OpenTween/ImageCache.cs

   1 // OpenTween - Client of Twitter
   2 // Copyright (c) 2013 kim_upsilon (@kim_upsilon) <https://upsilo.net/~upsilon/>
   3 // All rights reserved.
   4 //
   5 // This file is part of OpenTween.
   6 //
   7 // This program is free software; you can redistribute it and/or modify it
   8 // under the terms of the GNU General Public License as published by the Free
   9 // Software Foundation; either version 3 of the License, or (at your option)
  10 // any later version.
  11 //
  12 // This program is distributed in the hope that it will be useful, but
  13 // WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  14 // or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
  15 // for more details.
  16 //
  17 // You should have received a copy of the GNU General Public License along
  18 // with this program. If not, see <http://www.gnu.org/licenses/>, or write to
  19 // the Free Software Foundation, Inc., 51 Franklin Street - Fifth Floor,
  20 // Boston, MA 02110-1301, USA.
  21
  22 #nullable enable
  23
  24 using System;
  25 using System.Collections.Generic;
  26 using System.Linq;
  27 using System.Net;
  28 using System.Net.Http;
  29 using System.Text;
  30 using System.Threading;
  31 using System.Threading.Tasks;
  32 using System.Xml.Serialization;
  33 using OpenTween.Connection;
  34
  35 namespace OpenTween
  36 {
  37     public class ImageCache : IDisposable
  38     {
  39         /// <summary>
  40         /// キャッシュとして URL と取得した画像を対に保持する辞書
  41         /// </summary>
  42         internal LRUCacheDictionary<string, Task<MemoryImage>> InnerDictionary;
  43
  44         /// <summary>
  45         /// 非同期タスクをキャンセルするためのトークンのもと
  46         /// </summary>
  47         private CancellationTokenSource cancelTokenSource;
  48
  49         /// <summary>
  50         /// オブジェクトが破棄された否か
  51         /// </summary>
  52         private bool disposed = false;
  53
  54         public ImageCache()
  55         {
  56             this.InnerDictionary = new LRUCacheDictionary<string, Task<MemoryImage>>(trimLimit: 300, autoTrimCount: 100);
  57             this.InnerDictionary.CacheRemoved += (s, e) =>
  58             {
  59                 // まだ参照されている場合もあるのでDisposeはファイナライザ任せ
  60                 this.CacheRemoveCount++;
  61
  62                 var task = e.Item.Value;
  63                 if (task.Status != TaskStatus.RanToCompletion || task.IsFaulted)
  64                 {
  65                     // Task の例外がハンドルされないまま破棄されると AggregateException が発生するため try-catch で処理する Task を挟む
  66                     static async Task HandleException<T>(Task<T> t)
  67                     {
  68                         try
  69                         {
  70                             _ = await t.ConfigureAwait(false);
  71                         }
  72                         catch
  73                         {
  74                         }
  75                     }
  76                     _ = HandleException(task);
  77                 }
  78             };
  79
  80             this.cancelTokenSource = new CancellationTokenSource();
  81         }
  82
  83         /// <summary>
  84         /// 保持しているキャッシュの件数
  85         /// </summary>
  86         public long CacheCount
  87             => this.InnerDictionary.Count;
  88
  89         /// <summary>
  90         /// 破棄されたキャッシュの件数
  91         /// </summary>
  92         public int CacheRemoveCount { get; private set; }
  93
  94         /// <summary>
  95         /// 指定された URL にある画像を非同期に取得するメソッド
  96         /// </summary>
  97         /// <param name="address">取得先の URL</param>
  98         /// <param name="force">キャッシュを使用せずに取得する場合は true</param>
  99         /// <returns>非同期に画像を取得するタスク</returns>
 100         public Task<MemoryImage> DownloadImageAsync(string address, bool force = false)
 101         {
 102             var cancelToken = this.cancelTokenSource.Token;
 103
 104             this.InnerDictionary.TryGetValue(address, out var cachedImageTask);
 105
 106             if (cachedImageTask != null && !force)
 107                 return cachedImageTask;
 108
 109             cancelToken.ThrowIfCancellationRequested();
 110
 111             var imageTask = Task.Run(() => this.FetchImageAsync(address, cancelToken));
 112             this.InnerDictionary[address] = imageTask;
 113
 114             return imageTask;
 115         }
 116
 117         private async Task<MemoryImage> FetchImageAsync(string uri, CancellationToken cancelToken)
 118         {
 119             using var response = await Networking.Http.GetAsync(uri, cancelToken)
 120                 .ConfigureAwait(false);
 121
 122             response.EnsureSuccessStatusCode();
 123
 124             using var imageStream = await response.Content.ReadAsStreamAsync()
 125                 .ConfigureAwait(false);
 126
 127             return await MemoryImage.CopyFromStreamAsync(imageStream)
 128                 .ConfigureAwait(false);
 129         }
 130
 131         public MemoryImage? TryGetFromCache(string address)
 132         {
 133             if (!this.InnerDictionary.TryGetValue(address, out var imageTask) ||
 134                 imageTask.Status != TaskStatus.RanToCompletion)
 135                 return null;
 136
 137             return imageTask.Result;
 138         }
 139
 140         public MemoryImage? TryGetLargerOrSameSizeFromCache(string normalUrl, string size)
 141         {
 142             var sizes = new[] { "mini", "normal", "bigger", "original" };
 143             var minimumIndex = sizes.FindIndex(x => x == size);
 144
 145             foreach (var candidateSize in sizes.Skip(minimumIndex))
 146             {
 147                 var imageUrl = Twitter.CreateProfileImageUrl(normalUrl, candidateSize);
 148                 var image = this.TryGetFromCache(imageUrl);
 149                 if (image != null)
 150                     return image;
 151             }
 152
 153             return null;
 154         }
 155
 156         public void CancelAsync()
 157         {
 158             var oldTokenSource = this.cancelTokenSource;
 159             this.cancelTokenSource = new CancellationTokenSource();
 160
 161             oldTokenSource.Cancel();
 162             oldTokenSource.Dispose();
 163         }
 164
 165         protected virtual void Dispose(bool disposing)
 166         {
 167             if (this.disposed) return;
 168
 169             if (disposing)
 170             {
 171                 this.CancelAsync();
 172
 173                 foreach (var (_, task) in this.InnerDictionary)
 174                 {
 175                     if (task.Status == TaskStatus.RanToCompletion)
 176                         task.Result?.Dispose();
 177                 }
 178
 179                 this.InnerDictionary.Clear();
 180                 this.cancelTokenSource.Dispose();
 181             }
 182
 183             this.disposed = true;
 184         }
 185
 186         public void Dispose()
 187         {
 188             this.Dispose(true);
 189             GC.SuppressFinalize(this);
 190         }
 191
 192         ~ImageCache()
 193             => this.Dispose(false);
 194     }
 195 }