| | | 1 | | using System; |
| | | 2 | | using System.Threading; |
| | | 3 | | |
| | | 4 | | namespace AmbientServices; |
| | | 5 | | |
| | | 6 | | /// <summary> |
| | | 7 | | /// A static class that holds a property used to more conveniently access the ambient <see cref="IAmbientProgress"/>. |
| | | 8 | | /// </summary> |
| | | 9 | | /// <remarks> |
| | | 10 | | /// <pitch>The one-liner way to get the current operation's progress tracker without holding a service reference.</pitch |
| | | 11 | | /// <pledge>Returns the calling execution context's progress from the local (or, for <see cref="GlobalProgress"/>, the g |
| | | 12 | | /// <plan>A static facade over <c>Ambient.GetService<IAmbientProgressService>()</c> delegating to <see cref="IAmbi |
| | | 13 | | /// </remarks> |
| | | 14 | | public static class AmbientProgressService |
| | | 15 | | { |
| | | 16 | | private static readonly AmbientService<IAmbientProgressService> _Progress = Ambient.GetService<IAmbientProgressServi |
| | | 17 | | /// <summary> |
| | | 18 | | /// Gets the <see cref="IAmbientProgress"/> from the current local (or global) ambient progress service. |
| | | 19 | | /// </summary> |
| | | 20 | | public static IAmbientProgress? Progress => _Progress.Local?.Progress; |
| | | 21 | | /// <summary> |
| | | 22 | | /// Gets the <see cref="IAmbientProgress"/> from the global ambient progress service. |
| | | 23 | | /// </summary> |
| | | 24 | | [ExcludeFromCoverage] // this can't be fully tested without possibly affecting other tests and their coverage beca |
| | | 25 | | public static IAmbientProgress? GlobalProgress => _Progress.Global?.Progress; |
| | | 26 | | } |
| | | 27 | | |
| | | 28 | | |
| | | 29 | | /// <summary> |
| | | 30 | | /// A cancellation token source that works with ambient timers in addition to system timers. |
| | | 31 | | /// </summary> |
| | | 32 | | /// <remarks> |
| | | 33 | | /// <pitch>A <see cref="CancellationTokenSource"/> stand-in whose scheduled cancellations follow the ambient clock, so t |
| | | 34 | | /// <pledge> |
| | | 35 | | /// Which clock schedules timed cancellations is fixed at construction; under a paused clock, a scheduled cancellation f |
| | | 36 | | /// </pledge> |
| | | 37 | | /// <plan>Wraps a system <see cref="CancellationTokenSource"/> and schedules timed cancellation with a one-shot <see cre |
| | | 38 | | /// </remarks> |
| | | 39 | | public class AmbientCancellationTokenSource : IDisposable |
| | | 40 | | { |
| | 3 | 41 | | private static readonly AmbientService<IAmbientClock> _AmbientClock = Ambient.GetService<IAmbientClock>(); |
| | 3 | 42 | | private static readonly CancellationToken _AlreadyCancelled = AlreadyCancelledToken(); |
| | | 43 | | private static CancellationToken AlreadyCancelledToken() |
| | | 44 | | { |
| | 3 | 45 | | CancellationTokenSource source = new(); source.Cancel(); return source.Token; |
| | | 46 | | } |
| | | 47 | | |
| | | 48 | | #pragma warning disable IDE0052 // Remove unread private members I'd like to keep this around for debugging and just |
| | | 49 | | private readonly IAmbientClock? _clock; |
| | | 50 | | #pragma warning restore IDE0052 // Remove unread private members |
| | | 51 | | private CancellationTokenSource? _tokenSource; // note that if this is not nullable, you can't tell if the toke |
| | | 52 | | private AmbientEventTimer? _ambientTimer; |
