| | | 1 | | // Copyright (c) Microsoft Corporation. All rights reserved. |
| | | 2 | | // Licensed under the MIT License. |
| | | 3 | | |
| | | 4 | | using System; |
| | | 5 | | using System.Globalization; |
| | | 6 | | using System.Net.Sockets; |
| | | 7 | | using System.Threading; |
| | | 8 | | using System.Threading.Tasks; |
| | | 9 | | using Azure.Core; |
| | | 10 | | |
| | | 11 | | namespace Azure.Messaging.EventHubs.Core |
| | | 12 | | { |
| | | 13 | | /// <summary> |
| | | 14 | | /// The default retry policy for the Event Hubs client library, respecting the |
| | | 15 | | /// configuration specified as a set of <see cref="EventHubsRetryOptions" />. |
| | | 16 | | /// </summary> |
| | | 17 | | /// |
| | | 18 | | /// <seealso cref="EventHubsRetryOptions"/> |
| | | 19 | | /// |
| | | 20 | | internal class BasicRetryPolicy : EventHubsRetryPolicy |
| | | 21 | | { |
| | | 22 | | /// <summary>The seed to use for initializing random number generated for a given thread-specific instance.</sum |
| | 0 | 23 | | private static int s_randomSeed = Environment.TickCount; |
| | | 24 | | |
| | | 25 | | /// <summary>The random number generator to use for a specific thread.</summary> |
| | 0 | 26 | | private static readonly ThreadLocal<Random> RandomNumberGenerator = new ThreadLocal<Random>(() => new Random(Int |
| | | 27 | | |
| | | 28 | | /// <summary> |
| | | 29 | | /// The set of options responsible for configuring the retry |
| | | 30 | | /// behavior. |
| | | 31 | | /// </summary> |
| | | 32 | | /// |
| | 452 | 33 | | public EventHubsRetryOptions Options { get; } |
| | | 34 | | |
| | | 35 | | /// <summary> |
| | | 36 | | /// The factor to apply to the base delay for use as a base jitter value. |
| | | 37 | | /// </summary> |
| | | 38 | | /// |
| | | 39 | | /// <value>This factor is used as the basis for random jitter to apply to the calculated retry duration.</value> |
| | | 40 | | /// |
| | 0 | 41 | | public double JitterFactor { get; } = 0.08; |
| | | 42 | | |
| | | 43 | | /// <summary> |
| | | 44 | | /// The minimum number of seconds to increase the calculated retry duration when a |
| | | 45 | | /// service signals a request to throttle. |
| | | 46 | | /// </summary> |
| | | 47 | | /// |
| | 0 | 48 | | public int MinimumThrottleSeconds { get; } = 4; |
| | | 49 | | |
| | | 50 | | /// <summary> |
| | | 51 | | /// The maximum number of seconds to increase the calculated retry duration when a |
| | | 52 | | /// service signals a request to throttle. |
| | | 53 | | /// </summary> |
| | | 54 | | /// |
| | 0 | 55 | | public int MaximumThrottleSeconds { get; } = 8; |
| | | 56 | | |
| | | 57 | | /// <summary> |
| | | 58 | | /// Initializes a new instance of the <see cref="BasicRetryPolicy"/> class. |
| | | 59 | | /// </summary> |
| | | 60 | | /// |
| | | 61 | | /// <param name="retryOptions">The options which control the retry approach.</param> |
| | | 62 | | /// |
| | 100 | 63 | | public BasicRetryPolicy(EventHubsRetryOptions retryOptions) |
| | | 64 | | { |
| | 100 | 65 | | Argument.AssertNotNull(retryOptions, nameof(retryOptions)); |
| | 100 | 66 | | Options = retryOptions; |
| | 100 | 67 | | } |
| | | 68 | | |
| | | 69 | | /// <summary> |
| | | 70 | | /// Calculates the amount of time to allow the current attempt for an operation to |
| | | 71 | | /// complete before considering it to be timed out. |
| | | 72 | | /// </summary> |
| | | 73 | | /// |
