Viewing file:  keepalive.py (20.59 KB) -rw-r--r--
Select action/file-type:
 (+) |  (+) |  (+) | Code (+) | Session (+) |  (+) | SDB (+) |  (+) |  (+) |  (+) |  (+) |  (+) |
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2.1 of the License, or (at your option) any later version.
#
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, write to the
# Free Software Foundation, Inc.,
# 59 Temple Place, Suite 330,
# Boston, MA 02111-1307 USA
# This file is part of urlgrabber, a high-level cross-protocol url-grabber
# Copyright 2002-2004 Michael D. Stenner, Ryan Tomayko
"""An HTTP handler for urllib2 that supports HTTP 1.1 and keepalive.
>>> import urllib2
>>> from keepalive import HTTPHandler
>>> keepalive_handler = HTTPHandler()
>>> opener = urllib2.build_opener(keepalive_handler)
>>> urllib2.install_opener(opener)
>>>
>>> fo = urllib2.urlopen('http://www.python.org')
If a connection to a given host is requested, and all of the existing
connections are still in use, another connection will be opened. If
the handler tries to use an existing connection but it fails in some
way, it will be closed and removed from the pool.
To remove the handler, simply re-run build_opener with no arguments, and
install that opener.
You can explicitly close connections by using the close_connection()
method of the returned file-like object (described below) or you can
use the handler methods:
close_connection(host)
close_all()
open_connections()
NOTE: using the close_connection and close_all methods of the handler
should be done with care when using multiple threads.
* there is nothing that prevents another thread from creating new
connections immediately after connections are closed
* no checks are done to prevent in-use connections from being closed
>>> keepalive_handler.close_all()
EXTRA ATTRIBUTES AND METHODS
Upon a status of 200, the object returned has a few additional
attributes and methods, which should not be used if you want to
remain consistent with the normal urllib2-returned objects:
close_connection() - close the connection to the host
readlines() - you know, readlines()
status - the return status (ie 404)
reason - english translation of status (ie 'File not found')
If you want the best of both worlds, use this inside an
AttributeError-catching try:
>>> try: status = fo.status
>>> except AttributeError: status = None
Unfortunately, these are ONLY there if status == 200, so it's not
easy to distinguish between non-200 responses. The reason is that
urllib2 tries to do clever things with error codes 301, 302, 401,
and 407, and it wraps the object upon return.
For python versions earlier than 2.4, you can avoid this fancy error
handling by setting the module-level global HANDLE_ERRORS to zero.
You see, prior to 2.4, it's the HTTP Handler's job to determine what
to handle specially, and what to just pass up. HANDLE_ERRORS == 0
means "pass everything up". In python 2.4, however, this job no
longer belongs to the HTTP Handler and is now done by a NEW handler,
HTTPErrorProcessor. Here's the bottom line:
python version < 2.4
HANDLE_ERRORS == 1 (default) pass up 200, treat the rest as
errors
HANDLE_ERRORS == 0 pass everything up, error processing is
left to the calling code
python version >= 2.4
HANDLE_ERRORS == 1 pass up 200, treat the rest as errors
HANDLE_ERRORS == 0 (default) pass everything up, let the
other handlers (specifically,
HTTPErrorProcessor) decide what to do
In practice, setting the variable either way makes little difference
in python 2.4, so for the most consistent behavior across versions,
you probably just want to use the defaults, which will give you
exceptions on errors.
