programinfocache.h

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// -*- Mode: c++ -*-
// vim:set sw=4 ts=4 expandtab:
#ifndef PROGRAM_INFO_CACHE_H
#define PROGRAM_INFO_CACHE_H
 
// C++ headers
#include <cstdint>
#include <vector>
 
// Qt headers
#include <QWaitCondition>
#include <QDateTime>
#include <QMutex>
#include <QHash>
 
class ProgramInfoLoader;
class ProgramInfo;
class QObject;
 
class ProgramInfoCache
{
    friend class ProgramInfoLoader;
 
  public:
    enum UpdateState : std::uint8_t {
        PIC_NONE              = 0x00,
        PIC_MARK_CHANGED      = 0x01,
        PIC_RECGROUP_CHANGED  = 0x02,
        PIC_NO_ACTION         = 0x80,
    };
    Q_DECLARE_FLAGS(UpdateStates, UpdateState);
 
    explicit ProgramInfoCache(QObject *o)
        : m_listener(o) {}
    ~ProgramInfoCache();
 
    void ScheduleLoad(bool updateUI = true);
    bool IsLoadInProgress(void) const;
    void WaitForLoadToComplete(void) const;
 
    // All the following public methods must only be called from the UI Thread.
    void Refresh(void);
    void Add(const ProgramInfo &pginfo);
    bool Remove(uint recordingID);
    ProgramInfoCache::UpdateStates Update(const ProgramInfo &pginfo);
    void UpdateFileSize(uint recordingID, uint64_t filesize, UpdateStates flags);
    void GetOrdered(std::vector<ProgramInfo*> &list, bool newest_first = false);
    bool empty(void) const { return m_cache.empty(); }
    ProgramInfo *GetRecordingInfo(uint recordingID) const;
 
  private:
    void Load(bool updateUI = true);
    void Clear(void);
 
  private:
    // NOTE: Hash would be faster for lookups and updates, but we need a sorted
    // list for to rebuild the full list. Question is, which is done more?
    // We could store a hash, but sort the vector in GetOrdered which might
    // be a suitable compromise, fractionally slower initial load but faster
    // scrolling and updates
    using Cache = QHash<uint,ProgramInfo*>;
 
    mutable QMutex          m_lock;
    Cache                   m_cache;
    std::vector<ProgramInfo*> *m_nextCache      {nullptr};
    QObject                *m_listener          {nullptr};
    bool                    m_loadIsQueued      {false};
    uint                    m_loadsInProgress   {0};
    mutable QWaitCondition  m_loadWait;
};
 
Q_DECLARE_OPERATORS_FOR_FLAGS(ProgramInfoCache::UpdateStates)
 
#endif // PROGRAM_INFO_CACHE_H