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.Drawing;
  27 using System.Linq;
  28 using System.Net;
  29 using System.Net.Http;
  30 using System.Text;
  31 using System.Threading;
  32 using System.Threading.Tasks;
  33 using System.Xml.Serialization;
  34 using OpenTween.Connection;
  35
  36 namespace OpenTween
  37 {
  38     public class ImageCache : IDisposable
  39     {
  40         /// <summary>
  41         /// 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
  42         /// </summary>
  43         internal LRUCacheDictionary<string, Task<MemoryImage>> InnerDictionary;
  44
  45         /// <summary>
  46         /// 非同期タスクをキャンセルするためのトークンのもと
  47         /// </summary>
  48         private CancellationTokenSource cancelTokenSource;
  49
  50         /// <summary>
  51         /// オブジェクトが破棄された否か
  52         /// </summary>
  53         private bool disposed = false;
  54
  55         public ImageCache()
  56         {
  57             this.InnerDictionary = new LRUCacheDictionary<string, Task<MemoryImage>>(trimLimit: 300, autoTrimCount: 100);
  58             this.InnerDictionary.CacheRemoved += (s, e) =>
  59             {
  60                 this.CacheRemoveCount++;
  61
  62                 // 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
  63                 var task = e.Item.Value;
  64                 _ = AsyncExceptionBoundary.IgnoreException(task);
  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             this.InnerDictionary.TryGetValue(address, out var cachedImageTask);
  92
  93             if (cachedImageTask != null && !force)
  94                 return cachedImageTask;
  95
  96             cancelToken.ThrowIfCancellationRequested();
  97
  98             var imageTask = Task.Run(() => this.FetchImageAsync(address, cancelToken));
  99             this.InnerDictionary[address] = imageTask;
 100
 101             return imageTask;
 102         }
 103
 104         private async Task<MemoryImage> FetchImageAsync(string uri, CancellationToken cancelToken)
 105         {
 106             try
 107             {
 108                 using var response = await Networking.Http.GetAsync(uri, cancelToken)
 109                     .ConfigureAwait(false);
 110
 111                 response.EnsureSuccessStatusCode();
 112
 113                 using var imageStream = await response.Content.ReadAsStreamAsync()
 114                     .ConfigureAwait(false);
 115
 116                 return await MemoryImage.CopyFromStreamAsync(imageStream)
 117                     .ConfigureAwait(false);
 118             }
 119             catch (Exception ex)
 120                 when (ex is HttpRequestException or OperationCanceledException or InvalidImageException)
 121             {
 122                 return this.CreateBlankImage();
 123             }
 124         }
 125
 126         private MemoryImage CreateBlankImage()
 127         {
 128             using var bitmap = new Bitmap(1, 1);
 129             return MemoryImage.CopyFromImage(bitmap);
 130         }
 131
 132         public MemoryImage? TryGetFromCache(string address)
 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         public MemoryImage? TryGetLargerOrSameSizeFromCache(string normalUrl, string size)
 142         {
 143             var sizes = new[] { "mini", "normal", "bigger", "original" };
 144             var minimumIndex = sizes.FindIndex(x => x == size);
 145
 146             foreach (var candidateSize in sizes.Skip(minimumIndex))
 147             {
 148                 var imageUrl = Twitter.CreateProfileImageUrl(normalUrl, candidateSize);
 149                 var image = this.TryGetFromCache(imageUrl);
 150                 if (image != null)
 151                     return image;
 152             }
 153
 154             return null;
 155         }
 156
 157         public void CancelAsync()
 158         {
 159             var oldTokenSource = this.cancelTokenSource;
 160             this.cancelTokenSource = new CancellationTokenSource();
 161
 162             oldTokenSource.Cancel();
 163             oldTokenSource.Dispose();
 164         }
 165
 166         protected virtual void Dispose(bool disposing)
 167         {
 168             if (this.disposed) return;
 169
 170             if (disposing)
 171             {
 172                 this.CancelAsync();
 173
 174                 foreach (var (_, task) in this.InnerDictionary)
 175                 {
 176                     if (task.Status == TaskStatus.RanToCompletion)
 177                         task.Result?.Dispose();
 178                 }
 179
 180                 this.InnerDictionary.Clear();
 181                 this.cancelTokenSource.Dispose();
 182             }
 183
 184             this.disposed = true;
 185         }
 186
 187         public void Dispose()
 188         {
 189             this.Dispose(true);
 190             GC.SuppressFinalize(this);
 191         }
 192
 193         ~ImageCache()
 194             => this.Dispose(false);
 195     }
 196 }