"""
# $Id: keepalive.py,v 1.16 2006/09/22 00:58:05 mstenner Exp $
import urllib2
import httplib
import socket
import thread
DEBUG = None
import sslfactory
import sys
if sys.version_info < (2, 4): HANDLE_ERRORS = 1
else: HANDLE_ERRORS = 0
class ConnectionManager:
"""
The connection manager must be able to:
* keep track of all existing
"""
def __init__(self):
self._lock = thread.allocate_lock()
self._hostmap = {} # map hosts to a list of connections
self._connmap = {} # map connections to host
self._readymap = {} # map connection to ready state
def add(self, host, connection, ready):
self._lock.acquire()
try:
if not self._hostmap.has_key(host): self._hostmap[host] = []
self._hostmap[host].append(connection)
self._connmap[connection] = host
self._readymap[connection] = ready
finally:
self._lock.release()
def remove(self, connection):
self._lock.acquire()
try:
try:
host = self._connmap[connection]
except KeyError:
pass
else:
del self._connmap[connection]
del self._readymap[connection]
self._hostmap[host].remove(connection)
if not self._hostmap[host]: del self._hostmap[host]
finally:
self._lock.release()
def set_ready(self, connection, ready):
try: self._readymap[connection] = ready
except KeyError: pass
def get_ready_conn(self, host):
conn = None
self._lock.acquire()
try:
if self._hostmap.has_key(host):
for c in self._hostmap[host]:
if self._readymap[c]:
self._readymap[c] = 0
conn = c
break
finally:
self._lock.release()
return conn
def get_all(self, host=None):
if host:
return list(self._hostmap.get(host, []))
else:
return dict(self._hostmap)
class KeepAliveHandler:
def __init__(self):
self._cm = ConnectionManager()
#### Connection Management
def open_connections(self):
"""return a list of connected hosts and the number of connections
to each. [('foo.com:80', 2), ('bar.org', 1)]"""
return [(host, len(li)) for (host, li) in self._cm.get_all().items()]
def close_connection(self, host):
"""close connection(s) to <host>
host is the host:port spec, as in 'www.cnn.com:8080' as passed in.
no error occurs if there is no connection to that host."""
for h in self._cm.get_all(host):
self._cm.remove(h)
h.close()
def close_all(self):
"""close all open connections"""
for host, conns in self._cm.get_all().items():
for h in conns:
self._cm.remove(h)
h.close()
def _request_closed(self, request, host, connection):
"""tells us that this request is now closed and the the
connection is ready for another request"""
self._cm.set_ready(connection, 1)
def _remove_connection(self, host, connection, close=0):
if close: connection.close()
self._cm.remove(connection)
#### Transaction Execution
def do_open(self, req):
host = req.get_host()
if not host:
raise urllib2.URLError('no host given')
try:
h = self._cm.get_ready_conn(host)
while h:
r = self._reuse_connection(h, req, host)
# if this response is non-None, then it worked and we're
# done. Break out, skipping the else block.
if r: break
# connection is bad - possibly closed by server
# discard it and ask for the next free connection
h.close()
self._cm.remove(h)
h = self._cm.get_ready_conn(host)
else:
# no (working) free connections were found. Create a new one.
h = self._get_connection(host)
if DEBUG: DEBUG.info("creating new connection to %s (%d)",
host, id(h))
self._cm.add(host, h, 0)
self._start_transaction(h, req)
r = h.getresponse()
except (socket.error, httplib.HTTPException), err:
raise urllib2.URLError(err)
# if not a persistent connection, don't try to reuse it
if r.will_close: self._cm.remove(h)
if DEBUG: DEBUG.info("STATUS: %s, %s", r.status, r.reason)
r._handler = self
r._host = host
r._url = req.get_full_url()
r._connection = h
r.code = r.status
r.headers = r.msg
r.msg = r.reason
if r.status == 200 or not HANDLE_ERRORS:
return r
else:
return self.parent.error('http', req, r,
r.status, r.msg, r.headers)
def _reuse_connection(self, h, req, host):
"""start the transaction with a re-used connection
return a response object (r) upon success or None on failure.
This DOES not close or remove bad connections in cases where
it returns. However, if an unexpected exception occurs, it
will close and remove the connection before re-raising.
"""
try:
self._start_transaction(h, req)
r = h.getresponse()
# note: just because we got something back doesn't mean it
# worked. We'll check the version below, too.
except (socket.error, httplib.HTTPException):
r = None
except:
# adding this block just in case we've missed
# something we will still raise the exception, but
# lets try and close the connection and remove it
# first. We previously got into a nasty loop
# where an exception was uncaught, and so the
# connection stayed open. On the next try, the
# same exception was raised, etc. The tradeoff is
# that it's now possible this call will raise
# a DIFFERENT exception
if DEBUG: DEBUG.error("unexpected exception - closing " + \
"connection to %s (%d)", host, id(h))
self._cm.remove(h)
h.close()
raise
if r is None or r.version == 9:
