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Diffstat (limited to 'libs/waitress/trigger.py')
| -rw-r--r-- | libs/waitress/trigger.py | 203 |
1 files changed, 0 insertions, 203 deletions
diff --git a/libs/waitress/trigger.py b/libs/waitress/trigger.py deleted file mode 100644 index 6a57c1275..000000000 --- a/libs/waitress/trigger.py +++ /dev/null @@ -1,203 +0,0 @@ -############################################################################## -# -# Copyright (c) 2001-2005 Zope Foundation and Contributors. -# All Rights Reserved. -# -# This software is subject to the provisions of the Zope Public License, -# Version 2.1 (ZPL). A copy of the ZPL should accompany this distribution. -# THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED -# WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED -# WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS -# FOR A PARTICULAR PURPOSE -# -############################################################################## - -import os -import socket -import errno -import threading - -from . import wasyncore - -# 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] - - -class _triggerbase(object): - """OS-independent base class for OS-dependent trigger class.""" - - kind = None # subclass must set to "pipe" or "loopback"; used by repr - - def __init__(self): - self._closed = False - - # `lock` protects the `thunks` list from being traversed and - # appended to simultaneously. - self.lock = threading.Lock() - - # List of no-argument callbacks to invoke when the trigger is - # pulled. These run in the thread running the wasyncore mainloop, - # regardless of which thread pulls the trigger. - self.thunks = [] - - def readable(self): - return True - - def writable(self): - return False - - def handle_connect(self): - pass - - def handle_close(self): - self.close() - - # Override the wasyncore close() method, because it doesn't know about - # (so can't close) all the gimmicks we have open. Subclass must - # supply a _close() method to do platform-specific closing work. _close() - # will be called iff we're not already closed. - def close(self): - if not self._closed: - self._closed = True - self.del_channel() - self._close() # subclass does OS-specific stuff - - def pull_trigger(self, thunk=None): - if thunk: - with self.lock: - self.thunks.append(thunk) - self._physical_pull() - - def handle_read(self): - try: - self.recv(8192) - except (OSError, socket.error): - return - with self.lock: - for thunk in self.thunks: - try: - thunk() - except: - nil, t, v, tbinfo = wasyncore.compact_traceback() - self.log_info( - "exception in trigger thunk: (%s:%s %s)" % (t, v, tbinfo) - ) - self.thunks = [] - - -if os.name == "posix": - - class trigger(_triggerbase, wasyncore.file_dispatcher): - kind = "pipe" - - def __init__(self, map): - _triggerbase.__init__(self) - r, self.trigger = self._fds = os.pipe() - wasyncore.file_dispatcher.__init__(self, r, map=map) - - def _close(self): - for fd in self._fds: - os.close(fd) - self._fds = [] - wasyncore.file_dispatcher.close(self) - - def _physical_pull(self): - os.write(self.trigger, b"x") - - -else: # pragma: no cover - # Windows version; uses just sockets, because a pipe isn't select'able - # on Windows. - - class trigger(_triggerbase, wasyncore.dispatcher): - kind = "loopback" - - def __init__(self, map): - _triggerbase.__init__(self) - - # 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 wasyncore 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 wasyncore's - # select() ASAP. - w.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1) - - count = 0 - while True: - 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 as 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 RuntimeError("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 wasyncore's (self.)socket - a.close() - self.trigger = w - wasyncore.dispatcher.__init__(self, r, map=map) - - def _close(self): - # self.socket is r, and self.trigger is w, from __init__ - self.socket.close() - self.trigger.close() - - def _physical_pull(self): - self.trigger.send(b"x") |