Advertising topologyVersion in the hello reply is what tells a driver the
server speaks the streaming (awaitable) hello protocol — in the Node driver
it is the only condition checked. From the second heartbeat on, the driver
then monitored with an exhaust hello (exhaustAllowed + maxAwaitTimeMS) and
waited for a stream of replies carrying moreToCome. We answered once with
the flag clear and went back to reading, so every heartbeat failed with
"Server ended moreToCome unexpectedly", destroying the connection and
clearing the pool. MongoDB Compass showed this as a connect/disconnect loop
once per heartbeat.
We do not implement streaming hello, so we must not claim to. Omitting the
field keeps monitoring on the polling path, and agrees with the
maxWireVersion 8 we report: streaming hello arrived in wire version 9.
The existing e2e files all passed against the broken server — they issue
their commands and exit before the second heartbeat — so e2e5 watches SDAM
heartbeats on an idle connection instead.
Also renames mongo-light to mongo-lite throughout (binary, log messages,
docs, gitVersion). Unrelated to the fix above, but squashed in at request
rather than left as a commit whose message described only the fix.
The Node driver sends {field: /re/} as a BSON regex element (type 0x0B),
which the matcher previously only handled via the $regex operator form;
and dot paths with numeric segments (tags.0) were ignored because array
descent only recursed into embedded docs. Both are part of standard
MongoDB query semantics and were caught by the driver e2e suite.
server: unbounded Io async limit so the accept loop never wedges, and
treat header-read failures (client RST on pool teardown) as clean
disconnects. With the default cpu_count-1 limit, groupAsync's eager
fallback ran connection handlers inline on the accept-loop fiber once
that many connections were alive, stalling accept() and timing out
handshakes for further clients.
Add tests/e2e/: official driver CRUD, concurrency, and kill -9 recovery
suites (29 + 2 + 3 checks), plus unit tests for the query fixes.
