Class: Consul::Async::ProcessHandler

Inherits:
Object
  • Object
show all
Defined in:
lib/consul/async/process_handler.rb

Overview

Handle the full lifecycle of a process and allows to forward Posix signals to child process when needed.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(command, sig_reload: 'HUP', sig_term: 'TERM') ⇒ ProcessHandler

Returns a new instance of ProcessHandler.



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# File 'lib/consul/async/process_handler.rb', line 12

def initialize(command, sig_reload: 'HUP', sig_term: 'TERM')
  raise 'empty sig_term is not supported' unless sig_term

  @command = command
  @sig_reload = sig_reload
  @sig_term = sig_term
  @pid = nil
  @exit_status = nil
  @last_signal_sent = Time.now
  @reload_scheduled = false
end

Instance Attribute Details

#command ⇒ Object (readonly)

Returns the value of attribute command.



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# File 'lib/consul/async/process_handler.rb', line 10

def command
  @command
end

#exit_status ⇒ Object (readonly)

Returns the value of attribute exit_status.



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# File 'lib/consul/async/process_handler.rb', line 10

def exit_status
  @exit_status
end

#last_signal_sent ⇒ Object (readonly)

Returns the value of attribute last_signal_sent.



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# File 'lib/consul/async/process_handler.rb', line 10

def last_signal_sent
  @last_signal_sent
end

#pid ⇒ Object (readonly)

Returns the value of attribute pid.



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# File 'lib/consul/async/process_handler.rb', line 10

def pid
  @pid
end

#reload_scheduled ⇒ Object

Returns the value of attribute reload_scheduled.



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# File 'lib/consul/async/process_handler.rb', line 10

def reload_scheduled
  @reload_scheduled
end

#sig_reload ⇒ Object (readonly)

Returns the value of attribute sig_reload.



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# File 'lib/consul/async/process_handler.rb', line 10

def sig_reload
  @sig_reload
end

#sig_term ⇒ Object (readonly)

Returns the value of attribute sig_term.



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# File 'lib/consul/async/process_handler.rb', line 10

def sig_term
  @sig_term
end

Instance Method Details

#kill ⇒ Object 



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# File 'lib/consul/async/process_handler.rb', line 45

def kill
  return exit_status if pid.nil?

  the_pid = pid
  @pid = nil
  warn "[KILL] Sending SIG #{sig_term} to #{the_pid}..."
  begin
    warn "[KILL] waiting for #{the_pid}..."
    Process.kill(sig_term, the_pid)
  rescue Errno::ESRCH
    warn "[KILL] *** Process #{the_pid} has already been killed"
  end
  begin
    _pid, @exit_status = Process.waitpid2 the_pid
  rescue SystemCallError
    warn "[KILL] *** UNEXPECTED ERROR *** Failed to get return code for #{the_pid}"
  end
  exit_status
end

#process_status ⇒ Object

Raises:



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# File 'lib/consul/async/process_handler.rb', line 65

def process_status
  raise ProcessDoesNotExist, 'No child process' if pid.nil?

  begin
    cpid, result = Process.waitpid2(pid, Process::WNOHANG)
    raise ProcessDoesNotExist, "Unexpected PID: #{cpid}, was expecting #{pid}" unless cpid.nil? || cpid == pid

    result
  rescue Errno::ECHILD => e
    e2 = ProcessDoesNotExist.new e
    raise e2, "ChildProcess has been killed: #{e.message}", e.backtrace
  end
end

#reload ⇒ Object 



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# File 'lib/consul/async/process_handler.rb', line 31

def reload
  return if sig_reload.nil?

  @last_signal_sent = Time.now
  warn "Sending SIG #{sig_reload} to #{pid}..."
  @reload_scheduled = false
  begin
    Process.kill(sig_reload, pid)
  rescue Errno::ESRCH => e
    warn "*** Process #{pid} has already been killed: #{e.inspect}"
    raise e
  end
end

#start ⇒ Object 



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# File 'lib/consul/async/process_handler.rb', line 24

def start
  return pid unless pid.nil?

  @pid = Process.spawn(command)
  @last_signal_sent = Time.now
end