Class: StandardLedger::ProjectionJob

Inherits:
ActiveJob::Base
  • Object
show all
Defined in:
lib/standard_ledger/jobs/projection_job.rb

Overview

ActiveJob class that runs a single ‘:async`-mode projection after the entry’s outer transaction has committed. Enqueued by ‘StandardLedger::Modes::Async` from an `after_create_commit` callback.

The job resolves the projection definition by ‘target_association` (the only stable handle — the Definition struct doesn’t serialize cleanly through ActiveJob), looks up the target via the entry’s ‘belongs_to` setter, and runs `target.with_lock { projector_class.new.apply(target, entry) }`. The projector must be class-form (`via: ProjectorClass`) and should recompute the aggregate from the log inside `apply` for retry safety — async projections can run more than once when the job retries.

Retries are configurable per-projection via subclassing this job and overriding ‘retry_on`, or globally via `Config#default_async_retries` (default 3). When retries are exhausted, ActiveJob’s dead-letter behavior takes over — the job still emits ‘<prefix>.projection.failed` on every attempt so subscribers see the full retry history.

Notification payloads include ‘attempt:` (drawn from ActiveJob’s ‘executions` accessor — 1 on first attempt, increments per retry) so subscribers can distinguish first-try success from retry-success.

Instance Method Summary collapse

Instance Method Details

#perform(entry, target_association) ⇒ Object 



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# File 'lib/standard_ledger/jobs/projection_job.rb', line 56

def perform(entry, target_association)
  definition = entry.class.standard_ledger_projections.find { |d|
    d.mode == :async && d.target_association == target_association.to_sym
  }
  if definition.nil?
    raise StandardLedger::Error,
          "no :async projection #{target_association.inspect} on #{entry.class.name}"
  end

  target = entry.public_send(definition.target_association)
  return if target.nil?

  prefix = StandardLedger.config.notification_namespace
  started = Process.clock_gettime(Process::CLOCK_MONOTONIC)

  begin
    target.with_lock do
      definition.projector_class.new.apply(target, entry)
    end
  rescue StandardError => e
    duration_ms = (Process.clock_gettime(Process::CLOCK_MONOTONIC) - started) * 1000.0
    StandardLedger::EventEmitter.emit(
      "#{prefix}.projection.failed",
      entry: entry, target: target, projection: definition.target_association,
      mode: :async, error: e, duration_ms: duration_ms,
      attempt: executions
    )
    raise
  end

  duration_ms = (Process.clock_gettime(Process::CLOCK_MONOTONIC) - started) * 1000.0
  StandardLedger::EventEmitter.emit(
    "#{prefix}.projection.applied",
    entry: entry, target: target, projection: definition.target_association,
    mode: :async, duration_ms: duration_ms, attempt: executions
  )
end