Add CherryPy to third_party.

third_party/cherrypy/process/plugins.py

+"""Site services for use with a Web Site Process Bus."""
+
+import os
+import re
+import signal as _signal
+import sys
+import time
+import threading
+
+from cherrypy._cpcompat import basestring, get_daemon, get_thread_ident, ntob, set
+
+# _module__file__base is used by Autoreload to make
+# absolute any filenames retrieved from sys.modules which are not
+# already absolute paths.  This is to work around Python's quirk
+# of importing the startup script and using a relative filename
+# for it in sys.modules.
+#
+# Autoreload examines sys.modules afresh every time it runs. If an application
+# changes the current directory by executing os.chdir(), then the next time
+# Autoreload runs, it will not be able to find any filenames which are
+# not absolute paths, because the current directory is not the same as when the
+# module was first imported.  Autoreload will then wrongly conclude the file has
+# "changed", and initiate the shutdown/re-exec sequence.
+# See ticket #917.
+# For this workaround to have a decent probability of success, this module
+# needs to be imported as early as possible, before the app has much chance
+# to change the working directory.
+_module__file__base = os.getcwd()
+
+
+class SimplePlugin(object):
+    """Plugin base class which auto-subscribes methods for known channels."""
+    
+    bus = None
+    """A :class:`Bus <cherrypy.process.wspbus.Bus>`, usually cherrypy.engine."""
+    
+    def __init__(self, bus):
+        self.bus = bus
+    
+    def subscribe(self):
+        """Register this object as a (multi-channel) listener on the bus."""
+        for channel in self.bus.listeners:
+            # Subscribe self.start, self.exit, etc. if present.
+            method = getattr(self, channel, None)
+            if method is not None:
+                self.bus.subscribe(channel, method)
+    
+    def unsubscribe(self):
+        """Unregister this object as a listener on the bus."""
+        for channel in self.bus.listeners:
+            # Unsubscribe self.start, self.exit, etc. if present.
+            method = getattr(self, channel, None)
+            if method is not None:
+                self.bus.unsubscribe(channel, method)
+
+
+
+class SignalHandler(object):
+    """Register bus channels (and listeners) for system signals.
+    
+    You can modify what signals your application listens for, and what it does
+    when it receives signals, by modifying :attr:`SignalHandler.handlers`,
+    a dict of {signal name: callback} pairs. The default set is::
+    
+        handlers = {'SIGTERM': self.bus.exit,
+                    'SIGHUP': self.handle_SIGHUP,
+                    'SIGUSR1': self.bus.graceful,
+                   }
+    
+    The :func:`SignalHandler.handle_SIGHUP`` method calls
+    :func:`bus.restart()<cherrypy.process.wspbus.Bus.restart>`
+    if the process is daemonized, but
+    :func:`bus.exit()<cherrypy.process.wspbus.Bus.exit>`
+    if the process is attached to a TTY. This is because Unix window
+    managers tend to send SIGHUP to terminal windows when the user closes them.
+    
+    Feel free to add signals which are not available on every platform. The
+    :class:`SignalHandler` will ignore errors raised from attempting to register
+    handlers for unknown signals.
+    """
+    
+    handlers = {}
+    """A map from signal names (e.g. 'SIGTERM') to handlers (e.g. bus.exit)."""
+    
+    signals = {}
+    """A map from signal numbers to names."""
+    
+    for k, v in vars(_signal).items():
+        if k.startswith('SIG') and not k.startswith('SIG_'):
+            signals[v] = k
+    del k, v
+    
+    def __init__(self, bus):
+        self.bus = bus
+        # Set default handlers
+        self.handlers = {'SIGTERM': self.bus.exit,
+                         'SIGHUP': self.handle_SIGHUP,
+                         'SIGUSR1': self.bus.graceful,
+                         }
+
+        if sys.platform[:4] == 'java':
+            del self.handlers['SIGUSR1']
+            self.handlers['SIGUSR2'] = self.bus.graceful
+            self.bus.log("SIGUSR1 cannot be set on the JVM platform. "
+                         "Using SIGUSR2 instead.")
+            self.handlers['SIGINT'] = self._jython_SIGINT_handler
+
+        self._previous_handlers = {}
+    
+    def _jython_SIGINT_handler(self, signum=None, frame=None):
+        # See http://bugs.jython.org/issue1313
+        self.bus.log('Keyboard Interrupt: shutting down bus')
+        self.bus.exit()
+        
+    def subscribe(self):
+        """Subscribe self.handlers to signals."""
