Ben Chan | ad9da22 | 2013-05-08 14:41:20 -0700 | [diff] [blame] | 1 | # Copyright (c) 2013 The Chromium OS Authors. All rights reserved. |
| 2 | # Use of this source code is governed by a BSD-style license that can be |
| 3 | # found in the LICENSE file. |
| 4 | |
| 5 | """A collection of context managers for working with shill objects.""" |
| 6 | |
| 7 | import logging |
| 8 | import shill_proxy |
| 9 | |
| 10 | |
| 11 | class ContextError(Exception): |
| 12 | """An error raised by a context managers dealing with shill objects.""" |
| 13 | pass |
| 14 | |
| 15 | |
| 16 | class ServiceAutoConnectContext(object): |
| 17 | """A context manager for overriding a service's 'AutoConnect' property. |
| 18 | |
| 19 | As the service object of the same service may change during the lifetime |
| 20 | of the context, this context manager does not take a service object at |
| 21 | construction. Instead, it takes a |get_service| function at construction, |
| 22 | which it invokes to obtain a service object when entering and exiting the |
| 23 | context. It is assumed that |get_service| always returns a service object |
| 24 | that refers to the same service. |
| 25 | |
| 26 | Usage: |
| 27 | def get_service(): |
| 28 | # Some function that returns a service object. |
| 29 | |
| 30 | with ServiceAutoConnectContext(get_service, False): |
| 31 | # Within this context, the 'AutoConnect' property of the service |
| 32 | # returned by |get_service| is temporarily set to False if it's |
| 33 | # initially set to True. The property is restored to its initial |
| 34 | # value after the context ends. |
| 35 | |
| 36 | """ |
| 37 | def __init__(self, get_service, autoconnect): |
| 38 | self._get_service = get_service |
| 39 | self._autoconnect = autoconnect |
| 40 | self._initial_autoconnect = None |
| 41 | |
| 42 | |
| 43 | def __enter__(self): |
| 44 | service = self._get_service() |
| 45 | if service is None: |
| 46 | raise ContextError('Could not obtain a service object.') |
| 47 | |
| 48 | service_properties = service.GetProperties() |
| 49 | self._initial_autoconnect = shill_proxy.dbus2primitive( |
| 50 | service_properties[ |
| 51 | shill_proxy.ShillProxy.SERVICE_PROPERTY_AUTOCONNECT]) |
| 52 | if self._initial_autoconnect != self._autoconnect: |
| 53 | logging.info('ServiceAutoConnectContext: change autoconnect to %s', |
| 54 | self._autoconnect) |
| 55 | service.SetProperty( |
| 56 | shill_proxy.ShillProxy.SERVICE_PROPERTY_AUTOCONNECT, |
| 57 | self._autoconnect) |
| 58 | else: |
| 59 | logging.info('ServiceAutoConnectContext: autoconnect remains %s', |
| 60 | self._initial_autoconnect) |
| 61 | return self |
| 62 | |
| 63 | |
| 64 | def __exit__(self, exc_type, exc_value, traceback): |
| 65 | if self._initial_autoconnect != self._autoconnect: |
| 66 | service = self._get_service() |
| 67 | if service is None: |
| 68 | raise ContextError('Could not obtain a service object.') |
| 69 | |
| 70 | logging.info('ServiceAutoConnectContext: restore autoconnect to %s', |
| 71 | self._initial_autoconnect) |
| 72 | service.SetProperty( |
| 73 | shill_proxy.ShillProxy.SERVICE_PROPERTY_AUTOCONNECT, |
| 74 | self._initial_autoconnect) |
| 75 | return False |
| 76 | |
| 77 | |
| 78 | @property |
| 79 | def autoconnect(self): |
| 80 | """AutoConnect property value within this context.""" |
| 81 | return self._autoconnect |
| 82 | |
| 83 | |
| 84 | @property |
| 85 | def initial_autoconnect(self): |
| 86 | """Initial AutoConnect property value when entering this context.""" |
| 87 | return self._initial_autoconnect |