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- Committer: mbp at sourcefrog
- Date: 2005-04-08 05:39:46 UTC
- Revision ID: mbp@sourcefrog.net-20050408053946-1cb3415e1f8f58493034a5cf
- import lovely urlgrabber library
added
removed
urlgrabber/keepalive.py
1
# This library is free software; you can redistribute it and/or
2
# modify it under the terms of the GNU Lesser General Public
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# License as published by the Free Software Foundation; either
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# version 2.1 of the License, or (at your option) any later version.
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#
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# This library is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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# Lesser General Public License for more details.
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#
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# You should have received a copy of the GNU Lesser General Public
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# License along with this library; if not, write to the
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# Free Software Foundation, Inc.,
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# 59 Temple Place, Suite 330,
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# Boston, MA 02111-1307 USA
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# This file is part of urlgrabber, a high-level cross-protocol url-grabber
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# Copyright 2002-2004 Michael D. Stenner, Ryan Tomayko
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"""An HTTP handler for urllib2 that supports HTTP 1.1 and keepalive.
21
22
>>> import urllib2
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>>> from keepalive import HTTPHandler
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>>> keepalive_handler = HTTPHandler()
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>>> opener = urllib2.build_opener(keepalive_handler)
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>>> urllib2.install_opener(opener)
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>>>
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>>> fo = urllib2.urlopen('http://www.python.org')
29
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If a connection to a given host is requested, and all of the existing
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connections are still in use, another connection will be opened. If
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the handler tries to use an existing connection but it fails in some
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way, it will be closed and removed from the pool.
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35
To remove the handler, simply re-run build_opener with no arguments, and
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install that opener.
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38
You can explicitly close connections by using the close_connection()
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method of the returned file-like object (described below) or you can
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use the handler methods:
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42
close_connection(host)
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close_all()
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open_connections()
45
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NOTE: using the close_connection and close_all methods of the handler
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should be done with care when using multiple threads.
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* there is nothing that prevents another thread from creating new
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connections immediately after connections are closed
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* no checks are done to prevent in-use connections from being closed
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>>> keepalive_handler.close_all()
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54
EXTRA ATTRIBUTES AND METHODS
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Upon a status of 200, the object returned has a few additional
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attributes and methods, which should not be used if you want to
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remain consistent with the normal urllib2-returned objects:
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close_connection() - close the connection to the host
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readlines() - you know, readlines()
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status - the return status (ie 404)
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reason - english translation of status (ie 'File not found')
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If you want the best of both worlds, use this inside an
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AttributeError-catching try:
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68
>>> try: status = fo.status
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>>> except AttributeError: status = None
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Unfortunately, these are ONLY there if status == 200, so it's not
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easy to distinguish between non-200 responses. The reason is that
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urllib2 tries to do clever things with error codes 301, 302, 401,
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and 407, and it wraps the object upon return.
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For python versions earlier than 2.4, you can avoid this fancy error
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handling by setting the module-level global HANDLE_ERRORS to zero.
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You see, prior to 2.4, it's the HTTP Handler's job to determine what
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to handle specially, and what to just pass up. HANDLE_ERRORS == 0
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means "pass everything up". In python 2.4, however, this job no
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longer belongs to the HTTP Handler and is now done by a NEW handler,
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HTTPErrorProcessor. Here's the bottom line:
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python version < 2.4
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HANDLE_ERRORS == 1 (default) pass up 200, treat the rest as
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errors
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HANDLE_ERRORS == 0 pass everything up, error processing is
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left to the calling code
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python version >= 2.4
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HANDLE_ERRORS == 1 pass up 200, treat the rest as errors
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HANDLE_ERRORS == 0 (default) pass everything up, let the
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other handlers (specifically,
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HTTPErrorProcessor) decide what to do
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In practice, setting the variable either way makes little difference
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in python 2.4, so for the most consistent behavior across versions,
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you probably just want to use the defaults, which will give you
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exceptions on errors.
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"""
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# $Id: keepalive.py,v 1.9 2005/02/14 21:55:07 mstenner Exp $
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import urllib2
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import httplib
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import socket
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import thread
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DEBUG = 0
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def DBPRINT(*args): print ' '.join(args)
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112
import sys
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_python_version = map(int, sys.version.split()[0].split('.'))
