[server] prevent returning closed cursor to the database pool In since c8c6ad8 init_repository use repo.internal_cnx() instead of repo.system_source.get_connection() so it use the pool and we should not close cursors from the pool before returning it back. Otherwise we may have "connection already closed" error. This bug only trigger when connection-pool-size = 1. Since we are moving to use a dynamic pooler we need to get this fixed. This does not occur with sqlite since the connection wrapper instantiate new cursor everytime, but this occur with other databases.

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))