Module: DispatchPolicy::InflightTracker

Extended by:
ActiveSupport::Concern
Defined in:
lib/dispatch_policy/inflight_tracker.rb

Overview

Around-perform that records each job execution in dispatch_policy_inflight_jobs while it runs, so the concurrency gate can count active jobs per partition.

While the job runs we spawn a heartbeat thread that bumps ‘heartbeat_at` every `config.inflight_heartbeat_interval` seconds. Without this, jobs longer than `inflight_stale_after` (default 5 min) get their inflight row prematurely swept and the concurrency gate over-admits.

Defined Under Namespace

Classes: Heartbeat, ThreadSafeFlag

Constant Summary collapse

HEARTBEAT_KEY =

—– heartbeat thread —–

:__dispatch_policy_heartbeat_token__

Class Method Summary collapse

Class Method Details

.lookup_admitted_at(active_job_id) ⇒ Object

Reads the admitted_at column from the inflight row that the Tick pre-inserted. Used as the start-of-queue-wait reference for the adaptive_concurrency feedback signal (queue_lag = perform_start

  • admitted_at). nil if the row vanished or the lookup fails —

the observation is then skipped.



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# File 'lib/dispatch_policy/inflight_tracker.rb', line 83

def self.lookup_admitted_at(active_job_id)
  result = ActiveRecord::Base.connection.exec_query(
    "SELECT admitted_at FROM dispatch_policy_inflight_jobs WHERE active_job_id = $1 LIMIT 1",
    "lookup_admitted_at",
    [active_job_id]
  )
  row = result.first
  return nil unless row
  ts = row["admitted_at"]
  ts.is_a?(Time) ? ts : Time.parse(ts.to_s)
rescue StandardError
  nil
end

.record_adaptive_observations(policy:, gates:, partition_key:, admitted_at:, perform_start:, succeeded:) ⇒ Object 



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# File 'lib/dispatch_policy/inflight_tracker.rb', line 97

def self.record_adaptive_observations(policy:, gates:, partition_key:, admitted_at:, perform_start:, succeeded:)
  return if gates.empty?

  queue_lag_ms = if admitted_at
    ((perform_start - admitted_at) * 1000).to_i
  else
    # No admitted_at means we can't measure queue wait. Treat as 0
    # so the observation still increments sample_count and the
    # cap can grow if everything else is healthy.
    0
  end

  gates.each do |gate|
    gate.record_observation(
      policy_name:   policy.name,
      partition_key: partition_key,
      queue_lag_ms:  queue_lag_ms,
      succeeded:     succeeded
    )
  rescue StandardError => e
    DispatchPolicy.config.logger&.warn(
      "[dispatch_policy] adaptive observation failed for #{policy.name}/#{partition_key}: #{e.class}: #{e.message}"
    )
  end
end

.start_heartbeat(active_job_id) ⇒ Object 



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# File 'lib/dispatch_policy/inflight_tracker.rb', line 129

def self.start_heartbeat(active_job_id)
  interval = DispatchPolicy.config.inflight_heartbeat_interval.to_f
  return nil if interval <= 0

  stop_flag = Concurrent::AtomicBoolean.new(false) if defined?(Concurrent::AtomicBoolean)
  stop_flag ||= ThreadSafeFlag.new

  thread = Thread.new do
    Thread.current.name = "dispatch_policy.heartbeat:#{active_job_id}"

    until stop_flag.true?
      # Sleep in small slices so stop is responsive without polling tight.
      slept = 0.0
      slice = [interval, 1.0].min
      while slept < interval && !stop_flag.true?
        sleep(slice)
        slept += slice
      end
      break if stop_flag.true?

      begin
        ActiveRecord::Base.connection_pool.with_connection do
          Repository.heartbeat_inflight!(active_job_id: active_job_id)
        end
      rescue StandardError => e
        DispatchPolicy.config.logger&.warn("[dispatch_policy] heartbeat #{active_job_id} failed: #{e.class}: #{e.message}")
      end
    end
  end

  Heartbeat.new(thread, stop_flag)
end

.stop_heartbeat(heartbeat) ⇒ Object 



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# File 'lib/dispatch_policy/inflight_tracker.rb', line 162

def self.stop_heartbeat(heartbeat)
  return if heartbeat.nil?

  heartbeat.stop_flag.make_true
  # Wake the thread out of any in-progress sleep so we don't wait the full slice.
  heartbeat.thread.wakeup if heartbeat.thread.alive?
  heartbeat.thread.join(1.0)
rescue StandardError
  # Worst case: the thread is killed by GC; the inflight row gets a stale
  # heartbeat_at and the sweeper will reclaim it after inflight_stale_after.
end

.track(job) ⇒ Object 



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# File 'lib/dispatch_policy/inflight_tracker.rb', line 24

def self.track(job)
  policy_name = job.class.respond_to?(:dispatch_policy_name) && job.class.dispatch_policy_name
  return yield unless policy_name

  policy = DispatchPolicy.registry.fetch(policy_name)
  return yield unless policy

  # Mirror the stage-time fallback in JobExtension.around_enqueue_for:
  # when the job carries no explicit queue, use the policy's default.
  # Without this, a policy whose partition_by/shard_by reads queue_name
  # would compute a DIFFERENT partition_key here than at admission, so
  # the around_perform inflight row (and adaptive observations) would
  # land under the wrong scope and the concurrency gate's COUNT(*) would
  # miss them.
  queue_name    = job.queue_name&.to_s || policy.queue_name
  ctx           = policy.build_context(job.arguments, queue_name: queue_name)
  partition_key = policy.partition_key_for(ctx)

  Repository.insert_inflight!([{
    policy_name:    policy.name,
    partition_key:  partition_key,
    active_job_id:  job.job_id
  }])

  adaptive_gates = policy.gates.select { |g| g.name == :adaptive_concurrency }
  admitted_at    = adaptive_gates.any? ? lookup_admitted_at(job.job_id) : nil
  perform_start  = Time.current

  heartbeat = start_heartbeat(job.job_id)

  succeeded = false
  begin
    yield
    succeeded = true
  ensure
    stop_heartbeat(heartbeat)

    record_adaptive_observations(
      policy:        policy,
      gates:         adaptive_gates,
      partition_key: partition_key,
      admitted_at:   admitted_at,
      perform_start: perform_start,
      succeeded:     succeeded
    )

    begin
      Repository.delete_inflight!(active_job_id: job.job_id)
    rescue StandardError => e
      DispatchPolicy.config.logger&.warn("[dispatch_policy] failed to delete inflight row #{job.job_id}: #{e.class}: #{e.message}")
    end
  end
end