I am trying to use the asynchronous LDAP polling feature and have a
question about what appears to be a timing issue. When I run the code
below, I find that I must insert a sleep() before entering the while
loop or I get a ValueError exception.
If I sleep for around 0.01 seconds, the exception is intermittent
(from my system to this server). With the sleep at 0.10 seconds or
higher, I get the results I would expect from the server.
I would expect that whether I sleep or not should be irrelevant. If I
poll for a result and there is nothing available, then result()
should return with None and not generate an exception. Is that the
correct behavior? What am I missing?
I provided an example of the code output including the exception
itself and the sample code below. The code uses a public LDAP server
and should work from anywhere.
---=[begin: sample exception]=---
Polling ...
Traceback (most recent call last):
File "./sample.py", line 26, in ?
res = l.result(res_id, all=0, timeout=0)
File "/usr/lib/python2.4/site-packages/ldap/ldapobject.py", line
405, in result
res_type,res_data,res_msgid = self.result2(msgid,all,timeout)
File "/usr/lib/python2.4/site-packages/ldap/ldapobject.py", line
409, in result2
res_type, res_data, res_msgid, srv_ctrls = self.result3
(msgid,all,timeout)
File "/usr/lib/python2.4/site-packages/ldap/ldapobject.py", line
415, in result3
rtype, rdata, rmsgid, serverctrls = self._ldap_call
(self._l.result3,msgid,all,timeout)
ValueError: need more than 3 values to unpack
---=[end: sample exception]=---
---=[begin: sample code]=---
#!/usr/bin/python
import ldap,time
l = ldap.initialize('ldap://ldap.utexas.edu')
l.simple_bind_s() #anonymous bind
base = r'ou=people,dc=directory,dc=utexas,dc=edu'
scope = ldap.SCOPE_ONELEVEL
filt = r'(&(uid=yw*)(objectclass=inetOrgPerson))'
attrs = ['givenname']
res_id = l.search(base, scope, filt, attrs)
# exception occurs without this sleep -- WHY??
#time.sleep(0.1)
while 1:
print
print 'Polling ...'
# Set all=0 to retrieve a single entry
# Set timeout=0 to poll for a response
res = l.result(res_id, all=0, timeout=0)
if type(res) == tuple:
if res[0] == ldap.RES_SEARCH_ENTRY:
print 'Got LDAP ENTRY'
print 'Data: ', res[1]
elif res[0] == ldap.RES_SEARCH_RESULT:
print 'Got LDAP RESULT'
print 'Data: ',
if res[1] == []:
print '--empty--'
else:
print res[1]
break #exit while loop
else:
print '-'*60
print '*** UNEXPECTED LDAP RESULT ***'
print 'DEBUG (res): ', res
print '-'*60
else:
print 'DEBUG: type = ', type(res)
print 'DEBUG: value = ', repr(res)
continue
print
l.unbind_s()
---=[end: sample code]=---
Any help appreciated.
Yancey
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