TCP_KEEPALIVE is not enabled by default, so this prevents hanged up connections
in case of abrupt client termination. Add 'closed' flag to PostgresBackendReader
and pass it during handles join to prevent attempts to read from socket if we
errored out previously -- now with timeouts this is a common situation.
It looks like
2023-04-10T18:08:37.493448Z INFO {cid=68}:WAL
receiver{ttid=59f91ad4e821ab374f9ccdf918da3a85/16438f99d61572c72f0c7b0ed772785d}:
terminated: timed out
Presumably fixes https://github.com/neondatabase/neon/issues/3971
1) Remove allocation and data copy during each message read. Instead, parsing
functions now accept BytesMut from which data they form messages, with
pointers (e.g. in CopyData) pointing directly into BytesMut buffer. Accordingly,
move ConnectionError containing IO error subtype into framed.rs providing this
and leave in pq_proto only ProtocolError.
2) Remove anyhow from pq_proto.
3) Move FeStartupPacket out of FeMessage. Now FeStartupPacket::parse returns it
directly, eliminating dead code where user wants startup packet but has to match
for others.
proxy stream.rs is adapted to framed.rs with minimal changes. It also benefits
from framed.rs improvements described above.
- Add support for splitting async postgres_backend into read and write halfes.
Safekeeper needs this for bidirectional streams. To this end, encapsulate
reading-writing postgres messages to framed.rs with split support without any
additional changes (relying on BufRead for reading and BytesMut out buffer for
writing).
- Use async postgres_backend throughout safekeeper (and in proxy auth link
part).
- In both safekeeper COPY streams, do read-write from the same thread/task with
select! for easier error handling.
- Tidy up finishing CopyBoth streams in safekeeper sending and receiving WAL
-- join split parts back catching errors from them before returning.
Initially I hoped to do that read-write without split at all, through polling
IO:
https://github.com/neondatabase/neon/pull/3522
However that turned out to be more complicated than I initially expected
due to 1) borrow checking and 2) anon Future types. 1) required Rc<Refcell<...>>
which is Send construct just to satisfy the checker; 2) can be workaround with
transmute. But this is so messy that I decided to leave split.
To untie cyclic dependency between sync and async versions of postgres_backend,
copy QueryError and some logging/error routines to postgres_backend.rs. This is
temporal glue to make commits smaller, sync version will be dropped by the
upcoming commit completely.
