eventlet.green.zmq – ØMQ support

The zmq module wraps the Socket and Context found in pyzmq to be non blocking

eventlet.green.zmq.Context(io_threads=1)

Factory function replacement for zmq.core.context.Context

This factory ensures the zeromq hub is the active hub, and defers creation (or retreival) of the Context to the hub’s get_context() method

It’s a factory function due to the fact that there can only be one _Context instance per thread. This is due to the way zmq.core.poll.Poller works

class eventlet.green.zmq._Context

Bases: zmq.core.context.Context

Internal subclass of zmq.core.context.Context

socket(socket_type)

Overridden method to ensure that the green version of socket is used

Behaves the same as zmq.core.context.Context.socket(), but ensures that a Socket with all of its send and recv methods set to be non-blocking is returned

class eventlet.green.zmq.Socket

Bases: zmq.core.socket.Socket

Green version of :class:`zmq.core.socket.Socket

The following four methods are overridden:

  • _send_message
  • _send_copy
  • _recv_message
  • _recv_copy

To ensure that the zmq.NOBLOCK flag is set and that sending or recieving is deferred to the hub (using eventlet.hubs.trampoline()) if a zmq.EAGAIN (retry) error is raised

recv(flags=0, copy=True, track=False)

Override this instead of the internal _recv_* methods since those change and it’s not clear when/how they’re called in real code.

send(msg, flags=0, copy=True, track=False)

Override this instead of the internal _send_* methods since those change and it’s not clear when/how they’re called in real code.

bind(addr)

Bind the socket to an address.

This causes the socket to listen on a network port. Sockets on the other side of this connection will use Socket.connect(addr) to connect to this socket.

addr : str
The address string. This has the form ‘protocol://interface:port’, for example ‘tcp://127.0.0.1:5555’. Protocols supported include tcp, udp, pgm, epgm, inproc and ipc. If the address is unicode, it is encoded to utf-8 first.
bind_to_random_port(addr, min_port=49152, max_port=65536, max_tries=100)

Bind this socket to a random port in a range.

addr : str
The address string without the port to pass to Socket.bind().
min_port : int, optional
The minimum port in the range of ports to try (inclusive).
max_port : int, optional
The maximum port in the range of ports to try (exclusive).
max_tries : int, optional
The maximum number of bind attempts to make.
port : int
The port the socket was bound to.
ZMQBindError
if max_tries reached before successful bind
close(linger=None)

Close the socket.

If linger is specified, LINGER sockopt will be set prior to closing.

This can be called to close the socket by hand. If this is not called, the socket will automatically be closed when it is garbage collected.

connect(addr)

Connect to a remote 0MQ socket.

addr : str
The address string. This has the form ‘protocol://interface:port’, for example ‘tcp://127.0.0.1:5555’. Protocols supported are tcp, upd, pgm, inproc and ipc. If the address is unicode, it is encoded to utf-8 first.
getsockopt(option)

Get the value of a socket option.

See the 0MQ API documentation for details on specific options.

option : int

The option to get. Available values will depend on your version of libzmq. Examples include:

zmq.IDENTITY, HWM, LINGER, FD, EVENTS
optval : int or bytes
The value of the option as a bytestring or int.
getsockopt_string(option, encoding='utf-8')

Get the value of a socket option.

See the 0MQ documentation for details on specific options.

option : int
The option to retrieve. Currently, IDENTITY is the only gettable option that can return a string.
optval : unicode string (unicode on py2, str on py3)
The value of the option as a unicode string.
getsockopt_unicode(option, encoding='utf-8')

s.getsockopt_string(option, encoding=’utf-8’)

Get the value of a socket option.