+        for sig, func in self.handlers.items():
+            try:
+                self.set_handler(sig, func)
+            except ValueError:
+                pass
+    
+    def unsubscribe(self):
+        """Unsubscribe self.handlers from signals."""
+        for signum, handler in self._previous_handlers.items():
+            signame = self.signals[signum]
+            
+            if handler is None:
+                self.bus.log("Restoring %s handler to SIG_DFL." % signame)
+                handler = _signal.SIG_DFL
+            else:
+                self.bus.log("Restoring %s handler %r." % (signame, handler))
+            
+            try:
+                our_handler = _signal.signal(signum, handler)
+                if our_handler is None:
+                    self.bus.log("Restored old %s handler %r, but our "
+                                 "handler was not registered." %
+                                 (signame, handler), level=30)
+            except ValueError:
+                self.bus.log("Unable to restore %s handler %r." %
+                             (signame, handler), level=40, traceback=True)
+    
+    def set_handler(self, signal, listener=None):
+        """Subscribe a handler for the given signal (number or name).
+        
+        If the optional 'listener' argument is provided, it will be
+        subscribed as a listener for the given signal's channel.
+        
+        If the given signal name or number is not available on the current
+        platform, ValueError is raised.
+        """
+        if isinstance(signal, basestring):
+            signum = getattr(_signal, signal, None)
+            if signum is None:
+                raise ValueError("No such signal: %r" % signal)
+            signame = signal
+        else:
+            try:
+                signame = self.signals[signal]
+            except KeyError:
+                raise ValueError("No such signal: %r" % signal)
+            signum = signal
+        
+        prev = _signal.signal(signum, self._handle_signal)
+        self._previous_handlers[signum] = prev
+        
+        if listener is not None:
+            self.bus.log("Listening for %s." % signame)
+            self.bus.subscribe(signame, listener)
+    
+    def _handle_signal(self, signum=None, frame=None):
+        """Python signal handler (self.set_handler subscribes it for you)."""
+        signame = self.signals[signum]
+        self.bus.log("Caught signal %s." % signame)
+        self.bus.publish(signame)
+    
+    def handle_SIGHUP(self):
+        """Restart if daemonized, else exit."""
+        if os.isatty(sys.stdin.fileno()):
+            # not daemonized (may be foreground or background)
+            self.bus.log("SIGHUP caught but not daemonized. Exiting.")
+            self.bus.exit()
+        else:
+            self.bus.log("SIGHUP caught while daemonized. Restarting.")
+            self.bus.restart()
+
+
+try:
+    import pwd, grp
+except ImportError:
+    pwd, grp = None, None
+
+
+class DropPrivileges(SimplePlugin):
+    """Drop privileges. uid/gid arguments not available on Windows.
+    
+    Special thanks to Gavin Baker: http://antonym.org/node/100.
+    """
+    
+    def __init__(self, bus, umask=None, uid=None, gid=None):
+        SimplePlugin.__init__(self, bus)
+        self.finalized = False
+        self.uid = uid
+        self.gid = gid
+        self.umask = umask
+    
+    def _get_uid(self):
+        return self._uid
+    def _set_uid(self, val):
+        if val is not None:
+            if pwd is None:
+                self.bus.log("pwd module not available; ignoring uid.",
+                             level=30)
+                val = None
+            elif isinstance(val, basestring):
+                val = pwd.getpwnam(val)[2]
+        self._uid = val
+    uid = property(_get_uid, _set_uid,
+        doc="The uid under which to run. Availability: Unix.")
+    
+    def _get_gid(self):
+        return self._gid
+    def _set_gid(self, val):
+        if val is not None:
+            if grp is None:
+                self.bus.log("grp module not available; ignoring gid.",
+                             level=30)
+                val = None
+            elif isinstance(val, basestring):
+                val = grp.getgrnam(val)[2]
+        self._gid = val
+    gid = property(_get_gid, _set_gid,
+        doc="The gid under which to run. Availability: Unix.")
+    
+    def _get_umask(self):
+        return self._umask
+    def _set_umask(self, val):
+        if val is not None:
+            try:
+                os.umask
+            except AttributeError:
+                self.bus.log("umask function not available; ignoring umask.",
+                             level=30)
+                val = None
+        self._umask = val
+    umask = property(_get_umask, _set_umask,
+        doc="""The default permission mode for newly created files and directories.
+        
+        Usually expressed in octal format, for example, ``0644``.
+        Availability: Unix, Windows.
+        """)
+    
+    def start(self):
+        # uid/gid
+        def current_ids():
+            """Return the current (uid, gid) if available."""
