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"""Cobalt component base."""
__revision__ = '$Revision$'
__all__ = ["Component", "exposed", "automatic", "run_component"]
import inspect
import logging
import os
import pydoc
import sys
import time
import threading
import Bcfg2.Logger
from Bcfg2.Statistics import Statistics
from Bcfg2.SSLServer import XMLRPCServer
# Compatibility import
from Bcfg2.Bcfg2Py3k import xmlrpclib, urlparse, fprint
logger = logging.getLogger()
class NoExposedMethod (Exception):
"""There is no method exposed with the given name."""
def run_component(component_cls, listen_all, location, daemon, pidfile_name,
to_file, cfile, argv=None, register=True,
state_name=False, cls_kwargs={}, extra_getopt='', time_out=10,
protocol='xmlrpc/ssl', certfile=None, keyfile=None, ca=None):
# default settings
level = logging.INFO
logging.getLogger().setLevel(level)
Bcfg2.Logger.setup_logging(component_cls.implementation,
to_console=True,
to_syslog=True,
to_file=to_file,
level=level)
if daemon:
child_pid = os.fork()
if child_pid != 0:
return
os.setsid()
child_pid = os.fork()
if child_pid != 0:
os._exit(0)
redirect_file = open("/dev/null", "w+")
os.dup2(redirect_file.fileno(), sys.__stdin__.fileno())
os.dup2(redirect_file.fileno(), sys.__stdout__.fileno())
os.dup2(redirect_file.fileno(), sys.__stderr__.fileno())
os.chdir(os.sep)
pidfile = open(pidfile_name or "/dev/null", "w")
fprint(os.getpid(), pidfile)
pidfile.close()
component = component_cls(cfile=cfile, **cls_kwargs)
up = urlparse(location)
port = tuple(up[1].split(':'))
port = (port[0], int(port[1]))
try:
server = XMLRPCServer(listen_all,
port,
keyfile=keyfile,
certfile=certfile,
register=register,
timeout=time_out,
ca=ca,
protocol=protocol)
except:
logger.error("Server startup failed")
os._exit(1)
server.register_instance(component)
try:
server.serve_forever()
finally:
server.server_close()
component.shutdown()
def exposed(func):
"""Mark a method to be exposed publically.
Examples:
class MyComponent (Component):
@expose
def my_method (self, param1, param2):
do_stuff()
class MyComponent (Component):
def my_method (self, param1, param2):
do_stuff()
my_method = expose(my_method)
"""
func.exposed = True
return func
def automatic(func, period=10):
"""Mark a method to be run periodically."""
func.automatic = True
func.automatic_period = period
func.automatic_ts = -1
return func
def locking(func):
"""Mark a function as being internally thread safe"""
func.locking = True
return func
def readonly(func):
"""Mark a function as read-only -- no data effects in component inst"""
func.readonly = True
return func
class Component (object):
"""Base component.
Intended to be served as an instance by Cobalt.Component.XMLRPCServer
>>> server = Cobalt.Component.XMLRPCServer(location, keyfile)
>>> component = Cobalt.Component.Component()
>>> server.serve_instance(component)
Class attributes:
name -- logical component name (e.g., "queue-manager", "process-manager")
implementation -- implementation identifier (e.g., "BlueGene/L", "BlueGene/P")
Methods:
save -- pickle the component to a file
do_tasks -- perform automatic tasks for the component
"""
name = "component"
implementation = "generic"
def __init__(self, **kwargs):
"""Initialize a new component.
Keyword arguments:
statefile -- file in which to save state automatically
"""
self.statefile = kwargs.get("statefile", None)
self.logger = logging.getLogger("%s %s" % (self.implementation, self.name))
self.lock = threading.Lock()
self.instance_statistics = Statistics()
def do_tasks(self):
"""Perform automatic tasks for the component.
Automatic tasks are member callables with an attribute
automatic == True.
"""
for name, func in inspect.getmembers(self):
if name == '__call__':
if getattr(func, "automatic", False):
need_to_lock = not getattr(func, 'locking', False)
if (time.time() - func.automatic_ts) > \
func.automatic_period:
if need_to_lock:
t1 = time.time()
self.lock.acquire()
t2 = time.time()
self.instance_statistics.add_value('component_lock', t2-t1)
try:
mt1 = time.time()
try:
func()
except:
self.logger.error("Automatic method %s failed" \
% (name), exc_info=1)
finally:
mt2 = time.time()
if need_to_lock:
self.lock.release()
self.instance_statistics.add_value(name, mt2-mt1)
func.__dict__['automatic_ts'] = time.time()
def _resolve_exposed_method(self, method_name):
"""Resolve an exposed method.
Arguments:
method_name -- name of the method to resolve
"""
try:
func = getattr(self, method_name)
except AttributeError:
raise NoExposedMethod(method_name)
if not getattr(func, "exposed", False):
raise NoExposedMethod(method_name)
return func
def _dispatch(self, method, args, dispatch_dict):
"""Custom XML-RPC dispatcher for components.
method -- XML-RPC method name
args -- tuple of paramaters to method
"""
need_to_lock = True
if method in dispatch_dict:
method_func = dispatch_dict[method]
else:
try:
method_func = self._resolve_exposed_method(method)
except NoExposedMethod:
self.logger.error("Unknown method %s" % (method))
raise xmlrpclib.Fault(7, "Unknown method %s" % method)
except Exception:
e = sys.exc_info()[1]
if getattr(e, "log", True):
self.logger.error(e, exc_info=True)
raise xmlrpclib.Fault(getattr(e, "fault_code", 1), str(e))
if getattr(method_func, 'locking', False):
need_to_lock = False
if need_to_lock:
lock_start = time.time()
self.lock.acquire()
lock_done = time.time()
try:
method_start = time.time()
try:
result = method_func(*args)
finally:
method_done = time.time()
if need_to_lock:
self.lock.release()
self.instance_statistics.add_value('component_lock',
lock_done - lock_start)
self.instance_statistics.add_value(method, method_done - method_start)
except xmlrpclib.Fault:
raise
except Exception:
e = sys.exc_info()[1]
if getattr(e, "log", True):
self.logger.error(e, exc_info=True)
raise xmlrpclib.Fault(getattr(e, "fault_code", 1), str(e))
return result
def listMethods(self):
"""Custom XML-RPC introspective method list."""
return [
name for name, func in inspect.getmembers(self, callable)
if getattr(func, "exposed", False)
]
listMethods = exposed(listMethods)
def methodHelp(self, method_name):
"""Custom XML-RPC introspective method help.
Arguments:
method_name -- name of method to get help on
"""
try:
func = self._resolve_exposed_method(method_name)
except NoExposedMethod:
return ""
return pydoc.getdoc(func)
methodHelp = exposed(methodHelp)
def get_name(self):
"""The name of the component."""
return self.name
get_name = exposed(get_name)
def get_implementation(self):
"""The implementation of the component."""
return self.implementation
get_implementation = exposed(get_implementation)
def get_statistics(self, _):
"""Get current statistics about component execution"""
return self.instance_statistics.display()
get_statistics = exposed(get_statistics)
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