reqstrategy

Package reqstrategy provides functions for coordinating http.Client calls. It wraps typical call strategies like making simultaneous requests, retrying, racing etc.

First, define what request counts successful, there are two helpers adding rules to the request context

req, _ = http.NewRequest("GET", "http://localhost/", nil)
req = WithStatusRequired(req, 200, 404)

or do advanced validation using custom logic

req, _ = http.NewRequest("GET", "http://localhost/", nil)
req = WithValidator(req, func(resp *http.Response) error {
  if resp.StatusCode != http.StatusOK {
    return fmt.Error("oops")
  }
  return nil
})

Then, make a call

Do() is not much different from calling client.Do(request) except it runs the response validation. See WithValidator and WithSTatusRequired

resp, err := Do(http.DefaultClient, req)

Retry() re-attempts request with provided intervals. By manually providing intervals sequence you can have different wait strategies like exponential back-off (time.Second, 2 * time.Second, 4 * time.Second) or just multiple reties after same interval (time.Second, time.Second, time.Second). If Request had a context with timeout cancelation then it will be applied to entire chain

resp, err := Retry(http.DefaultClient, req, time.Second, time.Second, time.Second)

Race() runs multiple requests simultaneously returning first successulf result or error if all failed. Once result is determined all requests are cancelled through the context.

resps, err := Race(http.DefaultClient, req0, req1, reqX)

All() runs requests simultaneously returning responses in same order or error if at least one request failed. Once result is determined all requests are cancelled through the context.

resps, err := All(http.DefaultClient, req0, req1, reqX)

Some() runs requests simultaneously returning responses for successful requests and <nil> for failed ones. Error is returned only if all requests failed.

resps, err := Some(http.DefaultClient, req0, req1, reqX)