OpenShot Library | libopenshot  0.2.7
CacheMemory.h
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1 /**
2  * @file
3  * @brief Header file for CacheMemory class
4  * @author Jonathan Thomas <jonathan@openshot.org>
5  *
6  * @ref License
7  */
8 
9 /* LICENSE
10  *
11  * Copyright (c) 2008-2019 OpenShot Studios, LLC
12  * <http://www.openshotstudios.com/>. This file is part of
13  * OpenShot Library (libopenshot), an open-source project dedicated to
14  * delivering high quality video editing and animation solutions to the
15  * world. For more information visit <http://www.openshot.org/>.
16  *
17  * OpenShot Library (libopenshot) is free software: you can redistribute it
18  * and/or modify it under the terms of the GNU Lesser General Public License
19  * as published by the Free Software Foundation, either version 3 of the
20  * License, or (at your option) any later version.
21  *
22  * OpenShot Library (libopenshot) is distributed in the hope that it will be
23  * useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
24  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
25  * GNU Lesser General Public License for more details.
26  *
27  * You should have received a copy of the GNU Lesser General Public License
28  * along with OpenShot Library. If not, see <http://www.gnu.org/licenses/>.
29  */
30 
31 #ifndef OPENSHOT_CACHE_MEMORY_H
32 #define OPENSHOT_CACHE_MEMORY_H
33 
34 #include <map>
35 #include <deque>
36 #include <memory>
37 #include "CacheBase.h"
38 #include "Frame.h"
39 
40 namespace openshot {
41 
42  /**
43  * @brief This class is a memory-based cache manager for Frame objects.
44  *
45  * It is used by FileReaders (such as FFmpegReader) to cache recently accessed frames. Due to the
46  * high cost of decoding streams, once a frame is decoded, converted to RGB, and a Frame object is created,
47  * it critical to keep these Frames cached for performance reasons. However, the larger the cache, the more memory
48  * is required. You can set the max number of bytes to cache.
49  */
50  class CacheMemory : public CacheBase {
51  private:
52  std::map<int64_t, std::shared_ptr<openshot::Frame> > frames; ///< This map holds the frame number and Frame objects
53  std::deque<int64_t> frame_numbers; ///< This queue holds a sequential list of cached Frame numbers
54 
55  bool needs_range_processing; ///< Something has changed, and the range data needs to be re-calculated
56  std::string json_ranges; ///< JSON ranges of frame numbers
57  std::vector<int64_t> ordered_frame_numbers; ///< Ordered list of frame numbers used by cache
58  std::map<int64_t, int64_t> frame_ranges; ///< This map holds the ranges of frames, useful for quickly displaying the contents of the cache
59  int64_t range_version; ///< The version of the JSON range data (incremented with each change)
60 
61  /// Clean up cached frames that exceed the max number of bytes
62  void CleanUp();
63 
64  /// Calculate ranges of frames
65  void CalculateRanges();
66 
67  public:
68  /// Default constructor, no max bytes
69  CacheMemory();
70 
71  /// @brief Constructor that sets the max bytes to cache
72  /// @param max_bytes The maximum bytes to allow in the cache. Once exceeded, the cache will purge the oldest frames.
73  CacheMemory(int64_t max_bytes);
74 
75  // Default destructor
76  virtual ~CacheMemory();
77 
78  /// @brief Add a Frame to the cache
79  /// @param frame The openshot::Frame object needing to be cached.
80  void Add(std::shared_ptr<openshot::Frame> frame);
81 
82  /// Clear the cache of all frames
83  void Clear();
84 
85  /// Count the frames in the queue
86  int64_t Count();
87 
88  /// @brief Get a frame from the cache
89  /// @param frame_number The frame number of the cached frame
90  std::shared_ptr<openshot::Frame> GetFrame(int64_t frame_number);
91 
92  /// Gets the maximum bytes value
93  int64_t GetBytes();
94 
95  /// Get the smallest frame number
96  std::shared_ptr<openshot::Frame> GetSmallestFrame();
97 
98  /// @brief Move frame to front of queue (so it lasts longer)
99  /// @param frame_number The frame number of the cached frame
100  void MoveToFront(int64_t frame_number);
101 
102  /// @brief Remove a specific frame
103  /// @param frame_number The frame number of the cached frame
104  void Remove(int64_t frame_number);
105 
106  /// @brief Remove a range of frames
107  /// @param start_frame_number The starting frame number of the cached frame
108  /// @param end_frame_number The ending frame number of the cached frame
109  void Remove(int64_t start_frame_number, int64_t end_frame_number);
110 
111  // Get and Set JSON methods
112  std::string Json(); ///< Generate JSON string of this object
113  void SetJson(const std::string value); ///< Load JSON string into this object
114  Json::Value JsonValue(); ///< Generate Json::Value for this object
115  void SetJsonValue(const Json::Value root); ///< Load Json::Value into this object
116  };
117 
118 }
119 
120 #endif
Header file for CacheBase class.
Header file for Frame class.
All cache managers in libopenshot are based on this CacheBase class.
Definition: CacheBase.h:49
int64_t max_bytes
This is the max number of bytes to cache (0 = no limit)
Definition: CacheBase.h:52
This class is a memory-based cache manager for Frame objects.
Definition: CacheMemory.h:50
CacheMemory()
Default constructor, no max bytes.
Definition: CacheMemory.cpp:38
int64_t Count()
Count the frames in the queue.
void Add(std::shared_ptr< openshot::Frame > frame)
Add a Frame to the cache.
void SetJson(const std::string value)
Load JSON string into this object.
int64_t GetBytes()
Gets the maximum bytes value.
std::string Json()
Generate JSON string of this object.
std::shared_ptr< openshot::Frame > GetFrame(int64_t frame_number)
Get a frame from the cache.
void SetJsonValue(const Json::Value root)
Load Json::Value into this object.
void MoveToFront(int64_t frame_number)
Move frame to front of queue (so it lasts longer)
void Remove(int64_t frame_number)
Remove a specific frame.
void Clear()
Clear the cache of all frames.
Json::Value JsonValue()
Generate Json::Value for this object.
std::shared_ptr< openshot::Frame > GetSmallestFrame()
Get the smallest frame number.
This namespace is the default namespace for all code in the openshot library.
Definition: Compressor.h:47