categraf/pkg/retry

package retry

This package implements a configurable retry mechanism that can be embedded in any class needing a retry-on-error system.

It's flexible enough to support any process that exposes a func() error method, and can be extended for other retry strategies than we default ones.

Supported strategies:

• OneTry (default): don't retry, fail on the first error
• RetryCount: retry for a set number of attempts when TriggerRetry is called (returning a FailWillRetry error), then fail with a PermaFail
• Backoff: retry with a duration between two consecutive retries that double at each new try up to a maximum

How to embed the Retrier

Your class needs to:

• provide a function returning an error (nil on success)
• embed a Retrier object as an anonymous struct field (like a sync.Mutex)
• call self.SetupRetrier() with a valid Config struct

Have a look at retrier_test.go for an example.

How to use a class embedding Retrier

Assuming the class is properly initialised, you can use any of the public methods from retrier.go on that class:

• RetryStatus() will return the current status (defined in types.go)
• TriggerRetry() will either return nil if everything is OK, or an error (real type Retry.Error) if the attempt was unsuccessful.
• passing the error to Retry.IsErrWillRetry() and Retry.IsErrPermaFail() will tell you whether it's necessary to retry again, or just give up initialising this object
• retry throtling is implemented in case several users try to use a class. Calling NextRetry() will tell you when the next retry is possible. Before that time, all calls to TriggerRetry() will return a FailWillRetry error. The retry will not automatically run when that time is reached, you have to schedule a call to TriggerRetry.