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432 lines
16 KiB
432 lines
16 KiB
// --------------------------------------------------------------------------------------------------------------------
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// <copyright file="DiskCache.cs" company="James South">
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// Copyright (c) James South.
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// Licensed under the Apache License, Version 2.0.
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// </copyright>
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// <summary>
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// The disk cache.
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// </summary>
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// --------------------------------------------------------------------------------------------------------------------
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namespace ImageProcessor.Web.Caching
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{
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#region Using
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using System;
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using System.Collections.Generic;
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using System.Diagnostics.CodeAnalysis;
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using System.Globalization;
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using System.IO;
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using System.Linq;
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using System.Threading.Tasks;
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using System.Web;
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using System.Web.Hosting;
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using ImageProcessor.Extensions;
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using ImageProcessor.Web.Config;
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using ImageProcessor.Web.Helpers;
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#endregion
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/// <summary>
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/// The disk cache.
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/// </summary>
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internal sealed class DiskCache
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{
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#region Fields
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/// <summary>
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/// The maximum number of days to cache files on the system for.
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/// </summary>
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internal static readonly int MaxFileCachedDuration = ImageProcessorConfig.Instance.MaxCacheDays;
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/// <summary>
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/// The maximum number of files allowed in the directory.
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/// </summary>
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/// <remarks>
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/// NTFS directories can handle up to 10,000 files in the directory before slowing down.
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/// This will help us to ensure that don't go over that limit.
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/// <see cref="http://stackoverflow.com/questions/197162/ntfs-performance-and-large-volumes-of-files-and-directories"/>
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/// <see cref="http://stackoverflow.com/questions/115882/how-do-you-deal-with-lots-of-small-files"/>
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/// <see cref="http://stackoverflow.com/questions/1638219/millions-of-small-graphics-files-and-how-to-overcome-slow-file-system-access-on"/>
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/// </remarks>
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private const int MaxFilesCount = 50;
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/// <summary>
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/// The absolute path to virtual cache path on the server.
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/// </summary>
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private static readonly string AbsoluteCachePath =
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HostingEnvironment.MapPath(ImageProcessorConfig.Instance.VirtualCachePath);
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/// <summary>
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/// The request for the image.
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/// </summary>
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private readonly HttpRequest request;
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/// <summary>
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/// The request path for the image.
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/// </summary>
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private readonly string requestPath;
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/// <summary>
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/// The full path for the image.
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/// </summary>
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private readonly string fullPath;
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/// <summary>
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/// The image name
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/// </summary>
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private readonly string imageName;
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/// <summary>
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/// Whether the request is for a remote image.
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/// </summary>
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private readonly bool isRemote;
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#endregion
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#region Constructors
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/// <summary>
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/// Initializes a new instance of the <see cref="DiskCache"/> class.
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/// </summary>
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/// <param name="request">
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/// The request for the image.
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/// </param>
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/// <param name="requestPath">
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/// The request path for the image.
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/// </param>
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/// <param name="fullPath">
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/// The full path for the image.
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/// </param>
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/// <param name="imageName">
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/// The image name.
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/// </param>
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/// <param name="isRemote">
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/// Whether the request is for a remote image.
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/// </param>
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public DiskCache(HttpRequest request, string requestPath, string fullPath, string imageName, bool isRemote)
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{
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this.request = request;
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this.requestPath = requestPath;
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this.fullPath = fullPath;
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this.imageName = imageName;
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this.isRemote = isRemote;
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this.CachedPath = this.GetCachePath();
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}
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#endregion
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#region Properties
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/// <summary>
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/// Gets the cached path.
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/// </summary>
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internal string CachedPath { get; private set; }
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#endregion
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#region Methods
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#region Internal
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/// <summary>
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/// Gets the virtual path to the cached processed image.
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/// </summary>
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/// <returns>The virtual path to the cached processed image.</returns>
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internal string GetVirtualCachedPath()
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{
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string applicationPath = this.request.PhysicalApplicationPath;
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string virtualDir = this.request.ApplicationPath;
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virtualDir = virtualDir == "/" ? virtualDir : (virtualDir + "/");
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if (applicationPath != null)
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{
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return this.CachedPath.Replace(applicationPath, virtualDir).Replace(@"\", "/");
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}
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throw new InvalidOperationException(
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"We can only map an absolute back to a relative path if the application path is available.");
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}
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/// <summary>
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/// Adds an image to the cache.
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/// </summary>
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/// <param name="creationAndLastWriteDateTimes">
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/// The creation and last write times.