| | | 74 | | /// <param name="attemptCount">The number of total attempts that have been made, including the initial attempt b |
| | | 75 | | /// |
| | | 76 | | /// <returns>The amount of time to allow for an operation to complete.</returns> |
| | | 77 | | /// |
| | 116 | 78 | | public override TimeSpan CalculateTryTimeout(int attemptCount) => Options.TryTimeout; |
| | | 79 | | |
| | | 80 | | /// <summary> |
| | | 81 | | /// Calculates the amount of time to wait before another attempt should be made. |
| | | 82 | | /// </summary> |
| | | 83 | | /// |
| | | 84 | | /// <param name="lastException">The last exception that was observed for the operation to be retried.</param> |
| | | 85 | | /// <param name="attemptCount">The number of total attempts that have been made, including the initial attempt b |
| | | 86 | | /// |
| | | 87 | | /// <returns>The amount of time to delay before retrying the associated operation; if <c>null</c>, then the oper |
| | | 88 | | /// |
| | | 89 | | public override TimeSpan? CalculateRetryDelay(Exception lastException, |
| | | 90 | | int attemptCount) |
| | | 91 | | { |
| | 84 | 92 | | if ((Options.MaximumRetries <= 0) |
| | 84 | 93 | | || (Options.Delay == TimeSpan.Zero) |
| | 84 | 94 | | || (Options.MaximumDelay == TimeSpan.Zero) |
| | 84 | 95 | | || (attemptCount > Options.MaximumRetries) |
| | 84 | 96 | | || (!ShouldRetryException(lastException))) |
| | | 97 | | { |
| | 84 | 98 | | return null; |
| | | 99 | | } |
| | | 100 | | |
| | 0 | 101 | | var baseJitterSeconds = (Options.Delay.TotalSeconds * JitterFactor); |
| | | 102 | | |
| | 0 | 103 | | TimeSpan retryDelay = Options.Mode switch |
| | 0 | 104 | | { |
| | 0 | 105 | | EventHubsRetryMode.Fixed => CalculateFixedDelay(Options.Delay.TotalSeconds, baseJitterSeconds, RandomNum |
| | 0 | 106 | | EventHubsRetryMode.Exponential => CalculateExponentialDelay(attemptCount, Options.Delay.TotalSeconds, ba |
| | 0 | 107 | | _ => throw new NotSupportedException(string.Format(CultureInfo.CurrentCulture, Resources.UnknownRetryMod |
| | 0 | 108 | | }; |
| | | 109 | | |
| | | 110 | | // If the exception indicates a service throttle, adjust the delay for an |
| | | 111 | | // additional throttle factor. |
| | | 112 | | |
| | 0 | 113 | | if (IsThrottleException(lastException)) |
| | | 114 | | { |
| | 0 | 115 | | retryDelay = retryDelay.Add(TimeSpan.FromSeconds(RandomNumberGenerator.Value.Next(MinimumThrottleSeconds |
| | | 116 | | } |
| | | 117 | | |
| | | 118 | | // Adjust the delay, if needed, to keep within the maximum |
| | | 119 | | // duration. |
| | | 120 | | |
| | 0 | 121 | | if (Options.MaximumDelay < retryDelay) |
| | | 122 | | { |
| | 0 | 123 | | return Options.MaximumDelay; |
| | | 124 | | } |
| | | 125 | | |
| | 0 | 126 | | return retryDelay; |
| | | 127 | | } |
| | | 128 | | |
| | | 129 | | /// <summary> |
| | | 130 | | /// Determines if an exception should be retried. |
| | | 131 | | /// </summary> |
| | | 132 | | /// |
| | | 133 | | /// <param name="exception">The exception to consider.</param> |
| | | 134 | | /// |
| | | 135 | | /// <returns><c>true</c> to retry the exception; otherwise, <c>false</c>.</returns> |
| | | 136 | | /// |
| | | 137 | | private static bool ShouldRetryException(Exception exception) |
| | | 138 | | { |
| | 84 | 139 | | if ((exception is TaskCanceledException) || (exception is OperationCanceledException)) |
| | | 140 | | { |
| | 0 | 141 | | exception = exception?.InnerException; |
| | | 142 | | } |
| | 84 | 143 | | else if (exception is AggregateException aggregateEx) |
