1 """A wait callback to allow psycopg2 cooperation with eventlet.
3 Use `make_psycopg_green()` to enable eventlet support in Psycopg.
6 # Copyright (C) 2010 Daniele Varrazzo <daniele.varrazzo@gmail.com>
7 # and licensed under the MIT license:
9 # Permission is hereby granted, free of charge, to any person obtaining a copy
10 # of this software and associated documentation files (the "Software"), to deal
11 # in the Software without restriction, including without limitation the rights
12 # to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
13 # copies of the Software, and to permit persons to whom the Software is
14 # furnished to do so, subject to the following conditions:
16 # The above copyright notice and this permission notice shall be included in
17 # all copies or substantial portions of the Software.
19 # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
20 # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
21 # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
22 # AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
23 # LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
24 # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
28 from psycopg2 import extensions
30 from eventlet.hubs import trampoline
33 def make_psycopg_green():
34 """Configure Psycopg to be used with eventlet in non-blocking way."""
35 if not hasattr(extensions, 'set_wait_callback'):
37 "support for coroutines not available in this Psycopg version (%s)"
38 % psycopg2.__version__)
40 extensions.set_wait_callback(eventlet_wait_callback)
43 def eventlet_wait_callback(conn, timeout=-1):
44 """A wait callback useful to allow eventlet to work with Psycopg."""
47 if state == extensions.POLL_OK:
49 elif state == extensions.POLL_READ:
50 trampoline(conn.fileno(), read=True)
51 elif state == extensions.POLL_WRITE:
52 trampoline(conn.fileno(), write=True)
54 raise psycopg2.OperationalError(
55 "Bad result from poll: %r" % state)