include/vlc_picture_pool.h

   1 /*****************************************************************************
   2  * vlc_picture_pool.h: picture pool definitions
   3  *****************************************************************************
   4  * Copyright (C) 2009 VLC authors and VideoLAN
   5  * $Id$
   6  *
   7  * Authors: Laurent Aimar <fenrir _AT_ videolan _DOT_ org>
   8  *
   9  * This program is free software; you can redistribute it and/or modify it
  10  * under the terms of the GNU Lesser General Public License as published by
  11  * the Free Software Foundation; either version 2.1 of the License, or
  12  * (at your option) any later version.
  13  *
  14  * This program is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  17  * GNU Lesser General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU Lesser General Public License
  20  * along with this program; if not, write to the Free Software Foundation,
  21  * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  22  *****************************************************************************/
  23
  24 #ifndef VLC_PICTURE_POOL_H
  25 #define VLC_PICTURE_POOL_H 1
  26
  27 /**
  28  * \file
  29  * This file defines picture pool structures and functions in vlc
  30  */
  31
  32 #include <vlc_picture.h>
  33
  34 /**
  35  * Picture pool handle
  36  */
  37 typedef struct picture_pool_t picture_pool_t;
  38
  39 /**
  40  * Picture pool configuration
  41  */
  42 typedef struct {
  43     unsigned  picture_count;
  44     picture_t *const *picture;
  45
  46     int       (*lock)(picture_t *);
  47     void      (*unlock)(picture_t *);
  48 } picture_pool_configuration_t;
  49
  50 /**
  51  * Creates a pool of preallocated pictures. Free pictures can be allocated from
  52  * the pool, and are returned to the pool when they are no longer referenced.
  53  *
  54  * This avoids allocating and deallocationg pictures repeatedly, and ensures
  55  * that memory consumption remains within limits.
  56  *
  57  * To obtain a picture from the pool, use picture_pool_Get(). To increase and
  58  * decrease the reference count, use picture_Hold() and picture_Release()
  59  * respectively.
  60  *
  61  * If defined, picture_pool_configuration_t::lock will be called before
  62  * a picture is used, and picture_pool_configuration_t::unlock will be called
  63  * as soon as a picture is returned to the pool.
  64  * Those callbacks can modify picture_t::p and access picture_t::p_sys.
  65  *
  66  * @return A pointer to the new pool on success, or NULL on error
  67  * (pictures are <b>not</b> released on error).
  68  */
  69 VLC_API picture_pool_t * picture_pool_NewExtended( const picture_pool_configuration_t * ) VLC_USED;
  70
  71 /**
  72  * Creates a picture pool with pictures in a given array.
  73  * This is a convenience wrapper for picture_pool_NewExtended() without the
  74  * lock and unlock callbacks.
  75  *
  76  * @param count number of pictures in the array
  77  * @param tab array of pictures
  78  *
  79  * @return a pointer to the new pool on success, or NULL on error
  80  * (pictures are <b>not</b> released on error)
  81  */
  82 VLC_API picture_pool_t * picture_pool_New(unsigned count,
  83                                           picture_t *const *tab) VLC_USED;
  84
  85 /**
  86  * Allocates pictures from the heap and creates a picture pool with them.
  87  * This is a convenience wrapper for picture_NewFromFormat() and
  88  * picture_pool_New().
  89  *
  90  * @param fmt video format of pictures to allocate from the heap
  91  * @param count number of pictures to allocate
  92  *
  93  * @return a pointer to the new pool on success, NULL on error
  94  */
  95 VLC_API picture_pool_t * picture_pool_NewFromFormat(const video_format_t *fmt,
  96                                                     unsigned count) VLC_USED;
  97
  98 /**
  99  * Releases a pool created by picture_pool_NewExtended(), picture_pool_New()
 100  * or picture_pool_NewFromFormat().
 101  *
 102  * @note If there are no pending references to the pooled pictures, and the
 103  * picture_resource_t.pf_destroy callback was not NULL, it will be invoked.
 104  * Otherwise the default callback will be used.
 105  *
 106  * @warning If there are pending references (a.k.a. late pictures), the
 107  * pictures will remain valid until the all pending references are dropped by
 108  * picture_Release().
 109  */
 110 VLC_API void picture_pool_Release( picture_pool_t * );
 111
 112 /**
 113  * Obtains a picture from a pool if any is immediately available.
 114  *
 115  * The picture must be released with picture_Release().
 116  *
 117  * @return a picture, or NULL if all pictures in the pool are allocated
 118  *
 119  * @note This function is thread-safe.
 120  */
 121 VLC_API picture_t * picture_pool_Get( picture_pool_t * ) VLC_USED;
 122
 123 /**
 124  * Obtains a picture from a pool.
 125  *
 126  * The picture must be released with picture_Release().
 127  *
 128  * @return a picture or NULL on memory error
 129  *
 130  * @note This function is thread-safe.
 131  */
 132 VLC_API picture_t *picture_pool_Wait(picture_pool_t *) VLC_USED;
 133
 134 /**
 135  * Enumerates all pictures in a pool, both free and allocated.
 136  *
 137  * @param cb callback to invoke once for each picture
 138  * @param data opaque data parameter for the callback (first argument)
 139  *
 140  * @note Allocated pictures may be accessed asynchronously by other threads.
 141  * Therefore, only read-only picture parameters can be read by the callback,
 142  * typically picture_t.p_sys.
 143  * Provided those rules are respected, the function is thread-safe.
 144  */
 145 VLC_API void picture_pool_Enum( picture_pool_t *,
 146                                 void (*cb)(void *, picture_t *), void *data );
 147
 148 /**
 149  * Cancel the picture pool.
 150  *
 151  * It won't return any pictures via picture_pool_Get or picture_pool_Wait if
 152  * canceled is true. This function will also unblock picture_pool_Wait.
 153  * picture_pool_Reset will also reset the cancel state to false.
 154  */
 155 void picture_pool_Cancel( picture_pool_t *, bool canceled );
 156
 157 /**
 158  * Reserves pictures from a pool and creates a new pool with those.
 159  *
 160  * When the new pool is released, pictures are returned to the master pool.
 161  * If the master pool was already released, pictures will be destroyed.
 162  *
 163  * @param count number of picture to reserve
 164  *
 165  * @return the new pool, or NULL if there were not enough pictures available
 166  * or on error
 167  *
 168  * @note This function is thread-safe (but it might return NULL if other
 169  * threads have already allocated too many pictures).
 170  */
 171 VLC_API picture_pool_t * picture_pool_Reserve(picture_pool_t *, unsigned count)
 172 VLC_USED;
 173
 174 /**
 175  * @return the total number of pictures in the given pool
 176  * @note This function is thread-safe.
 177  */
 178 VLC_API unsigned picture_pool_GetSize(const picture_pool_t *);
 179
 180
 181 #endif /* VLC_PICTURE_POOL_H */
 182