previewgeneratorqueue.cpp

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#include "previewgeneratorqueue.h"

// C++
#include <algorithm>
using std::max;

// QT
#include <QCoreApplication>
#include <QFileInfo>

// libmythbase
#include "mythcorecontext.h"
#include "mythlogging.h"
#include "mythdirs.h"
#include "mthread.h"

// libmyth
#include "mythcontext.h"
#include "remoteutil.h"

// libmythtv
#include "previewgenerator.h"

#define LOC QString("PreviewQueue: ")

PreviewGeneratorQueue *PreviewGeneratorQueue::s_pgq = nullptr;

void PreviewGeneratorQueue::CreatePreviewGeneratorQueue(
    PreviewGenerator::Mode mode,
    uint maxAttempts, uint minBlockSeconds)
{
    s_pgq = new PreviewGeneratorQueue(mode, maxAttempts, minBlockSeconds);
}

void PreviewGeneratorQueue::TeardownPreviewGeneratorQueue()
{
    s_pgq->exit(0);
    s_pgq->wait();
    delete s_pgq;
    s_pgq = nullptr;
}

/*
 * Create the queue object for holding preview generators.
 *
 * Create the singleton queue of preview generators.  This should be
 * called once at program start-up.  All generation requests on this
 * queue will will be created with the maxAttempts and minBlockSeconds
 * parameters supplied here.
 *
 * \param[in] mode Local or Remote (or both)
 * \param[in] maxAttempts How many times total will the code attempt
 *            to generate a preview for a specific file, before giving
 *            up and ignoring all future requests.
 * \param[in] minBlockSeconds How long after a failed preview
 *            generation attempt will the code ignore subsequent
 *            requests.
 *
 * \note Never call this routine directly. Call the
 * CreatePreviewGeneratorQueue function instead.
 */
PreviewGeneratorQueue::PreviewGeneratorQueue(
    PreviewGenerator::Mode mode,
    uint maxAttempts, uint minBlockSeconds) :
    MThread("PreviewGeneratorQueue"),
    m_mode(mode),
    m_maxAttempts(maxAttempts), m_minBlockSeconds(minBlockSeconds)
{
    if (PreviewGenerator::kLocal & mode)
    {
        int idealThreads = QThread::idealThreadCount();
        m_maxThreads = (idealThreads >= 1) ? idealThreads * 2 : 2;
    }

    moveToThread(qthread());
    start();
}

PreviewGeneratorQueue::~PreviewGeneratorQueue()
{
    // disconnect preview generators
    QMutexLocker locker(&m_lock);
    // NOLINTNEXTLINE(modernize-loop-convert)
    for (auto it = m_previewMap.begin(); it != m_previewMap.end(); ++it)
    {
        if ((*it).m_gen)
            (*it).m_gen->deleteLater();
        (*it).m_gen = nullptr;
    }
    locker.unlock();
    wait();
}

void PreviewGeneratorQueue::GetPreviewImage(
    const ProgramInfo &pginfo,
    const QSize &outputsize,
    const QString &outputfile,
    long long time, bool in_seconds,
    const QString& token)
{
    if (!s_pgq)
        return;

    if (pginfo.GetPathname().isEmpty() ||
        pginfo.GetBasename() == pginfo.GetPathname())
    {
        return;
    }

    if (gCoreContext->GetNumSetting("JobAllowPreview", 1) == 0)
        return;

    QStringList extra;
    pginfo.ToStringList(extra);
    extra += token;
    extra += QString::number(outputsize.width());
    extra += QString::number(outputsize.height());
    extra += outputfile;
    extra += QString::number(time);
    extra += (in_seconds ? "1" : "0");
    auto *e = new MythEvent("GET_PREVIEW", extra);
    QCoreApplication::postEvent(s_pgq, e);
}

void PreviewGeneratorQueue::AddListener(QObject *listener)
{
    if (!s_pgq)
        return;

    QMutexLocker locker(&s_pgq->m_lock);
    s_pgq->m_listeners.insert(listener);
}

void PreviewGeneratorQueue::RemoveListener(QObject *listener)
{
    if (!s_pgq)
        return;