| | | 53 | | private int _cancelAfterChecks; |
| | | 54 | | private int _checks; |
| | | 55 | | |
| | | 56 | | /// <summary> |
| | | 57 | | /// Constructs an ambient cancellation token source using a system <see cref="CancellationTokenSource"/>. |
| | | 58 | | /// </summary> |
| | | 59 | | /// <param name="tokenSource">A <see cref="CancellationTokenSource"/> from the system. If null, makes a cancellatio |
| | 2 | 60 | | public AmbientCancellationTokenSource(CancellationTokenSource? tokenSource = null) |
| | | 61 | | { |
| | 2 | 62 | | _tokenSource = tokenSource ?? new CancellationTokenSource(); |
| | 2 | 63 | | } |
| | | 64 | | /// <summary> |
| | | 65 | | /// Constructs an ambient cancellation token source using the ambient clock. |
| | | 66 | | /// </summary> |
| | | 67 | | /// <param name="timeout">A <see cref="TimeSpan"/> indicating how long to wait before timing out.</param> |
| | | 68 | | public AmbientCancellationTokenSource(TimeSpan timeout) |
| | 3 | 69 | | : this(_AmbientClock.Override ?? _AmbientClock.Local, ValidatedDelay(timeout, nameof(timeout))) |
| | | 70 | | { |
| | 3 | 71 | | } |
| | | 72 | | /// <summary> |
| | | 73 | | /// Constructs an ambient cancellation token source using the ambient clock. |
| | | 74 | | /// </summary> |
| | | 75 | | /// <param name="timeoutMilliseconds">The number of milliseconds to wait before timing out.</param> |
| | | 76 | | public AmbientCancellationTokenSource(int timeoutMilliseconds) |
| | 2 | 77 | | : this(_AmbientClock.Override ?? _AmbientClock.Local, ValidatedDelay(timeoutMilliseconds, nameof(timeoutMillisec |
| | | 78 | | { |
| | 2 | 79 | | } |
| | | 80 | | /// <summary> |
| | | 81 | | /// Constructs an ambient cancellation token source using the specified clock. |
| | | 82 | | /// </summary> |
| | | 83 | | /// <param name="clock">The <see cref="IAmbientClock"/> to use for the token source.</param> |
| | | 84 | | /// <param name="timeout">An optional timeout indicating how long before the associated cancellation token should be |
| | 3 | 85 | | public AmbientCancellationTokenSource(IAmbientClock? clock, TimeSpan? timeout = null) |
| | | 86 | | { |
| | 3 | 87 | | if (timeout != null) ValidatedDelay(timeout.Value, nameof(timeout)); |
| | 3 | 88 | | _clock = clock; |
| | 3 | 89 | | _tokenSource = new CancellationTokenSource(); |
| | 3 | 90 | | if (timeout != null) |
| | | 91 | | { |
| | 3 | 92 | | ScheduleCancellation(timeout.Value); |
| | | 93 | | } |
| | 3 | 94 | | } |
| | | 95 | | |
| | | 96 | | /// <summary> |
| | | 97 | | /// Validates a cancellation delay the way <see cref="CancellationTokenSource"/> does and returns it as a <see cref= |
| | | 98 | | /// </summary> |
| | | 99 | | /// <remarks> |
| | | 100 | | /// Note that this deliberately does not defer to the scheduling timer's validation: <see cref="CancellationTokenSou |
| | | 101 | | /// </remarks> |
| | | 102 | | /// <param name="milliseconds">The number of milliseconds to delay, with -1 meaning never.</param> |
| | | 103 | | /// <param name="parameterName">The name of the parameter being validated, for the exception.</param> |
| | | 104 | | private static TimeSpan ValidatedDelay(double milliseconds, string parameterName) |
| | | 105 | | { |
| | 3 | 106 | | if (milliseconds < -1 || milliseconds > int.MaxValue) throw new ArgumentOutOfRangeException(parameterName); |
