mperham--sidekiq/lib/sidekiq/processor.rb

# frozen_string_literal: true
require 'sidekiq/util'
require 'sidekiq/fetch'
require 'sidekiq/job_logger'
require 'sidekiq/job_retry'
require 'thread'
require 'concurrent/map'
require 'concurrent/atomic/atomic_fixnum'

module Sidekiq
  ##
  # The Processor is a standalone thread which:
  #
  # 1. fetches a job from Redis
  # 2. executes the job
  #   a. instantiate the Worker
  #   b. run the middleware chain
  #   c. call #perform
  #
  # A Processor can exit due to shutdown (processor_stopped)
  # or due to an error during job execution (processor_died)
  #
  # If an error occurs in the job execution, the
  # Processor calls the Manager to create a new one
  # to replace itself and exits.
  #
  class Processor

    include Util

    attr_reader :thread
    attr_reader :job

    def initialize(mgr)
      @mgr = mgr
      @down = false
      @done = false
      @job = nil
      @thread = nil
      @strategy = (mgr.options[:fetch] || Sidekiq::BasicFetch).new(mgr.options)
      @reloader = Sidekiq.options[:reloader]
      @logging = Sidekiq::JobLogger.new
      @retrier = Sidekiq::JobRetry.new
    end

    def terminate(wait=false)
      @done = true
      return if !@thread
      @thread.value if wait
    end

    def kill(wait=false)
      @done = true
      return if !@thread
      # unlike the other actors, terminate does not wait
      # for the thread to finish because we don't know how
      # long the job will take to finish.  Instead we
      # provide a `kill` method to call after the shutdown
      # timeout passes.
      @thread.raise ::Sidekiq::Shutdown
      @thread.value if wait
    end

    def start
      @thread ||= safe_thread("processor", &method(:run))
    end

    private unless $TESTING

    def run
      begin
        while !@done
          process_one
        end
        @mgr.processor_stopped(self)
      rescue Sidekiq::Shutdown
        @mgr.processor_stopped(self)
      rescue Exception => ex
        @mgr.processor_died(self, ex)
      end
    end

    def process_one
      @job = fetch
      process(@job) if @job
      @job = nil
    end

    def get_one
      begin
        work = @strategy.retrieve_work
        (logger.info { "Redis is online, #{Time.now - @down} sec downtime" }; @down = nil) if @down
        work
      rescue Sidekiq::Shutdown
      rescue => ex
        handle_fetch_exception(ex)
      end
    end

    def fetch
      j = get_one
      if j && @done
        j.requeue
        nil
      else
        j
      end
    end

    def handle_fetch_exception(ex)
      if !@down
        @down = Time.now
        logger.error("Error fetching job: #{ex}")
        ex.backtrace.each do |bt|
          logger.error(bt)
        end
      end
      sleep(1)
      nil
    end

    def dispatch(job_hash, queue)
      # since middleware can mutate the job hash
      # we clone here so we report the original
      # job structure to the Web UI
      pristine = cloned(job_hash)

      @retrier.global(job_hash, queue) do
        @logging.call(job_hash, queue) do
          stats(pristine, queue) do
            # Rails 5 requires a Reloader to wrap code execution.  In order to
            # constantize the worker and instantiate an instance, we have to call
            # the Reloader.  It handles code loading, db connection management, etc.
            # Effectively this block denotes a "unit of work" to Rails.
            @reloader.call do
              klass  = job_hash['class'.freeze].constantize
              worker = klass.new
              worker.jid = job_hash['jid'.freeze]
              @retrier.local(worker, job_hash, queue) do
                yield worker
              end
            end
          end
        end
      end
    end

    def process(work)
      jobstr = work.job
      queue = work.queue_name

      ack = false
      begin
        # Treat malformed JSON like a process crash -- don't acknowledge it.
        # * In Sidekiq, the error will be logged but job discarded.
        # * In Sidekiq Pro, the error will be logged and the job retried when
        #   it is recovered by the reliability algorithm.  The job may act like
        #   a poison pill and never execute until manually removed but job loss
        #   is considered worse.
        job_hash = nil
        begin
          job_hash = Sidekiq.load_json(jobstr)
        rescue => ex
          Sidekiq.logger.error { "Pushing job to dead queue due to invalid JSON: #{ex}" }
          send_to_morgue(jobstr)
          ack = true
          raise
        end

        ack = true
        dispatch(job_hash, queue) do |worker|
          Sidekiq.server_middleware.invoke(worker, job_hash, queue) do
            execute_job(worker, cloned(job_hash['args'.freeze]))
          end
        end
      rescue Sidekiq::Shutdown
        # Had to force kill this job because it didn't finish
        # within the timeout.  Don't acknowledge the work since
        # we didn't properly finish it.
        ack = false
      rescue Exception => ex
        handle_exception(ex, { :context => "Job raised exception", :job => job_hash, :jobstr => jobstr })
        raise
      ensure
        work.acknowledge if ack
      end
    end

    def send_to_morgue(msg)
      now = Time.now.to_f
      Sidekiq.redis do |conn|
        conn.multi do
          conn.zadd('dead', now, msg)
          conn.zremrangebyscore('dead', '-inf', now - DeadSet.timeout)
          conn.zremrangebyrank('dead', 0, -DeadSet.max_jobs)
        end
      end
    end

    def execute_job(worker, cloned_args)
      worker.perform(*cloned_args)
    end

    def thread_identity
      @str ||= Thread.current.object_id.to_s(36)
    end

    WORKER_STATE = Concurrent::Map.new
    PROCESSED = Concurrent::AtomicFixnum.new
    FAILURE = Concurrent::AtomicFixnum.new

    def stats(job_hash, queue)
      tid = thread_identity
      WORKER_STATE[tid] = {:queue => queue, :payload => job_hash, :run_at => Time.now.to_i }

      begin
        yield
      rescue Exception
        FAILURE.increment
        raise
      ensure
        WORKER_STATE.delete(tid)
        PROCESSED.increment
      end
    end

    # Deep clone the arguments passed to the worker so that if
    # the job fails, what is pushed back onto Redis hasn't
    # been mutated by the worker.
    def cloned(thing)
      Marshal.load(Marshal.dump(thing))
    end

  end
end