[server] extract "no pooler" CnxSet class to a _BaseCnxSet class
So we get rid of "if self._queue is None" in each method of _CnxSetPool
Also add helper get_cnxset(source, size) to instantiate the correct pooler class.
from __future__ import print_function
try:
rtype, = __args__
except ValueError:
print('USAGE: cubicweb-ctl shell <instance> detect_cycle.py -- <relation type>')
print()
graph = {}
for fromeid, toeid in rql('Any X,Y WHERE X %s Y' % rtype):
graph.setdefault(fromeid, []).append(toeid)
from logilab.common.graph import get_cycles
for cycle in get_cycles(graph):
print('cycle', '->'.join(str(n) for n in cycle))