Scriba.Info (Scriba v0.1.0)

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Snapshot of a projection's runtime state, returned by Scriba.info/2.

Population

All fields are populated when Scriba.info/2 finds a registered Coordinator: :name, :version and the position fields (:safe_position, :stream_positions) come from the position cache; :status, :source and :target come from the Coordinator's status call. When no Coordinator is registered, Scriba.info/2 returns {:error, :not_found} rather than a partially-populated struct.

:status is one of :initializing | :running | :paused | :draining | :stopped. :source and :target are the {module, opts} specs the projection was started with.

:safe_position is introspection, not a replay point

It is the minimum across the streams currently in the position cache — a rough "how far behind is the laggard" figure. It reads too high in two ways: the cache preloads at most 10,000 streams, and streams this projection has never written to contribute nothing at all. Do not resume a replica from it. A real replay point is v0.3 work and needs an uncapped MIN(position) aggregate against Postgres.

Truncation

When a projection has more than 1000 distinct streams, :stream_positions becomes :truncated rather than a giant map. Callers needing specific per-stream positions in that case should use Scriba.info/2 with a streams: [list] option (added later) to scope the lookup. :safe_position is always populated regardless of truncation.

Summary

Types

t()

Types

t()

@type t() :: %Scriba.Info{
  name: String.t(),
  safe_position: non_neg_integer(),
  source: tuple() | nil,
  status: atom() | nil,
  stream_positions:
    %{required(String.t()) => non_neg_integer()} | :truncated | nil,
  target: tuple() | nil,
  version: pos_integer()
}