From 7a22e9e38eb6997fe793f088c94fac6f7e73e352 Mon Sep 17 00:00:00 2001
From: Yury Selivanov <yselivanov@sprymix.com>
Date: Sat, 8 Jun 2013 13:37:04 -0400
Subject: [PATCH] examples: Add py-postgresql non-blocking adapter
Demonstrates how easy it is to make existing codebase non-blocking
---
examples/postgres.py | 128 +++++++++++++++++++++++++++++++++++++++++++
1 file changed, 128 insertions(+)
create mode 100644 examples/postgres.py
diff --git a/examples/postgres.py b/examples/postgres.py
new file mode 100644
index 0000000..c6a4dae
--- /dev/null
+++ b/examples/postgres.py
@@ -0,0 +1,128 @@
+##
+# Copyright (c) 2008-2012 Sprymix Inc.
+# License: Apache 2.0
+##
+
+
+"""A non-blocking adapter for py-postgresql library.
+WARNING: This is just an experiment; use in production is not recommended.
+"""
+
+
+import postgresql
+from postgresql.python import socket as pg_socket
+from postgresql.driver import pq3
+
+from greentulip import socket as greensocket
+
+
+class SocketConnector:
+ def create_socket_factory(self, **params):
+ params['socket_extra'] = {'async': self.async}
+ return SocketFactory(**params)
+
+ def __init__(self, async=False):
+ self.async = async
+
+
+class IPConnector(pq3.IPConnector, SocketConnector):
+ def __init__(self, *args, async=False, **kw):
+ pq3.IPConnector.__init__(self, *args, **kw)
+ SocketConnector.__init__(self, async=async)
+
+
+class IP4(IPConnector, pq3.IP4):
+ pass
+
+
+class IP6(IPConnector, pq3.IP6):
+ pass
+
+
+class Host(SocketConnector, pq3.Host):
+ def __init__(self, *args, async=False, **kw):
+ pq3.Host.__init__(self, *args, **kw)
+ SocketConnector.__init__(self, async=async)
+
+
+class Unix(SocketConnector, pq3.Unix):
+ def __init__(self, unix=None, async=False, **kw):
+ pq3.Unix.__init__(self, unix=unix, **kw)
+ SocketConnector.__init__(self, async=async)
+
+
+class SocketFactory(pg_socket.SocketFactory):
+ def __init__(self, *args, socket_extra=None, **kw):
+ super().__init__(*args, **kw)
+ self.async = socket_extra.get('async', False) if socket_extra else False
+
+ def __call__(self, timeout=None):
+ if self.async:
+ s = greensocket.socket(*self.socket_create)
+ s.connect(self.socket_connect)
+ return s
+ else:
+ return super().__call__(timeout)
+
+
+class Driver(pq3.Driver):
+ def ip4(self, **kw):
+ return IP4(driver=self, **kw)
+
+ def ip6(self, **kw):
+ return IP6(driver=self, **kw)
+
+ def host(self, **kw):
+ return Host(driver=self, **kw)
+
+ def unix(self, **kw):
+ return Unix(driver=self, **kw)
+
+
+driver = Driver()
+
+
+def connector_factory(iri, async=False):
+ params = postgresql.iri.parse(iri)
+ settings = params.setdefault('settings', {})
+ settings['standard_conforming_strings'] = 'on'
+ params['async'] = async
+ return driver.fit(**params)
+
+
+if __name__ == '__main__':
+ import greentulip
+ import time
+ import tulip
+
+ @tulip.task
+ def sleeper():
+ # show that we're not blocked
+ while True:
+ yield from tulip.sleep(0.4)
+ print('.')
+
+ @greentulip.task
+ def db():
+ connection = connector_factory('pq://postgres@localhost:5432', async=True)()
+ connection.connect()
+
+ try:
+ print('>> sleeping')
+ st = time.monotonic()
+ connection.execute('SELECT pg_sleep(2)')
+ en = time.monotonic() - st
+ assert en >= 2
+ print('<< sleeping {:.3f}s'.format(en))
+
+ ps = connection.prepare('SELECT 42')
+ print('"SELECT 42" -> {!r}'.format(ps()))
+ finally:
+ connection.close()
+
+ @tulip.task
+ def run():
+ yield from tulip.wait([db(), sleeper()], return_when=tulip.FIRST_COMPLETED)
+
+ tulip.set_event_loop_policy(greentulip.GreenEventLoopPolicy())
+ tulip.get_event_loop().run_until_complete(run())