Class: Async::Container::Notify::Pipe

Inherits:
Client
  • Object
show all
Defined in:
lib/async/container/notify/pipe.rb

Overview

Implements a process readiness protocol using an inherited pipe file descriptor.

Constant Summary collapse

NOTIFY_PIPE =

The environment variable key which contains the pipe file descriptor.

"NOTIFY_PIPE"

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from Client

#error!, #ready!, #reloading!, #restarting!, #status!, #stopping!

Constructor Details

#initialize(io) ⇒ Pipe

Initialize the notification client.



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# File 'lib/async/container/notify/pipe.rb', line 32

def initialize(io)
  @io = io
end

Class Method Details

.open!(environment = ENV) ⇒ Object

Open a notification client attached to the current NOTIFY_PIPE if possible.



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# File 'lib/async/container/notify/pipe.rb', line 20

def self.open!(environment = ENV)
  if descriptor = environment.delete(NOTIFY_PIPE)
    self.new(::IO.for_fd(descriptor.to_i))
  end
rescue Errno::EBADF => error
  Console.error(self) {error}
  
  return nil
end

Instance Method Details

#before_spawn(arguments, options) ⇒ Object

Inserts or duplicates the environment given an argument array. Sets or clears it in a way that is suitable for Process.spawn.



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# File 'lib/async/container/notify/pipe.rb', line 38

def before_spawn(arguments, options)
  environment = environment_for(arguments)
  
  # Use `notify_pipe` option if specified:
  if notify_pipe = options.delete(:notify_pipe)
    options[notify_pipe] = @io
    environment[NOTIFY_PIPE] = notify_pipe.to_s
    
  # Use stdout if it's not redirected:
  # This can cause issues if the user expects stdout to be connected to a terminal.
  # elsif !options.key?(:out)
  #  options[:out] = @io
  #  environment[NOTIFY_PIPE] = "1"
    
  # Use fileno 3 if it's available:
  elsif !options.key?(3)
    options[3] = @io
    environment[NOTIFY_PIPE] = "3"
    
  # Otherwise, give up!
  else
    raise ArgumentError, "Please specify valid file descriptor for notify_pipe!"
  end
end

#send(**message) ⇒ Object

Formats the message using JSON and sends it to the parent controller. This is suitable for use with Channel.



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# File 'lib/async/container/notify/pipe.rb', line 65

def send(**message)
  data = ::JSON.dump(message) << "\n"
  
  @io.write(data)
  @io.flush
end