    QMutexLocker locker(&s_pgq->m_lock);
    s_pgq->m_listeners.remove(listener);
}

bool PreviewGeneratorQueue::event(QEvent *e)
{
    if (e->type() != MythEvent::MythEventMessage)
        return QObject::event(e);

    auto *me = dynamic_cast<MythEvent*>(e);
    if (me == nullptr)
        return false;
    if (me->Message() == "GET_PREVIEW")
    {
        const QStringList &list = me->ExtraDataList();
        QStringList::const_iterator it = list.begin();
        ProgramInfo evinfo(it, list.end());
        QString token;
        QSize outputsize;
        QString outputfile;
        long long time = -1LL;
        if (it != list.end())
            token = (*it++);
        if (it != list.end())
            outputsize.setWidth((*it++).toInt());
        if (it != list.end())
            outputsize.setHeight((*it++).toInt());
        if (it != list.end())
            outputfile = (*it++);
        if (it != list.end())
            time = (*it++).toLongLong();
        if (it != list.end())
        {
            bool time_fmt_sec = (*it++).toInt() != 0;
            GeneratePreviewImage(evinfo, outputsize, outputfile,
                                      time, time_fmt_sec, token);
        }
        return true;
    }
    if (me->Message() == "PREVIEW_SUCCESS" ||
        me->Message() == "PREVIEW_FAILED")
    {
        uint recordedingID = me->ExtraData(0).toUInt(); // pginfo->GetRecordingID()
        const QString& filename   = me->ExtraData(1); // outFileName
        const QString& msg        = me->ExtraData(2);
        const QString& datetime   = me->ExtraData(3);
        const QString& token      = me->ExtraData(4);

        {
            QMutexLocker locker(&m_lock);
            QMap<QString,QString>::iterator kit = m_tokenToKeyMap.find(token);
            if (kit == m_tokenToKeyMap.end())
            {
                LOG(VB_GENERAL, LOG_ERR, LOC +
                    QString("Failed to find token %1 in map.").arg(token));
                return true;
            }
            PreviewMap::iterator it = m_previewMap.find(*kit);
            if (it == m_previewMap.end())
            {
                LOG(VB_GENERAL, LOG_ERR, LOC +
                    QString("Failed to find key %1 in map.").arg(*kit));
                return true;
            }

            if ((*it).m_gen)
                (*it).m_gen->deleteLater();
            (*it).m_gen           = nullptr;
            (*it).m_genStarted    = false;
            if (me->Message() == "PREVIEW_SUCCESS")
            {
                (*it).m_attempts      = 0;
                (*it).m_lastBlockTime = 0;
                (*it).m_blockRetryUntil = QDateTime();
            }
            else
            {
                (*it).m_lastBlockTime =
                    max(m_minBlockSeconds, (*it).m_lastBlockTime * 2);
                (*it).m_blockRetryUntil =
                    MythDate::current().addSecs((*it).m_lastBlockTime);
            }

            QStringList list;
            list.push_back(QString::number(recordedingID));
            list.push_back(filename);
            list.push_back(msg);
            list.push_back(datetime);
            for (const auto & tok : qAsConst((*it).m_tokens))
            {
                kit = m_tokenToKeyMap.find(tok);
                if (kit != m_tokenToKeyMap.end())
                    m_tokenToKeyMap.erase(kit);
                list.push_back(tok);
            }

            if (list.size() > 4)
            {
                for (auto *listener : qAsConst(m_listeners))
                {
                    auto *le = new MythEvent(me->Message(), list);
                    QCoreApplication::postEvent(listener, le);
                }
                (*it).m_tokens.clear();
            }

            m_running = (m_running > 0) ? m_running - 1 : 0;
        }

        UpdatePreviewGeneratorThreads();

        return true;
    }
    return false;
}

void PreviewGeneratorQueue::SendEvent(
    const ProgramInfo &pginfo,
    const QString &eventname,
    const QString &filename, const QString &token, const QString &msg,
    const QDateTime &dt)
{
    QStringList list;
    list.push_back(QString::number(pginfo.GetRecordingID()));
    list.push_back(filename);
    list.push_back(msg);
    list.push_back(dt.toUTC().toString(Qt::ISODate));
    list.push_back(token);

    QMutexLocker locker(&m_lock);
    for (auto *listener : qAsConst(m_listeners))
    {
        auto *e = new MythEvent(eventname, list);
        QCoreApplication::postEvent(listener, e);
    }
}

QString PreviewGeneratorQueue::GeneratePreviewImage(
    ProgramInfo &pginfo,
    const QSize &size,
    const QString &outputfile,
    long long time, bool in_seconds,
    const QString& token)
{
    QString key = QString("%1_%2x%3_%4%5")
        .arg(pginfo.GetBasename()).arg(size.width()).arg(size.height())
        .arg(time).arg(in_seconds?"s":"f");

    if (pginfo.GetAvailableStatus() == asPendingDelete)
    {
        SendEvent(pginfo, "PREVIEW_FAILED", key, token,
                  "Pending Delete", QDateTime());
        return QString();
    }

