HttpError429Handler Class

Namespace
Kampute.HttpClient.ErrorHandlers
Assembly
  • Kampute.HttpClient.dll

Definition

Handles '429 Too Many Requests' HTTP responses by attempting to back off and retry the request according to a specified or default backoff strategy.
public class HttpError429Handler : IHttpErrorHandler
Inheritance
Implements

Remarks

This handler provides a mechanism to respond to HTTP 429 errors by retrying the request after a delay. The delay duration and retry logic can be customized through the OnBackoffStrategy delegate. If the delegate is not provided, or does not specify a strategy, the handler will look for a rate limit reset header in the response. If the header is present, its value is used to determine the backoff duration. If the header is not present, no retries will be attempted.

Constructors

HttpError429Handler()

Initializes a new instance of HttpError429Handler class.
public HttpError429Handler()

Properties

OnBackoffStrategy

A delegate that allows customization of the backoff strategy when a 429 Too Many Requests' response is received.
public Func<HttpResponseErrorContext, Nullable<DateTimeOffset>, IHttpBackoffProvider> OnBackoffStrategy { get; set; }

Property Value

Func<HttpResponseErrorContext, Nullable<DateTimeOffset>, IHttpBackoffProvider>
A function that takes an HttpResponseErrorContext and an optional DateTimeOffset representing the rate limit reset time, and returns an IHttpBackoffProvider to define the backoff strategy.

Remarks

If this delegate is set and returns an IHttpBackoffProvider, the returned strategy is used for the retry operation. If it is not set, or returns null, the handler will defer to the Retry-After header in the response.

The delegate receives the following parameters:

  • context– Provides context about the HTTP response indicating a '429 Too Many Requests' error. It is encapsulated within an HttpResponseErrorContext instance, allowing for an informed decision on the retry strategy.
  • resetTime– Indicates the time when the rate limit will be lifted as a DateTimeOffset value. If the server specifies a reset time via response headers, this parameter provides that time, allowing the client to know when to resume requests. If the server does not specify a reset time, the value will be null.

Methods

CanHandle(HttpStatusCode)

Determines whether this handler can process the specified HTTP status code.
public bool CanHandle(HttpStatusCode statusCode)

Parameters

statusCode HttpStatusCode
The HTTP status code to evaluate.

Returns

bool
true if the handler can process the status code; otherwise, false.

Remarks

This implementation specifically handles the HTTP '429 Too Many Requests' status code.

CreateScheduler(HttpResponseErrorContext)

Creates a scheduler for retrying the failed request based on the error context.
protected virtual IRetryScheduler CreateScheduler(HttpResponseErrorContext ctx)

Parameters

ctx HttpResponseErrorContext
The context containing information about the HTTP response that indicates a failure.

Returns

IRetryScheduler
An IRetryScheduler that schedules the retry attempts.

Exceptions

ArgumentNullException
Thrown if ctx is null.

Remarks

This method first attempts to use the OnBackoffStrategy delegate to obtain a retry strategy. If the delegate is not provided or returns null, and a rate limit reset header is present, the value of this header is used to create a retry delay. If neither condition is met, no retries will be attempted.

Explicit Interface Implementations

IHttpErrorHandler.DecideOnRetryAsync(HttpResponseErrorContext, CancellationToken)

Evaluates whether a failed request should be retried based on the error context.
Task<HttpErrorHandlerResult> IHttpErrorHandler.DecideOnRetryAsync(HttpResponseErrorContext ctx, CancellationToken cancellationToken)

Parameters

ctx HttpResponseErrorContext
The context containing information about the HTTP response that indicates a failure.
cancellationToken CancellationToken
A token for canceling the operation.

Returns

Task<HttpErrorHandlerResult>
A task that resolves to an HttpErrorHandlerResult.

Exceptions

ArgumentNullException
Thrown if ctx is null.

See Also