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# frozen_string_literal: true
module Karafka
# Class used to catch signals from ruby Signal class in order to manage Karafka stop
# @note There might be only one process - this class is a singleton
class Process
# Signal types that we handle
HANDLED_SIGNALS = %i[
SIGINT
SIGQUIT
SIGTERM
SIGTTIN
].freeze
HANDLED_SIGNALS.each do |signal|
# Assigns a callback that will happen when certain signal will be send
# to Karafka server instance
# @note It does not define the callback itself -it needs to be passed in a block
# @example Define an action that should be taken on_sigint
# process.on_sigint do
# Karafka.logger.info('Log something here')
# exit
# end
define_method :"on_#{signal.to_s.downcase}" do |&block|
@callbacks[signal] << block
end
end
# Creates an instance of process and creates empty hash for callbacks
def initialize
@callbacks = Hash.new { |hsh, key| hsh[key] = [] }
end
# Method catches all HANDLED_SIGNALS and performs appropriate callbacks (if defined)
# @note If there are no callbacks, this method will just ignore a given signal that was sent
def supervise
HANDLED_SIGNALS.each { |signal| trap_signal(signal) }
end
private
# Traps a single signal and performs callbacks (if any) or just ignores this signal
# @param [Symbol] signal type that we want to catch
def trap_signal(signal)
trap(signal) do
notice_signal(signal)
(@callbacks[signal] || []).each(&:call)
end
end
# Informs monitoring about trapped signal
# @param [Symbol] signal type that we received
# @note We cannot perform logging from trap context, that's why
# we have to spin up a new thread to do this
def notice_signal(signal)
Thread.new do
Karafka.monitor.instrument('process.notice_signal', caller: self, signal: signal)
end
end
end
end
Version data entries
16 entries across 16 versions & 1 rubygems