Module: Legion::Extensions::MicrosoftTeams::Helpers::ThrottleAware

Included in:
Actor::ApiIngest, Actor::MeetingIngest, Actor::PresencePoller
Defined in:
lib/legion/extensions/microsoft_teams/helpers/throttle_aware.rb

Overview

Mixin that lets an Actors::Every-style poller honour a Graph throttle by deferring its own next run instead of re-firing on its fixed timer interval.

Background: Faraday::RetryAfter raises Errors::Throttled centrally when it exhausts retries (or when the advertised wait alone exceeds the retry budget), and Faraday::ThrottleCircuit opens a shared circuit so the whole fleet stops hammering a quota that Graph has already flagged. But the actors that drive those calls schedule themselves with a Concurrent::TimerTask whose execution_interval is fixed at boot. Catching Throttled in a rescue block stops the current tick, but the next tick still fires on the original cadence — so a poller on a 30–300s interval keeps walking straight back into an open circuit, emitting an ERROR every interval and contributing nothing but log noise (and, via the shared circuit, refreshing the block for cheaper callers).

This mixin closes that gap. An actor wraps its Graph work in #with_throttle_deferral. On Errors::Throttled it records a "suppress until" instant of now + retry_after (falling back to a bounded default when the server gave no usable Retry-After). Subsequent ticks short-circuit via #throttle_suppressed? until that instant passes, so the actor effectively reschedules itself at now + retry_after rather than now + interval — exactly the behaviour the throttle integration spec and the 0.6.51 CHANGELOG flagged as the outstanding follow-up.

State is per-actor-instance and guarded by a monitor because an actor's manual runs on a Concurrent thread-pool worker. The mixin reads the carried retry_after only when retry_after_known? is true; otherwise it applies DEFAULT_DEFERRAL so a throttle with a missing/garbage header still backs the poller off rather than letting it spin.

Constant Summary collapse

DEFAULT_DEFERRAL =

Fallback deferral (seconds) used when a Throttled carries no usable retry_after (header absent or unparseable). One minute matches Microsoft Graph's documented typical Retry-After and the circuit middleware's DEFAULT_FALLBACK_TTL.

60.0
MAX_DEFERRAL =

Hard ceiling (seconds) on a single deferral so a pathological advertised Retry-After can't park a poller for an unbounded time. Mirrors the circuit middleware's 600s cap in ThrottleCircuit#set_hard_circuit.

600.0

Instance Method Summary collapse

Instance Method Details

#defer_for(seconds, now: Time.now) ⇒ Object

Open (or extend) a deferral window of seconds from now. A later throttle never shortens an existing window — we keep the furthest-out instant so overlapping throttles compose safely.



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# File 'lib/legion/extensions/microsoft_teams/helpers/throttle_aware.rb', line 103

def defer_for(seconds, now: Time.now)
  window = clamp_deferral(seconds)
  target = now + window
  throttle_monitor.synchronize do
    @throttled_until = if @throttled_until.nil? || target > @throttled_until
                         target
                       else
                         @throttled_until
                       end
  end
  window
end

#reset_throttle_deferral ⇒ Object

Clear any active deferral. Called implicitly is unnecessary — #throttle_suppressed? expires on its own once the clock passes throttled_until — but exposed for tests and explicit resets.



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# File 'lib/legion/extensions/microsoft_teams/helpers/throttle_aware.rb', line 119

def reset_throttle_deferral
  throttle_monitor.synchronize { @throttled_until = nil }
end

#throttle_remaining(now: Time.now) ⇒ Object

Seconds remaining in the current deferral window (0.0 if none / elapsed). Useful for logging and for tests.



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# File 'lib/legion/extensions/microsoft_teams/helpers/throttle_aware.rb', line 92

def throttle_remaining(now: Time.now)
  until_at = throttled_until
  return 0.0 if until_at.nil?

  remaining = until_at - now
  remaining.positive? ? remaining : 0.0
end

#throttle_suppressed?(now: Time.now) ⇒ Boolean

Returns true while the actor is inside a deferral window opened by a previous throttle.

Returns:

  • (Boolean) —

    true while the actor is inside a deferral window opened by a previous throttle.



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# File 'lib/legion/extensions/microsoft_teams/helpers/throttle_aware.rb', line 79

def throttle_suppressed?(now: Time.now)
  until_at = throttled_until
  !until_at.nil? && now < until_at
end

#throttled_until ⇒ Object

The instant before which the actor should not poll again, or nil if no deferral is active. Thread-safe read.



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# File 'lib/legion/extensions/microsoft_teams/helpers/throttle_aware.rb', line 86

def throttled_until
  throttle_monitor.synchronize { @throttled_until }
end

#with_throttle_deferral(now: Time.now) ⇒ Object?

Run block unless the actor is currently deferring after a recent throttle. If a Throttled escapes the block, record the deferral window and swallow it (the throttle has already been logged at the middleware/circuit layer; re-raising would just trip the actor's generic rescue StandardError and double-log).

Parameters:

  • now (Time) (defaults to: Time.now) —

    injectable clock for deterministic tests

Returns:

  • (Object, nil) —

    the block's value, or nil when suppressed or when a throttle was caught



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# File 'lib/legion/extensions/microsoft_teams/helpers/throttle_aware.rb', line 65

def with_throttle_deferral(now: Time.now)
  if throttle_suppressed?(now: now)
    log_throttle_skip(now: now)
    return nil
  end

  yield
rescue Legion::Extensions::MicrosoftTeams::Errors::Throttled => e
  defer_after_throttle(e, now: now)
  nil
end