Detailed steps to reproduce the problem?

The gist here illustrates how setting an operation-level timeout on v1 does not result in maxTimeMS being set on the command message.

History

CSOT context wrapping was implemented in GODRIVER-2496, the CSOT spec was still being modified during the initial implementation. Wrapping prevents operation-level server-side timeouts, a feature that was likely overlooked. Though, it is worth noting that

1. Adding operation-level server side timeouts would technically be a breaking change since users might be relying on the context.DeadlineExceeded error / closed connection that results from timing out the read portion of the round trip
2. Operation-level timeouts may still cause the "read" portion of a round trip to time out, closing the connection to the server.

Timing out the read portion of the round trip is the source of high connection churn described in HELP-56519. Adding operation-level timeouts could minimize this churn by short-circuiting the read timeout with server-side timeouts. However, this is only true if rttMin / rtt90 is large enough (potentially just positive):

func Execute(ctx context.Context) {
	for { // While retries are possible

		maxTimeMS := getRemainingTimeout(ctx) - rttMin

		// We would construct a wire message with maxTimeMS
		conn.Write(createWireMessage(maxTimeMS))

		// Read until the buffer is filled / the context is timed out. Once timed
		// out, then the connection is closed and the DB will presumably terminate
		// the op.
		conn.Read(getRemaintingTimeout(ctx))
	}
}

Definition of done: what must be done to consider the task complete?

The v2 PR proposed in GODRIVER-2348 ensures that operation-level timeouts are included in the calculation of maxTimeMS. This portion of the PR should be back-ported to v1, after consideration for the breaking change described in (1) of the "history" section.

The exact Go version used, with patch level:

go version go1.21.4 darwin/arm64

The exact version of the Go driver used:

1.11.7

Describe how MongoDB is set up. Local vs Hosted, version, topology, load balanced, etc.

local, 8.0.0-alpha-4884-g0c18d0a, replica set, not load balanced

The operating system and version (e.g. Windows 7, OSX 10.8, ...)

OSX 14.3

Security Vulnerabilities

NA