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#!/usr/bin/env python

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# -*- coding: utf-8 -*-

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# This file is part of Beremiz

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# Copyright (C) 2019: Edouard TISSERANT

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# See COPYING file for copyrights details.

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from __future__ import absolute_import

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import errno

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from threading import RLock, Timer

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try:

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    from runtime.spawn_subprocess import Popen

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except ImportError:

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    from subprocess import Popen

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from twisted.web.server import Site

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from twisted.web.resource import Resource

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from twisted.internet import reactor

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from twisted.web.static import File

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from autobahn.twisted.websocket import WebSocketServerFactory, WebSocketServerProtocol

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from autobahn.websocket.protocol import WebSocketProtocol

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from autobahn.twisted.resource import  WebSocketResource

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# TODO multiclient :

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# session list lock

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# svghmi_sessions = []

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# svghmi_watchdogs = []

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svghmi_session = None

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svghmi_watchdog = None

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svghmi_send_collect = PLCBinary.svghmi_send_collect

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svghmi_send_collect.restype = ctypes.c_int # error or 0

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svghmi_send_collect.argtypes = [

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    ctypes.POINTER(ctypes.c_uint32),  # size

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    ctypes.POINTER(ctypes.c_void_p)]  # data ptr

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# TODO multiclient : switch to arrays

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svghmi_recv_dispatch = PLCBinary.svghmi_recv_dispatch

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svghmi_recv_dispatch.restype = ctypes.c_int # error or 0

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svghmi_recv_dispatch.argtypes = [

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    ctypes.c_uint32,  # size

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    ctypes.c_char_p]  # data ptr

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# TODO multiclient : switch to arrays

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class HMISession(object):

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    def __init__(self, protocol_instance):

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        global svghmi_session

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        # Single client :

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        # Creating a new HMISession closes pre-existing HMISession

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        if svghmi_session is not None:

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            svghmi_session.close()

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        svghmi_session = self

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        self.protocol_instance = protocol_instance

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        # TODO multiclient :

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        # svghmi_sessions.append(self)

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        # get a unique bit index amont other svghmi_sessions,

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        # so that we can match flags passed by C->python callback

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    def close(self):

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        global svghmi_session

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        if svghmi_session == self:

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            svghmi_session = None

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        self.protocol_instance.sendClose(WebSocketProtocol.CLOSE_STATUS_CODE_NORMAL)

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    def onMessage(self, msg):

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        # pass message to the C side recieve_message()

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        return svghmi_recv_dispatch(len(msg), msg)

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        # TODO multiclient : pass client index as well

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    def sendMessage(self, msg):

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        self.protocol_instance.sendMessage(msg, True)

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        return 0

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class Watchdog(object):

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    def __init__(self, initial_timeout, interval, callback):

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        self._callback = callback

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        self.lock = RLock()

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        self.initial_timeout = initial_timeout

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        self.interval = interval

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        self.callback = callback

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        with self.lock:

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            self._start()

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    def _start(self, rearm=False):

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        duration = self.interval if rearm else self.initial_timeout

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        if duration:

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            self.timer = Timer(duration, self.trigger)

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            self.timer.start()

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        else:

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            self.timer = None

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    def _stop(self):

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        if self.timer is not None:

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            self.timer.cancel()

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            self.timer = None

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    def cancel(self):

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        with self.lock:

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            self._stop()

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    def feed(self, rearm=True):

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        with self.lock:

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            self._stop()

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            self._start(rearm)

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    def trigger(self):

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        self._callback()

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        # wait for initial timeout on re-start

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        self.feed(rearm=False)

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class HMIProtocol(WebSocketServerProtocol):

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

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        self._hmi_session = None

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        WebSocketServerProtocol.__init__(self, *args, **kwargs)

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    def onOpen(self):

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        assert(self._hmi_session is None)

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        self._hmi_session = HMISession(self)

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    def onClose(self, wasClean, code, reason):

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        self._hmi_session = None

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    def onMessage(self, msg, isBinary):

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        assert(self._hmi_session is not None)

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        result = self._hmi_session.onMessage(msg)

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        if result == 1 :  # was heartbeat

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            if svghmi_watchdog is not None:

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                svghmi_watchdog.feed()

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class HMIWebSocketServerFactory(WebSocketServerFactory):

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    protocol = HMIProtocol

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svghmi_root = None

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svghmi_listener = None

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svghmi_send_thread = None

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def SendThreadProc():

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    global svghmi_session

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    size = ctypes.c_uint32()

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    ptr = ctypes.c_void_p()

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    res = 0

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    while True:

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        res=svghmi_send_collect(ctypes.byref(size), ctypes.byref(ptr))

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        if res == 0:

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            # TODO multiclient : dispatch to sessions

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            if svghmi_session is not None:

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                svghmi_session.sendMessage(ctypes.string_at(ptr.value,size.value))

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        elif res == errno.ENODATA:

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            # this happens when there is no data after wakeup

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            # because of hmi data refresh period longer than PLC common ticktime

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            pass 

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        else:

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            # this happens when finishing

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            break

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def watchdog_trigger():

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    print("SVGHMI watchdog trigger")

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# Called by PLCObject at start

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def _runtime_svghmi0_start():

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    global svghmi_listener, svghmi_root, svghmi_send_thread

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    svghmi_root = Resource()

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    svghmi_root.putChild("ws", WebSocketResource(HMIWebSocketServerFactory()))

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    svghmi_listener = reactor.listenTCP(8008, Site(svghmi_root))

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    # start a thread that call the C part of SVGHMI

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    svghmi_send_thread = Thread(target=SendThreadProc, name="SVGHMI Send")

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    svghmi_send_thread.start()

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# Called by PLCObject at stop

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def _runtime_svghmi0_stop():

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    global svghmi_listener, svghmi_root, svghmi_send_thread, svghmi_session

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    if svghmi_session is not None:

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        svghmi_session.close()

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    svghmi_root.delEntity("ws")

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    svghmi_root = None

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    svghmi_listener.stopListening()

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    svghmi_listener = None

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    # plc cleanup calls svghmi_(locstring)_cleanup and unlocks send thread

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    svghmi_send_thread.join()

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    svghmi_send_thread = None

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class NoCacheFile(File):

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    def render_GET(self, request):

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        request.setHeader(b"Cache-Control", b"no-cache, no-store")

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        return File.render_GET(self, request)

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    render_HEAD = render_GET

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