OpenTween/ThrottlingTimer.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     public class ThrottlingTimer : IDisposable
  34     {
  35         private const int TIMER_DISABLED = 0;
  36         private const int TIMER_ENABLED = 1;
  37
  38         private readonly Timer throttlingTimer;
  39         private readonly Func<Task> timerCallback;
  40
  41         private long lastCalledTick;
  42         private long lastInvokedTick;
  43         private int refreshTimerEnabled = TIMER_DISABLED;
  44
  45         public TimeSpan Interval { get; }
  46         public TimeSpan MaxWait { get; }
  47         public bool InvokeLeading { get; }
  48         public bool InvokeTrailing { get; }
  49
  50         private DateTimeUtc LastCalled
  51         {
  52             get => new DateTimeUtc(Interlocked.Read(ref this.lastCalledTick));
  53             set => Interlocked.Exchange(ref this.lastCalledTick, value.UtcTicks);
  54         }
  55
  56         private DateTimeUtc LastInvoked
  57         {
  58             get => new DateTimeUtc(Interlocked.Read(ref this.lastInvokedTick));
  59             set => Interlocked.Exchange(ref this.lastInvokedTick, value.UtcTicks);
  60         }
  61
  62         public ThrottlingTimer(Func<Task> timerCallback, TimeSpan interval, TimeSpan maxWait, bool leading, bool trailing)
  63         {
  64             this.timerCallback = timerCallback;
  65             this.Interval = interval;
  66             this.MaxWait = maxWait;
  67             this.LastCalled = DateTimeUtc.MinValue;
  68             this.LastInvoked = DateTimeUtc.MinValue;
  69             this.InvokeLeading = leading;
  70             this.InvokeTrailing = trailing;
  71             this.throttlingTimer = new Timer(this.Execute);
  72         }
  73
  74         public void Call()
  75         {
  76             this.LastCalled = DateTimeUtc.Now;
  77
  78             if (this.refreshTimerEnabled == TIMER_DISABLED)
  79             {
  80                 this.refreshTimerEnabled = TIMER_ENABLED;
  81                 this.LastInvoked = DateTimeUtc.MinValue;
  82                 _ = Task.Run(async () =>
  83                 {
  84                     if (this.InvokeLeading)
  85                         await this.timerCallback().ConfigureAwait(false);
  86
  87                     this.throttlingTimer.Change(dueTime: this.Interval, period: Timeout.InfiniteTimeSpan);
  88                 });
  89             }
  90         }
  91
  92         private async void Execute(object _)
  93         {
  94             var lastCalled = this.LastCalled;
  95             var lastInvoked = this.LastInvoked;
  96
  97             var timerExpired = lastCalled < lastInvoked;
  98             if (timerExpired)
  99             {
 100                 // 前回実行時より後に lastInvoked が更新されていなければタイマーを止める
 101                 this.refreshTimerEnabled = TIMER_DISABLED;
 102
 103                 if (this.InvokeTrailing)
 104                     await this.timerCallback().ConfigureAwait(false);
 105             }
 106             else
 107             {
 108                 var now = DateTimeUtc.Now;
 109
 110                 if ((now - lastInvoked) >= this.MaxWait)
 111                     await this.timerCallback().ConfigureAwait(false);
 112
 113                 this.LastInvoked = now;
 114
 115                 // dueTime は Execute が呼ばれる度に再設定する (period は使用しない)
 116                 // これにより timerCallback の実行に Interval 以上の時間が掛かっても重複して実行されることはなくなる
 117                 lock (this.throttlingTimer)
 118                     this.throttlingTimer.Change(dueTime: this.Interval, period: Timeout.InfiniteTimeSpan);
 119             }
 120         }
 121
 122         public void Dispose()
 123             => this.throttlingTimer.Dispose();
 124
 125         // lodash.js の _.throttle, _.debounce 的な処理をしたかったメソッド群
 126         public static ThrottlingTimer Throttle(Func<Task> callback, TimeSpan wait, bool leading = true, bool trailing = true)
 127             => new ThrottlingTimer(callback, wait, maxWait: wait, leading, trailing);
 128
 129         public static ThrottlingTimer Debounce(Func<Task> callback, TimeSpan wait, bool leading = false, bool trailing = true)
 130             => new ThrottlingTimer(callback, wait, maxWait: TimeSpan.MaxValue, leading, trailing);
 131     }
 132 }