    // keep in sync with default filename in PreviewGenerator::RunReal
    QString filename = (outputfile.isEmpty()) ?
        pginfo.GetPathname() + ".png" : outputfile;
    QString ret_file = filename;
    QString ret;

    bool is_special = !outputfile.isEmpty() || time >= 0 ||
        (size.width() != 0) || (size.height() != 0);

    bool needs_gen = true;
    if (!is_special)
    {
        QDateTime previewLastModified;
        bool streaming = !filename.startsWith("/");
        bool locally_accessible = false;
        bool bookmark_updated = false;

        QDateTime bookmark_ts = pginfo.GetBookmarkUpdate();
        QDateTime cmp_ts;
        if (bookmark_ts.isValid())
            cmp_ts = bookmark_ts;
        else if (MythDate::current() >= pginfo.GetRecordingEndTime())
            cmp_ts = pginfo.GetLastModifiedTime();
        else
            cmp_ts = pginfo.GetRecordingStartTime();

        if (streaming)
        {
            ret_file = QString("%1/%2")
                .arg(GetRemoteCacheDir()).arg(filename.section('/', -1));

            QFileInfo finfo(ret_file);
            if (finfo.isReadable() && finfo.lastModified() >= cmp_ts)
            {
                // This is just an optimization to avoid
                // hitting the backend if our cached copy
                // is newer than the bookmark, or if we have
                // a preview and do not update it when the
                // bookmark changes.
                previewLastModified = finfo.lastModified();
            }
            else if (!IsGeneratingPreview(key))
            {
                previewLastModified =
                    RemoteGetPreviewIfModified(pginfo, ret_file);
            }
        }
        else
        {
            QFileInfo fi(filename);
            if ((locally_accessible = fi.isReadable()))
                previewLastModified = fi.lastModified();
        }

        bookmark_updated =
            (!previewLastModified.isValid() || (previewLastModified <= cmp_ts));

        if (bookmark_updated && bookmark_ts.isValid() &&
            previewLastModified.isValid())
        {
            ClearPreviewGeneratorAttempts(key);
        }

        bool preview_exists = previewLastModified.isValid();

#if 0
        QString alttext = (bookmark_ts.isValid()) ? QString() :
            QString("\n\t\t\tcmp_ts:               %1")
            .arg(cmp_ts.toString(Qt::ISODate));
        LOG(VB_GENERAL, LOG_INFO,
            QString("previewLastModified:  %1\n\t\t\t"
                    "bookmark_ts:          %2%3\n\t\t\t"
                    "pginfo.lastmodified:  %4")
                .arg(previewLastModified.toString(Qt::ISODate))
                .arg(bookmark_ts.toString(Qt::ISODate))
                .arg(alttext)
                .arg(pginfo.GetLastModifiedTime(MythDate::ISODate)) +
            QString("Title: %1\n\t\t\t")
                .arg(pginfo.toString(ProgramInfo::kTitleSubtitle)) +
            QString("File  '%1' \n\t\t\tCache '%2'")
                .arg(filename).arg(ret_file) +
            QString("\n\t\t\tPreview Exists: %1, Bookmark Updated: %2, "
                    "Need Preview: %3")
                .arg(preview_exists).arg(bookmark_updated)
                .arg((bookmark_updated || !preview_exists)));
#endif

        needs_gen = bookmark_updated || !preview_exists;

        if (!needs_gen)
        {
            if (locally_accessible)
                ret = filename;
            else if (preview_exists && QFileInfo(ret_file).isReadable())
                ret = ret_file;
        }
    }

    if (needs_gen && !IsGeneratingPreview(key))
    {
        uint attempts = IncPreviewGeneratorAttempts(key);
        if (attempts < m_maxAttempts)
        {
            LOG(VB_PLAYBACK, LOG_INFO, LOC +
                QString("Requesting preview for '%1'") .arg(key));
            auto *pg = new PreviewGenerator(&pginfo, token, m_mode);
            if (!outputfile.isEmpty() || time >= 0 ||
                size.width() || size.height())
            {
                pg->SetPreviewTime(time, in_seconds);
                pg->SetOutputFilename(outputfile);
                pg->SetOutputSize(size);
            }

            SetPreviewGenerator(key, pg);

