CacheMemory.cpp

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// Copyright (c) 2008-2019 OpenShot Studios, LLC
//
// SPDX-License-Identifier: LGPL-3.0-or-later
 
#include "CacheMemory.h"
#include "Exceptions.h"
#include "Frame.h"
 
using namespace std;
using namespace openshot;
 
// Default constructor, no max bytes
CacheMemory::CacheMemory() : CacheBase(0) {
    // Set cache type name
    cache_type = "CacheMemory";
    range_version = 0;
    needs_range_processing = false;
}
 
// Constructor that sets the max bytes to cache
CacheMemory::CacheMemory(int64_t max_bytes) : CacheBase(max_bytes) {
    // Set cache type name
    cache_type = "CacheMemory";
    range_version = 0;
    needs_range_processing = false;
}
 
// Default destructor
CacheMemory::~CacheMemory()
{
    Clear();
 
    // remove mutex
    delete cacheMutex;
}
 
// Add a Frame to the cache
void CacheMemory::Add(std::shared_ptr<Frame> frame)
{
    // Create a scoped lock, to protect the cache from multiple threads
    const std::lock_guard<std::recursive_mutex> lock(*cacheMutex);
    int64_t frame_number = frame->number;
 
    // Freshen frame if it already exists
    if (frames.count(frame_number))
        // Move frame to front of queue
        MoveToFront(frame_number);
 
    else
    {
        // Add frame to queue and map
        frames[frame_number] = frame;
        frame_numbers.push_front(frame_number);
        ordered_frame_numbers.push_back(frame_number);
        needs_range_processing = true;
 
        // Clean up old frames
        CleanUp();
    }
}
 
// Check if frame is already contained in cache
bool CacheMemory::Contains(int64_t frame_number) {
    if (frames.count(frame_number) > 0) {
        return true;
    } else {
        return false;
    }
}
 
// Get a frame from the cache (or NULL shared_ptr if no frame is found)
std::shared_ptr<Frame> CacheMemory::GetFrame(int64_t frame_number)
{
    // Create a scoped lock, to protect the cache from multiple threads
    const std::lock_guard<std::recursive_mutex> lock(*cacheMutex);
 
    // Does frame exists in cache?
    if (frames.count(frame_number))
        // return the Frame object
        return frames[frame_number];
 
    else
        // no Frame found
        return std::shared_ptr<Frame>();
}
 
// @brief Get an array of all Frames
std::vector<std::shared_ptr<openshot::Frame>> CacheMemory::GetFrames()
{
    // Create a scoped lock, to protect the cache from multiple threads
    const std::lock_guard<std::recursive_mutex> lock(*cacheMutex);
 
    std::vector<std::shared_ptr<openshot::Frame>> all_frames;
    std::vector<int64_t>::iterator itr_ordered;
    for(itr_ordered = ordered_frame_numbers.begin(); itr_ordered != ordered_frame_numbers.end(); ++itr_ordered)
    {
        int64_t frame_number = *itr_ordered;
        all_frames.push_back(GetFrame(frame_number));
    }
 
    return all_frames;
}
 
// Get the smallest frame number (or NULL shared_ptr if no frame is found)
std::shared_ptr<Frame> CacheMemory::GetSmallestFrame()
{
    // Create a scoped lock, to protect the cache from multiple threads
    const std::lock_guard<std::recursive_mutex> lock(*cacheMutex);
 
    // Loop through frame numbers
    std::deque<int64_t>::iterator itr;
    int64_t smallest_frame = -1;
    for(itr = frame_numbers.begin(); itr != frame_numbers.end(); ++itr)
    {
        if (*itr < smallest_frame || smallest_frame == -1)
            smallest_frame = *itr;
    }
 
    // Return frame (if any)
    if (smallest_frame != -1) {
        return frames[smallest_frame];
    } else {
        return NULL;
    }
}
 
// Gets the maximum bytes value
int64_t CacheMemory::GetBytes()
{
    // Create a scoped lock, to protect the cache from multiple threads
    const std::lock_guard<std::recursive_mutex> lock(*cacheMutex);
 
    int64_t total_bytes = 0;
 
    // Loop through frames, and calculate total bytes
    std::deque<int64_t>::reverse_iterator itr;
    for(itr = frame_numbers.rbegin(); itr != frame_numbers.rend(); ++itr)
    {
        total_bytes += frames[*itr]->GetBytes();
    }
 
    return total_bytes;
}
 
// Remove a specific frame
void CacheMemory::Remove(int64_t frame_number)
{
    Remove(frame_number, frame_number);
}
 