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/// </param>
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internal void AddImageToCache(Tuple<DateTime, DateTime> creationAndLastWriteDateTimes)
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{
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string key = Path.GetFileNameWithoutExtension(this.CachedPath);
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CachedImage cachedImage = new CachedImage
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{
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Key = key,
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Path = this.CachedPath,
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CreationTimeUtc = creationAndLastWriteDateTimes.Item1,
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LastWriteTimeUtc = creationAndLastWriteDateTimes.Item2
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};
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CacheIndexer.Add(cachedImage);
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}
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/// <summary>
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/// Returns a value indicating whether the original file is new or has been updated.
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/// </summary>
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/// <returns>
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/// True if the the original file is new or has been updated; otherwise, false.
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/// </returns>
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internal async Task<bool> IsNewOrUpdatedFileAsync()
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{
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string path = this.CachedPath;
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bool isUpdated = false;
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CachedImage cachedImage;
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if (this.isRemote)
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{
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cachedImage = await CacheIndexer.GetValueAsync(path);
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if (cachedImage != null)
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{
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// Can't check the last write time so check to see if the cached image is set to expire
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// or if the max age is different.
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if (this.IsExpired(cachedImage.CreationTimeUtc))
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{
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CacheIndexer.Remove(path);
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isUpdated = true;
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}
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}
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else
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{
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// Nothing in the cache so we should return true.
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isUpdated = true;
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}
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}
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else
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{
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// Test now for locally requested files.
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cachedImage = await CacheIndexer.GetValueAsync(path);
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if (cachedImage != null)
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{
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FileInfo imageFileInfo = new FileInfo(this.requestPath);
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if (imageFileInfo.Exists)
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{
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// Pull the latest info.
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imageFileInfo.Refresh();
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// Check to see if the last write time is different of whether the
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// cached image is set to expire or if the max age is different.
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if (!this.RoughDateTimeCompare(imageFileInfo.LastWriteTimeUtc, cachedImage.LastWriteTimeUtc)
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|| this.IsExpired(cachedImage.CreationTimeUtc))
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{
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CacheIndexer.Remove(path);
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isUpdated = true;
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}
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}
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}
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else
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{
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// Nothing in the cache so we should return true.
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isUpdated = true;
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}
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}
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return isUpdated;
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}
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/// <summary>
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/// Gets the <see cref="T:System.DateTime"/> set to the last write time of the file.
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/// </summary>
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/// <returns>
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/// The last write time of the file.
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/// </returns>
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internal async Task<DateTime> GetLastWriteTimeAsync()
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{
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DateTime dateTime = DateTime.UtcNow;
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CachedImage cachedImage = await CacheIndexer.GetValueAsync(this.CachedPath);
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if (cachedImage != null)
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{
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dateTime = cachedImage.LastWriteTimeUtc;
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}
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return dateTime;
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}
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/// <summary>
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/// Sets the LastWriteTime of the cached file to match the original file.
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/// </summary>
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/// <returns>
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/// The <see cref="T:System.DateTime"/> set to the last write time of the file.
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/// </returns>
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internal async Task<Tuple<DateTime, DateTime>> SetCachedLastWriteTimeAsync()
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{
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// Create Action delegate for SetCachedLastWriteTime.
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return await TaskHelpers.Run(() => this.SetCachedLastWriteTime());
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}
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/// <summary>
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/// Trims a cached folder ensuring that it does not exceed the maximum file count.
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/// </summary>
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/// <param name="path">
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/// The path to the folder.
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/// </param>
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/// <returns>
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/// The <see cref="T:System.Threading.Tasks.Task"/>.
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/// </returns>
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internal async Task TrimCachedFolderAsync(string path)
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{
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await TaskHelpers.Run(() => this.TrimCachedFolders(path));
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}
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#endregion
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#region Private
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/// <summary>
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/// Sets the LastWriteTime of the cached file to match the original file.
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/// </summary>
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/// <returns>
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/// The <see cref="T:System.DateTime"/> of the original and cached file.
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/// </returns>
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private Tuple<DateTime, DateTime> SetCachedLastWriteTime()
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{
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FileInfo cachedFileInfo = new FileInfo(this.CachedPath);
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DateTime creationTime = DateTime.MinValue.ToUniversalTime();
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DateTime lastWriteTime = DateTime.MinValue.ToUniversalTime();
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if (this.isRemote)
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{
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if (cachedFileInfo.Exists)
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{
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creationTime = cachedFileInfo.CreationTimeUtc;
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lastWriteTime = cachedFileInfo.LastWriteTimeUtc;
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}
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}
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else
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{
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FileInfo imageFileInfo = new FileInfo(this.requestPath);
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if (imageFileInfo.Exists && cachedFileInfo.Exists)
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{
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DateTime dateTime = imageFileInfo.LastWriteTimeUtc;
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creationTime = cachedFileInfo.CreationTimeUtc;
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cachedFileInfo.LastWriteTimeUtc = dateTime;
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lastWriteTime = dateTime;
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}
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}
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return new Tuple<DateTime, DateTime>(creationTime, lastWriteTime);
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}
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/// <summary>
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/// Trims a cached folder ensuring that it does not exceed the maximum file count.