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if _python_version < [2, 4]: HANDLE_ERRORS = 1
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else: HANDLE_ERRORS = 0
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117
class ConnectionManager:
118
"""
119
The connection manager must be able to:
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* keep track of all existing
121
"""
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def __init__(self):
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self._lock = thread.allocate_lock()
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self._hostmap = {} # map hosts to a list of connections
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self._connmap = {} # map connections to host
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self._readymap = {} # map connection to ready state
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def add(self, host, connection, ready):
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self._lock.acquire()
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try:
131
if not self._hostmap.has_key(host): self._hostmap[host] = []
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self._hostmap[host].append(connection)
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self._connmap[connection] = host
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self._readymap[connection] = ready
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finally:
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self._lock.release()
137
138
def remove(self, connection):
139
self._lock.acquire()
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try:
141
try:
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host = self._connmap[connection]
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except KeyError:
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pass
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else:
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del self._connmap[connection]
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del self._readymap[connection]
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self._hostmap[host].remove(connection)
149
if not self._hostmap[host]: del self._hostmap[host]
150
finally:
151
self._lock.release()
152
153
def set_ready(self, connection, ready):
154
try: self._readymap[connection] = ready
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except KeyError: pass
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157
def get_ready_conn(self, host):
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conn = None
159
self._lock.acquire()
160
try:
161
if self._hostmap.has_key(host):
162
for c in self._hostmap[host]:
163
if self._readymap[c]:
164
self._readymap[c] = 0
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conn = c
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break
167
finally:
168
self._lock.release()
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return conn
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def get_all(self, host=None):
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if host:
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return list(self._hostmap.get(host, []))
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else:
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return dict(self._hostmap)
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class HTTPHandler(urllib2.HTTPHandler):
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def __init__(self):
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self._cm = ConnectionManager()
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#### Connection Management
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def open_connections(self):
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"""return a list of connected hosts and the number of connections
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to each. [('foo.com:80', 2), ('bar.org', 1)]"""
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return [(host, len(li)) for (host, li) in self._cm.get_all().items()]
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def close_connection(self, host):
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"""close connection(s) to <host>
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host is the host:port spec, as in 'www.cnn.com:8080' as passed in.
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no error occurs if there is no connection to that host."""
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for h in self._cm.get_all(host):
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self._cm.remove(h)
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h.close()
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def close_all(self):
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"""close all open connections"""
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for host, conns in self._cm.get_all().items():
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for h in conns:
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self._cm.remove(h)
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h.close()
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def _request_closed(self, request, host, connection):
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"""tells us that this request is now closed and the the
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connection is ready for another request"""
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self._cm.set_ready(connection, 1)
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def _remove_connection(self, host, connection, close=0):
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if close: connection.close()
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self._cm.remove(connection)
210
211
#### Transaction Execution
212
def http_open(self, req):
213
return self.do_open(HTTPConnection, req)
214
215
def do_open(self, http_class, req):
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host = req.get_host()
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if not host:
218
raise urllib2.URLError('no host given')
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220
try:
221
h = self._cm.get_ready_conn(host)
222
while h:
223
r = self._reuse_connection(h, req, host)
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# if this response is non-None, then it worked and we're
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# done. Break out, skipping the else block.
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if r: break
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# connection is bad - possibly closed by server
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# discard it and ask for the next free connection
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h.close()
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self._cm.remove(h)
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h = self._cm.get_ready_conn(host)
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else:
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# no (working) free connections were found. Create a new one.
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h = http_class(host)
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if DEBUG: DBPRINT("creating new connection to %s (%d)" % \
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(host, id(h)))
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self._cm.add(host, h, 0)
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self._start_transaction(h, req)
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r = h.getresponse()
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except (socket.error, httplib.HTTPException), err:
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raise urllib2.URLError(err)
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# if not a persistent connection, don't try to reuse it
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if r.will_close: self._cm.remove(h)
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if DEBUG: DBPRINT("STATUS: %s, %s" % (r.status, r.reason))
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r._handler = self
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r._host = host
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r._url = req.get_full_url()
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r._connection = h
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r.code = r.status
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if r.status == 200 or not HANDLE_ERRORS:
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return r
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else:
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return self.parent.error('http', req, r, r.status, r.reason, r.msg)
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260
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def _reuse_connection(self, h, req, host):
262
"""start the transaction with a re-used connection
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return a response object (r) upon success or None on failure.
264
This DOES not close or remove bad connections in cases where
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it returns. However, if an unexpected exception occurs, it
266
will close and remove the connection before re-raising.
267
"""
268
try:
269
self._start_transaction(h, req)
270
r = h.getresponse()
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# note: just because we got something back doesn't mean it
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# worked. We'll check the version below, too.
