

{

#if defined(Q_OS_LINUX)

    return QString("*.so");

#elif defined(Q_OS_MAC)

    return QString("*.dylib");

#elif defined(Q_OS_WIN32)

    return QString("*.dll");

#else

    return QString("*.qtplugin");

#endif

}

// Watched directory has changed

void HbPluginNameCache::directoryChanged(const QString &path)

{

    TRACE_ENTRY_ARGS(path)

    // Invalidate cache contents for the path

    removePath(path);

    mThread->scanDirectory(path);

    TRACE_EXIT

}

// Constructor

HbLockedPluginLoader::HbLockedPluginLoader(HbPluginNameCache &nameCache, const QString &fileName,

    QObject *parent) : mMutex(nameCache.mThread->lock())

{

    QMutexLocker locker(&mMutex);

    mLoader = new QPluginLoader(fileName, parent);

}

// Constructor

HbLockedPluginLoader::HbLockedPluginLoader(QMutex &mutex, const QString &fileName,

    QObject *parent) : mMutex(mutex)

{

    QMutexLocker locker(&mMutex);

    mLoader = new QPluginLoader(fileName, parent);

}

// Destructor

HbLockedPluginLoader::~HbLockedPluginLoader()

{

    QMutexLocker locker(&mMutex);

    delete mLoader;

}

// Locked instance

// QPluginLoader is not re-entrant if two loaders are accessing the same plugin

QObject *HbLockedPluginLoader::instance()

{

    QMutexLocker locker(&mMutex);

    return mLoader->instance();

}

// Locked load

bool HbLockedPluginLoader::load()

{

    QMutexLocker locker(&mMutex);

    return mLoader->load();

}

// Locked unload

bool HbLockedPluginLoader::unload()

{

    QMutexLocker locker(&mMutex);

    return mLoader->unload();

}