Class: Snipr::ProcessSignaller

Inherits:
Object
  • Object
show all
Extended by:
Forwardable
Defined in:
lib/snipr/process_signaller.rb

Overview

Class that can send signals to targetted processes or their parent processes and invoke callbacks around the actions. Delegates process location to a ProcessLocator. Is configured using a block on initialization as follows:

signaller = ProcessSignaller.new do |signaller|

signaller.include       /resque/
signaller.exclude       /scheduler/
signaller.signal        "USR1"
signaller.target_parent false
singaller.dry_run

signaller.on_no_processes do
  puts "No processes"
end

signaller.before_signal do |signal, process|
  puts "Sending #{signal} to #{process.pid}"
end

signaller.after_signal do |signal, process|
  puts "Sent #{signal} to #{process.pid}"
end

signaller.on_error do |e, signal, process|
  puts "Ooops, got #{e} sending #{signal} to #{process.pid}"
end

end

signaller.send_signals

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(&block) ⇒ ProcessSignaller 



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# File 'lib/snipr/process_signaller.rb', line 44

def initialize(&block)
  @locator = ProcessLocator.new
  on_no_processes {}
  before_signal {}
  after_signal {}
  on_error {|e, process, signal| raise e}
  block.call(self)
end

Instance Attribute Details

#locator(locator = nil) ⇒ Object

Specify or access the locator collaborator that is responsible for collecting the processes to operate on



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# File 'lib/snipr/process_signaller.rb', line 86

def locator(locator=nil)
  @locator ||= (locator || ProcessLocator.new)
end

#signal(signal) ⇒ Object (readonly)

Specify the signal to send to the targetted processes. This should be a string that maps one of the values listed here:

ruby-doc.org/core-1.8.7/Signal.html#method-c-list



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# File 'lib/snipr/process_signaller.rb', line 75

def signal
  @signal
end

Instance Method Details

#after_signal(&callback) ⇒ Object

Callback invoked immediately after sending a signal to a process. Will send both the signal and the KernelProcess object as returned by the locator.



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# File 'lib/snipr/process_signaller.rb', line 108

def after_signal(&callback)
  @after_signal = callback
end

#before_signal(&callback) ⇒ Object

Callback invoked immediately before sending a signal to a process. Will send both the signal and the KernelProcess object as returned by the locator.



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# File 'lib/snipr/process_signaller.rb', line 100

def before_signal(&callback)
  @before_signal = callback
end

#dry_run ⇒ Object

Invoke if you want to have callbacks invoked, but not actually send signals to located processes.



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# File 'lib/snipr/process_signaller.rb', line 131

def dry_run
  @dry_run = true
end

#on_error(&callback) ⇒ Object

Callback invoked if an error is encountered. If this is within the context of attempting to send a signal to a process, then the exception, signal and KernelProcess object are sent. Otherwise, only the exception is sent.



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# File 'lib/snipr/process_signaller.rb', line 117

def on_error(&callback)
  @on_error = callback
end

#on_no_processes(&callback) ⇒ Object

Callback invoked when no processes are found



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# File 'lib/snipr/process_signaller.rb', line 92

def on_no_processes(&callback)
  @on_no_processes = callback
end

#send_signals ⇒ Object

Send the specified signal to all located processes, invoking callbacks as appropriate.



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# File 'lib/snipr/process_signaller.rb', line 56

def send_signals
  processes = @locator.locate

  if processes.empty?
    @on_no_processes.call
  else
    processes.each do |process|
      signal_process(process)
    end
  end
rescue StandardError => e
  @on_error.call(e)
end

#target_parent(flag = false) ⇒ Object

Set to true if the signal should be sent to the parent of any located processes. Defaults to false.



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# File 'lib/snipr/process_signaller.rb', line 124

def target_parent(flag=false)
  @target_parent = flag
end