class Sidekiq::Capsule

end
end
cap.queues = %w(single)
cap.concurrency = 1
config.capsule(“single-threaded”) do |cap|
Sidekiq.configure_server do |config|
the jobs with one thread, meaning the jobs will be processed serially.
This capsule will pull jobs from the “single” queue and process
Capsules in their initializer.
One “default” Capsule is started but the user may declare additional
process one or more queues with a given concurrency.
A Sidekiq::Capsule is the set of resources necessary to

def client_middleware

capsules share the same chains. Easier to debug that way.
Avoid if possible and add middleware globally so all
Allow the middleware to be different per-capsule. 
def client_middleware
  @client_chain ||= config.client_middleware.copy_for(self)
  yield @client_chain if block_given?
  @client_chain
end

def fetcher 

def fetcher
  @fetcher ||= begin
    inst = (config[:fetch_class] || Sidekiq::BasicFetch).new(self)
    inst.setup(config[:fetch_setup]) if inst.respond_to?(:setup)
    inst
  end
end

def initialize(name, config) 

def initialize(name, config)
  @name = name
  @config = config
  @queues = ["default"]
  @weights = {"default" => 0}
  @concurrency = config[:concurrency]
  @mode = :strict
end

def local_redis_pool 

def local_redis_pool
  # connection pool is lazy, it will not create connections unless you actually need them
  # so don't be skimpy!
  @redis ||= config.new_redis_pool(@concurrency, name)
end

def logger 

def logger
  config.logger
end

def lookup(name) 

def lookup(name)
  config.lookup(name)
end

def queues=(val)

- :random - all queues have weight of 1
- :weighted - queues have arbitrary weight between 1 and N
- :strict - all queues have 0 weight and are checked strictly in order
Sidekiq checks queues in three modes: 
def queues=(val)
  @weights = {}
  @queues = Array(val).each_with_object([]) do |qstr, memo|
    arr = qstr
    arr = qstr.split(",") if qstr.is_a?(String)
    name, weight = arr
    @weights[name] = weight.to_i
    [weight.to_i, 1].max.times do
      memo << name
    end
  end
  @mode = if @weights.values.all?(&:zero?)
    :strict
  elsif @weights.values.all? { |x| x == 1 }
    :random
  else
    :weighted
  end
end

def redis 

def redis
  raise ArgumentError, "requires a block" unless block_given?
  redis_pool.with do |conn|
    retryable = true
    begin
      yield conn
    rescue RedisClientAdapter::BaseError => ex
      # 2550 Failover can cause the server to become a replica, need
      # to disconnect and reopen the socket to get back to the primary.
      # 4495 Use the same logic if we have a "Not enough replicas" error from the primary
      # 4985 Use the same logic when a blocking command is force-unblocked
      # The same retry logic is also used in client.rb
      if retryable && ex.message =~ /READONLY|NOREPLICAS|UNBLOCKED/
        conn.close
        retryable = false
        retry
      end
      raise
    end
  end
end

def redis_pool 

def redis_pool
  Thread.current[:sidekiq_redis_pool] || local_redis_pool
end

def server_middleware 

def server_middleware
  @server_chain ||= config.server_middleware.copy_for(self)
  yield @server_chain if block_given?
  @server_chain
end

def stop 

def stop
  fetcher&.bulk_requeue([])
end