See the 0MQ documentation for details on specific options.

option : int
The option to retrieve. Currently, IDENTITY is the only gettable option that can return a string.
optval : unicode string (unicode on py2, str on py3)
The value of the option as a unicode string.
poll(timeout=None, flags=POLLIN)

Poll the socket for events. The default is to poll forever for incoming events. Timeout is in milliseconds, if specified.

timeout : int [default: None]
The timeout (in milliseconds) to wait for an event. If unspecified (or secified None), will wait forever for an event.
flags : bitfield (int) [default: POLLIN]
The event flags to poll for (any combination of POLLIN|POLLOUT). The default is to check for incoming events (POLLIN).
events : bitfield (int)
The events that are ready and waiting. Will be 0 if no events were ready by the time timeout was reached.
recv(flags=0, copy=True, track=False)

Override this instead of the internal _recv_* methods since those change and it’s not clear when/how they’re called in real code.

recv_json(flags=0)

Receive a Python object as a message using json to serialize.

flags : int
Any valid recv flag.
obj : Python object
The Python object that arrives as a message.
recv_multipart(flags=0, copy=True, track=False)

Receive a multipart message as a list of bytes or Frame objects.

flags : int, optional
Any supported flag: NOBLOCK. If NOBLOCK is set, this method will raise a ZMQError with EAGAIN if a message is not ready. If NOBLOCK is not set, then this method will block until a message arrives.
copy : bool, optional
Should the message frame(s) be received in a copying or non-copying manner? If False a Frame object is returned for each part, if True a copy of the bytes is made for each frame.
track : bool, optional
Should the message frame(s) be tracked for notification that ZMQ has finished with it? (ignored if copy=True)
msg_parts : list
A list of frames in the multipart message; either Frames or bytes, depending on copy.
recv_pyobj(flags=0)

Receive a Python object as a message using pickle to serialize.

flags : int
Any valid recv flag.
obj : Python object
The Python object that arrives as a message.
recv_string(flags=0, encoding='utf-8')

Receive a unicode string, as sent by send_string.

flags : int
Any valid recv flag.
encoding : str [default: ‘utf-8’]
The encoding to be used
s : unicode string (unicode on py2, str on py3)
The Python unicode string that arrives as encoded bytes.
recv_unicode(flags=0, encoding='utf-8')

s.recv_string(flags=0, encoding=’utf-8’)

Receive a unicode string, as sent by send_string.

flags : int
Any valid recv flag.
encoding : str [default: ‘utf-8’]
The encoding to be used
s : unicode string (unicode on py2, str on py3)
The Python unicode string that arrives as encoded bytes.
send(msg, flags=0, copy=True, track=False)

Override this instead of the internal _send_* methods since those change and it’s not clear when/how they’re called in real code.

send_json(obj, flags=0)

Send a Python object as a message using json to serialize.

obj : Python object
The Python object to send.
flags : int
Any valid send flag.
send_multipart(msg_parts, flags=0, copy=True, track=False)

Send a sequence of buffers as a multipart message.

msg_parts : iterable
A sequence of objects to send as a multipart message. Each element can be any sendable object (Frame, bytes, buffer-providers)
flags : int, optional
SNDMORE is handled automatically for frames before the last.
copy : bool, optional
Should the frame(s) be sent in a copying or non-copying manner.
track : bool, optional
Should the frame(s) be tracked for notification that ZMQ has finished with it (ignored if copy=True).

None : if copy or not track MessageTracker : if track and not copy

a MessageTracker object, whose pending property will be True until the last send is completed.
send_pyobj(obj, flags=0, protocol=-1)

Send a Python object as a message using pickle to serialize.

obj : Python object
The Python object to send.
flags : int
Any valid send flag.
protocol : int
The pickle protocol number to use. Default of -1 will select the highest supported number. Use 0 for multiple platform support.
send_string(u, flags=0, copy=False, encoding='utf-8')

Send a Python unicode string as a message with an encoding.

0MQ communicates with raw bytes, so you must encode/decode text (unicode on py2, str on py3) around 0MQ.

u : Python unicode string (unicode on py2, str on py3)
The unicode string to send.
flags : int, optional
Any valid send flag.
encoding : str [default: ‘utf-8’]
The encoding to be used
send_unicode(u, flags=0, copy=False, encoding='utf-8')

s.send_string(u, flags=0, copy=False, encoding=’utf-8’)

Send a Python unicode string as a message with an encoding.

0MQ communicates with raw bytes, so you must encode/decode text (unicode on py2, str on py3) around 0MQ.

u : Python unicode string (unicode on py2, str on py3)
The unicode string to send.
flags : int, optional
Any valid send flag.
encoding : str [default: ‘utf-8’]
The encoding to be used
setsockopt(option, optval)

Set socket options.

