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This additionally causes any server error HTTP status codes (500s) to be retried.
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This additionally causes any server error HTTP status codes (500s) to be retried.
Construct a Service to be used for the client.
Construct a Service to be used for the methodName
method.
Construct a Service to be used for the methodName
method.
used for scoping metrics (e.g. "clnt/your_client_label/method_name").
MethodBuilder
is a collection of APIs for client configuration at a higher level than the Finagle 6 APIs while improving upon the deprecated ClientBuilder.MethodBuilder
provides:All of these can be customized per method (or endpoint) while sharing a single underlying Finagle client. Concretely, a single service might offer both
GET statuses/show/:id
as well asPOST statuses/update
, whilst each having wildly different characteristics. TheGET
is idempotent and has a tight latency distribution while thePOST
is not idempotent and has a wide latency distribution. If users want different configurations, withoutMethodBuilder
they must create separate Finagle clients for each grouping. While long-lived clients in Finagle are not expensive, they are not free. They create duplicate metrics and waste heap, file descriptors, and CPU.Example
A client that has timeouts and retries on a 418 status code.
Timeouts
Defaults to using the StackClient's configuration.
An example of setting a per-request timeout of 50 milliseconds and a total timeout of 100 milliseconds:
Retries
Retries are intended to help clients improve success rate by trying failed requests additional times. Care must be taken by developers to only retry when it is known to be safe to issue the request multiple times. This is because the client cannot always be sure what the backend service has done. An example of a request that is safe to retry would be a read-only request.
Defaults to using the client's ResponseClassifier to retry failures marked as retryable. See withRetryForClassifier for details.
A com.twitter.finagle.service.RetryBudget is used to prevent retries from overwhelming the backend service. The budget is shared across clients created from an initial
MethodBuilder
. As such, even if the retry rules deem the request retryable, it may not be retried if there is insufficient budget.Finagle will automatically retry failures that are known to be safe to retry via com.twitter.finagle.service.RequeueFilter. This includes WriteExceptions and retryable nacks. As these should have already been retried, we avoid retrying them again by ignoring them at this layer.
Additional information regarding retries can be found in the user guide.
The classifier is also used to determine the logical success metrics of the method. Logical here means after any retries are run. For example should a request result in retryable failure on the first attempt, but succeed upon retry, this is exposed through metrics as a success. Logical success rate metrics are scoped to "clnt/your_client_label/method_name/logical" and get "success" and "requests" counters along with a "request_latency_ms" stat.
Unsuccessful requests are logged at
com.twitter.logging.Level.DEBUG
level. Further details, including the request and response, are available atTRACE
level.The user guide.
com.twitter.finagle.Http.Client.methodBuilder to construct instances.