commit 858db1a8c8f71cbefb8ff2c896ff9aa86d761a47
author Damien Neil <dneil@google.com> Tue Nov 05 11:26:18 2024 -0800
committer Damien Neil <dneil@google.com> Wed Nov 06 19:35:40 2024 +0000
tree f5bd17ee763fc2d91257fe4a39b37b6864e57107
parent 0aa844c2c8b6054d98e91f074355d5a50528934c

http2: surface errors occurring very early in a client conn's lifetime

When we create a new connection for a request, the request should
fail if the connection attempt fails.

There is a race condition which can cause this to not happen:

- net/http sends a request to a http2.Transport
- the http2.Transport returns ErrNoCachedConn
- net/http creates a new tls.Conn and passes it to the http2.Transport
- the http2.Transport adds the conn to its connection pool
- the connection immediately encounters an error
- the http2.Transport removes the conn from its connection pool
- net/http resends the request to the http2.Transport
- the http2.Transport returns ErrNoCachedConn, and the process repeates

If the request is sent to the http2.Transport before the connection
encounters an error, then the request fails. But otherwise, we get
stuck in an infinite loop of the http2.Transport asking for a new
connection, receiving one, and throwing it away.

To fix this, leave a dead connection in the pool for a short while
if it has never had a request sent to it. If a dead connection is
used for a new request, return an error and remove the connection
from the pool.

Change-Id: I64eb15a8f1512a6bda52db423072b945fab6f4b5
Reviewed-on: https://go-review.googlesource.com/c/net/+/625398
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Jonathan Amsterdam <jba@google.com>