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eddsctrl_server/eddsctrlserver
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#!/usr/bin/python2.7
# -*- coding: utf-8 -*-
"""package eddsctrl_server
author Benoit Dubois
copyright FEMTO ENGINEERING
license GPL v3.0+
brief DDS controller, server part.
details This package provides interface to handle DDS package.
This package implements server part of a client/server architecture.
Code inspired from Python Module of the Week website (BSD licence):
http://pymotw.com/2/select/
for the logic and from:
http://eli.thegreenplace.net/2011/08/02/length-prefix-framing-for-protocol-buffers/
for the message using the length prefix technique.
"""
import logging
CONSOLE_LOG_LEVEL = logging.DEBUG
FILE_LOG_LEVEL = logging.DEBUG
import os
try:
import configparser
except ImportError:
import ConfigParser as configparser
try:
from queue import Queue, Empty
except ImportError:
from Queue import Queue, Empty
from struct import pack, unpack
from select import select
from socket import socket, AF_INET, SOCK_STREAM
from dds.ad9912dev import Ad9912Dev as DdsDevice # for actual use
#from dds.dds_emul import TestUsbDds as DdsDevice # for test without DDS
from eddsctrl_server.constants import APP_NAME, SERVER_PORT, SERVERHOST, \
DEFAULT_IFREQ, DEFAULT_OFREQ, DEFAULT_AMP, DEFAULT_PHY, \
CFG_SERVER_FILE, LOG_SERVER_FILE
#==============================================================================
class EDdsCtrlServer(object):
"""Class dedicated to interface socket client with DDS device.
Provide a basic interface to handle client queries:
Message is built using the length prefix technique: length is sent as a
packed 4-byte little-endian integer.
Allow only 4 queries, changement of output frequency, input frequency,
phase or amplitude value.
Message structure is simple:
- Length of message,
- Exclamation mark
- Character identifier,
- Exclamation mark
- Value
- Exclamation mark
There are 8 valid identifiers:
- 'o[?]' for set/get output frequency
- 'i[?]' for set/get input frequency
- 'p[?]' for set/get phase
- 'a[?]' for set/get amplitude
"""
def __init__(self, settings_file=None):
"""Constructor: initialize the server.
:param settings_file: file containing setting data value (str)
:returns: None
"""
# Retrieve parameter values from 'ini' file
if settings_file is None:
raise ValueError("Parameter settings_file missing.")
self._settingsf = settings_file
config = configparser.ConfigParser()
config.read(settings_file)
try:
self._port = config.getint('dds_ctrl', 'server_port')
ifreq = config.getfloat('dds_ctrl', 'ifreq')
ofreq = config.getfloat('dds_ctrl', 'ofreq')
phase = config.getfloat('dds_ctrl', 'phase')
amp = config.getint('dds_ctrl', 'amp')
except KeyError as ex:
logging.critical("Correct or delete the configuration file.")
raise KeyError("Key %s not found in configuration file:"% str(ex))
# Init devices
self._init_dds(ifreq, ofreq, phase, amp)
self._init_server()
# Start threaded server
self._server_loop()
def _init_dds(self, ifreq, ofreq, phase, amp):
"""Create and configure a DDS object.
:param ifreq: dds input frequency (float)
:param ofreq: dds output frequency (float)
:param phase: dds output phase (float)
:param amp: dds output amplitude (int)
:returns: None
"""
self._dds = DdsDevice()
try:
self._dds.set_ifreq(ifreq)
self._dds.set_ofreq(ofreq)
self._dds.set_phy(phase)
self._dds.set_amp(amp)
self._dds.set_hstl_output_state(False)
self._dds.set_cmos_output_state(False)
except Exception as ex:
raise Exception("Unexpected error during DDS initialisation: %s" \
% str(ex))
logging.debug("DDS inititialization done")
def _init_server(self):
"""Create and configure a basic server object.
