- avoid panic by checking for Ok(None) response from
tonic::Streaming::message() instead of just using unwrap()
- There was a race condition, if the caller sent the message, but the
receiver task concurrently received Ok(None) indicating the stream
was closed. (I didn't see that in action, but I think it could happen
by reading the code)
After reading the code a few times, I didn't quite understand what it
was, to be honest, or how it was going to be used. Remove it now to
reduce noise, but we can resurrect it from git history if we need it
in the future.
Add a new 'pageserver_connection_info' field in the compute spec. It
replaces the old 'pageserver_connstring' field with a more complicated
struct that includes both libpq and grpc URLs, for each shard (or only
one of the the URLs, depending on the configuration). It also includes
a flag suggesting which one to use; compute_ctl now uses it to decide
which protocol to use for the basebackup.
This is compatible with everything that's in production, because the
control plane never used the 'pageserver_connstring' field. That was
added a long time ago with the idea that it would replace the code
that digs the 'neon.pageserver_connstring' GUC from the list of
Postgres settings, but we never got around to do that in the control
plane. Hence, it was only used with neon_local. But the plan now is to
pass the 'pageserver_connection_info' from the control plane, and once
that's fully deployed everywhere, the code to parse
'neon.pageserver_connstring' in compute_ctl can be removed.
The 'grpc' flag on an endpoint in endpoint config is now more of a
suggestion. Compute_ctl gets both URLs, so it can choose to use libpq
or grpc as it wishes. It currently always obeys the 'prefer_grpc' flag
that's part of the connection info though. Postgres however uses grpc
iff the new rust-based communicator is enabled.
TODO/plan for the control plane:
- Start to pass `pageserver_connection_info` in the spec file.
- Also keep the current `neon.pageserver_connstring` setting for now,
for backwards compatibility with old computes
After that, the `pageserver_connection_info.prefer_grpc` flag in the
spec file can be used to control whether compute_ctl uses grpc or
libpq. The actual compute's grpc usage will be controlled by the
`neon.enable_new_communicator` GUC. It can be set separately from
'prefer_grpc'.
Later:
- Once all old computes are gone, remove the code to pass
`neon.pageserver_connstring`
There were conflicts because of the differences in the page_api
protocol that was merged to main vs what was on the branch. I adapted
the code for the protocol in main.
Erik Grinaker
Heikki Linnakangas
Elizabeth Murray
Elizabeth Murray