# httplib falls back to assuming HTTP 0.9 if it gets a
# bad header back. This is most likely to happen if
# the socket has been closed by the server since we
# last used the connection.
if DEBUG: DEBUG.info("failed to re-use connection to %s (%d)",
host, id(h))
r = None
else:
if DEBUG: DEBUG.info("re-using connection to %s (%d)", host, id(h))
return r
def _start_transaction(self, h, req):
try:
if req.has_data():
data = req.get_data()
h.putrequest('POST', req.get_selector())
if not req.headers.has_key('Content-type'):
h.putheader('Content-type',
'application/x-www-form-urlencoded')
if not req.headers.has_key('Content-length'):
h.putheader('Content-length', '%d' % len(data))
else:
h.putrequest('GET', req.get_selector())
except (socket.error, httplib.HTTPException), err:
raise urllib2.URLError(err)
for args in self.parent.addheaders:
h.putheader(*args)
for k, v in req.headers.items():
h.putheader(k, v)
h.endheaders()
if req.has_data():
h.send(data)
def _get_connection(self, host):
return NotImplementedError
class HTTPHandler(KeepAliveHandler, urllib2.HTTPHandler):
def __init__(self):
KeepAliveHandler.__init__(self)
def http_open(self, req):
return self.do_open(req)
def _get_connection(self, host):
return HTTPConnection(host)
class HTTPSHandler(KeepAliveHandler, urllib2.HTTPSHandler):
def __init__(self, ssl_factory=None):
KeepAliveHandler.__init__(self)
if not ssl_factory:
ssl_factory = sslfactory.get_factory()
self._ssl_factory = ssl_factory
def https_open(self, req):
return self.do_open(req)
def _get_connection(self, host):
return self._ssl_factory.get_https_connection(host)
class HTTPResponse(httplib.HTTPResponse):
# we need to subclass HTTPResponse in order to
# 1) add readline() and readlines() methods
# 2) add close_connection() methods
# 3) add info() and geturl() methods
# in order to add readline(), read must be modified to deal with a
# buffer. example: readline must read a buffer and then spit back
# one line at a time. The only real alternative is to read one
# BYTE at a time (ick). Once something has been read, it can't be
# put back (ok, maybe it can, but that's even uglier than this),
# so if you THEN do a normal read, you must first take stuff from
# the buffer.
# the read method wraps the original to accomodate buffering,
# although read() never adds to the buffer.
# Both readline and readlines have been stolen with almost no
# modification from socket.py
def __init__(self, sock, debuglevel=0, strict=0, method=None):
if method: # the httplib in python 2.3 uses the method arg
httplib.HTTPResponse.__init__(self, sock, debuglevel, method)
else: # 2.2 doesn't
httplib.HTTPResponse.__init__(self, sock, debuglevel)
self.fileno = sock.fileno
self.code = None
self._rbuf = ''
self._rbufsize = 8096
self._handler = None # inserted by the handler later
self._host = None # (same)
self._url = None # (same)
self._connection = None # (same)
_raw_read = httplib.HTTPResponse.read
def close(self):
if self.fp:
self.fp.close()
self.fp = None
if self._handler:
self._handler._request_closed(self, self._host,
self._connection)
def close_connection(self):
self._handler._remove_connection(self._host, self._connection, close=1)
self.close()
def info(self):
return self.headers
def geturl(self):
return self._url
def read(self, amt=None):
# the _rbuf test is only in this first if for speed. It's not
# logically necessary
if self._rbuf and not amt is None:
L = len(self._rbuf)
if amt > L:
amt -= L
else:
s = self._rbuf[:amt]
self._rbuf = self._rbuf[amt:]
return s
s = self._rbuf + self._raw_read(amt)
self._rbuf = ''
return s
def readline(self, limit=-1):
data = ""
i = self._rbuf.find('\n')
while i < 0 and not (0 < limit <= len(self._rbuf)):
new = self._raw_read(self._rbufsize)
if not new: break
i = new.find('\n')
if i >= 0: i = i + len(self._rbuf)
self._rbuf = self._rbuf + new
if i < 0: i = len(self._rbuf)
else: i = i+1
if 0 <= limit < len(self._rbuf): i = limit
data, self._rbuf = self._rbuf[:i], self._rbuf[i:]
return data
def readlines(self, sizehint = 0):
total = 0
list = []
