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'''This is a baseclass not intended for instantiation'''
__revision__ = '$Revision: 1.34 $'
from elementtree.ElementTree import XML
from syslog import syslog, LOG_ERR, LOG_INFO
from xml.parsers.expat import ExpatError
from os import stat
from stat import ST_MTIME
class GeneratorError(Exception):
'''Generator runtime error used to inform upper layers of internal generator failure'''
pass
class GeneratorInitError(Exception):
'''Constructor time error that allows the upper layer to proceed in the face of
generator initialization failures'''
pass
class Generator(object):
'''This is a class that generators can be subclassed from.
__name__, __version__, and __author__ must be set for the module
__provides__ is a dictionary mapping listing the entity type and name to a function name
__requires__ is a set of external published data needed for operation
__croninterval__ is the frequency in second with which the Cron method should be executed'''
__name__ = None
__version__ = None
__croninterval__ = False
__provides__ = {}
__requires__ = []
def __init__(self, core, datastore):
object.__init__(self)
self.core = core
self.data = "%s/%s" % (datastore, self.__name__)
self.external = {}
def LogError(self, msg):
syslog(LOG_ERR, "%s: %s" % (self.__name__, msg))
def CompleteSetup(self):
'''Read any external required publication data'''
self.ReadAll()
def Cron(self):
'''Cron defines periodic tasks to maintain data coherence'''
pass
def Publish(self, key, value):
'''publish a value for external consumption'''
self.core.Publish(self.__name__, key, value)
def Read(self, key):
'''Read a publication value'''
self.core.ReadValue(key)
def ReadAll(self):
'''Read all required publication values'''
for field in self.__requires__:
self.external[field] = self.Read(field)
def Notify(self, region):
'''Generate change notification for region'''
pass
def get_probes(self, client):
'''Get appropriate probes for client'''
return []
def accept_probe_data(self, client, probedata):
'''Recieve probe response for client'''
return
class FileBacked(object):
'''This object caches file data in memory.
HandleEvent is called whenever fam registers an event.
Index can parse the data into member data as required.
This object is meant to be used as a part of DirectoryBacked.'''
def __init__(self, name):
object.__init__(self)
self.data = ''
self.name = name
self.mtime = 0
#self.readonce = 0
#self.HandleEvent()
def HandleEvent(self, event=None):
'''Read file upon update'''
oldmtime = self.mtime
try:
self.mtime = stat(self.name)[ST_MTIME]
except OSError:
syslog(LOG_ERR, "Failed to stat file %s" % (self.name))
if self.mtime > oldmtime:
try:
# if self.readonce == 0:
# self.readonce = 1
# else:
# syslog(LOG_INFO, "Updated file %s" % (self.name))
self.data = file(self.name).read()
self.Index()
except IOError:
syslog(LOG_ERR, "Failed to read file %s" % (self.name))
def Index(self):
'''Update local data structures based on current file state'''
pass
class DirectoryBacked(object):
'''This object is a coherent cache for a filesystem hierarchy of files.'''
__child__ = FileBacked
def __init__(self, name, fam):
object.__init__(self)
self.name = name
self.fam = fam
self.entries = {}
self.inventory = False
fam.AddMonitor(name, self)
def __getitem__(self, key):
return self.entries[key]
def __iter__(self):
return self.entries.iteritems()
def AddEntry(self, name):
'''Add new entry to data structures upon file creation'''
if self.entries.has_key(name):
syslog(LOG_INFO, "got multiple adds for %s" % name)
else:
if ((name[-1] == '~') or (name[:2] == '.#') or (name == 'SCCS') or (name[-4:] == '.swp')):
return
self.entries[name] = self.__child__('%s/%s' % (self.name, name))
self.entries[name].HandleEvent()
def HandleEvent(self, event):
'''Propagate fam events to underlying objects'''
action = event.code2str()
if action == 'exists':
if event.filename != self.name:
self.AddEntry(event.filename)
elif action == 'created':
self.AddEntry(event.filename)
elif action == 'changed':
if self.entries.has_key(event.filename):
self.entries[event.filename].HandleEvent(event)
elif action == 'deleted':
if self.entries.has_key(event.filename):
del self.entries[event.filename]
elif action in ['endExist']:
pass
else:
print "Got unknown event %s %s %s" % (event.requestID, event.code2str(), event.filename)
class XMLFileBacked(FileBacked):
'''This object is a coherent cache for an XML file to be used as a part of DirectoryBacked.'''
