Class: Nodule::ZeroMQ

Inherits:
Tempfile show all
Defined in:
lib/nodule/zeromq.rb

Overview

A resource for setting up and testing ZeroMQ message flows. The most basic usage will provide auto-generated IPC URI’s, which can be handy for testing. More advanced usage uses the built-in tap device to sniff messages while they’re in-flight.

Instance Attribute Summary collapse

Attributes inherited from Tempfile

#file

Attributes inherited from Base

#prefix, #read_count, #readers, #running, #topology

Instance Method Summary collapse

Methods inherited from Tempfile

#touch

Methods inherited from Base

#add_reader, #add_readers, #clear!, #join_topology!, #output, #output!, #output?, #read_until, #require_read_count, #run_readers, #verbose, #wait_with_backoff

Constructor Details

#initialize(opts) ⇒ ZeroMQ

:connect and :bind are allowed at the same time and must be of the same socket type. ZMQ::SUB sockets that are connected/bound will subscribe to “” by default.

For the rest of the options, see Hastur::Test::Resource::Base.

Parameters:

  • opts (Hash{Symbol => Object}) —

    named parameters

  • [String] (Hash) —

    a customizable set of options

  • [Fixnum] (Hash) —

    a customizable set of options

  • [String,Symbol] (Hash) —

    a customizable set of options



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# File 'lib/nodule/zeromq.rb', line 43

def initialize(opts)
  opts[:suffix] ||= '.zmq'

  super(opts)

  @ctx = ::ZMQ::Context.new
  @zmq_thread = nil
  @error_count = 0
  @sockprocs = []
  @limit = nil
  @timeout_started = false
  @stopped = false

  # Sockets cannot be used across thread boundaries, so use a ZMQ::PAIR socket both to synchronize thread
  # startup and pass writes form main -> thread. The .socket method will return the PAIR socket.
  @pipe_uri = "inproc://pair-#{Nodule.next_seq}"
  @pipe = @ctx.socket(::ZMQ::PAIR)
  @child = @ctx.socket(::ZMQ::PAIR)
  setsockopt(@pipe, :hwm, 1)
  setsockopt(@child, :hwm, 1)
  setsockopt(@pipe, ::ZMQ::LINGER, 1.0)
  setsockopt(@child, ::ZMQ::LINGER, 1.0)
  @pipe.bind(@pipe_uri)
  @child.connect(@pipe_uri)

  case opts[:uri]
    # Socket files are specified so they land in PWD, in the future we might want to specify a temp
    # dir, but that has a whole different bag of issues, so stick with simple until it's needed.
    when :gen, :generate
      @uri = "ipc://#{@file.to_s}"
    when String
      @uri = opts[:uri]
    else
      raise ArgumentError.new "Invalid URI specifier: (#{opts[:uri].class}) '#{opts[:uri]}'"
  end

  if opts[:connect] and opts[:bind] and opts[:connect] != opts[:bind]
    raise ArgumentError.new "ZMQ socket types must be the same when enabling :bind and :connect"
  end

  # only set type and create a socket if :bind or :connect is specified
  # otherwise, the caller probably just wants to generate a URI, or possibly
  # use a pre-created socket? (not supported yet)
  if @type = (opts[:connect] || opts[:bind])
    @socket = @ctx.socket(@type)
    setsockopt(@socket, :hwm, 1)
    setsockopt(@socket, ::ZMQ::LINGER, 1.0)

    if opts[:connect]
      @sockprocs << proc { @socket.connect(@uri) } # deferred
    end

    if opts[:bind]
      @sockprocs << proc { @socket.bind(@uri) } # deferred
    end

    # by default, subscribe to "" on ZMQ::SUB sockets, since that's what we want
    # the vast majority of the time. Also allow specifying a subscription for those
    # times we want something else.
    if @type == ::ZMQ::SUB
      if opts[:subscribe]
        @sockprocs << proc { subscribe(opts[:subscribe]) }
      else
        @sockprocs << proc { subscribe("") }
      end
    end
  end

  if opts[:limit]
    @limit = opts[:limit]
  end
end

Instance Attribute Details

#ctx ⇒ Object (readonly)

Returns the value of attribute ctx.



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# File 'lib/nodule/zeromq.rb', line 12

def ctx
  @ctx
end

#error_count ⇒ Object (readonly)

Returns the value of attribute error_count.



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# File 'lib/nodule/zeromq.rb', line 12

def error_count
  @error_count
end

#limit ⇒ Object (readonly)

Returns the value of attribute limit.



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# File 'lib/nodule/zeromq.rb', line 12

def limit
  @limit
end

#method ⇒ Object (readonly)

Returns the value of attribute method.



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# File 'lib/nodule/zeromq.rb', line 12

def method
  @method
end

#type ⇒ Object (readonly)

Returns the value of attribute type.



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# File 'lib/nodule/zeromq.rb', line 12

def type
  @type
end

#uri ⇒ Object (readonly)

Returns the value of attribute uri.



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# File 'lib/nodule/zeromq.rb', line 12

def uri
  @uri
end

Instance Method Details

#done? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/nodule/zeromq.rb', line 151

def done?
  @stopped
end

#run ⇒ Object 



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# File 'lib/nodule/zeromq.rb', line 116

def run
  super
  return if @sockprocs.empty?

  # wrap the block in a block so errors don't simply vanish until join time
  @zmq_thread = Thread.new do
    Thread.current.abort_on_exception

    # sockets have to be created inside the thread that uses them
    @sockprocs.each { |p| p.call }

    _zmq_read()
    verbose "child thread #{Thread.current} shutting down"

    @child.close
    @socket.close if @socket
  end

  Thread.pass

  @stopped = @zmq_thread.alive? ? false : true
end

#socket ⇒ Object 



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# File 'lib/nodule/zeromq.rb', line 139

def socket
  @pipe
end

#stop ⇒ Object

send a message to the child thread telling it to exit and join the thread



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# File 'lib/nodule/zeromq.rb', line 197

def stop
  return if @stopped

  @pipe.send_strings(["exit"], 1)

  Thread.pass

  super

  @zmq_thread.join if @zmq_thread
  @pipe.close if @pipe

  @stopped = true
end

#stop! ⇒ Object

If the thread is still alive, force an exception in the thread and continue to do the things stop does.



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# File 'lib/nodule/zeromq.rb', line 179

def stop!
  if @zmq_thread.alive?
    STDERR.puts "force stop! called, issuing Thread.raise"
    @zmq_thread.raise "force stop! called"
  end

  stop
  wait 1

  @zmq_thread.join if @zmq_thread
  @pipe.close if @pipe

  @stopped = true
end

#subscribe(subscription) ⇒ Object

For PUB sockets only, subscribe to a prefix.

Parameters:

  • subscription (String) —

    prefix, usually “”



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# File 'lib/nodule/zeromq.rb', line 147

def subscribe(subscription)
  @pipe.send_strings ["subscribe", subscription]
end

#to_s ⇒ Object

Return the URI generated/provided for this resource. For tapped devices, the “front” side of the tap is returned.



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# File 'lib/nodule/zeromq.rb', line 216

def to_s
  @uri
end

#wait(timeout = 60) ⇒ Object

Wait for the ZMQ thread to exit on its own, mostly useful with :limit => Fixnum.

This does not signal the child thread.



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# File 'lib/nodule/zeromq.rb', line 160

def wait(timeout=60)
  countdown = timeout.to_f

  while countdown > 0
    if @zmq_thread and @zmq_thread.alive?
      sleep 0.1
      countdown = countdown - 0.1
    else
      break
    end
  end

  super()
end