:returns: None
"""
try:
self.server = socket(AF_INET, SOCK_STREAM)
self.server.setblocking(0)
host = SERVERHOST # Get local machine name
self.server.bind((host, self._port)) # Bind to the port
self.server.listen(3) # Now wait for client connection
except IOError as ex:
raise IOError("EDDSCTRLSERVER: %s, have you closed properly the " \
"server? " % str(ex))
except Exception as ex:
raise Exception("EDDSCTRLSERVER: unexpected error during server " \
"initialisation: %s" % str(ex))
# Sockets from which we expect to read
self.inputs = [self.server]
# Sockets to which we expect to write
self.outputs = []
# Outgoing message queues (socket:Queue)
self.message_queues = {}
logging.debug("Server initialization done")
def _server_loop(self):
"""Main server loop: Handle connection, read and write on server socket.
:returns: None
"""
while self.inputs:
# Await an event on a readable socket descriptor
readable, writable, exceptional = select(self.inputs, \
self.outputs, \
self.inputs)
# Handle inputs
self._handle_readable(readable)
# Handle outputs
self._handle_writable(writable)
# Handle exceptional condition
self._handle_exceptional(exceptional)
def _handle_readable(self, socket_list):
"""Read message from client.
Message is built using the length prefix technique. See:
http://eli.thegreenplace.net/2011/08/02/length-prefix-framing-for-protocol-buffers/
:param socket_list: List of socket usable to receive data
:returns: None
"""
for sock in socket_list:
# Received a connect to the server (listening) socket
if sock is self.server:
self._accept_connect()
# Established connection
else:
header_data = self._recv_n_bytes(sock, 4)
if header_data == None:
logging.error("Message seems received but no data to read")
return
if len(header_data) == 4:
msg_len = unpack('<L', header_data)[0]
data = self._recv_n_bytes(sock, msg_len)
# Check message validity
if data == None:
logging.error("Message received but no data to read")
return
if len(data) != msg_len:
logging.error("Bad message length")
return
logging.debug("receive %s from %s", \
data, sock.getpeername())
# Handle message
ret_data = self._input_msg_handler(data)
# Return data to client
self.message_queues[sock].put(ret_data)
# Add output channel for response
if sock not in self.outputs:
self.outputs.append(sock)
else:
# Interpret empty result as closed connection
logging.info("Closing connection after reading no data")
# Stop listening for input on the connection
if sock in self.outputs:
self.outputs.remove(sock)
self.inputs.remove(sock)
sock.close()
# Remove message queue
del self.message_queues[sock]
def _handle_writable(self, socket_list):
"""Send message to client.
:param socket_list: List of socket object usable to send data
:returns: None
"""
for sock in socket_list:
try:
next_msg = self.message_queues[sock].get_nowait()
except Empty:
self.outputs.remove(sock)
else:
self._send_msg(sock, next_msg)
logging.debug("send %s to %s", next_msg, sock.getpeername())
def _handle_exceptional(self, socket_list):
"""Handle error with socket by closing it.
:param socket_list: List of socket object in exceptional condition
:returns: None
"""
try:
for sock in socket_list:
logging.warning("handling exceptional condition for %s", \
sock.getpeername())
# Stop listening for input on the connection
self.inputs.remove(sock)
if sock in outputs:
self.outputs.remove(sock)
sock.close()
# Remove message queue
del self.message_queues[sock]
except Exception as ex:
logging.error("Unexpected error: %s", ex)
def _input_msg_handler(self, msg):
"""Handle message from clients. Message format is defined in
:class:`eddsctrl.server.eddsctrlsserver.EDdsCtrlServer`.
Message contains a command to update DDS device state.
:param msg: A formated string message (str)
:returns: Return actual value of parameter in DDS (float)
"""
split_msg = msg.split("!")
index = split_msg[1].strip('\0') # Remove extra binary NULL characters
value = split_msg[2]
config = configparser.ConfigParser()
config.read(self._settingsf)
if index == "o":
retval = self._dds.set_ofreq(float(value))
config.set('dds_ctrl', 'ofreq', str(self._dds.get_ofreq()))
elif index == "p":
retval = self._dds.set_phy(float(value))
config.set('dds_ctrl', 'phase', str(self._dds.get_phy()))
elif index == "a":
retval = self._dds.set_amp(int(value))
config.set('dds_ctrl', 'amp', str(self._dds.get_amp()))
elif index == "i":
retval = self._dds.set_ifreq(float(value))
config.set('dds_ctrl', 'ifreq', str(self._dds.get_ifreq()))
elif index == "o?":
retval = self._dds.get_ofreq()
elif index == "p?":
retval = self._dds.get_phy()
elif index == "a?":
retval = self._dds.get_amp()
elif index == "i?":
retval = self._dds.get_ifreq()
else: # Bad identifier, message not valid
logging.error("Bad identifier," \
"expected o[?], p[?], a[?] or i[?]: ", \
index, " given")
return
# Write modification to setting file
with open(self._settingsf, 'w') as fd:
config.write(fd)
# Note that value actually writed in DDS (retval) can be a bit different
# than value sended to DDS (value).
msg = "!" + index + "!" + str(retval) + "!"