| | 3 | 107 | | return TimeSpan.FromMilliseconds(milliseconds); |
| | | 108 | | } |
| | | 109 | | /// <summary> |
| | | 110 | | /// Validates a cancellation delay the way <see cref="CancellationTokenSource"/> does and returns it unchanged. |
| | | 111 | | /// </summary> |
| | | 112 | | /// <param name="delay">A <see cref="TimeSpan"/> indicating how long to delay, with -1 milliseconds meaning never.</ |
| | | 113 | | /// <param name="parameterName">The name of the parameter being validated, for the exception.</param> |
| | | 114 | | private static TimeSpan ValidatedDelay(TimeSpan delay, string parameterName) |
| | | 115 | | { |
| | 3 | 116 | | return ValidatedDelay(delay.TotalMilliseconds, parameterName); |
| | | 117 | | } |
| | | 118 | | |
| | | 119 | | private void ScheduleCancellation(TimeSpan delay) |
| | | 120 | | { |
| | 3 | 121 | | double milliseconds = delay.TotalMilliseconds; |
| | | 122 | | // never? then there is nothing to schedule |
| | 3 | 123 | | if (milliseconds < 0) return; |
| | | 124 | | // already due? then cancel right now, because a timer cannot be given a zero interval |
| | 3 | 125 | | if (milliseconds == 0) |
| | | 126 | | { |
| | 2 | 127 | | _tokenSource?.Cancel(); |
| | 2 | 128 | | return; |
| | | 129 | | } |
| | 3 | 130 | | AmbientEventTimer timer = new AmbientEventTimer(delay); |
| | 3 | 131 | | _ambientTimer = timer; |
| | | 132 | | void handler(object? source, System.Timers.ElapsedEventArgs e) |
| | | 133 | | { |
| | | 134 | | // Use the captured timer: Dispose() may null _ambientTimer concurrently while SkipAhead raises Elapsed. |
| | 3 | 135 | | timer.Elapsed -= handler; |
| | 3 | 136 | | _tokenSource?.Cancel(); |
| | 3 | 137 | | timer.Dispose(); |
| | 3 | 138 | | if (ReferenceEquals(_ambientTimer, timer)) |
| | 3 | 139 | | _ambientTimer = null; |
| | 3 | 140 | | } |
| | | 141 | | |
| | 3 | 142 | | timer.Elapsed += handler; // note that the handler will keep the timer and the token source alive until the ev |
| | 3 | 143 | | timer.Enabled = true; |
| | 3 | 144 | | } |
| | | 145 | | |
| | | 146 | | /// <summary> |
| | | 147 | | /// Gets the <see cref="CancellationToken"/> associated with the source. |
| | | 148 | | /// </summary> |
| | 3 | 149 | | public CancellationToken Token => _tokenSource?.Token ?? _AlreadyCancelled; |
| | | 150 | | /// <summary> |
| | | 151 | | /// Gets whether or not a cancellation has been requested. |
| | | 152 | | /// </summary> |
| | | 153 | | public bool IsCancellationRequested |
| | | 154 | | { |
| | | 155 | | get |
| | | 156 | | { |
| | 2 | 157 | | if (_cancelAfterChecks != 0 && Interlocked.Increment(ref _checks) > _cancelAfterChecks) _tokenSource?.Cancel |
| | 2 | 158 | | return _tokenSource?.IsCancellationRequested ?? true; |
| | | 159 | | } |
| | | 160 | | } |
| | | 161 | | /// <summary> |
| | | 162 | | /// Gets the number of checks that have been made towards cancellation (see <see cref="CancelAfterChecks(int)"/>. |
| | | 163 | | /// </summary> |
| | 2 | 164 | | public int Checks => _checks; |
| | | 165 | | /// <summary> |
| | | 166 | | /// Marks the associated token as canceled. |
| | | 167 | | /// </summary> |
| | 2 | 168 | | public void Cancel() { Cancel(false); } |
| | | 169 | | /// <summary> |
| | | 170 | | /// Marks the associated token as canceled. |
| | | 171 | | /// </summary> |
| | | 172 | | /// <param name="throwOnFirstException">true if exceptions should immediately propagate, otherwise false.</param> |