See the 0MQ API documentation for details on specific options.

option : int

The option to set. Available values will depend on your version of libzmq. Examples include:

zmq.SUBSCRIBE, UNSUBSCRIBE, IDENTITY, HWM, LINGER, FD
optval : int or bytes
The value of the option to set.
setsockopt_string(option, optval, encoding='utf-8')

Set socket options with a unicode object it is simply a wrapper for setsockopt to protect from encoding ambiguity.

See the 0MQ documentation for details on specific options.

option : int
The name of the option to set. Can be any of: SUBSCRIBE, UNSUBSCRIBE, IDENTITY
optval : unicode string (unicode on py2, str on py3)
The value of the option to set.
encoding : str
The encoding to be used, default is utf8
setsockopt_unicode(option, optval, encoding='utf-8')

s.setsockopt_string(option, optval, encoding=’utf-8’)

Set socket options with a unicode object it is simply a wrapper for setsockopt to protect from encoding ambiguity.

See the 0MQ documentation for details on specific options.

option : int
The name of the option to set. Can be any of: SUBSCRIBE, UNSUBSCRIBE, IDENTITY
optval : unicode string (unicode on py2, str on py3)
The value of the option to set.
encoding : str
The encoding to be used, default is utf8

zmq – The pyzmq ØMQ python bindings

pyzmq [1] Is a python binding to the C++ ØMQ [2] library written in Cython [3]. The following is auto generated pyzmq's from documentation.

class zmq.core.context.Context

Context(io_threads=1)

Manage the lifecycle of a 0MQ context.

io_threads : int
The number of IO threads.
destroy(linger=None)

Close all sockets associated with this context, and then terminate the context. If linger is specified, the LINGER sockopt of the sockets will be set prior to closing.

WARNING:

destroy involves calling zmq_close(), which is NOT threadsafe. If there are active sockets in other threads, this must not be called.

static instance()

Returns a global Context instance.

Most single-threaded applications have a single, global Context. Use this method instead of passing around Context instances throughout your code.

A common pattern for classes that depend on Contexts is to use a default argument to enable programs with multiple Contexts but not require the argument for simpler applications:

class MyClass(object):
def __init__(self, context=None):
self.context = context or Context.instance()
socket(socket_type)

Create a Socket associated with this Context.

socket_type : int
The socket type, which can be any of the 0MQ socket types: REQ, REP, PUB, SUB, PAIR, DEALER, ROUTER, PULL, PUSH, XSUB, XPUB.
term()

Close or terminate the context.

This can be called to close the context by hand. If this is not called, the context will automatically be closed when it is garbage collected.

class zmq.core.socket.Socket

Socket(context, socket_type)

A 0MQ socket.

These objects will generally be constructed via the socket() method of a Context object.

Note: 0MQ Sockets are not threadsafe. DO NOT share them across threads.

context : Context
The 0MQ Context this Socket belongs to.
socket_type : int
The socket type, which can be any of the 0MQ socket types: REQ, REP, PUB, SUB, PAIR, XREQ, DEALER, XREP, ROUTER, PULL, PUSH, XPUB, XSUB.

.Context.socket : method for creating a socket bound to a Context.

class zmq.core.poll.Poller

Poller()

A stateful poll interface that mirrors Python’s built-in poll.

modify(socket, flags=POLLIN|POLLOUT)

Modify the flags for an already registered 0MQ socket or native fd.

poll(timeout=None)

Poll the registered 0MQ or native fds for I/O.

timeout : float, int
The timeout in milliseconds. If None, no timeout (infinite). This is in milliseconds to be compatible with select.poll(). The underlying zmq_poll uses microseconds and we convert to that in this function.
register(socket, flags=POLLIN|POLLOUT)

Register a 0MQ socket or native fd for I/O monitoring.

register(s,0) is equivalent to unregister(s).

socket : zmq.Socket or native socket
A zmq.Socket or any Python object having a fileno() method that returns a valid file descriptor.
flags : int
The events to watch for. Can be POLLIN, POLLOUT or POLLIN|POLLOUT. If flags=0, socket will be unregistered.
unregister(socket)

Remove a 0MQ socket or native fd for I/O monitoring.

socket : Socket
The socket instance to stop polling.
[1]http://github.com/zeromq/pyzmq
[2]http://www.zeromq.com
[3]http://www.cython.org

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