frappy/secop/stringio.py

#!/usr/bin/env python
#  -*- coding: utf-8 -*-
# *****************************************************************************
# This program is free software; you can redistribute it and/or modify it under
# the terms of the GNU General Public License as published by the Free Software
# Foundation; either version 2 of the License, or (at your option) any later
# version.
#
# This program is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
# FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
# details.
#
# You should have received a copy of the GNU General Public License along with
# this program; if not, write to the Free Software Foundation, Inc.,
# 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
#
# Module authors:
#   Markus Zolliker <markus.zolliker@psi.ch>
# *****************************************************************************
"""Line oriented stream communication

implements TCP/IP and is be used as a base for SerialIO
"""

import re
import threading
import time

from secop.datatypes import ArrayOf, BoolType, \
    FloatRange, StringType, TupleOf, ValueType
from secop.errors import CommunicationFailedError, \
    CommunicationSilentError, ConfigError
from secop.lib.asynconn import AsynConn, ConnectionClosed
from secop.modules import Attached, Command, \
    Communicator, Done, Module, Parameter, Property
from secop.poller import REGULAR


class StringIO(Communicator):
    """line oriented communicator

    self healing is assured by polling the parameter 'is_connected'
    """
    uri = Property('hostname:portnumber', datatype=StringType())
    end_of_line = Property('end_of_line character', datatype=ValueType(),
                           default='\n', settable=True)
    encoding = Property('used encoding', datatype=StringType(),
                        default='ascii', settable=True)
    identification = Property('''
                              identification

                              a list of tuples with commands and expected responses as regexp,
                              to be sent on connect''',
                              datatype=ArrayOf(TupleOf(StringType(), StringType())), default=[], export=False)

    timeout = Parameter('timeout', datatype=FloatRange(0), default=2)
    wait_before = Parameter('wait time before sending', datatype=FloatRange(), default=0)
    is_connected = Parameter('connection state', datatype=BoolType(), readonly=False, poll=REGULAR)
    pollinterval = Parameter('reconnect interval', datatype=FloatRange(0), readonly=False, default=10)

    _reconnectCallbacks = None

    def earlyInit(self):
        self._conn = None
        self._lock = threading.RLock()
        eol = self.end_of_line
        if isinstance(eol, (tuple, list)):
            if len(eol) not in (1, 2):
                raise ValueError('invalid end_of_line: %s' % eol)
        else:
            eol = [eol]
        # eol for read and write might be distinct
        self._eol_read = self._convert_eol(eol[0])
        if not self._eol_read:
            raise ValueError('end_of_line for read must not be empty')
        self._eol_write = self._convert_eol(eol[-1])
        self._last_error = None

    def _convert_eol(self, value):
        if isinstance(value, str):
            return value.encode(self.encoding)
        if isinstance(value, int):
            return bytes([value])
        if isinstance(value, bytes):
            return value
        raise ValueError('invalid end_of_line: %s' % repr(value))

    def connectStart(self):
        if not self.is_connected:
            uri = self.uri
            self._conn = AsynConn(uri, self._eol_read)
            self.is_connected = True
            for command, regexp in self.identification:
                reply = self.communicate(command)
                if not re.match(regexp, reply):
                    self.closeConnection()
                    raise CommunicationFailedError('bad response: %s does not match %s' %
                                                   (reply, regexp))

    def closeConnection(self):
        """close connection

        self.is_connected MUST be set to False by implementors
        """
        self._conn.disconnect()
        self._conn = None
        self.is_connected = False

    def read_is_connected(self):
        """try to reconnect, when not connected

        self.is_connected is changed only by self.connectStart or self.closeConnection
        """
        if self.is_connected:
            return Done  # no need for intermediate updates
        try:
            self.connectStart()
            if self._last_error:
                self.log.info('connected')
                self._last_error = 'connected'
                self.callCallbacks()
                return Done
        except Exception as e:
            if str(e) == self._last_error:
                raise CommunicationSilentError(str(e))
            self._last_error = str(e)
            self.log.error(self._last_error)
            raise
        return Done

    def write_is_connected(self, value):
        """value = True: connect if not yet done
        value = False: disconnect (will be reconnected automatically)
        """
        if not value:
            self.closeConnection()
            return False
        return self.read_is_connected()

    def registerReconnectCallback(self, name, func):
        """register reconnect callback

        if the callback fails or returns False, it is cleared
        """
        if self._reconnectCallbacks is None:
            self._reconnectCallbacks = {name: func}
        else:
            self._reconnectCallbacks[name] = func

    def callCallbacks(self):
        for key, cb in list(self._reconnectCallbacks.items()):
            try:
                removeme = not cb()
            except Exception as e:
                self.log.error('callback: %s' % e)
                removeme = True
            if removeme:
                self._reconnectCallbacks.pop(key)

    def communicate(self, command):
        """send a command and receive a reply

        using end_of_line, encoding and self._lock
        for commands without reply, the command must be joined with a query command,
        wait_before is respected for end_of_lines within a command.
        """
        if not self.is_connected:
            self.read_is_connected()  # try to reconnect
            if not self._conn:
                raise CommunicationSilentError('can not connect to %r' % self.uri)
        try:
            with self._lock:
                # read garbage and wait before send
                if self.wait_before and self._eol_write:
                    cmds = command.encode(self.encoding).split(self._eol_write)
                else:
                    cmds = [command.encode(self.encoding)]
                garbage = None
                try:
                    for cmd in cmds:
                        if self.wait_before:
                            time.sleep(self.wait_before)
                        if garbage is None:  # read garbage only once
                            garbage = self._conn.flush_recv()
                            if garbage:
                                self.log.debug('garbage: %r', garbage)
                        self._conn.send(cmd + self._eol_write)
                    reply = self._conn.readline(self.timeout)
                except ConnectionClosed:
                    self.closeConnection()
                    raise CommunicationFailedError('disconnected')
                reply = reply.decode(self.encoding)
                self.log.debug('recv: %s', reply)
                return reply
        except Exception as e:
            if str(e) == self._last_error:
                raise CommunicationSilentError(str(e))
            self._last_error = str(e)
            self.log.error(self._last_error)
            raise

    @Command(ArrayOf(StringType()), result=ArrayOf(StringType()))
    def multicomm(self, commands):
        """communicate multiple request/replies in one row"""
        replies = []
        with self._lock:
            for cmd in commands:
                replies.append(self.communicate(cmd))
        return replies


class HasIodev(Module):
    """Mixin for modules using a communicator

    not only StringIO !
    """
    iodev = Attached()
    uri = Property('uri for automatic creation of the attached communication module',
                   StringType(), default='')

    iodevDict = {}

    def __init__(self, name, logger, opts, srv):
        iodev = opts.get('iodev')
        Module.__init__(self, name, logger, opts, srv)
        if self.uri:
            opts = {'uri': self.uri, 'description': 'communication device for %s' % name,
                    'export': False}
            ioname = self.iodevDict.get(self.uri)
            if not ioname:
                ioname = iodev or name + '_iodev'
                iodev = self.iodevClass(ioname, srv.log.getChild(ioname), opts, srv)
                srv.modules[ioname] = iodev
                self.iodevDict[self.uri] = ioname
            self.iodev = ioname
        elif not self.iodev:
            raise ConfigError("Module %s needs a value for either 'uri' or 'iodev'" % name)

    def initModule(self):
        try:
            self._iodev.read_is_connected()
        except (CommunicationFailedError, AttributeError):
            # AttributeError: for missing _iodev?
            pass
        super().initModule()

    def sendRecv(self, command):
        return self._iodev.communicate(command)