servo/client.py

# Copyright 2013 The ChromiumOS Authors
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
"""Classes and objects for the Servo Client API.
"""

import re
from xmlrpc.client import Fault
from xmlrpc.client import ServerProxy


DEFAULT_HOST = "localhost"
DEFAULT_PORT = 9999


class ServoClientError(Exception):
    """Error class for ServoRequest"""

    def __init__(self, text, xmlexc):
        """Constructor for ServoClientError Class

        This class wraps Fault exceptions.

        Args:
          text: a string, error message generated by caller of exception handler
          xmlexc: Fault object supplied by the caught exception. In some
                  cases is replaced with None and ignored.

        Fault.faultString has the following format:

        <type 'exception type'>:'actual error message'

        we filter out the actual error message to make it available for the
        downstream exception handler
        """
        if xmlexc:
            xml_error = re.sub("^.*>:", "", xmlexc.faultString)
            self.message = "%s :: %s" % (text, xml_error)
        else:
            self.message = text


class ServoClient:
    """Class to link client to servod via xmlrpc.

    Beyond method initialize, the remaining methods (doc_all, doc, get, get_all,
    set) have a corresponding method implemented in servod's server.
    """

    def __init__(self, host=DEFAULT_HOST, port=DEFAULT_PORT, verbose=False):
        """Constructor for ServoClient Class

        Args:
          host: name or IP address of servo server host
          port: TCP port on which servod is listening on
          verbose: enable verbose messaging across ServerProxy
        """
        self._verbose = verbose
        remote = "http://%s:%s" % (host, port)
        self._server = ServerProxy(remote, verbose=self._verbose, allow_none=True)

    def doc_all(self):
        """Get the doc string for all controls from servo.

        Returns:
         string of all doc strings of controls from servo.
        """
        return self._server.doc_all()

    def doc(self, name):
        """Get the doc string from servo for control name.

        Args:
          name: string, name of control to retrieve doc string for.

        Returns:
         doc string for control name

        Raises:
          ServoClientError: If error occurs retrieving doc string.
        """
        try:
            return self._server.doc(name)
        except Fault as e:
            raise ServoClientError("Problem docstring '%s'" % name, e)

    def get(self, name):
        """Get the value from servo for control name.

        Args:
          name: string, name of control to get value for.

        Returns:
         value currently set on control name

        Raises:
          ServoClientError: If error occurs getting value.
        """
        try:
            return self._server.get(name)
        except Fault as e:
            raise ServoClientError("Problem getting '%s'" % name, e)

    def get_all(self):
        """Get all controls current values.

        Returns:
          String of all controls and their current values
        """
        return self._server.get_all(self._verbose)

    def set_get_all(self, controls):
        """Set &| get one or more control values.

        Args:
          controls: string, controls to set &| get.

        Raises:
          ServoClientError: If error occurs setting value.
        """
        try:
            rv = self._server.set_get_all(controls)
        except Fault as e:
            # TODO(tbroch) : more detail of failure.  Note xmlrpclib only
            #                passes one exception above
            raise ServoClientError("Problem with %s" % (controls), e)
        return rv

    def set(self, name, value):
        """Set the value from servo for control name.

        Args:
          name: string, name of control to set.
          value: string, value to set control to.

        Raises:
          ServoClientError: If error occurs setting value.
        """
        try:
            self._server.set(name, value)
        except Fault as e:
            # TODO(tbroch) : more detail of failure.  Note xmlrpclib only
            #                passes one exception above
            raise ServoClientError("Problem setting '%s' to '%s'" % (name, value), e)

    def ftdii2c(self, args):
        """Calling a method of Fi2c."""
        self._server.ftdii2c(args)

    def hwinit(self):
        """Initialize the controls."""
        self._server.hwinit()