supabase / supavisor / 27245246003

77%

Build Type

push

github

Committed by web-flow

Commit Message

perf(db_handler): use LRU eviction for backend prepared statements (#980)

## What kind of change does this PR introduce?

Performance improvement.

## What is the current behavior?

When the per-backend prepared statement set hits the 200-statement
limit, eviction picks 40 entries at random (`Enum.take_random`) and
sends `Close` for them. Hot statements get evicted with the same
probability as cold ones,
so under churn we can drop a frequently used statement and pay for a
fresh `Parse` round-trip on the next `Bind`. Relates to #69 / #239.

## What is the new behavior?
   
Replaces the `MapSet`-backed set with a small LRU storage
(`Supavisor.Protocol.PreparedStatements.BackendStorage`). Recency is
bumped on `Parse` and on `Bind` for statements already known to the
backend. Eviction now drops the least recently used statements first, so
hot ones stay around.

No default behavior change still gated by the
`named_prepared_statements` feature flag. Telemetry
(`prepared_statements_evicted`) is unchanged. Covered by unit tests
(basic API + edge cases) and a `StreamData` property test that checks
the LRU ordering invariant across arbitrary `put`/`touch`/`delete`
sequences.

---------

Co-authored-by: felipe stival <14948182+v0idpwn@users.noreply.github.com>

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1 existing line in 1 file now uncovered.

2572 of 3361 relevant lines covered (76.52%)

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