1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
|
#/*******************************************************************************
#* Portions Copyright (C) 2008 Novell, Inc. All rights reserved.
#*
#* Redistribution and use in source and binary forms, with or without
#* modification, are permitted provided that the following conditions are met:
#*
#* - Redistributions of source code must retain the above copyright notice,
#* this list of conditions and the following disclaimer.
#*
#* - Redistributions in binary form must reproduce the above copyright notice,
#* this list of conditions and the following disclaimer in the documentation
#* and/or other materials provided with the distribution.
#*
#* - Neither the name of Novell, Inc. nor the names of its
#* contributors may be used to endorse or promote products derived from this
#* software without specific prior written permission.
#*
#* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS IS''
#* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
#* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
#* ARE DISCLAIMED. IN NO EVENT SHALL Novell, Inc. OR THE CONTRIBUTORS
#* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
#* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
#* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
#* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
#* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
#* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
#* POSSIBILITY OF SUCH DAMAGE.
#*
#* Authors: Matt Ryan (mrayn novell.com)
#* Brad Nicholes (bnicholes novell.com)
#******************************************************************************/
import imp
import logging
import os
import sys
from gmetad_config import getConfig
_plugins = [] # Holds a list of all of the plugins
def load_plugins(pdir):
''' This method is called to discover and load all of the plugins that are
contained in the specified plugin directory. '''
global _plugins
# Make sure we have a valid plugin directory
if not os.path.isdir(pdir):
logging.warning('No such plugin directory "%s", no plugins loaded' % pdir)
return
# Add the plugin directory to the python search path
sys.path.append(pdir)
# Iterate through all of the files in the plugin directory to try to find gmetad modules.
# All gmetad modules will be derived from the GmetadPlugin base class.
for plugin_candidate in os.listdir(pdir):
if plugin_candidate.startswith('.'): continue
if not plugin_candidate.endswith('.py'): continue
plugin_name = plugin_candidate[:len(plugin_candidate)-3]
# Tell python to find the module from the file path
fp, pathname, description = imp.find_module(plugin_name)
try:
try:
# Tell python to load the module.
_module = imp.load_module(plugin_name, fp, pathname, description)
# All modules should have a get_plugin() factory function. This function creates a
# new instance of the module class
plugin = _module.get_plugin()
if not isinstance(plugin, GmetadPlugin):
logging.warning('Plugin %s is not a gmetad plugin' % plugin_name)
else:
_plugins.append(plugin)
except Exception, e:
logging.warning('Failed to load plugin %s (caught exception %s)' % (plugin_name, e))
finally:
if fp: fp.close()
def start_plugins():
global _plugins
# Call the start method. All modules should have a start method.
for plugin in _plugins:
plugin.start()
def stop_plugins():
global _plugins
# Call the stop method. All modules should have a stop method.
for plugin in _plugins:
plugin.stop()
def notify_plugins(clusterNode):
global _plugins
# Call the notify method. All modules should have a notify method.
for plugin in _plugins:
plugin.notify(clusterNode)
class GmetadPlugin:
''' This is the base class for all gmetad plugins. '''
def __init__(self, cfgid):
# All modules are intialized with a module id that should match a section id
# found in the configuration file.
self.cfgid = cfgid
self._parseConfig(getConfig().getSection(cfgid))
def _parseConfig(self, cfgdata):
'''Should be overridden by subclasses to parse configuration data, if any.'''
pass
def notify(self, clusterNode):
'''Called by the engine when the internal data structure has changed.
Should be overridden by subclasses that should be pulling data out of
the data structure when the data structure is updated.'''
pass
def start(self):
'''Called by the engine during initialization to get the plugin going. Must
be overridden by subclasses.'''
raise Exception, 'No definition provided for plugin "start" method.'
def stop(self):
'''Called by the engine during shutdown to allow the plugin to shutdown. Must
be overridden by subclasses.'''
raise Exception, 'No definition provided for plugin "stop" method.'
|
