## Problem
Some awkwardness in the measured API.
Missing process metrics.
## Summary of changes
Update measured to use the new convenience setup features.
Added measured-process lib.
Added measured support for libmetrics
## Problem
- Previously, an async mutex was held for the duration of
`ComputeHook::notify`. This served multiple purposes:
- Ensure updates to a given tenant are sent in the proper order
- Prevent concurrent calls into neon_local endpoint updates in test
environments (neon_local is not safe to call concurrently)
- Protect the inner ComputeHook::state hashmap that is used to calculate
when to send notifications.
This worked, but had the major downside that while we're waiting for a
compute hook request to the control plane to succeed, we can't notify
about any other tenants. Notifications block progress of live
migrations, so this is a problem.
## Summary of changes
- Protect `ComputeHook::state` with a sync lock instead of an async lock
- Use a separate async lock ( `ComputeHook::neon_local_lock` ) for
preventing concurrent calls into neon_local, and only take this in the
neon_local code path.
- Add per-tenant async locks in ShardedComputeHookTenant, and use these
to ensure that only one remote notification can be sent at once per
tenant. If several shards update concurrently, their updates will be
coalesced.
- Add an explicit semaphore that limits concurrency of calls into the
cloud control plane.
The binary etc were renamed some time ago, but the path in the source
tree remained "attachment_service" to avoid disruption to ongoing PRs.
There aren't any big PRs out right now, so it's a good time to cut over.
- Rename `attachment_service` to `storage_controller`
- Move it to the top level for symmetry with `storage_broker` & to avoid
mixing the non-prod neon_local stuff (`control_plane/`) with the storage
controller which is a production component.