+            name, group = None, None
+            if pwd:
+                name = pwd.getpwuid(os.getuid())[0]
+            if grp:
+                group = grp.getgrgid(os.getgid())[0]
+            return name, group
+        
+        if self.finalized:
+            if not (self.uid is None and self.gid is None):
+                self.bus.log('Already running as uid: %r gid: %r' %
+                             current_ids())
+        else:
+            if self.uid is None and self.gid is None:
+                if pwd or grp:
+                    self.bus.log('uid/gid not set', level=30)
+            else:
+                self.bus.log('Started as uid: %r gid: %r' % current_ids())
+                if self.gid is not None:
+                    os.setgid(self.gid)
+                    os.setgroups([])
+                if self.uid is not None:
+                    os.setuid(self.uid)
+                self.bus.log('Running as uid: %r gid: %r' % current_ids())
+        
+        # umask
+        if self.finalized:
+            if self.umask is not None:
+                self.bus.log('umask already set to: %03o' % self.umask)
+        else:
+            if self.umask is None:
+                self.bus.log('umask not set', level=30)
+            else:
+                old_umask = os.umask(self.umask)
+                self.bus.log('umask old: %03o, new: %03o' %
+                             (old_umask, self.umask))
+        
+        self.finalized = True
+    # This is slightly higher than the priority for server.start
+    # in order to facilitate the most common use: starting on a low
+    # port (which requires root) and then dropping to another user.
+    start.priority = 77
+
+
+class Daemonizer(SimplePlugin):
+    """Daemonize the running script.
+    
+    Use this with a Web Site Process Bus via::
+    
+        Daemonizer(bus).subscribe()
+    
+    When this component finishes, the process is completely decoupled from
+    the parent environment. Please note that when this component is used,
+    the return code from the parent process will still be 0 if a startup
+    error occurs in the forked children. Errors in the initial daemonizing
+    process still return proper exit codes. Therefore, if you use this
+    plugin to daemonize, don't use the return code as an accurate indicator
+    of whether the process fully started. In fact, that return code only
+    indicates if the process succesfully finished the first fork.
+    """
+    
+    def __init__(self, bus, stdin='/dev/null', stdout='/dev/null',
+                 stderr='/dev/null'):
+        SimplePlugin.__init__(self, bus)
+        self.stdin = stdin
+        self.stdout = stdout
+        self.stderr = stderr
+        self.finalized = False
+    
+    def start(self):
+        if self.finalized:
+            self.bus.log('Already deamonized.')
+        
+        # forking has issues with threads:
+        # http://www.opengroup.org/onlinepubs/000095399/functions/fork.html
+        # "The general problem with making fork() work in a multi-threaded
+        #  world is what to do with all of the threads..."
+        # So we check for active threads:
+        if threading.activeCount() != 1:
+            self.bus.log('There are %r active threads. '
+                         'Daemonizing now may cause strange failures.' %
+                         threading.enumerate(), level=30)
+        
+        # See http://www.erlenstar.demon.co.uk/unix/faq_2.html#SEC16
+        # (or http://www.faqs.org/faqs/unix-faq/programmer/faq/ section 1.7)
+        # and http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/66012
+        
+        # Finish up with the current stdout/stderr
+        sys.stdout.flush()
+        sys.stderr.flush()
+        
+        # Do first fork.
+        try:
+            pid = os.fork()
+            if pid == 0:
+                # This is the child process. Continue.
+                pass
+            else:
+                # This is the first parent. Exit, now that we've forked.
+                self.bus.log('Forking once.')
+                os._exit(0)
+        except OSError:
+            # Python raises OSError rather than returning negative numbers.
+            exc = sys.exc_info()[1]
+            sys.exit("%s: fork #1 failed: (%d) %s\n"
+                     % (sys.argv[0], exc.errno, exc.strerror))
+        
+        os.setsid()
+        
+        # Do second fork
+        try:
+            pid = os.fork()
+            if pid > 0:
+                self.bus.log('Forking twice.')
+                os._exit(0) # Exit second parent
+        except OSError:
+            exc = sys.exc_info()[1]
+            sys.exit("%s: fork #2 failed: (%d) %s\n"
+                     % (sys.argv[0], exc.errno, exc.strerror))
+        
+        os.chdir("/")
+        os.umask(0)
+        
+        si = open(self.stdin, "r")
+        so = open(self.stdout, "a+")
+        se = open(self.stderr, "a+")
+
+        # os.dup2(fd, fd2) will close fd2 if necessary,
+        # so we don't explicitly close stdin/out/err.
