# -*- Mode: Python; tab-width: 4 -*-
VERSION_STRING = "$Id$"
import asyncore
import asynchat
import os
import socket
import string
import thread
import errno
if os.name == 'posix':
class trigger (asyncore.file_dispatcher):
"Wake up a call to select() running in the main thread"
# This is useful in a context where you are using Medusa's I/O
# subsystem to deliver data, but the data is generated by another
# thread. Normally, if Medusa is in the middle of a call to
# select(), new output data generated by another thread will have
# to sit until the call to select() either times out or returns.
# If the trigger is 'pulled' by another thread, it should immediately
# generate a READ event on the trigger object, which will force the
# select() invocation to return.
# A common use for this facility: letting Medusa manage I/O for a
# large number of connections; but routing each request through a
# thread chosen from a fixed-size thread pool. When a thread is
# acquired, a transaction is performed, but output data is
# accumulated into buffers that will be emptied more efficiently
# by Medusa. [picture a server that can process database queries
# rapidly, but doesn't want to tie up threads waiting to send data
# to low-bandwidth connections]
# The other major feature provided by this class is the ability to
# move work back into the main thread: if you call pull_trigger()
# with a thunk argument, when select() wakes up and receives the
# event it will call your thunk from within that thread. The main
# purpose of this is to remove the need to wrap thread locks around
# Medusa's data structures, which normally do not need them. [To see
# why this is true, imagine this scenario: A thread tries to push some
# new data onto a channel's outgoing data queue at the same time that
# the main thread is trying to remove some]
def __init__ (self):
r, w = os.pipe()
self.trigger = w
asyncore.file_dispatcher.__init__ (self, r)
self.lock = thread.allocate_lock()
self.thunks = []
def __repr__ (self):
return '<select-trigger (pipe) at %x>' % id(self)
def readable (self):
return 1
def writable (self):
return 0
def handle_connect (self):
pass
def pull_trigger (self, thunk=None):
# print 'PULL_TRIGGER: ', len(self.thunks)
if thunk:
try:
self.lock.acquire()
self.thunks.append (thunk)
finally:
self.lock.release()
os.write (self.trigger, 'x')
def handle_read (self):
self.recv (8192)
try:
self.lock.acquire()
for thunk in self.thunks:
try:
thunk()
except:
(file, fun, line), t, v, tbinfo = asyncore.compact_traceback()
print 'exception in trigger thunk: (%s:%s %s)' % (t, v, tbinfo)
self.thunks = []
finally:
self.lock.release()
else:
# win32-safe version
class BindError(Exception):
pass
class trigger(asyncore.dispatcher):
def __init__ (self):
# The __init__ code is taken from ZODB 3.4.1's
# ZEO/zrpc/trigger.py, to worm around problems in the original
# Windows __init__ code.
# Get a pair of connected sockets. The trigger is the 'w'
# end of the pair, which is connected to 'r'. 'r' is put
# in the asyncore socket map. "pulling the trigger" then
# means writing something on w, which will wake up r.
w = socket.socket()
# Disable buffering -- pulling the trigger sends 1 byte,
# and we want that sent immediately, to wake up asyncore's
# select() ASAP.
w.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)
count = 0
while 1:
count += 1
# Bind to a local port; for efficiency, let the OS pick
# a free port for us.
# Unfortunately, stress tests showed that we may not
# be able to connect to that port ("Address already in
# use") despite that the OS picked it. This appears
# to be a race bug in the Windows socket implementation.
# So we loop until a connect() succeeds (almost always
# on the first try). See the long thread at
# http://mail.zope.org/pipermail/zope/2005-July/160433.html
# for hideous details.
a = socket.socket()
a.bind(("127.0.0.1", 0))
connect_address = a.getsockname() # assigned (host, port) pair
a.listen(1)
try:
w.connect(connect_address)
break # success
except socket.error, detail:
if detail[0] != errno.WSAEADDRINUSE:
# "Address already in use" is the only error
# I've seen on two WinXP Pro SP2 boxes, under
# Pythons 2.3.5 and 2.4.1.
raise
# (10048, 'Address already in use')
# assert count <= 2 # never triggered in Tim's tests
if count >= 10: # I've never seen it go above 2
a.close()
w.close()
raise BindError("Cannot bind trigger!")
