WorkflowRetryPolicy.cs

// ------------------------------------------------------------------------
// Copyright 2023 The Dapr Authors
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//     http://www.apache.org/licenses/LICENSE-2.0
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// ------------------------------------------------------------------------
using System;
using System.Threading;
using Microsoft.DurableTask;

namespace Dapr.Workflow
{
    /// <summary>
    /// A declarative retry policy that can be configured for activity or child workflow calls.
    /// </summary>
    public class WorkflowRetryPolicy
    {
        readonly RetryPolicy durableRetryPolicy;

        /// <summary>
        /// Initializes a new instance of the <see cref="WorkflowRetryPolicy"/> class.
        /// </summary>
        /// <param name="maxNumberOfAttempts">The maximum number of task invocation attempts. Must be 1 or greater.</param>
        /// <param name="firstRetryInterval">The amount of time to delay between the first and second attempt.</param>
        /// <param name="backoffCoefficient">
        /// The exponential back-off coefficient used to determine the delay between subsequent retries. Must be 1.0 or greater.
        /// </param>
        /// <param name="maxRetryInterval">
        /// The maximum time to delay between attempts, regardless of<paramref name="backoffCoefficient"/>.
        /// </param>
        /// <param name="retryTimeout">The overall timeout for retries.</param>
        /// <remarks>
        /// The value <see cref="Timeout.InfiniteTimeSpan"/> can be used to specify an unlimited timeout for
        /// <paramref name="maxRetryInterval"/> or <paramref name="retryTimeout"/>.
        /// </remarks>
        /// <exception cref="ArgumentOutOfRangeException">
        /// Thrown if any of the following are true:
        /// <list type="bullet">
        ///   <item>The value for <paramref name="maxNumberOfAttempts"/> is less than or equal to zero.</item>
        ///   <item>The value for <paramref name="firstRetryInterval"/> is less than or equal to <see cref="TimeSpan.Zero"/>.</item>
        ///   <item>The value for <paramref name="backoffCoefficient"/> is less than 1.0.</item>
        ///   <item>The value for <paramref name="maxRetryInterval"/> is less than <paramref name="firstRetryInterval"/>.</item>
        ///   <item>The value for <paramref name="retryTimeout"/> is less than <paramref name="firstRetryInterval"/>.</item>
        /// </list>
        /// </exception>
        public WorkflowRetryPolicy(
            int maxNumberOfAttempts,
            TimeSpan firstRetryInterval,
            double backoffCoefficient = 1.0,
            TimeSpan? maxRetryInterval = null,
            TimeSpan? retryTimeout = null)
        {
            this.durableRetryPolicy = new RetryPolicy(
                maxNumberOfAttempts,
                firstRetryInterval,
                backoffCoefficient,
                maxRetryInterval,
                retryTimeout);
        }

        /// <summary>
        /// Gets the max number of attempts for executing a given task.
        /// </summary>
        public int MaxNumberOfAttempts => this.durableRetryPolicy.MaxNumberOfAttempts;

        /// <summary>
        /// Gets the amount of time to delay between the first and second attempt.
        /// </summary>
        public TimeSpan FirstRetryInterval => this.durableRetryPolicy.FirstRetryInterval;

        /// <summary>
        /// Gets the exponential back-off coefficient used to determine the delay between subsequent retries.
        /// </summary>
        /// <value>
        /// Defaults to 1.0 for no back-off.
        /// </value>
        public double BackoffCoefficient => this.durableRetryPolicy.BackoffCoefficient;

        /// <summary>
        /// Gets the maximum time to delay between attempts.
        /// </summary>
        /// <value>
        /// Defaults to 1 hour.
        /// </value>
        public TimeSpan MaxRetryInterval => this.durableRetryPolicy.MaxRetryInterval;

        /// <summary>
        /// Gets the overall timeout for retries. No further attempts will be made at executing a task after this retry
        /// timeout expires.
        /// </summary>
        /// <value>
        /// Defaults to <see cref="Timeout.InfiniteTimeSpan"/>.
        /// </value>
        public TimeSpan RetryTimeout => this.durableRetryPolicy.RetryTimeout;

        internal RetryPolicy GetDurableRetryPolicy() => this.durableRetryPolicy;
    }
}