| | 2 | 173 | | public void Cancel(bool throwOnFirstException) { _tokenSource?.Cancel(throwOnFirstException); } |
| | | 174 | | /// <summary> |
| | | 175 | | /// Schedules a cancellation after the specified time. |
| | | 176 | | /// </summary> |
| | | 177 | | /// <param name="millisecondsDelay">The number of milliseconds to delay before cancelling.</param> |
| | | 178 | | public void CancelAfter(int millisecondsDelay) |
| | | 179 | | { |
| | 2 | 180 | | TimeSpan delay = ValidatedDelay(millisecondsDelay, nameof(millisecondsDelay)); |
| | 2 | 181 | | if (_ambientTimer != null) _ambientTimer.Dispose(); |
| | 2 | 182 | | ScheduleCancellation(delay); |
| | 2 | 183 | | } |
| | | 184 | | /// <summary> |
| | | 185 | | /// Schedules a cancellation after the specified time. |
| | | 186 | | /// </summary> |
| | | 187 | | /// <param name="delay">A <see cref="TimeSpan"/> indicating how long to delay before cancelling.</param> |
| | | 188 | | public void CancelAfter(TimeSpan delay) |
| | | 189 | | { |
| | 2 | 190 | | TimeSpan validatedDelay = ValidatedDelay(delay, nameof(delay)); |
| | 2 | 191 | | if (_ambientTimer != null) _ambientTimer.Dispose(); |
| | 2 | 192 | | ScheduleCancellation(validatedDelay); |
| | 2 | 193 | | } |
| | | 194 | | /// <summary> |
| | | 195 | | /// Schedules a cancellation after a certain number of checks to see if the token was canceled. |
| | | 196 | | /// This is useful mainly for aborting processes part way through in order to test error handling and recovery. |
| | | 197 | | /// Leaves any time-delayed cancellation in place. If the underlying token source has been canceled, a new not-yet- |
| | | 198 | | /// </summary> |
| | | 199 | | /// <param name="numberOfChecks">The number of checks to cancel after.</param> |
| | | 200 | | public void CancelAfterChecks(int numberOfChecks) |
| | | 201 | | { |
| | | 202 | | // already canceled? create a new underlying cancellation source |
| | 2 | 203 | | if (_tokenSource?.IsCancellationRequested == true) _tokenSource = new(); |
| | 2 | 204 | | Interlocked.Exchange(ref _checks, 0); |
| | 2 | 205 | | Interlocked.Exchange(ref _cancelAfterChecks, numberOfChecks); |
| | 2 | 206 | | } |
| | | 207 | | |
| | | 208 | | #region IDisposable Support |
| | | 209 | | /// <summary> |
| | | 210 | | /// Implementation of the standard dispose pattern. |
| | | 211 | | /// </summary> |
| | | 212 | | /// <param name="disposing">Whether or not this instance is being disposed, as opposed to finalized.</param> |
| | | 213 | | protected virtual void Dispose(bool disposing) |
| | | 214 | | { |
| | 3 | 215 | | if (disposing) |
| | | 216 | | { |
| | 3 | 217 | | _tokenSource?.Dispose(); |
| | 3 | 218 | | _tokenSource = null; |
| | 3 | 219 | | _ambientTimer?.Dispose(); |
| | 3 | 220 | | _ambientTimer = null; |
| | | 221 | | } |
| | 3 | 222 | | } |
| | | 223 | | /// <summary> |
| | | 224 | | /// Disposes of this instance. |
| | | 225 | | /// </summary> |
| | | 226 | | public void Dispose() |
| | | 227 | | { |
| | 3 | 228 | | Dispose(true); |
| | 3 | 229 | | GC.SuppressFinalize(this); |
| | 3 | 230 | | } |
| | | 231 | | #endregion |
| | | 232 | | } |
| | | 233 | | [AttributeUsage(AttributeTargets.All)] |
| | | 234 | | internal sealed class ExcludeFromCoverageAttribute : Attribute |
| | | 235 | | { |
| | | 236 | | } |