75 lines
3.0 KiB
C#
75 lines
3.0 KiB
C#
using Microsoft.Extensions.Logging;
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using Polly;
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using Polly.CircuitBreaker;
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using Polly.Retry;
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using System;
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using System.Net.Http;
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namespace WebMVC.Infrastructure
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{
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public class HttpClientDefaultPolicies
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{
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//Config for Retries with exponential backoff policy
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const int MAX_RETRIES = 6;
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const int SECONDS_BASE_FOR_EXPONENTIAL_BACKOFF = 2;
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//Config for Circuit Breaker policy
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const int EXCEPTIONS_ALLOWED_BEFORE_CIRCUIT_BREAKES = 5;
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const int DURATION_OF_BREAK_IN_MINUTES = 1;
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private readonly ILogger<HttpClientDefaultPolicies> _logger;
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public HttpClientDefaultPolicies(ILogger<HttpClientDefaultPolicies> logger)
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{
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_logger = logger ?? throw new ArgumentNullException(nameof(logger));
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}
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public IAsyncPolicy<HttpResponseMessage> GetWaitAndRetryPolicy()
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{
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RetryPolicy retryPolicy =
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Policy.Handle<HttpRequestException>()
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.WaitAndRetryAsync(
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// Maximum number of retries
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MAX_RETRIES,
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// exponential backofff (2sg, 4sg, 8sg, 16sg, 32sg. etc.)
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retryAttempt => TimeSpan.FromSeconds(Math.Pow(SECONDS_BASE_FOR_EXPONENTIAL_BACKOFF, retryAttempt)),
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// on retry
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(exception, timeSpan, retryCount, context) =>
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{
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var msg = $"Retry {retryCount} implemented with Polly's RetryPolicy " +
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$"of {context.PolicyKey} " +
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$"at {context.OperationKey}, " +
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$"due to: {exception}.";
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_logger.LogWarning(msg);
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_logger.LogDebug(msg);
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});
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return retryPolicy.AsAsyncPolicy<HttpResponseMessage>();
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}
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public IAsyncPolicy<HttpResponseMessage> GetCircuitBreakerPolicy()
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{
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CircuitBreakerPolicy circuitBreakerPolicy =
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Policy.Handle<HttpRequestException>()
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.CircuitBreakerAsync(
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// Number of exceptions before breaking the circuit
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EXCEPTIONS_ALLOWED_BEFORE_CIRCUIT_BREAKES,
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// Duration of break
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TimeSpan.FromMinutes(DURATION_OF_BREAK_IN_MINUTES),
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(exception, duration) =>
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{
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// On circuit opened (Circuit is broken)
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_logger.LogTrace("Circuit has been broken");
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},
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() =>
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{
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// on circuit closed
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_logger.LogTrace("Circuit has been reset");
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});
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return circuitBreakerPolicy.AsAsyncPolicy<HttpResponseMessage>();
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}
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}
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}
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