net/http: also make Transport retry POST request if no bytes were written #15723
We should retry non-idempotent HTTP requests (like POSTs) too if no bytes were ever written.
A fix for #15446 adds tracking of the number of bytes written. This makes this trivial to fix, but it's too late for Go 1.7.
Easy to switch early in Go 1.8. Could also use a few more tests.
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In https://golang.org/3210, Transport errors occurring before receiving response headers were wrapped in another error type to indicate to the retry logic elsewhere that the request might be re-tryable. But a check for err == io.EOF was missed, which then became false once io.EOF was wrapped in the beforeRespHeaderError type. The beforeRespHeaderError was too fragile. Remove it. I tried to fix it in an earlier version of this CL and just broke different things instead. Also remove the "markBroken" method. It's redundant and confusing. Also, rename the checkTransportResend method to shouldRetryRequest and make it return a bool instead of an error. This also helps readability. Now the code recognizes the two main reasons we'd want to retry a request: because we never wrote the request in the first place (so: count the number of bytes we've written), or because the server hung up on us before we received response headers for an idempotent request. As an added bonus, this could make POST requests safely re-tryable since we know we haven't written anything yet. But it's too late in Go 1.7 to enable that, so we'll do that later (filed #15723). This also adds a new internal (package http) test, since testing this blackbox at higher levels in transport_test wasn't possible. Fixes #15446 Change-Id: I2c1dc03b1f1ebdf3f04eba81792bd5c4fb6b6b66 Reviewed-on: https://go-review.googlesource.com/23160 Reviewed-by: Andrew Gerrand <firstname.lastname@example.org> Run-TryBot: Brad Fitzpatrick <email@example.com> TryBot-Result: Gobot Gobot <firstname.lastname@example.org>
This rolls back https://golang.org/cl/27117 partly, softening it so it only retries POST/PUT/DELETE etc requests where there's no Body (nil or NoBody). This is a little useless, since most idempotent requests have a body (except maybe DELETE), but it's late in the Go 1.8 release cycle and I want to do the proper fix. The proper fix will look like what we did for http2 and only retrying the request if Request.GetBody is defined, and then creating a new request for the next attempt. See https://golang.org/cl/33971 for the http2 fix. Updates #15723 Fixes #18239 Updates #18241 Change-Id: I6ebaa1fd9b19b5ccb23c8d9e7b3b236e71cf57f3 Reviewed-on: https://go-review.googlesource.com/34134 Run-TryBot: Brad Fitzpatrick <email@example.com> TryBot-Result: Gobot Gobot <firstname.lastname@example.org> Reviewed-by: Tom Bergan <email@example.com>