return msg
@staticmethod
def _send_msg(sock, msg):
"""Method for sending 'msg' to socket.
Message is built using the length prefix technique. See:
http://eli.thegreenplace.net/2011/08/02/length-prefix-framing-for-protocol-buffers/
:param sock: a valid socket object
:param msg: message to be send (str)
:returns: None
"""
header = pack('<L', len(msg))
try:
sock.sendall(header + msg)
except IOError as ex:
logging.error("Error during sending: %s", ex)
@staticmethod
def _recv_n_bytes(sock, n):
"""Convenience method for receiving exactly n bytes from socket
(assuming it's open and connected).
:param sock: socket object which receives the n bytes
:param n: number of bytes to be received (int)
:returns: data received (str)
"""
data = ''
while len(data) < n:
try:
chunk = sock.recv(n - len(data))
if chunk == '':
break
data += chunk
except IOError as ex:
logging.error("Socket error in _recv_n_bytes: %s", ex)
return
except Exception as ex:
logging.error("Error in _recv_n_bytes: %s", ex)
return
return data
def _accept_connect(self):
"""Server accept connection from client.
:returns: a new socket object related to client connection (socket)
"""
# A "readable" server socket is ready to accept a connection
connection, client_address = self.server.accept()
logging.info("New connection from %s", client_address)
connection.setblocking(0)
self.inputs.append(connection)
self.outputs.append(connection)
# Give the connection a queue for data we want to send
self.message_queues[connection] = Queue()
return connection
#==============================================================================
def reset_settings(settings_file):
"""Resets the "settings" file with default values.
:param settings_file: file containing setting data value (str)
:returns: None
"""
config = configparser.ConfigParser()
config.add_section('dds_ctrl')
config.set('dds_ctrl', 'server_port', str(SERVER_PORT))
config.set('dds_ctrl', 'ofreq', str(DEFAULT_OFREQ))
config.set('dds_ctrl', 'phase', str(DEFAULT_PHY))
config.set('dds_ctrl', 'amp', str(DEFAULT_AMP))
config.set('dds_ctrl', 'ifreq', str(DEFAULT_IFREQ))
# Write modification to setting file
with open(settings_file, 'w') as fd:
fd.truncate(0) # Reset file contents
config.write(fd)
logging.info("Settings file reseted.")
#==============================================================================
def configure_logging():
"""Configures logs.
"""
date_fmt = "%d/%m/%Y %H:%M:%S"
log_format = "%(asctime)s %(levelname) -8s %(filename)s " + \
" %(funcName)s (%(lineno)d): %(message)s"
logging.basicConfig(level=FILE_LOG_LEVEL, \
datefmt=date_fmt, \
format=log_format, \
filename=LOG_SERVER_FILE, \
filemode='w')
console = logging.StreamHandler()
# define a Handler which writes messages to the sys.stderr
console.setLevel(CONSOLE_LOG_LEVEL)
# set a format which is simpler for console use
console_format = '%(levelname) -8s %(filename)s (%(lineno)d): %(message)s'
formatter = logging.Formatter(console_format)
# tell the handler to use this format
console.setFormatter(formatter)
# add the handler to the root logger
logging.getLogger('').addHandler(console)
#==============================================================================
def eddsctrlserver(settings_file):
configure_logging()
if os.path.isfile(settings_file) is False:
logging.error("Settings file missing: create one with default values.")
reset_settings(settings_file)
EDdsCtrlServer(settings_file)
#==============================================================================
if __name__ == '__main__':
# Ctrl-c closes the application
import signal
signal.signal(signal.SIGINT, signal.SIG_DFL)
eddsctrlserver(CFG_SERVER_FILE)
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