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# Copyright (c) 2012-2015 Denis Bilenko. See LICENSE for details.
"""
Native thread-based hostname resolver.
"""
import _socket
from gevent._compat import text_type
from gevent.hub import get_hub
__all__ = ['Resolver']
# trigger import of encodings.idna to avoid https://github.com/gevent/gevent/issues/349
text_type('foo').encode('idna')
class Resolver(object):
"""
Implementation of the resolver API using native threads and native resolution
functions.
Using the native resolution mechanisms ensures the highest
compatibility with what a non-gevent program would return
including good support for platform specific configuration
mechanisms. The use of native (non-greenlet) threads ensures that
a caller doesn't block other greenlets.
This implementation also has the benefit of being very simple in comparison to
:class:`gevent.resolver_ares.Resolver`.
.. tip::
Most users find this resolver to be quite reliable in a
properly monkey-patched environment. However, there have been
some reports of long delays, slow performance or even hangs,
particularly in long-lived programs that make many, many DNS
requests. If you suspect that may be happening to you, try the
ares resolver (and submit a bug report).
"""
def __init__(self, hub=None):
if hub is None:
hub = get_hub()
self.pool = hub.threadpool
if _socket.gaierror not in hub.NOT_ERROR:
# Do not cause lookup failures to get printed by the default
# error handler. This can be very noisy.
hub.NOT_ERROR += (_socket.gaierror, _socket.herror)
def __repr__(self):
return '<gevent.resolver_thread.Resolver at 0x%x pool=%r>' % (id(self), self.pool)
def close(self):
pass
# from briefly reading socketmodule.c, it seems that all of the functions
# below are thread-safe in Python, even if they are not thread-safe in C.
def gethostbyname(self, *args):
return self.pool.apply(_socket.gethostbyname, args)
def gethostbyname_ex(self, *args):
return self.pool.apply(_socket.gethostbyname_ex, args)
def getaddrinfo(self, *args, **kwargs):
return self.pool.apply(_socket.getaddrinfo, args, kwargs)
def gethostbyaddr(self, *args, **kwargs):
return self.pool.apply(_socket.gethostbyaddr, args, kwargs)
def getnameinfo(self, *args, **kwargs):
return self.pool.apply(_socket.getnameinfo, args, kwargs)
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