OpenTween/ThrottleTimer.cs

   1 // OpenTween - Client of Twitter
   2 // Copyright (c) 2018 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.Threading;
  26 using System.Threading.Tasks;
  27
  28 namespace OpenTween
  29 {
  30     /// <summary>
  31     /// コールバック先の関数を <see cref="Interval"/> 未満の頻度で呼ばないよう制御するタイマー
  32     /// </summary>
  33     /// <remarks>
  34     /// lodash の <c>_.throttle()</c> に相当する機能となっている
  35     /// </remarks>
  36     public class ThrottleTimer : IDisposable
  37     {
  38         private readonly ITimer throttlingTimer;
  39         private readonly Func<Task> timerCallback;
  40         private readonly object lockObject = new();
  41
  42         private bool calledSinceLastInvoke;
  43         private bool refreshTimerEnabled;
  44
  45         public TimeSpan Interval { get; }
  46
  47         public ThrottleTimer(Func<Task> timerCallback, TimeSpan interval)
  48         {
  49             this.timerCallback = timerCallback;
  50             this.Interval = interval;
  51             this.throttlingTimer = this.CreateTimer(this.Execute);
  52             this.calledSinceLastInvoke = false;
  53             this.refreshTimerEnabled = false;
  54         }
  55
  56         protected virtual ITimer CreateTimer(Func<Task> callback)
  57             => new AsyncTimer(callback);
  58
  59         public async Task Call()
  60         {
  61             bool startTimer;
  62             lock (this.lockObject)
  63             {
  64                 this.calledSinceLastInvoke = true;
  65                 if (this.refreshTimerEnabled)
  66                 {
  67                     startTimer = false;
  68                 }
  69                 else
  70                 {
  71                     startTimer = true;
  72                     this.refreshTimerEnabled = true;
  73                 }
  74             }
  75
  76             if (startTimer)
  77             {
  78                 await this.Invoke().ConfigureAwait(false);
  79                 this.throttlingTimer.Change(dueTime: this.Interval, period: Timeout.InfiniteTimeSpan);
  80             }
  81         }
  82
  83         private async Task Execute()
  84         {
  85             bool invoke;
  86             lock (this.lockObject)
  87             {
  88                 if (this.calledSinceLastInvoke)
  89                 {
  90                     invoke = true;
  91                 }
  92                 else
  93                 {
  94                     invoke = false;
  95                     this.refreshTimerEnabled = false;
  96                 }
  97             }
  98
  99             if (invoke)
 100             {
 101                 await this.Invoke().ConfigureAwait(false);
 102                 this.throttlingTimer.Change(dueTime: this.Interval, period: Timeout.InfiniteTimeSpan);
 103             }
 104         }
 105
 106         private async Task Invoke()
 107         {
 108             await Task.Run(async () =>
 109             {
 110                 lock (this.lockObject)
 111                     this.calledSinceLastInvoke = false;
 112
 113                 await this.timerCallback().ConfigureAwait(false);
 114             });
 115         }
 116
 117         public void Dispose()
 118             => this.throttlingTimer.Dispose();
 119
 120         public static ThrottleTimer Create(Func<Task> callback, TimeSpan wait)
 121             => new(callback, wait);
 122     }
 123 }