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