## Problem
https://github.com/neondatabase/cloud/issues/30539
If the current leader cancels the `call` function, then it has removed
the jobs from the queue, but will never finish sending the responses.
Because of this, it is not cancellation safe.
## Summary of changes
Document these functions as not cancellation safe. Move cancellation of
the queued jobs into the queue itself.
## Alternatives considered
1. We could spawn the task that runs the batch, since that won't get
cancelled.
* This requires `fn call(self: Arc<Self>)` or `fn call(&'static self)`.
2. We could add another scopeguard and return the requests back to the
queue.
* This requires that requests are always retry safe, and also requires
requests to be `Clone`.
See #11942
Idea:
* if connections are short lived, they can get enqueued and then also
remove themselves later if they never made it to redis. This reduces the
load on the queue.
* short lived connections (<10m, most?) will only issue 1 command, we
remove the delete command and rely on ttl.
* we can enqueue as many commands as we want, as we can always cancel
the enqueue, thanks to the ~~intrusive linked lists~~ `BTreeMap`.
libs/pqproto is designed for safekeeper/pageserver with maximum
throughput.
proxy only needs it for handshakes/authentication where throughput is
not a concern but memory efficiency is. For this reason, we switch to
using read_exact and only allocating as much memory as we need to.
All reads return a `&'a [u8]` instead of a `Bytes` because accidental
sharing of bytes can cause fragmentation. Returning the reference
enforces all callers only hold onto the bytes they absolutely need. For
example, before this change, `pqproto` was allocating 8KiB for the
initial read `BytesMut`, and proxy was holding the `Bytes` in the
`StartupMessageParams` for the entire connection through to passthrough.
This upgrades the `proxy/` crate as well as the forked libraries in
`libs/proxy/` to edition 2024.
Also reformats the imports of those forked libraries via:
```
cargo +nightly fmt -p proxy -p postgres-protocol2 -p postgres-types2 -p tokio-postgres2 -- -l --config imports_granularity=Module,group_imports=StdExternalCrate,reorder_imports=true
```
It can be read commit-by-commit: the first commit has no formatting
changes, only changes to accomodate the new edition.
Part of #10918
## Problem
Because dashmap 6 switched to hashbrown RawTable API, it required us to
use unsafe code in the upgrade:
https://github.com/neondatabase/neon/pull/8107
## Summary of changes
Switch to clashmap, a fork maintained by me which removes much of the
unsafe and ultimately switches to HashTable instead of RawTable to
remove much of the unsafe requirement on us.
## Problem
The approach of having CancelMap as an in-memory structure increases
code complexity,
as well as putting additional load for Redis streams.
## Summary of changes
- Implement a set of KV ops for Redis client;
- Remove cancel notifications code;
- Send KV ops over the bounded channel to the handling background task
for removing and adding the cancel keys.
Closes#9660
