x/net/http2: add Transport.WriteByteTimeout

[neild]

There are currently two ways to detect a broken HTTP/2 connection:

• If a Read or Write to the net.Conn fails.
• If no frames are received from the connection for ReadIdleTimeout, and no response is received from the subsequent ping within PingTimeout.

Pings are a reliable way to detect a broken connection (with the fix for #48810), but there are times when it would be nice to passively detect an unresponsive peer without needing to actively ping them.

I propose adding an additional knob to http2.Transport:

// WriteTimeout is the timeout after which the connection will be closed
// if no data can be written to it. The timeout begins when data is written
// to the connection, and is extended if any bytes can be written.
// If zero, no write timeout is set.
WriteTimeout time.Duration

Unlike ReadIdleTimeout, WriteTimeout will apply only at the time we try to write to a connection. Unlike per-request timeouts, WriteTimeout applies to the connection as a whole.

[gopherbot]

Change https://golang.org/cl/354431 mentions this issue: http2: add Transport.WriteTimeout

[rsc]

This proposal has been added to the active column of the proposals project
and will now be reviewed at the weekly proposal review meetings.
— rsc for the proposal review group

[neild]

Perhaps a better name is (http2.Transport).WriteByteTimeout, since http.Server has a WriteTimeout field which applies to writing an entire response.

[rsc]

Based on the discussion above, this proposal seems like a likely accept.
— rsc for the proposal review group

[rsc]

No change in consensus, so accepted. 🎉
This issue now tracks the work of implementing the proposal.
— rsc for the proposal review group