            LOG(VB_PLAYBACK, LOG_INFO, LOC +
                QString("Requested preview for '%1'").arg(key));
        }
        else
        {
            LOG(VB_GENERAL, LOG_ERR, LOC +
                QString("Attempted to generate preview for '%1' "
                        "%2 times; >= max(%3)")
                    .arg(key).arg(attempts).arg(m_maxAttempts));
        }
    }
    else if (needs_gen)
    {
        LOG(VB_PLAYBACK, LOG_INFO, LOC +
            QString("Not requesting preview for %1,"
                    "as it is already being generated")
                .arg(pginfo.toString(ProgramInfo::kTitleSubtitle)));
        IncPreviewGeneratorPriority(key, token);
    }

    UpdatePreviewGeneratorThreads();

    if (!ret.isEmpty())
    {
        QString msg = "On Disk";
        QDateTime dt = QFileInfo(ret).lastModified();
        SendEvent(pginfo, "PREVIEW_SUCCESS", ret, token, msg, dt);
    }
    else
    {
        uint queue_depth = 0;
        uint token_cnt = 0;
        GetInfo(key, queue_depth, token_cnt);
        QString msg = QString("Queue depth %1, our tokens %2")
            .arg(queue_depth).arg(token_cnt);
        SendEvent(pginfo, "PREVIEW_QUEUED", ret, token, msg, QDateTime());
    }

    return ret;
}

void PreviewGeneratorQueue::GetInfo(
    const QString &key, uint &queue_depth, uint &token_cnt)
{
    QMutexLocker locker(&m_lock);
    queue_depth = m_queue.size();
    PreviewMap::iterator pit = m_previewMap.find(key);
    token_cnt = (pit == m_previewMap.end()) ? 0 : (*pit).m_tokens.size();
}

void PreviewGeneratorQueue::IncPreviewGeneratorPriority(
    const QString &key, const QString& token)
{
    QMutexLocker locker(&m_lock);
    m_queue.removeAll(key);

    PreviewMap::iterator pit = m_previewMap.find(key);
    if (pit == m_previewMap.end())
        return;

    if ((*pit).m_gen && !(*pit).m_genStarted)
        m_queue.push_back(key);

    if (!token.isEmpty())
    {
        m_tokenToKeyMap[token] = key;
        (*pit).m_tokens.insert(token);
    }
}

void PreviewGeneratorQueue::UpdatePreviewGeneratorThreads(void)
{
    QMutexLocker locker(&m_lock);
    QStringList &q = m_queue;
    if (!q.empty() && (m_running < m_maxThreads))
    {
        QString fn = q.back();
        q.pop_back();
        PreviewMap::iterator it = m_previewMap.find(fn);
        if (it != m_previewMap.end() && (*it).m_gen && !(*it).m_genStarted)
        {
            m_running++;
            (*it).m_gen->start();
            (*it).m_genStarted = true;
        }
    }
}

void PreviewGeneratorQueue::SetPreviewGenerator(
    const QString &key, PreviewGenerator *g)
{
    if (!g)
        return;

    {
        QMutexLocker locker(&m_lock);
        m_tokenToKeyMap[g->GetToken()] = key;
        PreviewGenState &state = m_previewMap[key];
        if (state.m_gen)
        {
            if (g && state.m_gen != g)
            {
                if (!g->GetToken().isEmpty())
                    state.m_tokens.insert(g->GetToken());
                g->deleteLater();
                g = nullptr;
            }
        }
        else
        {
            g->AttachSignals(this);
            state.m_gen = g;
            state.m_genStarted = false;
            if (!g->GetToken().isEmpty())
                state.m_tokens.insert(g->GetToken());
        }
    }

    IncPreviewGeneratorPriority(key, "");
}

bool PreviewGeneratorQueue::IsGeneratingPreview(const QString &key) const
{
    PreviewMap::const_iterator it;
    QMutexLocker locker(&m_lock);

    if ((it = m_previewMap.find(key)) == m_previewMap.end())
        return false;

    if ((*it).m_blockRetryUntil.isValid())
        return MythDate::current() < (*it).m_blockRetryUntil;

    return (*it).m_gen;
}

uint PreviewGeneratorQueue::IncPreviewGeneratorAttempts(const QString &key)
{
    QMutexLocker locker(&m_lock);
    return m_previewMap[key].m_attempts++;
}

void PreviewGeneratorQueue::ClearPreviewGeneratorAttempts(const QString &key)
{
    QMutexLocker locker(&m_lock);
    m_previewMap[key].m_attempts = 0;
    m_previewMap[key].m_lastBlockTime = 0;
    m_previewMap[key].m_blockRetryUntil =
        MythDate::current().addSecs(-60);
}