273
except (socket.error, httplib.HTTPException):
274
r = None
275
except:
276
# adding this block just in case we've missed
277
# something we will still raise the exception, but
278
# lets try and close the connection and remove it
279
# first. We previously got into a nasty loop
280
# where an exception was uncaught, and so the
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# connection stayed open. On the next try, the
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# same exception was raised, etc. The tradeoff is
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# that it's now possible this call will raise
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# a DIFFERENT exception
285
if DEBUG: DBPRINT("unexpected exception - " \
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"closing connection to %s (%d)" % (host, id(h)))
287
self._cm.remove(h)
288
h.close()
289
raise
290
291
if r is None or r.version == 9:
292
# httplib falls back to assuming HTTP 0.9 if it gets a
293
# bad header back. This is most likely to happen if
294
# the socket has been closed by the server since we
295
# last used the connection.
296
if DEBUG: DBPRINT("failed to re-use connection to %s (%d)" \
297
% (host, id(h)))
298
r = None
299
else:
300
if DEBUG: DBPRINT("re-using connection to %s (%d)" % (host, id(h)))
301
302
return r
303
304
def _start_transaction(self, h, req):
305
try:
306
if req.has_data():
307
data = req.get_data()
308
h.putrequest('POST', req.get_selector())
309
if not req.headers.has_key('Content-type'):
310
h.putheader('Content-type',
311
'application/x-www-form-urlencoded')
312
if not req.headers.has_key('Content-length'):
313
h.putheader('Content-length', '%d' % len(data))
314
else:
315
h.putrequest('GET', req.get_selector())
316
except (socket.error, httplib.HTTPException), err:
317
raise urllib2.URLError(err)
318
319
for args in self.parent.addheaders:
320
h.putheader(*args)
321
for k, v in req.headers.items():
322
h.putheader(k, v)
323
h.endheaders()
324
if req.has_data():
325
h.send(data)
326
327
class HTTPResponse(httplib.HTTPResponse):
328
# we need to subclass HTTPResponse in order to
329
# 1) add readline() and readlines() methods
330
# 2) add close_connection() methods
331
# 3) add info() and geturl() methods
332
333
# in order to add readline(), read must be modified to deal with a
334
# buffer. example: readline must read a buffer and then spit back
335
# one line at a time. The only real alternative is to read one
336
# BYTE at a time (ick). Once something has been read, it can't be
337
# put back (ok, maybe it can, but that's even uglier than this),
338
# so if you THEN do a normal read, you must first take stuff from
339
# the buffer.
340
341
# the read method wraps the original to accomodate buffering,
342
# although read() never adds to the buffer.
343
# Both readline and readlines have been stolen with almost no
344
# modification from socket.py
345
346
347
def __init__(self, sock, debuglevel=0, strict=0, method=None):
348
if method: # the httplib in python 2.3 uses the method arg
349
httplib.HTTPResponse.__init__(self, sock, debuglevel, method)
350
else: # 2.2 doesn't
351
httplib.HTTPResponse.__init__(self, sock, debuglevel)
352
self.fileno = sock.fileno
353
self.code = None
354
self._rbuf = ''
355
self._rbufsize = 8096
356
self._handler = None # inserted by the handler later
357
self._host = None # (same)
358
self._url = None # (same)
359
self._connection = None # (same)
360
361
_raw_read = httplib.HTTPResponse.read
362
363
def close(self):
364
if self.fp:
365
self.fp.close()
366
self.fp = None
367
if self._handler:
368
self._handler._request_closed(self, self._host,
369
self._connection)
370
371
def close_connection(self):
372
self._handler._remove_connection(self._host, self._connection, close=1)
373
self.close()
374
375
def info(self):
376
return self.msg
377
378
def geturl(self):
379
return self._url
380
381
def read(self, amt=None):
382
# the _rbuf test is only in this first if for speed. It's not
383
# logically necessary
384
if self._rbuf and not amt is None:
385
L = len(self._rbuf)
386
if amt > L:
387
amt -= L
388
else:
389
s = self._rbuf[:amt]
390
self._rbuf = self._rbuf[amt:]
391
return s
392
393
s = self._rbuf + self._raw_read(amt)
394
self._rbuf = ''
395
return s
396
397
def readline(self, limit=-1):
398
data = ""
399
i = self._rbuf.find('\n')
400
while i < 0 and not (0 < limit <= len(self._rbuf)):
401
new = self._raw_read(self._rbufsize)
402
if not new: break
403
i = new.find('\n')
404
if i >= 0: i = i + len(self._rbuf)
405
self._rbuf = self._rbuf + new
406
if i < 0: i = len(self._rbuf)
407
else: i = i+1
408
if 0 <= limit < len(self._rbuf): i = limit
409
data, self._rbuf = self._rbuf[:i], self._rbuf[i:]
