Provide a sensible way to retry indefinitely

[edigaryev]

Imagine a Go server that is dependent on some bootstrap data and there's little sense in continuing the execution unless that data is retrieved.

With all the perks this package gives (precise delay control, exponential backoff, context support) it would be nice to use it for this case, however, it's currently not possible to do this cleanly:

• specifying retry.Attempts(0) does not work as one might expect: Retry Attempt 0 Returns Without Call and Has Empty Error #41
• specifying retry.Attempts(arbitrarily large number) is not semantically sound as we don't know the exact number of attempts in advance
• specifying retry.Attempts(math.MaxUint32) is a bad idea due to:

  retry-go/retry.go

  Line 120 in 1065640

  errorLog = make(Error, config.attempts)

It would be nice if retry.Attempts(0) could be used for this case, as retry.Attempts(0) is kinda useless in the current implementation: it always results in All attempts fail: ... error.

[edigaryev]

Just realized that we've still bounded by the uint counter value passed into the OnRetryFunc.

Looks like in this case this can be fixed by not allocating config.attempts straight away (see above).

...or worked around by specifying LastErrorOnly(true) in each retry.Do() invocation. Perhaps, a global variable like some packages do to configure them once before using?

[JaSei]

Hi, @edigaryev. I take the point. I feel Attempts(0) could be like infinite attempts, probably it's more logical than current behavior #41.
I will look at it, or PR is welcome.

[JaSei]

v4 released #49