// Remove range of frames
void CacheMemory::Remove(int64_t start_frame_number, int64_t end_frame_number)
{
    // Create a scoped lock, to protect the cache from multiple threads
    const std::lock_guard<std::recursive_mutex> lock(*cacheMutex);
 
    // Loop through frame numbers
    std::deque<int64_t>::iterator itr;
    for(itr = frame_numbers.begin(); itr != frame_numbers.end();)
    {
        if (*itr >= start_frame_number && *itr <= end_frame_number)
        {
            // erase frame number
            itr = frame_numbers.erase(itr);
        }else
            itr++;
    }
 
    // Loop through ordered frame numbers
    std::vector<int64_t>::iterator itr_ordered;
    for(itr_ordered = ordered_frame_numbers.begin(); itr_ordered != ordered_frame_numbers.end();)
    {
        if (*itr_ordered >= start_frame_number && *itr_ordered <= end_frame_number)
        {
            // erase frame number
            frames.erase(*itr_ordered);
            itr_ordered = ordered_frame_numbers.erase(itr_ordered);
        }else
            itr_ordered++;
    }
 
    // Needs range processing (since cache has changed)
    needs_range_processing = true;
}
 
// Move frame to front of queue (so it lasts longer)
void CacheMemory::MoveToFront(int64_t frame_number)
{
    // Create a scoped lock, to protect the cache from multiple threads
    const std::lock_guard<std::recursive_mutex> lock(*cacheMutex);
 
    // Does frame exists in cache?
    if (frames.count(frame_number))
    {
        // Loop through frame numbers
        std::deque<int64_t>::iterator itr;
        for(itr = frame_numbers.begin(); itr != frame_numbers.end(); ++itr)
        {
            if (*itr == frame_number)
            {
                // erase frame number
                frame_numbers.erase(itr);
 
                // add frame number to 'front' of queue
                frame_numbers.push_front(frame_number);
                break;
            }
        }
    }
}
 
// Clear the cache of all frames
void CacheMemory::Clear()
{
    // Create a scoped lock, to protect the cache from multiple threads
    const std::lock_guard<std::recursive_mutex> lock(*cacheMutex);
 
    frames.clear();
    frame_numbers.clear();
    frame_numbers.shrink_to_fit();
    ordered_frame_numbers.clear();
    ordered_frame_numbers.shrink_to_fit();
    needs_range_processing = true;
}
 
// Count the frames in the queue
int64_t CacheMemory::Count()
{
    // Create a scoped lock, to protect the cache from multiple threads
    const std::lock_guard<std::recursive_mutex> lock(*cacheMutex);
 
    // Return the number of frames in the cache
    return frames.size();
}
 
// Clean up cached frames that exceed the number in our max_bytes variable
void CacheMemory::CleanUp()
{
    // Do we auto clean up?
    if (max_bytes > 0)
    {
        // Create a scoped lock, to protect the cache from multiple threads
        const std::lock_guard<std::recursive_mutex> lock(*cacheMutex);
 
        while (GetBytes() > max_bytes && frame_numbers.size() > 20)
        {
            // Get the oldest frame number.
            int64_t frame_to_remove = frame_numbers.back();
 
            // Remove frame_number and frame
            Remove(frame_to_remove);
        }
    }
}
 
 
// Generate JSON string of this object
std::string CacheMemory::Json() {
 
    // Return formatted string
    return JsonValue().toStyledString();
}
 
// Generate Json::Value for this object
Json::Value CacheMemory::JsonValue() {
 
    // Process range data (if anything has changed)
    CalculateRanges();
 
    // Create root json object
    Json::Value root = CacheBase::JsonValue(); // get parent properties
    root["type"] = cache_type;
 
    root["version"] = std::to_string(range_version);
 
    // Parse and append range data (if any)
    try {
        const Json::Value ranges = openshot::stringToJson(json_ranges);
        root["ranges"] = ranges;
    } catch (...) { }
 
    // return JsonValue
    return root;
}
 
// Load JSON string into this object
void CacheMemory::SetJson(const std::string value) {
 
    try
    {
        // Parse string to Json::Value
        const Json::Value root = openshot::stringToJson(value);
        // Set all values that match
        SetJsonValue(root);
    }
    catch (const std::exception& e)
    {
        // Error parsing JSON (or missing keys)
        throw InvalidJSON("JSON is invalid (missing keys or invalid data types)");
    }
}
 
// Load Json::Value into this object
void CacheMemory::SetJsonValue(const Json::Value root) {
 
    // Close timeline before we do anything (this also removes all open and closing clips)
    Clear();
 
    // Set parent data
    CacheBase::SetJsonValue(root);
 
    if (!root["type"].isNull())
        cache_type = root["type"].asString();
}