OpenShot Library | libopenshot  0.2.2
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  * @section LICENSE
7  *
8  * Copyright (c) 2008-2014 OpenShot Studios, LLC
9  * <http://www.openshotstudios.com/>. This file is part of
10  * OpenShot Library (libopenshot), an open-source project dedicated to
11  * delivering high quality video editing and animation solutions to the
12  * world. For more information visit <http://www.openshot.org/>.
13  *
14  * OpenShot Library (libopenshot) is free software: you can redistribute it
15  * and/or modify it under the terms of the GNU Lesser General Public License
16  * as published by the Free Software Foundation, either version 3 of the
17  * License, or (at your option) any later version.
18  *
19  * OpenShot Library (libopenshot) is distributed in the hope that it will be
20  * useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
22  * GNU Lesser General Public License for more details.
23  *
24  * You should have received a copy of the GNU Lesser General Public License
25  * along with OpenShot Library. If not, see <http://www.gnu.org/licenses/>.
26  */
27 
28 #ifndef OPENSHOT_CACHE_MEMORY_H
29 #define OPENSHOT_CACHE_MEMORY_H
30 
31 #include <map>
32 #include <deque>
33 #include <memory>
34 #include "CacheBase.h"
35 #include "Frame.h"
36 #include "Exceptions.h"
37 
38 namespace openshot {
39 
40  /**
41  * @brief This class is a memory-based cache manager for Frame objects.
42  *
43  * It is used by FileReaders (such as FFmpegReader) to cache recently accessed frames. Due to the
44  * high cost of decoding streams, once a frame is decoded, converted to RGB, and a Frame object is created,
45  * it critical to keep these Frames cached for performance reasons. However, the larger the cache, the more memory
46  * is required. You can set the max number of bytes to cache.
47  */
48  class CacheMemory : public CacheBase {
49  private:
50  map<int64_t, std::shared_ptr<Frame> > frames; ///< This map holds the frame number and Frame objects
51  deque<int64_t> frame_numbers; ///< This queue holds a sequential list of cached Frame numbers
52 
53  bool needs_range_processing; ///< Something has changed, and the range data needs to be re-calculated
54  string json_ranges; ///< JSON ranges of frame numbers
55  vector<int64_t> ordered_frame_numbers; ///< Ordered list of frame numbers used by cache
56  map<int64_t, int64_t> frame_ranges; ///< This map holds the ranges of frames, useful for quickly displaying the contents of the cache
57  int64_t range_version; ///< The version of the JSON range data (incremented with each change)
58 
59  /// Clean up cached frames that exceed the max number of bytes
60  void CleanUp();
61 
62  /// Calculate ranges of frames
63  void CalculateRanges();
64 
65  public:
66  /// Default constructor, no max bytes
67  CacheMemory();
68 
69  /// @brief Constructor that sets the max bytes to cache
70  /// @param max_bytes The maximum bytes to allow in the cache. Once exceeded, the cache will purge the oldest frames.
71  CacheMemory(int64_t max_bytes);
72 
73  // Default destructor
74  ~CacheMemory();
75 
76  /// @brief Add a Frame to the cache
77  /// @param frame The openshot::Frame object needing to be cached.
78  void Add(std::shared_ptr<Frame> frame);
79 
80  /// Clear the cache of all frames
81  void Clear();
82 
83  /// Count the frames in the queue
84  int64_t Count();
85 
86  /// @brief Get a frame from the cache
87  /// @param frame_number The frame number of the cached frame
88  std::shared_ptr<Frame> GetFrame(int64_t frame_number);
89 
90  /// Gets the maximum bytes value
91  int64_t GetBytes();
92 
93  /// Get the smallest frame number
94  std::shared_ptr<Frame> GetSmallestFrame();
95 
96  /// @brief Move frame to front of queue (so it lasts longer)
97  /// @param frame_number The frame number of the cached frame
98  void MoveToFront(int64_t frame_number);
99 
100  /// @brief Remove a specific frame
101  /// @param frame_number The frame number of the cached frame
102  void Remove(int64_t frame_number);
103 
104  /// @brief Remove a range of frames
105  /// @param start_frame_number The starting frame number of the cached frame
106  /// @param end_frame_number The ending frame number of the cached frame
107  void Remove(int64_t start_frame_number, int64_t end_frame_number);
108 
109  /// Get and Set JSON methods
110  string Json(); ///< Generate JSON string of this object
111  void SetJson(string value); ///< Load JSON string into this object
112  Json::Value JsonValue(); ///< Generate Json::JsonValue for this object
113  void SetJsonValue(Json::Value root); ///< Load Json::JsonValue into this object
114  };
115 
116 }
117 
118 #endif
openshot::CacheMemory::Clear
void Clear()
Clear the cache of all frames.
Definition: CacheMemory.cpp:278
openshot::CacheMemory::Count
int64_t Count()
Count the frames in the queue.
Definition: CacheMemory.cpp:290
openshot::CacheMemory::SetJsonValue
void SetJsonValue(Json::Value root)
Load Json::JsonValue into this object.
Definition: CacheMemory.cpp:376
openshot::CacheMemory::GetBytes
int64_t GetBytes()
Gets the maximum bytes value.
Definition: CacheMemory.cpp:193
openshot::CacheMemory::GetFrame
std::shared_ptr< Frame > GetFrame(int64_t frame_number)
Get a frame from the cache.
Definition: CacheMemory.cpp:155
openshot::CacheBase::max_bytes
int64_t max_bytes
This is the max number of bytes to cache (0 = no limit)
Definition: CacheBase.h:49
openshot
This namespace is the default namespace for all code in the openshot library.
Definition: AudioBufferSource.h:45
openshot::CacheMemory::Json
string Json()
Get and Set JSON methods.
Definition: CacheMemory.cpp:321
openshot::CacheMemory::Add
void Add(std::shared_ptr< Frame > frame)
Add a Frame to the cache.
Definition: CacheMemory.cpp:130
openshot::CacheMemory::Remove
void Remove(int64_t frame_number)
Remove a specific frame.
Definition: CacheMemory.cpp:211
openshot::CacheMemory::JsonValue
Json::Value JsonValue()
Generate Json::JsonValue for this object.
Definition: CacheMemory.cpp:328
openshot::CacheBase
All cache managers in libopenshot are based on this CacheBase class.
Definition: CacheBase.h:45
CacheBase.h
Header file for CacheBase class.
openshot::CacheMemory::~CacheMemory
~CacheMemory()
Definition: CacheMemory.cpp:50
openshot::CacheMemory
This class is a memory-based cache manager for Frame objects.
Definition: CacheMemory.h:48
Frame.h
Header file for Frame class.
openshot::CacheMemory::GetSmallestFrame
std::shared_ptr< Frame > GetSmallestFrame()
Get the smallest frame number.
Definition: CacheMemory.cpp:171
openshot::CacheMemory::SetJson
void SetJson(string value)
Load JSON string into this object.
Definition: CacheMemory.cpp:353
openshot::CacheMemory::CacheMemory
CacheMemory()
Default constructor, no max bytes.
Definition: CacheMemory.cpp:34
openshot::CacheMemory::MoveToFront
void MoveToFront(int64_t frame_number)
Move frame to front of queue (so it lasts longer)
Definition: CacheMemory.cpp:252
Exceptions.h
Header file for all Exception classes.