File indexing completed on 2024-04-28 15:39:58

 /* SPDX-FileCopyrightText: 2018 Robert Krawitz <rlk@alum.mit.edu>
 
    SPDX-License-Identifier: GPL-2.0-or-later
 */
 
 #ifndef IMAGESCOUT_H
 #define IMAGESCOUT_H
 
 #include <kpabase/FileName.h>
 
 #include <QAtomicInt>
 #include <QList>
 #include <QMutex>
 #include <QQueue>
 
 namespace DB
 {
 
 typedef QQueue<DB::FileName> ImageScoutQueue;
 typedef void (*PreloadFunc)(const DB::FileName &);
 class ImageScoutThread;
 
 /**
  * Scout thread for image loading: preload images from disk to have them in
  * RAM to mask I/O latency.
  */
 class ImageScout
 {
 public:
     // count is an atomic variable containing the number of images
     // that have been loaded thus far.  Used to prevent the scout from
     // getting too far ahead, if it's able to run faster than the
     // loader.  Which usually it can't; with hard disks on any halfway
     // decent system, the loader can run faster than the disk.
     ImageScout(ImageScoutQueue &, QAtomicInt &count, int threads = 1);
     ~ImageScout();
     // Specify scout buffer size.  May not be called after starting the scout.
     void setBufSize(int);
     int getBufSize();
     // Specify how far we're allowed to run ahead of the loader, in images.
     // May not be called after starting the scout.
     void setMaxSeekAhead(int);
     int getMaxSeekAhead();
     // Specify how many bytes we read before moving on.
     // May not be called after starting the scout.
     void setReadLimit(int);
     int getReadLimit();
     // Specify an alternate function to preload the file.
     // This function may perform useful work.  Note that this is not
     // guaranteed to be called, so anything using this must be
     // prepared to do the work later.
     void setPreloadFunc(PreloadFunc);
     PreloadFunc getPreloadFunc();
     // Start the scout running
     void start();
 
 private:
     QMutex m_mutex;
     QList<ImageScoutThread *> m_scoutList;
     QAtomicInt m_preloadedCount;
     QAtomicInt m_skippedCount;
     bool m_isStarted;
     int m_scoutBufSize;
     int m_maxSeekAhead;
     int m_readLimit;
     PreloadFunc m_preloadFunc;
 };
 }
 
 #endif /* IMAGESCOUT_H */
 
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