Class: ZMQ::Context

Inherits:
Object
  • Object
show all
Defined in:
lib/ffi-rzmq/context.rb

Overview

Recommended to use the default for io_threads since most programs will not saturate I/O.

The rule of thumb is to make io_threads equal to the number gigabits per second that the application will produce.

The io_threads number specifies the size of the thread pool allocated by 0mq for processing incoming/outgoing messages.

Returns a context object when allocation succeeds. It’s necessary for passing to the #Socket constructor when allocating new sockets. All sockets live within a context.

Also, Sockets should only be accessed from the thread where they were first created. Do not pass sockets between threads; pass in the context and allocate a new socket per thread. If you must use threads, then make sure to execute a full memory barrier (e.g. mutex) as you pass a socket from one thread to the next.

To connect sockets between contexts, use inproc or ipc transport and set up a 0mq socket between them. This is also the recommended technique for allowing sockets to communicate between threads.

context = ZMQ::Context.create
if context
  socket = context.socket(ZMQ::REQ)
  if socket
    ...
  else
    STDERR.puts "Socket allocation failed"
  end
else
  STDERR.puts "Context allocation failed"
end

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(opts = {}) ⇒ Context

Returns a new instance of Context.



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# File 'lib/ffi-rzmq/context.rb', line 54

def initialize(opts = {})
  if opts.respond_to?(:empty?)
    @io_threads = opts[:io_threads] || IO_THREADS_DFLT
    @max_sockets = opts[:max_sockets] || MAX_SOCKETS_DFLT
  else
    @io_threads = opts || 1
    @max_sockets = MAX_SOCKETS_DFLT
  end

  @context = LibZMQ.zmq_ctx_new
  ZMQ::Util.error_check 'zmq_ctx_new', (@context.nil? || @context.null?) ? -1 : 0

  rc = LibZMQ.zmq_ctx_set(@context, ZMQ::IO_THREADS, @io_threads)
  ZMQ::Util.error_check 'zmq_ctx_set', rc

  rc = LibZMQ.zmq_ctx_set(@context, ZMQ::MAX_SOCKETS, @max_sockets)
  ZMQ::Util.error_check 'zmq_ctx_set', rc

  define_finalizer
end

Instance Attribute Details

#context ⇒ Object (readonly) Also known as: pointer

Returns the value of attribute context.



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# File 'lib/ffi-rzmq/context.rb', line 45

def context
  @context
end

#io_threads ⇒ Object (readonly)

Returns the value of attribute io_threads.



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# File 'lib/ffi-rzmq/context.rb', line 45

def io_threads
  @io_threads
end

#max_sockets ⇒ Object (readonly)

Returns the value of attribute max_sockets.



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# File 'lib/ffi-rzmq/context.rb', line 45

def max_sockets
  @max_sockets
end

Class Method Details

.create(opts = {}) ⇒ Object

Use the factory method Context#create to make contexts.



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# File 'lib/ffi-rzmq/context.rb', line 50

def self.create(opts = {})
  new(opts) rescue nil
end

Instance Method Details

#socket(type) ⇒ Object

Short-cut to allocate a socket for a specific context.

Takes several type values:

#ZMQ::REQ
#ZMQ::REP
#ZMQ::PUB
#ZMQ::SUB
#ZMQ::PAIR
#ZMQ::PULL
#ZMQ::PUSH
#ZMQ::DEALER
#ZMQ::ROUTER

Returns a #ZMQ::Socket when the allocation succeeds, nil if it fails.



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# File 'lib/ffi-rzmq/context.rb', line 109

def socket type
  sock = nil
  begin
    sock = Socket.new @context, type
  rescue ContextError => e
    sock = nil
  end

  sock
end

#terminate ⇒ Object

Call to release the context and any remaining data associated with past sockets. This will close any sockets that remain open; further calls to those sockets will return -1 to indicate the operation failed.

Returns 0 for success, -1 for failure.



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# File 'lib/ffi-rzmq/context.rb', line 82

def terminate
  unless @context.nil? || @context.null?
    remove_finalizer
    rc = LibZMQ.terminate_context(@context)
    @context = nil
    rc || 0
  else
    0
  end
end