Class: Sidekiq::Fetcher

Inherits:
Object
  • Object
show all
Includes:
Celluloid, Util
Defined in:
lib/sidekiq/fetch.rb

Overview

The Fetcher blocks on Redis, waiting for a message to process from the queues. It gets the message and hands it to the Manager to assign to a ready Processor.

Constant Summary collapse

TIMEOUT = 
1

Instance Method Summary collapse

Methods included from Util

#constantize, logger, #logger, logger=, #process_id, #redis, #watchdog

Constructor Details

#initialize(mgr, queues) ⇒ Fetcher

Returns a new instance of Fetcher.



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# File 'lib/sidekiq/fetch.rb', line 15

def initialize(mgr, queues)
  @mgr = mgr
  @queues = queues.map { |q| "queue:#{q}" }
  @unique_queues = @queues.uniq
end

Instance Method Details

#fetch ⇒ Object

Fetching is straightforward: the Manager makes a fetch request for each idle processor when Sidekiq starts and then issues a new fetch request every time a Processor finishes a message.

Because we have to shut down cleanly, we can’t block forever and we can’t loop forever. Instead we reschedule a new fetch if the current fetch turned up nothing.



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# File 'lib/sidekiq/fetch.rb', line 29

def fetch
  watchdog('Fetcher#fetch died') do
    begin
      queue = nil
      msg = nil
      Sidekiq.redis { |conn| queue, msg = conn.blpop(*queues_cmd) }

      if msg
        @mgr.assign!(msg, queue.gsub(/.*queue:/, ''))
      else
        after(0) { fetch }
      end
    rescue => ex
      logger.error("Error fetching message: #{ex}")
      logger.error(ex.backtrace.first)
      sleep(TIMEOUT)
      after(0) { fetch }
    end
  end
end