SLE Common Class Variables Should be Instance Variables

[christianmkuss]

In ait/dsn/common.py there is the following code block

class SLE(object):
    ''' SLE interface "base" class
    The SLE class provides SLE interface-agnostic methods and attributes
    for interfacing with SLE.
    '''
    _state = 'unbound'
    _handlers = defaultdict(list)
    _data_queue = gevent.queue.Queue()
    _invoke_id = 0

    def __init__(self, *args, **kwargs):

These class level variables will become shared by any instance inheriting from SLE which will create issues if multiple of RAF, RCF, or CLTU are created in the same scope. Looking at the examples in ait/dsn/bin/examples, I'm not sure this is a super common use case, but it is one I ran across. I believe it may also be avoidable by running each instance in threads.

For example, I have configured a test bed that streams RAF frames over port 5307 and accepts CLTU over port 5112, after accepting bind, start, and similar logic.

import time
from ait.dsn.sle import RAF, CLTU

raf_mngr = RAF(
    hostnames=['localhost'],
    port=5307,
    inst_id='sagr=LSE-SSC.spack=Test.rsl-fg=1.raf=onlc1',
    auth_level="none"
)

cltu_mngr = CLTU(
    hostnames=['localhost'],
    port=5112,
    inst_id="sagr=111.spack=-default.fsl-fg=1.cltu=cltu1",
    auth_level="none"
)

# RAF connect, bind, and start
raf_mngr.connect()

raf_mngr.bind()
while raf_mngr._state != "ready":
    time.sleep(1)

raf_mngr.start(None, None)
while raf_mngr._state != "active":
    time.sleep(1)

# CLTU connect, bind, and start
cltu_mngr.connect()

cltu_mngr.bind()
while cltu_mngr._state != "ready":
    time.sleep(1)

cltu_mngr.start()
while cltu_mngr._state != "active":
    time.sleep(1)

while True:
    time.sleep(0)

Running this outputs (with print(type(handler)) added to ait.dsn.sle.common::data_processor)

2022-12-07T14:41:05.827 | INFO     | Starting conn monitor for <class 'ait.dsn.sle.raf.RAF'>
2022-12-07T14:41:05.827 | INFO     | Configuring SLE connection...
2022-12-07T14:41:05.828 | INFO     | SLE connection configuration successful
2022-12-07T14:41:05.828 | INFO     | Sending Bind request ...
<class 'ait.dsn.sle.raf.RAF'>
2022-12-07T14:41:05.832 | INFO     | Bind successful
2022-12-07T14:41:06.834 | INFO     | Sending data start invocation ...
<class 'ait.dsn.sle.raf.RAF'>
2022-12-07T14:41:06.839 | INFO     | Start successful
<class 'ait.dsn.sle.raf.RAF'>
2022-12-07T14:41:07.850 | INFO     | Connection to DSN successful through localhost.
2022-12-07T14:41:07.851 | INFO     | Starting conn monitor for <class 'ait.dsn.sle.cltu.CLTU'>
2022-12-07T14:41:07.851 | INFO     | Configuring SLE connection...
2022-12-07T14:41:07.852 | INFO     | SLE connection configuration successful
2022-12-07T14:41:07.852 | INFO     | Sending Bind request ...
<class 'ait.dsn.sle.raf.RAF'>
2022-12-07T14:41:07.856 | INFO     | Bind unsuccessful. State already in READY or ACTIVE.
2022-12-07T14:41:07.856 | INFO     | Sending Peer Abort
2022-12-07T14:41:07.858 | INFO     | Bind successful
<class 'ait.dsn.sle.cltu.CLTU'>
2022-12-07T14:41:07.865 | ERROR    | Unable to decode PDU. Skipping ...
<class 'ait.dsn.sle.raf.RAF'>
<class 'ait.dsn.sle.cltu.CLTU'>
2022-12-07T14:41:09.863 | ERROR    | Unable to decode PDU. Skipping ...
<class 'ait.dsn.sle.raf.RAF'>
<class 'ait.dsn.sle.raf.RAF'>
<class 'ait.dsn.sle.cltu.CLTU'>
2022-12-07T14:41:11.874 | ERROR    | Unable to decode PDU. Skipping ...
<class 'ait.dsn.sle.raf.RAF'>
<class 'ait.dsn.sle.cltu.CLTU'>
2022-12-07T14:41:13.877 | ERROR    | Unable to decode PDU. Skipping ...

This shows that the CLTU instance is able to decode but then the incoming RAF frames are put into a queue that is shared between CLTU and RAF (hence the error "Unable to decode PDU. Skipping ...")

[christianmkuss]

I have changes made and can open a PR.