__identifier__ = 'name'
def __init__(self, filename):
self.label = "dummy"
self.entries = []
FileBacked.__init__(self, filename)
def Index(self):
'''Build local data structures'''
try:
xdata = XML(self.data)
except ExpatError:
syslog(LOG_ERR, "Failed to parse %s"%(self.name))
return
self.label = xdata.attrib[self.__identifier__]
self.entries = xdata.getchildren()
def __iter__(self):
return iter(self.entries)
class SingleXMLFileBacked(XMLFileBacked):
'''This object is a coherent cache for an independent XML File.'''
def __init__(self, filename, fam):
XMLFileBacked.__init__(self, filename)
fam.AddMonitor(filename, self)
class ScopedXMLFile(SingleXMLFileBacked):
'''Scoped XML files are coherent files with Metadata structured data'''
__containers__ = ['Class', 'Host', 'Image']
def __init__(self, filename, fam):
self.store = {}
self.__provides__ = {}
SingleXMLFileBacked.__init__(self, filename, fam)
def StoreRecord(self, metadata, entry):
'''Store scoped record based on metadata'''
if not self.store.has_key(entry.tag):
self.store[entry.tag] = {}
if not self.store[entry.tag].has_key(entry.attrib['name']):
self.store[entry.tag][entry.attrib['name']] = []
self.store[entry.tag][entry.attrib['name']].append((metadata, entry))
def Index(self):
'''Build internal data structures'''
try:
xdata = XML(self.data)
except ExpatError, msg:
syslog(LOG_ERR, "Failed to parse %s"%(self.name))
syslog(LOG_ERR, msg)
return
self.store = {}
for entry in xdata.getchildren():
if entry.tag not in self.__containers__:
self.StoreRecord(('Global','all'), entry)
else:
name = (entry.tag, entry.get('name'))
[self.StoreRecord(name, child) for child in entry.getchildren()]
# now to build the __provides__ table
for key in self.__provides__.keys():
del self.__provides__[key]
for key in self.store.keys():
self.__provides__[key] = {}
for name in self.store[key].keys():
self.__provides__[key][name] = self.FetchRecord
# also need to sort all leaf node lists
self.store[key][name].sort(self.Sort)
def Sort(self, meta1, meta2):
'''Sort based on specificity'''
order = ['Global', 'Image', 'Profile', 'Class', 'Host']
return order.index(meta1[0][0]) - order.index(meta2[0][0])
def MatchMetadata(self, mdata, metadata):
'''Match internal metadata representation against metadata'''
(mtype, mvalue) = mdata
if mtype == 'Global':
return True
elif mtype == 'Profile':
if mvalue == metadata.profile:
return True
elif mtype == 'Image':
if mvalue == metadata.image:
return True
elif mtype == 'Class':
if mvalue in metadata.classes:
return True
elif mtype == 'Host':
if mvalue == metadata.hostname:
return True
return False
def FetchRecord(self, entry, metadata):
'''Build a data for specified metadata'''
dlist = self.store[entry.tag][entry.get('name')]
useful = [ent for ent in dlist if self.MatchMetadata(ent[0], metadata)]
if not useful:
syslog(LOG_ERR, "Failed to FetchRecord %s:%s"%(entry.tag, entry.get('name')))
else:
data = useful[-1][-1]
entry.attrib.update(data.attrib)
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