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/// </summary>
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/// <param name="path">
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/// The path to the folder.
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/// </param>
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private void TrimCachedFolders(string path)
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{
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// ReSharper disable once AssignNullToNotNullAttribute
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DirectoryInfo directoryInfo = new DirectoryInfo(Path.GetDirectoryName(path));
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DirectoryInfo parentDirectoryInfo = directoryInfo.Parent;
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// ReSharper disable once PossibleNullReferenceException
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foreach (DirectoryInfo enumerateDirectory in parentDirectoryInfo.EnumerateDirectories())
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{
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IEnumerable<FileInfo> files = enumerateDirectory.EnumerateFiles().OrderBy(f => f.CreationTimeUtc);
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int count = files.Count();
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foreach (FileInfo fileInfo in files)
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{
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try
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{
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// If the group count is equal to the max count minus 1 then we know we
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// have reduced the number of items below the maximum allowed.
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// We'll cleanup any orphaned expired files though.
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if (!this.IsExpired(fileInfo.CreationTimeUtc) && count <= MaxFilesCount - 1)
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{
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break;
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}
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// Remove from the cache and delete each CachedImage.
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CacheIndexer.Remove(fileInfo.Name);
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fileInfo.Delete();
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count -= 1;
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}
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// ReSharper disable once EmptyGeneralCatchClause
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catch
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{
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// Do nothing; skip to the next file.
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}
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}
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}
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}
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/// <summary>
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/// Gets the full transformed cached path for the image.
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/// The images are stored in paths that are based upon the sha1 of their full request path
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/// taking the individual characters of the hash to determine their location.
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/// This allows us to store millions of images.
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/// </summary>
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/// <returns>The full cached path for the image.</returns>
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[SuppressMessage("StyleCop.CSharp.DocumentationRules", "SA1650:ElementDocumentationMustBeSpelledCorrectly", Justification = "Reviewed. Suppression is OK here.")]
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private string GetCachePath()
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{
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string cachedPath = string.Empty;
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if (AbsoluteCachePath != null)
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{
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// Use an sha1 hash of the full path including the querystring to create the image name.
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// That name can also be used as a key for the cached image and we should be able to use
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// The characters of that hash as subfolders.
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string parsedExtension = ImageHelpers.GetExtension(this.fullPath);
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string fallbackExtension = this.imageName.Substring(this.imageName.LastIndexOf(".", StringComparison.Ordinal) + 1);
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string encryptedName = this.fullPath.ToSHA1Fingerprint();
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// Collision rate of about 1 in 10000 for the folder structure.
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string pathFromKey = string.Join("\\", encryptedName.ToCharArray().Take(6));
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string cachedFileName = string.Format(
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"{0}.{1}",
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encryptedName,
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!string.IsNullOrWhiteSpace(parsedExtension) ? parsedExtension.Replace(".", string.Empty) : fallbackExtension);
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cachedPath = Path.Combine(AbsoluteCachePath, pathFromKey, cachedFileName);
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}
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return cachedPath;
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}
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/// <summary>
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/// The rough date time compare.
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/// </summary>
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/// <param name="first">
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/// The first.
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/// </param>
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/// <param name="second">
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/// The second.
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/// </param>
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/// <returns>
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/// The <see cref="bool"/> true if the DateTimes roughly compare; otherwise, false.
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/// </returns>
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private bool RoughDateTimeCompare(DateTime first, DateTime second)
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{
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if (first.ToString(CultureInfo.InvariantCulture) == second.ToString(CultureInfo.InvariantCulture))
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{
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return true;
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}
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return false;
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}
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/// <summary>
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/// Gets a value indicating whether the given images creation date is out with
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/// the prescribed limit.
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/// </summary>
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/// <param name="creationDate">
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/// The creation date.
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/// </param>
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/// <returns>
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/// The true if the date is out with the limit, otherwise; false.
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/// </returns>
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private bool IsExpired(DateTime creationDate)
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{
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return creationDate.AddDays(MaxFileCachedDuration) < DateTime.UtcNow.AddDays(-MaxFileCachedDuration);
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}
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#endregion
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#endregion
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}
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}
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