while 1:
line = self.readline()
if not line: break
list.append(line)
total += len(line)
if sizehint and total >= sizehint:
break
return list
class HTTPConnection(httplib.HTTPConnection):
# use the modified response class
response_class = HTTPResponse
class HTTPSConnection(httplib.HTTPSConnection):
response_class = HTTPResponse
#########################################################################
##### TEST FUNCTIONS
#########################################################################
def error_handler(url):
global HANDLE_ERRORS
orig = HANDLE_ERRORS
keepalive_handler = HTTPHandler()
opener = urllib2.build_opener(keepalive_handler)
urllib2.install_opener(opener)
pos = {0: 'off', 1: 'on'}
for i in (0, 1):
print " fancy error handling %s (HANDLE_ERRORS = %i)" % (pos[i], i)
HANDLE_ERRORS = i
try:
fo = urllib2.urlopen(url)
foo = fo.read()
fo.close()
try: status, reason = fo.status, fo.reason
except AttributeError: status, reason = None, None
except IOError, e:
print " EXCEPTION: %s" % e
raise
else:
print " status = %s, reason = %s" % (status, reason)
HANDLE_ERRORS = orig
hosts = keepalive_handler.open_connections()
print "open connections:", hosts
keepalive_handler.close_all()
def continuity(url):
import md5
format = '%25s: %s'
# first fetch the file with the normal http handler
opener = urllib2.build_opener()
urllib2.install_opener(opener)
fo = urllib2.urlopen(url)
foo = fo.read()
fo.close()
m = md5.new(foo)
print format % ('normal urllib', m.hexdigest())
# now install the keepalive handler and try again
opener = urllib2.build_opener(HTTPHandler())
urllib2.install_opener(opener)
fo = urllib2.urlopen(url)
foo = fo.read()
fo.close()
m = md5.new(foo)
print format % ('keepalive read', m.hexdigest())
fo = urllib2.urlopen(url)
foo = ''
while 1:
f = fo.readline()
if f: foo = foo + f
else: break
fo.close()
m = md5.new(foo)
print format % ('keepalive readline', m.hexdigest())
def comp(N, url):
print ' making %i connections to:\n %s' % (N, url)
sys.stdout.write(' first using the normal urllib handlers')
# first use normal opener
opener = urllib2.build_opener()
urllib2.install_opener(opener)
t1 = fetch(N, url)
print ' TIME: %.3f s' % t1
sys.stdout.write(' now using the keepalive handler ')
# now install the keepalive handler and try again
opener = urllib2.build_opener(HTTPHandler())
urllib2.install_opener(opener)
t2 = fetch(N, url)
print ' TIME: %.3f s' % t2
print ' improvement factor: %.2f' % (t1/t2, )
def fetch(N, url, delay=0):
import time
lens = []
starttime = time.time()
for i in range(N):
if delay and i > 0: time.sleep(delay)
fo = urllib2.urlopen(url)
foo = fo.read()
fo.close()
lens.append(len(foo))
diff = time.time() - starttime
j = 0
for i in lens[1:]:
j = j + 1
if not i == lens[0]:
print "WARNING: inconsistent length on read %i: %i" % (j, i)
return diff
def test_timeout(url):
global DEBUG
dbbackup = DEBUG
class FakeLogger:
def debug(self, msg, *args): print msg % args
info = warning = error = debug
DEBUG = FakeLogger()
print " fetching the file to establish a connection"
fo = urllib2.urlopen(url)
data1 = fo.read()
fo.close()
i = 20
print " waiting %i seconds for the server to close the connection" % i
while i > 0:
sys.stdout.write('\r %2i' % i)
sys.stdout.flush()
time.sleep(1)
i -= 1
sys.stderr.write('\r')
print " fetching the file a second time"
fo = urllib2.urlopen(url)
data2 = fo.read()
fo.close()
if data1 == data2:
print ' data are identical'
else:
print ' ERROR: DATA DIFFER'
DEBUG = dbbackup
def test(url, N=10):
print "checking error hander (do this on a non-200)"
try: error_handler(url)
except IOError, e:
print "exiting - exception will prevent further tests"
sys.exit()
print
print "performing continuity test (making sure stuff isn't corrupted)"
continuity(url)
print
print "performing speed comparison"
comp(N, url)
print
print "performing dropped-connection check"
test_timeout(url)
if __name__ == '__main__':
import time
import sys
try:
N = int(sys.argv[1])
url = sys.argv[2]
except:
print "%s <integer> <url>" % sys.argv[0]
else:
test(url, N)
|