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'''Bcfg2.Server.Core provides the runtime support for bcfg2 modules'''
__revision__ = '$Revision$'
from os import stat
from stat import ST_MODE, S_ISDIR
from sys import exc_info
from syslog import syslog, LOG_ERR
from traceback import extract_tb
from time import time
import _fam
from Bcfg2.Server.Generator import GeneratorError, GeneratorInitError
class PublishError(Exception):
'''This error is raised upon publication failures'''
pass
class fam(object):
'''The fam object is a set of callbacks for file alteration events'''
def __init__(self):
object.__init__(self)
self.fm = _fam.open()
self.users = {}
self.handles = {}
def fileno(self):
'''return fam file handle number'''
return self.fm.fileno()
def AddMonitor(self, path, obj=None):
'''add a monitor to path, installing a callback to obj.HandleEvent'''
mode = stat(path)[ST_MODE]
if S_ISDIR(mode):
handle = self.fm.monitorDirectory(path, None)
#print "adding callback for directory %s to %s, handle :%s:" % ( path, obj, handle.requestID())
else:
handle = self.fm.monitorFile(path, None)
self.handles[handle.requestID()] = handle
if obj != None:
self.users[handle.requestID()] = obj
return handle.requestID()
def HandleEvent(self):
'''Route a fam event to the proper callback'''
event = self.fm.nextEvent()
reqid = event.requestID
if self.users.has_key(reqid):
#print "dispatching event %s %s to obj %s handle :%s:" % (event.code2str(), event.filename, self.users[reqid], event.requestID)
self.users[reqid].HandleEvent(event)
class PublishedValue(object):
'''This is for data shared between generators'''
def __init__(self, owner, key, value):
object.__init__(self)
self.owner = owner
self.key = key
self.value = value
def Update(self, owner, value):
'''Update the value after an ownership check succeeds'''
if owner != self.owner:
raise PublishError, (self.key, owner)
self.value = value
class Core(object):
'''The Core object is the container for all Bcfg2 Server logic, and modules'''
def __init__(self, repository, structures, generators):
object.__init__(self)
self.datastore = repository
self.fam = fam()
self.pubspace = {}
self.structures = []
self.cron = {}
for structure in structures:
try:
mod = getattr(__import__("Bcfg2.Server.Structures.%s" %
(structure)).Server.Structures, structure)
except ImportError:
syslog(LOG_ERR, "Failed to load structure %s" % (structure))
continue
struct = getattr(mod, structure)
self.structures.append(struct(self, self.datastore))
self.generators = []
for generator in generators:
try:
mod = getattr(__import__("Bcfg2.Server.Generators.%s" %
(generator)).Server.Generators, generator)
except ImportError:
syslog(LOG_ERR, 'Failed to load generator %s' % (generator))
continue
gen = getattr(mod, generator)
try:
self.generators.append(gen(self, self.datastore))
except GeneratorInitError:
syslog(LOG_ERR, "Failed to instantiate generator %s" % gen.__name__)
except:
print "Unexpected initiantiation failure for generator %s" % gen.__name__
syslog(LOG_ERR, "Unexpected initiantiation failure for generator %s" % gen.__name__)
(trace, val, trb)=exc_info()
for line in extract_tb(trb):
syslog(LOG_ERR, ' File "%s", line %i, in %s\n %s\n'%line)
syslog(LOG_ERR, "%s: %s\n"%(trace, val))
del trace, val, trb
# we need to inventory and setup generators
# Process generator requirements
for gen in self.generators:
for prq in gen.__requires__:
if not self.pubspace.has_key(prq):
raise GeneratorError, (gen.name, prq)
gen.CompleteSetup()
def PublishValue(self, owner, key, value):
'''Publish a shared generator value'''
if not self.pubspace.has_key(key):
# This is a new entry
self.pubspace[key] = PublishedValue(owner, key, value)
else:
# This is an old entry. Update can fai
try:
self.pubspace[key].Update(owner, value)
except PublishError:
syslog(LOG_ERR, "Publish conflict for %s. Owner %s, Modifier %s"%
(key, self.pubspace[key].owner, owner))
def ReadValue(self, key):
'''Read a value published by another generator'''
if self.pubspace.has_key(key):
return self.pubspace[key].value
raise KeyError, key
def GetStructures(self, metadata):
'''Get all structures for client specified by metadata'''
return reduce(lambda x, y:x+y,
[struct.Construct(metadata) for struct in self.structures])
def BindStructure(self, structure, metadata):
'''Bind a complete structure'''
for entry in [child for child in structure.getchildren() if child.tag not in ['SymLink', 'Directory']]:
try:
self.Bind(entry, metadata)
except GeneratorError:
syslog(LOG_ERR, "Failed to bind entry: %s %s" % (entry.tag, entry.get('name')))
def Bind(self, entry, metadata):
'''Bind an entry using the appropriate generator'''
glist = [gen for gen in self.generators if
gen.__provides__.get(entry.tag, {}).has_key(entry.get('name'))]
if len(glist) == 1:
return glist[0].__provides__[entry.tag][entry.get('name')](entry, metadata)
elif len(glist) > 1:
print "Data Integrity error for %s %s" % (entry.tag, entry.get('name'))
else:
for gen in self.generators:
if hasattr(gen, "FindHandler"):
return gen.FindHandler(entry)(entry, metadata)
raise GeneratorError, (entry.tag, entry.get('name'))
def RunCronTasks(self):
'''Run periodic tasks for generators'''
generators = [gen for gen in self.generators if gen.__croninterval__]
for generator in generators:
current = time()
if ((current - self.cron.get(generator, 0)) > generator.__croninterval__):
generator.Cron()
self.cron[generator] = current
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