ImageManager/RequestQueue.h

   1 /* Copyright (C) 2003-2006 Jesper K. Pedersen <blackie@kde.org>
   2
   3    This program is free software; you can redistribute it and/or
   4    modify it under the terms of the GNU General Public
   5    License as published by the Free Software Foundation; either
   6    version 2 of the License, or (at your option) any later version.
   7
   8    This program is distributed in the hope that it will be useful,
   9    but WITHOUT ANY WARRANTY; without even the implied warranty of
  10    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11    General Public License for more details.
  12
  13    You should have received a copy of the GNU General Public License
  14    along with this program; see the file COPYING.  If not, write to
  15    the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  16    Boston, MA 02110-1301, USA.
  17 */
  18 #ifndef REQUESTQUEUE_H
  19 #define REQUESTQUEUE_H
  20
  21 #include <QQueue>
  22 #include <QSet>
  23 #include "StopAction.h"
  24 #include "ImageManager/ImageRequest.h"
  25
  26 namespace ImageManager
  27 {
  28 class ImageClient;
  29
  30 // RequestQueue for ImageRequests. Non-synchronized, locking has to be
  31 // provided by the user.
  32 class RequestQueue :public QObject
  33 {
  34     Q_OBJECT
  35
  36 public:
  37     RequestQueue();
  38
  39     // Add a new request to the input queue in the right priority level.
  40     // @return 'true', if this is not a request already pending.
  41     bool addRequest( ImageRequest* request );
  42
  43     // Return the next needed ImageRequest from the queue or NULL if there
  44     // is none. The ownership is returned back to the caller so it has to
  45     // delete it.
  46     ImageRequest* popNext();
  47
  48     // Remove all pending requests from the given client.
  49     void cancelRequests( ImageClient* client, StopAction action );
  50
  51     bool isRequestStillValid( ImageRequest* request );
  52     void removeRequest( ImageRequest* );
  53
  54 private:
  55     // A Reference to a ImageRequest withvalue semantic.
  56     // This only stores the pointer to an ImageRequest object but behaves
  57     // regarding the less-than and equals-operator like the object.
  58     // This allows to store ImageRequests with value-semantic in a Set.
  59     class ImageRequestReference {
  60     public:
  61         ImageRequestReference() : _ptr(0) {}
  62         ImageRequestReference(const ImageRequestReference& other)
  63             : _ptr(other._ptr) {}
  64         ImageRequestReference(const ImageRequest* ptr) : _ptr(ptr) {}
  65
  66         bool operator<(const ImageRequestReference &other) const {
  67             return *_ptr < *other._ptr;
  68         }
  69         bool operator==(const ImageRequestReference &other) const {
  70             return *_ptr == *other._ptr;
  71         }
  72         operator const ImageRequest&() const {
  73             return *_ptr;
  74         }
  75     private:
  76         const ImageRequest* _ptr;
  77     };
  78
  79     typedef QList<QQueue<ImageRequest*> > QueueType;
  80
  81     /** @short Priotized list of queues (= 1 priority queue) of image requests
  82      * that are waiting for processing
  83      */
  84     QueueType _queues;
  85
  86     /**
  87      * Set of unique requests currently pending; used to discard the exact
  88      * same requests.
  89      * TODO(hzeller): seems, that the unique-pending requests tried to be
  90      * handled in different places in kpa but sometimes in a snakeoil
  91      * way (it compares pointers instead of the content -> clean up that).
  92      */
  93     QSet<ImageRequestReference> _uniquePending;
  94
  95     // All active requests that have a client
  96     QSet<ImageRequest*> _activeRequests;
  97 };
  98
  99 }
 100
 101 #endif /* REQUESTQUEUE_H */
 102