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#
# This is a simple facility for exposing internal SNMP Engine
# working details to pysnmp applications. These details are
# basically local scope variables at a fixed point of execution.
#
# Two modes of operations are offered:
# 1. App can request an execution point context by execution point ID.
# 2. App can register its callback function (and context) to be invoked
# once execution reaches specified point. All local scope variables
# will be passed to the callback as in #1.
#
# It's important to realize that execution context is only guaranteed
# to exist to functions that are at the same or deeper level of invocation
# relative to execution point specified.
#
from pysnmp import error
class MetaObserver:
def __init__(self):
self.__observers = {}
self.__contexts = {}
self.__execpoints = {}
def registerObserver(self, cbFun, *execpoints, **kwargs):
if cbFun in self.__contexts:
raise error.PySnmpError('duplicate observer %s' % cbFun)
else:
self.__contexts[cbFun] = kwargs.get('cbCtx')
for execpoint in execpoints:
if not execpoint in self.__observers:
self.__observers[execpoint] = []
self.__observers[execpoint].append(cbFun)
def unregisterObserver(self, cbFun=None):
if cbFun is None:
self.__observers.clear()
self.__contexts.clear()
else:
for execpoint in dict(self.__observers):
if cbFun in self.__observers[execpoint]:
self.__observers[execpoint].remove(cbFun)
if not self.__observers[execpoint]:
del self.__observers[execpoint]
def storeExecutionContext(self, snmpEngine, execpoint, variables):
self.__execpoints[execpoint] = variables
if execpoint in self.__observers:
for cbFun in self.__observers[execpoint]:
cbFun(snmpEngine, execpoint, variables, self.__contexts[cbFun])
def clearExecutionContext(self, snmpEngine, *execpoints):
if execpoints:
for execpoint in execpoints:
del self.__execpoints[execpoint]
else:
self.__execpoints.clear()
def getExecutionContext(self, execpoint):
return self.__execpoints[execpoint]
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