| | | 144 | | { |
| | 0 | 145 | | exception = aggregateEx?.Flatten().InnerException; |
| | | 146 | | } |
| | | 147 | | |
| | | 148 | | switch (exception) |
| | | 149 | | { |
| | | 150 | | case null: |
| | 0 | 151 | | return false; |
| | | 152 | | |
| | | 153 | | case EventHubsException ex: |
| | 0 | 154 | | return ex.IsTransient; |
| | | 155 | | |
| | | 156 | | case TimeoutException _: |
| | | 157 | | case SocketException _: |
| | 0 | 158 | | return true; |
| | | 159 | | |
| | | 160 | | default: |
| | 84 | 161 | | return false; |
| | | 162 | | } |
| | | 163 | | } |
| | | 164 | | |
| | | 165 | | /// <summary> |
| | | 166 | | /// Determines if an exception represents a request to throttle. |
| | | 167 | | /// </summary> |
| | | 168 | | /// |
| | | 169 | | /// <param name="exception">The exception to consider.</param> |
| | | 170 | | /// |
| | | 171 | | /// <returns><c>true</c> to consider the exception as a throttle request; otherwise, <c>false</c>.</returns> |
| | | 172 | | /// |
| | | 173 | | private static bool IsThrottleException(Exception exception) => |
| | 0 | 174 | | exception switch |
| | 0 | 175 | | { |
| | 0 | 176 | | EventHubsException ex when (ex.Reason == EventHubsException.FailureReason.ServiceBusy) => true, |
| | 0 | 177 | | _ => false |
| | 0 | 178 | | }; |
| | | 179 | | |
| | | 180 | | /// <summary> |
| | | 181 | | /// Calculates the delay for an exponential back-off. |
| | | 182 | | /// </summary> |
| | | 183 | | /// |
| | | 184 | | /// <param name="attemptCount">The number of total attempts that have been made, including the initial attempt b |
| | | 185 | | /// <param name="baseDelaySeconds">The delay to use as a basis for the exponential back-off, in seconds.</param> |
| | | 186 | | /// <param name="baseJitterSeconds">The delay to use as the basis for a random jitter value, in seconds.</param> |
| | | 187 | | /// <param name="random">The random number generator to use for the calculation.</param> |
| | | 188 | | /// |
| | | 189 | | /// <returns>The recommended duration to delay before retrying; this value does not take the maximum delay or el |
| | | 190 | | /// |
| | | 191 | | private static TimeSpan CalculateExponentialDelay(int attemptCount, |
| | | 192 | | double baseDelaySeconds, |
| | | 193 | | double baseJitterSeconds, |
| | | 194 | | Random random) => |
| | 0 | 195 | | TimeSpan.FromSeconds((Math.Pow(2, attemptCount) * baseDelaySeconds) + (random.NextDouble() * baseJitterSecon |
| | | 196 | | |
| | | 197 | | /// <summary> |
| | | 198 | | /// Calculates the delay for a fixed back-off. |
| | | 199 | | /// </summary> |
| | | 200 | | /// |
| | | 201 | | /// <param name="baseDelaySeconds">The delay to use as a basis for the fixed back-off, in seconds.</param> |
| | | 202 | | /// <param name="baseJitterSeconds">The delay to use as the basis for a random jitter value, in seconds.</param> |
| | | 203 | | /// <param name="random">The random number generator to use for the calculation.</param> |
| | | 204 | | /// |
| | | 205 | | /// <returns>The recommended duration to delay before retrying; this value does not take the maximum delay or el |
| | | 206 | | /// |
| | | 207 | | private static TimeSpan CalculateFixedDelay(double baseDelaySeconds, |
| | | 208 | | double baseJitterSeconds, |
| | | 209 | | Random random) => |
| | 0 | 210 | | TimeSpan.FromSeconds(baseDelaySeconds + (random.NextDouble() * baseJitterSeconds)); |
| | | 211 | | } |
| | | 212 | | } |