class Async::Container::Notify::Socket

Implements the systemd NOTIFY_SOCKET process readiness protocol. See <www.freedesktop.org/software/systemd/man/sd_notify.html> for more details of the underlying protocol.

Constants

MAXIMUM_MESSAGE_SIZE

The maximum allowed size of the UDP message.

NOTIFY_SOCKET

The name of the environment variable which contains the path to the notification socket.

Public Class Methods

new(path) click to toggle source

Initialize the notification client. @parameter path [String] The path to the UNIX socket used for sending messages to the process manager.

# File lib/async/container/notify/socket.rb, line 50
def initialize(path)
        @path = path
        @endpoint = IO::Endpoint.unix(path, ::Socket::SOCK_DGRAM)
end
open!(environment = ENV) click to toggle source

Open a notification client attached to the current {NOTIFY_SOCKET} if possible.

# File lib/async/container/notify/socket.rb, line 42
def self.open!(environment = ENV)
        if path = environment.delete(NOTIFY_SOCKET)
                self.new(path)
        end
end

Public Instance Methods

dump(message) click to toggle source

Dump a message in the format requied by `sd_notify`. @parameter message [Hash] Keys and values should be string convertible objects. Values which are `true`/`false` are converted to `1`/`0` respectively.

# File lib/async/container/notify/socket.rb, line 57
def dump(message)
        buffer = String.new
        
        message.each do |key, value|
                # Conversions required by NOTIFY_SOCKET specifications:
                if value == true
                        value = 1
                elsif value == false
                        value = 0
                end
                
                buffer << "#{key.to_s.upcase}=#{value}\n"
        end
        
        return buffer
end
error!(text, **message) click to toggle source

Send the specified error. `sd_notify` requires an `errno` key, which defaults to `-1` to indicate a generic error.

# File lib/async/container/notify/socket.rb, line 92
def error!(text, **message)
        message[:errno] ||= -1
        
        send(status: text, **message)
end
send(**message) click to toggle source

Send the given message. @parameter message [Hash]

# File lib/async/container/notify/socket.rb, line 76
def send(**message)
        data = dump(message)
        
        if data.bytesize > MAXIMUM_MESSAGE_SIZE
                raise ArgumentError, "Message length #{message.bytesize} exceeds #{MAXIMUM_MESSAGE_SIZE}: #{message.inspect}"
        end
        
        Sync do
                @endpoint.connect do |peer|
                        peer.send(data)
                end
        end
end