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general purpose bidirectional packet stream connection

Project description

Latest release 20191004: PacketConnection: new optional parameter packet_grace to tune the send delay for additional packets before a flush, default DEFAULT_PACKET_GRACE (0.01s), 0 for no delay. Add a crude packet level activity ticker.

A general purpose bidirectional packet stream connection.

Class Packet

MRO: cs.binary.PacketField, abc.ABC
A protocol packet.

Class PacketConnection

A bidirectional binary connection for exchanging requests and responses.

Method PacketConnection.__init__(self, recv, send, request_handler=None, name=None, packet_grace=None, tick=None)

Initialise the PacketConnection.

Parameters:

  • recv: inbound binary stream. If this is an int it is taken to be an OS file descriptor, otherwise it should be a cs.buffer.CornuCopyBuffer or a file like object with a read1 or read method.
  • send: outbound binary stream. If this is an int it is taken to be an OS file descriptor, otherwise it should be a file like object with .write(bytes) and .flush() methods. For a file descriptor sending is done via an os.dup() of the supplied descriptor, so the caller remains responsible for closing the original descriptor.
  • packet_grace: default pause in the packet sending worker to allow another packet to be queued before flushing the output stream. Default: DEFAULT_PACKET_GRACEs. A value of 0 will flush immediately if the queue is empty.
  • request_handler: an optional callable accepting (rq_type, flags, payload). The request_handler may return one of 5 values on success:
    • None: response will be 0 flags and an empty payload.
    • int: flags only. Response will be the flags and an empty payload.
    • bytes: payload only. Response will be 0 flags and the payload.
    • str: payload only. Response will be 0 flags and the str encoded as bytes using UTF-8.
    • (int, bytes): Specify flags and payload for response. An unsuccessful request should raise an exception, which will cause a failure response packet.
  • tick: optional tick parameter, default None. If None, do nothing. If a Boolean, call tick_fd_2 if true, otherwise do nothing. Otherwise tick should be a callable accepting a byteslike value.

Class Request_State

MRO: builtins.tuple
RequestState(decode_response, result)

Function tick_fd_2(bs)

A low level tick function to write a short binary tick to the standard error file descriptor.

This may be called by the send and receive workers to give an indication of activity type.

Release Log

Release 20191004: PacketConnection: new optional parameter packet_grace to tune the send delay for additional packets before a flush, default DEFAULT_PACKET_GRACE (0.01s), 0 for no delay. Add a crude packet level activity ticker.

Release 20190221: DISTINFO requirement updates.

Release 20181228: Initial PyPI release.

Project details


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