Class: Watchcat

Inherits:
Object
  • Object
show all
Defined in:
lib/watchcat.rb

Overview

Overview

Ruby/Watchcat is a library for the development of watchcatd-aware applications. It requires watchcatd to be installed and running, and communicates with it via UNIX sockets.

Constant Summary collapse

DEFAULT_TIMEOUT = 
60
DEFAULT_DEVICE = 
'/var/run/watchcat.socket'
DEFAULT_SIGNAL = 
Signal.list['KILL']

Instance Method Summary collapse

Constructor Details

#initialize(args = {}) ⇒ Watchcat

Create a new Watchcat object. The parameter hash may have the following symbols:

timeout

If watchcatd doesn’t receive a heartbeat after this period (in seconds), it will signal the process. (default: 60)

signal

Defines which signal will be sent to the process after the timeout expires. Can be a string like ‘HUP’ or ‘SIGHUP’ or an integer like 9. (default: 9)

info

Should be a string which is added to the log generated by watchcatd when it signals a process. (default: nil)

device

The watchcat device. (default: /var/run/watchcat.socket). Use for debugging purposes.

If a block is given, the Watchcat object will be yielded and automatically closed on block termination.



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# File 'lib/watchcat.rb', line 54

def initialize(args = {}) # :yield:
  timeout = args[:timeout] || DEFAULT_TIMEOUT
  device  = args[:device] || DEFAULT_DEVICE
  info    = args[:info] ? args[:info].to_s : ''

  unless timeout.is_a? Fixnum
    raise ArgumentError, 'timeout must be an integer'
  end

  signal = signal_number(args[:signal])
  @sock  = create_socket(device)
  msg    = build_message(timeout, signal, info)

  safe_write(@sock, msg)
  unless safe_read(@sock, 256) == "ok\n"
    @sock.close
    # Probably not the best error, but it matches libwcat.
    raise Errno::EPERM
  end

  if block_given?
    begin
      yield(self)
    ensure
      @sock.close
    end
  end
  return self
end

Instance Method Details

#close ⇒ Object

Close communication with watchcatd.



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# File 'lib/watchcat.rb', line 91

def close
  begin
    @sock.close
  rescue Errno::EINTR
    retry
  end
  return nil
end

#heartbeat ⇒ Object

Send a heartbeat to watchcatd, telling it we’re still alive.



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# File 'lib/watchcat.rb', line 85

def heartbeat
  safe_write(@sock, '.')
  return nil
end