tree e8a00ae810eee7ae9b8e928500242814ad135886
parent 816bbcc483633869d7953fd4e3717c7a3b215a27
author Dmitri Shuralyov <dmitshur@golang.org> 1656337001 -0400
committer Gopher Robot <gobot@golang.org> 1656538778 +0000

maintner: don't try to download negative bytes

If the maintnerd server restarts with some uncommitted transactions,
clients may end up having more downloaded bytes than the server, after
the server restarts. We're invariably heading towards an ErrSplit if
this happens (which is fine, otherwise we'd need to add more code to
avoid duplicate event processing and it's unlikely to be worthwhile).

In such a situation, don't try to download new data from the server,
since that's guaranteed to fail with a 416 Range Not Satisfiable error.
Do try to reuse the prefix of the existing data as long as its checksum
matches, otherwise download the new version of the growing file.

Fixes golang/go#26922.
Updates golang/go#51211.

Change-Id: Ide099ee0740e854cfe764db8c3b4341836a237f4
Reviewed-on: https://go-review.googlesource.com/c/build/+/414434
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Alex Rakoczy <jenny@golang.org>
Run-TryBot: Dmitri Shuralyov <dmitshur@golang.org>