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         /// innerDictionary の排他制御のためのロックオブジェクト
  51         /// </summary>
  52         private readonly object lockObject = new object();
  53
  54         /// <summary>
  55         /// オブジェクトが破棄された否か
  56         /// </summary>
  57         private bool disposed = false;
  58
  59         public ImageCache()
  60         {
  61             this.InnerDictionary = new LRUCacheDictionary<string, Task<MemoryImage>>(trimLimit: 300, autoTrimCount: 100);
  62             this.InnerDictionary.CacheRemoved += (s, e) => {
  63                 // 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
  64                 this.CacheRemoveCount++;
  65             };
  66
  67             this.cancelTokenSource = new CancellationTokenSource();
  68         }
  69
  70         /// <summary>
  71         /// 保持しているキャッシュの件数
  72         /// </summary>
  73         public long CacheCount
  74             => this.InnerDictionary.Count;
  75
  76         /// <summary>
  77         /// 破棄されたキャッシュの件数
  78         /// </summary>
  79         public int CacheRemoveCount { get; private set; }
  80
  81         /// <summary>
  82         /// 指定された URL にある画像を非同期に取得するメソッド
  83         /// </summary>
  84         /// <param name="address">取得先の URL</param>
  85         /// <param name="force">キャッシュを使用せずに取得する場合は true</param>
  86         /// <returns>非同期に画像を取得するタスク</returns>
  87         public Task<MemoryImage> DownloadImageAsync(string address, bool force = false)
  88         {
  89             var cancelToken = this.cancelTokenSource.Token;
  90
  91             return Task.Run(() =>
  92             {
  93                 lock (this.lockObject)
  94                 {
  95                     this.InnerDictionary.TryGetValue(address, out var cachedImageTask);
  96
  97                     if (cachedImageTask != null)
  98                     {
  99                         if (force)
 100                             this.InnerDictionary.Remove(address);
 101                         else
 102                             return cachedImageTask;
 103                     }
 104
 105                     cancelToken.ThrowIfCancellationRequested();
 106
 107                     var imageTask = this.FetchImageAsync(address, cancelToken);
 108                     this.InnerDictionary[address] = imageTask;
 109
 110                     return imageTask;
 111                 }
 112             },
 113             cancelToken);
 114         }
 115
 116         private async Task<MemoryImage> FetchImageAsync(string uri, CancellationToken cancelToken)
 117         {
 118             using var response = await Networking.Http.GetAsync(uri, cancelToken)
 119                 .ConfigureAwait(false);
 120
 121             response.EnsureSuccessStatusCode();
 122
 123             using var imageStream = await response.Content.ReadAsStreamAsync()
 124                 .ConfigureAwait(false);
 125
 126             return await MemoryImage.CopyFromStreamAsync(imageStream)
 127                 .ConfigureAwait(false);
 128         }
 129
 130         public MemoryImage? TryGetFromCache(string address)
 131         {
 132             lock (this.lockObject)
 133             {
 134                 if (!this.InnerDictionary.TryGetValue(address, out var imageTask) ||
 135                     imageTask.Status != TaskStatus.RanToCompletion)
 136                     return null;
 137
 138                 return imageTask.Result;
 139             }
 140         }
 141
 142         public void CancelAsync()
 143         {
 144             lock (this.lockObject)
 145             {
 146                 var oldTokenSource = this.cancelTokenSource;
 147                 this.cancelTokenSource = new CancellationTokenSource();
 148
 149                 oldTokenSource.Cancel();
 150                 oldTokenSource.Dispose();
 151             }
 152         }
 153
 154         protected virtual void Dispose(bool disposing)
 155         {
 156             if (this.disposed) return;
 157
 158             if (disposing)
 159             {
 160                 this.CancelAsync();
 161
 162                 lock (this.lockObject)
 163                 {
 164                     foreach (var (_, task) in this.InnerDictionary)
 165                     {
 166                         if (task.Status == TaskStatus.RanToCompletion)
 167                             task.Result?.Dispose();
 168                     }
 169
 170                     this.InnerDictionary.Clear();
 171                     this.cancelTokenSource.Dispose();
 172                 }
 173             }
 174
 175             this.disposed = true;
 176         }
 177
 178         public void Dispose()
 179         {
 180             this.Dispose(true);
 181             GC.SuppressFinalize(this);
 182         }
 183
 184         ~ImageCache()
 185             => this.Dispose(false);
 186     }
 187 }