410
return data
411
412
def readlines(self, sizehint = 0):
413
total = 0
414
list = []
415
while 1:
416
line = self.readline()
417
if not line: break
418
list.append(line)
419
total += len(line)
420
if sizehint and total >= sizehint:
421
break
422
return list
423
424
425
class HTTPConnection(httplib.HTTPConnection):
426
# use the modified response class
427
response_class = HTTPResponse
428
429
#########################################################################
430
##### TEST FUNCTIONS
431
#########################################################################
432
433
def error_handler(url):
434
global HANDLE_ERRORS
435
orig = HANDLE_ERRORS
436
keepalive_handler = HTTPHandler()
437
opener = urllib2.build_opener(keepalive_handler)
438
urllib2.install_opener(opener)
439
pos = {0: 'off', 1: 'on'}
440
for i in (0, 1):
441
print " fancy error handling %s (HANDLE_ERRORS = %i)" % (pos[i], i)
442
HANDLE_ERRORS = i
443
try:
444
fo = urllib2.urlopen(url)
445
foo = fo.read()
446
fo.close()
447
try: status, reason = fo.status, fo.reason
448
except AttributeError: status, reason = None, None
449
except IOError, e:
450
print " EXCEPTION: %s" % e
451
raise
452
else:
453
print " status = %s, reason = %s" % (status, reason)
454
HANDLE_ERRORS = orig
455
hosts = keepalive_handler.open_connections()
456
print "open connections:", hosts
457
keepalive_handler.close_all()
458
459
def continuity(url):
460
import md5
461
format = '%25s: %s'
462
463
# first fetch the file with the normal http handler
464
opener = urllib2.build_opener()
465
urllib2.install_opener(opener)
466
fo = urllib2.urlopen(url)
467
foo = fo.read()
468
fo.close()
469
m = md5.new(foo)
470
print format % ('normal urllib', m.hexdigest())
471
472
# now install the keepalive handler and try again
473
opener = urllib2.build_opener(HTTPHandler())
474
urllib2.install_opener(opener)
475
476
fo = urllib2.urlopen(url)
477
foo = fo.read()
478
fo.close()
479
m = md5.new(foo)
480
print format % ('keepalive read', m.hexdigest())
481
482
fo = urllib2.urlopen(url)
483
foo = ''
484
while 1:
485
f = fo.readline()
486
if f: foo = foo + f
487
else: break
488
fo.close()
489
m = md5.new(foo)
490
print format % ('keepalive readline', m.hexdigest())
491
492
def comp(N, url):
493
print ' making %i connections to:\n %s' % (N, url)
494
495
sys.stdout.write(' first using the normal urllib handlers')
496
# first use normal opener
497
opener = urllib2.build_opener()
498
urllib2.install_opener(opener)
499
t1 = fetch(N, url)
500
print ' TIME: %.3f s' % t1
501
502
sys.stdout.write(' now using the keepalive handler ')
503
# now install the keepalive handler and try again
504
opener = urllib2.build_opener(HTTPHandler())
505
urllib2.install_opener(opener)
506
t2 = fetch(N, url)
507
print ' TIME: %.3f s' % t2
508
print ' improvement factor: %.2f' % (t1/t2, )
509
510
def fetch(N, url, delay=0):
511
lens = []
512
starttime = time.time()
513
for i in range(N):
514
if delay and i > 0: time.sleep(delay)
515
fo = urllib2.urlopen(url)
516
foo = fo.read()
517
fo.close()
518
lens.append(len(foo))
519
diff = time.time() - starttime
520
521
j = 0
522
for i in lens[1:]:
523
j = j + 1
524
if not i == lens[0]:
525
print "WARNING: inconsistent length on read %i: %i" % (j, i)
526
527
return diff
528
529
def test_timeout(url):
530
global DEBUG, DBPRINT
531
dbp = DBPRINT
532
def DBPRINT(*args): print ' ' + ' '.join(args)
533
DEBUG=1
534
print " fetching the file to establish a connection"
535
fo = urllib2.urlopen(url)
536
data1 = fo.read()
537
fo.close()
538
539
i = 20
540
print " waiting %i seconds for the server to close the connection" % i
541
while i > 0:
542
sys.stdout.write('\r %2i' % i)
543
sys.stdout.flush()
544
time.sleep(1)
545
i -= 1
546
sys.stderr.write('\r')
547
548
print " fetching the file a second time"
549
fo = urllib2.urlopen(url)
550
data2 = fo.read()
551
fo.close()
552
553
if data1 == data2:
554
print ' data are identical'
555
else:
556
print ' ERROR: DATA DIFFER'
557
558
DEBUG=0
559
DBPRINT = dbp
560
561
562
def test(url, N=10):
563
print "checking error hander (do this on a non-200)"
564
try: error_handler(url)
565
except IOError, e:
566
print "exiting - exception will prevent further tests"
567
sys.exit()
568
print
569
print "performing continuity test (making sure stuff isn't corrupted)"
570
continuity(url)
571
print
572
print "performing speed comparison"
573
comp(N, url)
574
print
575
print "performing dropped-connection check"
576
test_timeout(url)
577
578
if __name__ == '__main__':
579
import time
580
import sys
581
try:
582
N = int(sys.argv[1])
583
url = sys.argv[2]
584
except:
585
print "%s <integer> <url>" % sys.argv[0]
586
else:
587
test(url, N)
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