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using System;
using System.Diagnostics.CodeAnalysis;
using System.Globalization;
using System.IO;
using System.Text.Json;
using Jellyfin.Extensions.Json;
using Jellyfin.MediaEncoding.Hls.Extractors;
using Jellyfin.MediaEncoding.Keyframes;
using MediaBrowser.Common.Configuration;
using MediaBrowser.Common.Extensions;
using Microsoft.Extensions.Logging;
namespace Jellyfin.MediaEncoding.Hls.Cache;
/// <inheritdoc />
public class CacheDecorator : IKeyframeExtractor
{
private readonly IKeyframeExtractor _keyframeExtractor;
private readonly ILogger<CacheDecorator> _logger;
private readonly string _keyframeExtractorName;
private static readonly JsonSerializerOptions _jsonOptions = JsonDefaults.Options;
private readonly string _keyframeCachePath;
/// <summary>
/// Initializes a new instance of the <see cref="CacheDecorator"/> class.
/// </summary>
/// <param name="applicationPaths">An instance of the <see cref="IApplicationPaths"/> interface.</param>
/// <param name="keyframeExtractor">An instance of the <see cref="IKeyframeExtractor"/> interface.</param>
/// <param name="logger">An instance of the <see cref="ILogger{CacheDecorator}"/> interface.</param>
public CacheDecorator(IApplicationPaths applicationPaths, IKeyframeExtractor keyframeExtractor, ILogger<CacheDecorator> logger)
{
ArgumentNullException.ThrowIfNull(applicationPaths);
ArgumentNullException.ThrowIfNull(keyframeExtractor);
_keyframeExtractor = keyframeExtractor;
_logger = logger;
_keyframeExtractorName = keyframeExtractor.GetType().Name;
// TODO make the dir configurable
_keyframeCachePath = Path.Combine(applicationPaths.DataPath, "keyframes");
}
/// <inheritdoc />
public bool IsMetadataBased => _keyframeExtractor.IsMetadataBased;
/// <inheritdoc />
public bool TryExtractKeyframes(string filePath, [NotNullWhen(true)] out KeyframeData? keyframeData)
{
keyframeData = null;
var cachePath = GetCachePath(_keyframeCachePath, filePath);
if (TryReadFromCache(cachePath, out var cachedResult))
{
keyframeData = cachedResult;
return true;
}
if (!_keyframeExtractor.TryExtractKeyframes(filePath, out var result))
{
_logger.LogDebug("Failed to extract keyframes using {ExtractorName}", _keyframeExtractorName);
return false;
}
_logger.LogDebug("Successfully extracted keyframes using {ExtractorName}", _keyframeExtractorName);
keyframeData = result;
SaveToCache(cachePath, keyframeData);
return true;
}
private static void SaveToCache(string cachePath, KeyframeData keyframeData)
{
var json = JsonSerializer.Serialize(keyframeData, _jsonOptions);
Directory.CreateDirectory(Path.GetDirectoryName(cachePath) ?? throw new ArgumentException($"Provided path ({cachePath}) is not valid.", nameof(cachePath)));
File.WriteAllText(cachePath, json);
}
private static string GetCachePath(string keyframeCachePath, string filePath)
{
var lastWriteTimeUtc = File.GetLastWriteTimeUtc(filePath);
ReadOnlySpan<char> filename = (filePath + "_" + lastWriteTimeUtc.Ticks.ToString(CultureInfo.InvariantCulture)).GetMD5() + ".json";
var prefix = filename[..1];
return Path.Join(keyframeCachePath, prefix, filename);
}
private static bool TryReadFromCache(string cachePath, [NotNullWhen(true)] out KeyframeData? cachedResult)
{
if (File.Exists(cachePath))
{
var bytes = File.ReadAllBytes(cachePath);
cachedResult = JsonSerializer.Deserialize<KeyframeData>(bytes, _jsonOptions);
return cachedResult is not null;
}
cachedResult = null;
return false;
}
}
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