# Close `a` and try again. Note: I originally put a short
# sleep() here, but it didn't appear to help or hurt.
a.close()
r, addr = a.accept() # r becomes asyncore's (self.)socket
a.close()
self.trigger = w
asyncore.dispatcher.__init__ (self, r)
self.lock = thread.allocate_lock()
self.thunks = []
self._trigger_connected = 0
def __repr__(self):
return '<select-trigger (loopback) at %x>' % id(self)
def readable(self):
return 1
def writable(self):
return 0
def handle_connect(self):
pass
def pull_trigger(self, thunk=None):
if thunk:
try:
self.lock.acquire()
self.thunks.append (thunk)
finally:
self.lock.release()
self.trigger.send ('x')
def handle_read(self):
self.recv(8192)
try:
self.lock.acquire()
for thunk in self.thunks:
try:
thunk()
except:
(file, fun, line), t, v, tbinfo = asyncore.compact_traceback()
print 'exception in trigger thunk: (%s:%s %s)' % (t, v, tbinfo)
self.thunks = []
finally:
self.lock.release()
the_trigger = None
class trigger_file:
"A 'triggered' file object"
buffer_size = 4096
def __init__ (self, parent):
global the_trigger
if the_trigger is None:
the_trigger = trigger()
self.parent = parent
self.buffer = ''
def write (self, data):
self.buffer = self.buffer + data
if len(self.buffer) > self.buffer_size:
d, self.buffer = self.buffer, ''
the_trigger.pull_trigger (
lambda d=d,p=self.parent: p.push (d)
)
def writeline (self, line):
self.write (line+'\r\n')
def writelines (self, lines):
self.write (
string.joinfields (
lines,
'\r\n'
) + '\r\n'
)
def flush (self):
if self.buffer:
d, self.buffer = self.buffer, ''
the_trigger.pull_trigger (
lambda p=self.parent,d=d: p.push (d)
)
def softspace (self, *args):
pass
def close (self):
# in a derived class, you may want to call trigger_close() instead.
self.flush()
self.parent = None
def trigger_close (self):
d, self.buffer = self.buffer, ''
p, self.parent = self.parent, None
the_trigger.pull_trigger (
lambda p=p,d=d: (p.push(d), p.close_when_done())
)
if __name__ == '__main__':
import time
def thread_function (output_file, i, n):
print 'entering thread_function'
while n:
time.sleep (5)
output_file.write ('%2d.%2d %s\r\n' % (i, n, output_file))
output_file.flush()
n = n - 1
output_file.close()
print 'exiting thread_function'
class thread_parent (asynchat.async_chat):
def __init__ (self, conn, addr):
self.addr = addr
asynchat.async_chat.__init__ (self, conn)
self.set_terminator ('\r\n')
self.buffer = ''
self.count = 0
def collect_incoming_data (self, data):
self.buffer = self.buffer + data
def found_terminator (self):
data, self.buffer = self.buffer, ''
if not data:
asyncore.close_all()
print "done"
return
n = string.atoi (string.split (data)[0])
tf = trigger_file (self)
self.count = self.count + 1
thread.start_new_thread (thread_function, (tf, self.count, n))
class thread_server (asyncore.dispatcher):
def __init__ (self, family=socket.AF_INET, address=('', 9003)):
asyncore.dispatcher.__init__ (self)
self.create_socket (family, socket.SOCK_STREAM)
self.set_reuse_addr()
self.bind (address)
self.listen (5)
def handle_accept (self):
conn, addr = self.accept()
tp = thread_parent (conn, addr)
thread_server()
#asyncore.loop(1.0, use_poll=1)
try:
asyncore.loop ()
except:
asyncore.close_all()