debian-mirror-gitlab/app/workers/concerns/reenqueuer.rb
2020-08-09 17:44:08 +05:30

99 lines
2.5 KiB
Ruby

# frozen_string_literal: true
#
# A concern that helps run exactly one instance of a worker, over and over,
# until it returns false or raises.
#
# To ensure the worker is always up, you can schedule it every minute with
# sidekiq-cron. Excess jobs will immediately exit due to an exclusive lease.
#
# The worker must define:
#
# - `#perform`
# - `#lease_timeout`
#
# The worker spec should include `it_behaves_like 'reenqueuer'` and
# `it_behaves_like 'it is rate limited to 1 call per'`.
#
# Optionally override `#minimum_duration` to adjust the rate limit.
#
# When `#perform` returns false, the job will not be reenqueued. Instead, we
# will wait for the next one scheduled by sidekiq-cron.
#
# #lease_timeout should be longer than the longest possible `#perform`.
# The lease is normally released in an ensure block, but it is possible to
# orphan the lease by killing Sidekiq, so it should also be as short as
# possible. Consider that long-running jobs are generally not recommended.
# Ideally, every job finishes within 25 seconds because that is the default
# wait time for graceful termination.
#
# Timing: It runs as often as Sidekiq allows. We rate limit with sleep for
# now: https://gitlab.com/gitlab-org/gitlab/issues/121697
module Reenqueuer
extend ActiveSupport::Concern
prepended do
include ExclusiveLeaseGuard
include ReenqueuerSleeper
sidekiq_options retry: false
end
def perform(*args)
try_obtain_lease do
reenqueue(*args) do
ensure_minimum_duration(minimum_duration) do
super
end
end
end
end
private
def reenqueue(*args)
self.class.perform_async(*args) if yield
end
# Override as needed
def minimum_duration
5.seconds
end
module ReenqueuerSleeper
# The block will run, and then sleep until the minimum duration. Returns the
# block's return value.
#
# Usage:
#
# ensure_minimum_duration(5.seconds) do
# # do something
# end
#
def ensure_minimum_duration(minimum_duration)
start_time = Time.current
result = yield
sleep_if_time_left(minimum_duration, start_time)
result
end
private
def sleep_if_time_left(minimum_duration, start_time)
time_left = calculate_time_left(minimum_duration, start_time)
sleep(time_left) if time_left > 0
end
def calculate_time_left(minimum_duration, start_time)
minimum_duration - elapsed_time(start_time)
end
def elapsed_time(start_time)
Time.current - start_time
end
end
end