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libopenshot/src/CacheMemory.h

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3.2 KiB
C++

/**
* @file
* @brief Header file for CacheMemory class
* @author Jonathan Thomas <jonathan@openshot.org>
*
* @ref License
*/
// Copyright (c) 2008-2019 OpenShot Studios, LLC
//
// SPDX-License-Identifier: LGPL-3.0-or-later
#ifndef OPENSHOT_CACHE_MEMORY_H
#define OPENSHOT_CACHE_MEMORY_H
#include "CacheBase.h"
namespace openshot {
class Frame;
/**
* @brief This class is a memory-based cache manager for Frame objects.
*
* It is used by FileReaders (such as FFmpegReader) to cache recently accessed frames. Due to the
* high cost of decoding streams, once a frame is decoded, converted to RGB, and a Frame object is created,
* it critical to keep these Frames cached for performance reasons. However, the larger the cache, the more memory
* is required. You can set the max number of bytes to cache.
*/
class CacheMemory : public CacheBase {
private:
std::map<int64_t, std::shared_ptr<openshot::Frame> > frames; ///< This map holds the frame number and Frame objects
std::deque<int64_t> frame_numbers; ///< This queue holds a sequential list of cached Frame numbers
/// Clean up cached frames that exceed the max number of bytes
void CleanUp();
public:
/// Default constructor, no max bytes
CacheMemory();
/// @brief Constructor that sets the max bytes to cache
/// @param max_bytes The maximum bytes to allow in the cache. Once exceeded, the cache will purge the oldest frames.
CacheMemory(int64_t max_bytes);
// Default destructor
virtual ~CacheMemory();
/// @brief Add a Frame to the cache
/// @param frame The openshot::Frame object needing to be cached.
void Add(std::shared_ptr<openshot::Frame> frame);
/// Clear the cache of all frames
void Clear();
/// @brief Check if frame is already contained in cache
/// @param frame_number The frame number to be checked
bool Contains(int64_t frame_number);
/// Count the frames in the queue
int64_t Count();
/// @brief Get a frame from the cache
/// @param frame_number The frame number of the cached frame
std::shared_ptr<openshot::Frame> GetFrame(int64_t frame_number);
/// @brief Get an array of all Frames
std::vector<std::shared_ptr<openshot::Frame>> GetFrames();
/// Gets the maximum bytes value
int64_t GetBytes();
/// Get the smallest frame number
std::shared_ptr<openshot::Frame> GetSmallestFrame();
/// @brief Move frame to front of queue (so it lasts longer)
/// @param frame_number The frame number of the cached frame
void Touch(int64_t frame_number);
/// @brief Remove a specific frame
/// @param frame_number The frame number of the cached frame
void Remove(int64_t frame_number);
/// @brief Remove a range of frames
/// @param start_frame_number The starting frame number of the cached frame
/// @param end_frame_number The ending frame number of the cached frame
void Remove(int64_t start_frame_number, int64_t end_frame_number);
// Get and Set JSON methods
std::string Json(); ///< Generate JSON string of this object
void SetJson(const std::string value); ///< Load JSON string into this object
Json::Value JsonValue(); ///< Generate Json::Value for this object
void SetJsonValue(const Json::Value root); ///< Load Json::Value into this object
};
}
#endif