/// <summary>
/// Build default circuit breaker, wait and retry and Timeout policy.
/// </summary>
/// <param name="transientPolicySettings">retry,timeout and circuit breaker settings.</param>
/// <returns>policy wrapper.</returns>
public virtual PolicyWrap <HttpResponseMessage> GetDefaultPolicy(TransientPolicySettings transientPolicySettings)
{
//Time out policy to set Http Client request timeout.
TimeoutPolicy timeoutPolicy = Policy.TimeoutAsync(TimeSpan.FromSeconds(transientPolicySettings.HttpTimeOut), timeoutStrategy: TimeoutStrategy.Pessimistic, TimeOutHandler);
//If http client requiest fails, it will be retried.
IAsyncPolicy <HttpResponseMessage> retryPolicy = Policy.HandleResult <HttpResponseMessage>(r => !r.IsSuccessStatusCode)
.Or <HttpRequestException>()
.WaitAndRetryAsync(transientPolicySettings.RetryAttempts, retryafter => TimeSpan.FromSeconds(Math.Pow(2, retryafter) / 2), OnRetry);
//Circuit breaker to fail fast.
IAsyncPolicy <HttpResponseMessage> cb = HttpPolicyExtensions
.HandleTransientHttpError()
.AdvancedCircuitBreakerAsync(
transientPolicySettings.CircuitBreakerSettings.FailureThreshold,
TimeSpan.FromSeconds(transientPolicySettings.CircuitBreakerSettings.SamplingDuration),
transientPolicySettings.CircuitBreakerSettings.MinimumThroughput,
TimeSpan.FromSeconds(transientPolicySettings.CircuitBreakerSettings.DurationOfBreak),
OnBreak,
OnReset,
OnHalfOpen);
//above policies are wrapped.
return(timeoutPolicy.WrapAsync(retryPolicy.WrapAsync(cb)));
}
/// <summary>
/// Register instance in DI.
/// </summary>
/// <typeparam name="TClient">Interface implemented by a type.</typeparam>
/// <typeparam name="TImplementation">A type implements TClient interface.</typeparam>
/// <param name="services">instance of IServiceCollection.</param>
/// <param name="transientPolicySettings">transient poicy settings.</param>
public static void RegisterInstace <TClient, TImplementation>(this IServiceCollection services, TransientPolicySettings transientPolicySettings)
where TClient : class
where TImplementation : class, TClient
{
PolicyBuilder policyBuilder = new PolicyBuilder();
var defaultPolicy = policyBuilder.GetDefaultPolicy(transientPolicySettings);
services.AddHttpClient <TClient, TImplementation>()
.AddPolicyHandler(t => { return(defaultPolicy); })
.CorrelateRequests("X-Correlation-ID")
.ConfigurePrimaryHttpMessageHandler(() => new HttpClientHandler()
{
AllowAutoRedirect = false,
AutomaticDecompression = DecompressionMethods.Deflate | DecompressionMethods.GZip
});
}
