我们从Python开源项目中，提取了以下28个代码示例，用于说明如何使用psycopg2.extensions.POLL_WRITE。
def test_flush_on_write(self): # a very large query requires a flush loop to be sent to the backend curs = self.conn.cursor() for mb in 1, 5, 10, 20, 50: size = mb * 1024 * 1024 stub = PollableStub(self.conn) curs.execute("select %s;", ('x' * size,)) self.wait(stub) self.assertEqual(size, len(curs.fetchone()[0])) if stub.polls.count(ext.POLL_WRITE) > 1: return # This is more a testing glitch than an error: it happens # on high load on linux: probably because the kernel has more # buffers ready. A warning may be useful during development, # but an error is bad during regression testing. import warnings warnings.warn("sending a large query didn't trigger block on write.")
def test_flush_on_write(self): # a very large query requires a flush loop to be sent to the backend conn = self.conn stub = self.set_stub_wait_callback(conn) curs = conn.cursor() for mb in 1, 5, 10, 20, 50: size = mb * 1024 * 1024 del stub.polls[:] curs.execute("select %s;", ('x' * size,)) self.assertEqual(size, len(curs.fetchone()[0])) if stub.polls.count(psycopg2.extensions.POLL_WRITE) > 1: return # This is more a testing glitch than an error: it happens # on high load on linux: probably because the kernel has more # buffers ready. A warning may be useful during development, # but an error is bad during regression testing. import warnings warnings.warn("sending a large query didn't trigger block on write.")
def crappy_callback(self, conn): """green callback failing after `self.to_error` time it is called""" import select from psycopg2.extensions import POLL_OK, POLL_READ, POLL_WRITE while 1: if self.to_error is not None: self.to_error -= 1 if self.to_error <= 0: raise ZeroDivisionError("I accidentally the connection") try: state = conn.poll() if state == POLL_OK: break elif state == POLL_READ: select.select([conn.fileno()], [], []) elif state == POLL_WRITE: select.select([], [conn.fileno()], []) else: raise conn.OperationalError("bad state from poll: %s" % state) except KeyboardInterrupt: conn.cancel() # the loop will be broken by a server error continue
def wait_select(conn): """Wait until a connection or cursor has data available. The function is an example of a wait callback to be registered with `~psycopg2.extensions.set_wait_callback()`. This function uses :py:func:`~select.select()` to wait for data available. """ import select from psycopg2.extensions import POLL_OK, POLL_READ, POLL_WRITE while 1: state = conn.poll() if state == POLL_OK: break elif state == POLL_READ: select.select([conn.fileno()], [], []) elif state == POLL_WRITE: select.select([], [conn.fileno()], []) else: raise conn.OperationalError("bad state from poll: %s" % state)
def wait_select(conn): """Wait until a connection or cursor has data available. The function is an example of a wait callback to be registered with `~psycopg2.extensions.set_wait_callback()`. This function uses :py:func:`~select.select()` to wait for data available. """ import select from psycopg2.extensions import POLL_OK, POLL_READ, POLL_WRITE while 1: try: state = conn.poll() if state == POLL_OK: break elif state == POLL_READ: select.select([conn.fileno()], [], []) elif state == POLL_WRITE: select.select([], [conn.fileno()], []) else: raise conn.OperationalError("bad state from poll: %s" % state) except KeyboardInterrupt: conn.cancel() # the loop will be broken by a server error continue
def eventlet_wait_callback(conn, timeout=-1): """A wait callback useful to allow eventlet to work with Psycopg.""" while 1: state = conn.poll() if state == extensions.POLL_OK: break elif state == extensions.POLL_READ: trampoline(conn.fileno(), read=True) elif state == extensions.POLL_WRITE: trampoline(conn.fileno(), write=True) else: raise psycopg2.OperationalError( "Bad result from poll: %r" % state)
def gevent_wait_callback(conn, timeout=None): """A wait callback useful to allow gevent to work with Psycopg.""" while 1: state = conn.poll() if state == extensions.POLL_OK: break elif state == extensions.POLL_READ: wait_read(conn.fileno(), timeout=timeout) elif state == extensions.POLL_WRITE: wait_write(conn.fileno(), timeout=timeout) else: raise psycopg2.OperationalError( "Bad result from poll: %r" % state)