+        # See http://docs.python.org/lib/os-fd-ops.html
+        os.dup2(si.fileno(), sys.stdin.fileno())
+        os.dup2(so.fileno(), sys.stdout.fileno())
+        os.dup2(se.fileno(), sys.stderr.fileno())
+        
+        self.bus.log('Daemonized to PID: %s' % os.getpid())
+        self.finalized = True
+    start.priority = 65
+
+
+class PIDFile(SimplePlugin):
+    """Maintain a PID file via a WSPBus."""
+    
+    def __init__(self, bus, pidfile):
+        SimplePlugin.__init__(self, bus)
+        self.pidfile = pidfile
+        self.finalized = False
+    
+    def start(self):
+        pid = os.getpid()
+        if self.finalized:
+            self.bus.log('PID %r already written to %r.' % (pid, self.pidfile))
+        else:
+            open(self.pidfile, "wb").write(ntob("%s" % pid, 'utf8'))
+            self.bus.log('PID %r written to %r.' % (pid, self.pidfile))
+            self.finalized = True
+    start.priority = 70
+    
+    def exit(self):
+        try:
+            os.remove(self.pidfile)
+            self.bus.log('PID file removed: %r.' % self.pidfile)
+        except (KeyboardInterrupt, SystemExit):
+            raise
+        except:
+            pass
+
+
+class PerpetualTimer(threading._Timer):
+    """A responsive subclass of threading._Timer whose run() method repeats.
+    
+    Use this timer only when you really need a very interruptible timer;
+    this checks its 'finished' condition up to 20 times a second, which can
+    results in pretty high CPU usage 
+    """
+    
+    def run(self):
+        while True:
+            self.finished.wait(self.interval)
+            if self.finished.isSet():
+                return
+            try:
+                self.function(*self.args, **self.kwargs)
+            except Exception:
+                self.bus.log("Error in perpetual timer thread function %r." %
+                             self.function, level=40, traceback=True)
+                # Quit on first error to avoid massive logs.
+                raise
+
+
+class BackgroundTask(threading.Thread):
+    """A subclass of threading.Thread whose run() method repeats.
+    
+    Use this class for most repeating tasks. It uses time.sleep() to wait
+    for each interval, which isn't very responsive; that is, even if you call
+    self.cancel(), you'll have to wait until the sleep() call finishes before
+    the thread stops. To compensate, it defaults to being daemonic, which means
+    it won't delay stopping the whole process.
+    """
+    
+    def __init__(self, interval, function, args=[], kwargs={}, bus=None):
+        threading.Thread.__init__(self)
+        self.interval = interval
+        self.function = function
+        self.args = args
+        self.kwargs = kwargs
+        self.running = False
+        self.bus = bus
+    
+    def cancel(self):
+        self.running = False
+    
+    def run(self):
+        self.running = True
+        while self.running:
+            time.sleep(self.interval)
+            if not self.running:
+                return
+            try:
+                self.function(*self.args, **self.kwargs)
+            except Exception:
+                if self.bus:
+                    self.bus.log("Error in background task thread function %r."
+                                 % self.function, level=40, traceback=True)
+                # Quit on first error to avoid massive logs.
+                raise
+    
+    def _set_daemon(self):
+        return True
+
+
+class Monitor(SimplePlugin):
+    """WSPBus listener to periodically run a callback in its own thread."""
+    
+    callback = None
+    """The function to call at intervals."""
+    
+    frequency = 60
+    """The time in seconds between callback runs."""
+    
+    thread = None
+    """A :class:`BackgroundTask<cherrypy.process.plugins.BackgroundTask>` thread."""
+    
+    def __init__(self, bus, callback, frequency=60, name=None):
+        SimplePlugin.__init__(self, bus)
+        self.callback = callback
+        self.frequency = frequency
+        self.thread = None
+        self.name = name
+    
+    def start(self):
+        """Start our callback in its own background thread."""
+        if self.frequency > 0:
+            threadname = self.name or self.__class__.__name__
+            if self.thread is None:
+                self.thread = BackgroundTask(self.frequency, self.callback,
+                                             bus = self.bus)
+                self.thread.setName(threadname)
+                self.thread.start()
+                self.bus.log("Started monitor thread %r." % threadname)
+            else:
+                self.bus.log("Monitor thread %r already started." % threadname)
+    start.priority = 70
+    
+    def stop(self):
+        """Stop our callback's background task thread."""
+        if self.thread is None:
+            self.bus.log("No thread running for %s." % self.name or self.__class__.__name__)
+        else:
+            if self.thread is not threading.currentThread():
+                name = self.thread.getName()
+                self.thread.cancel()
+                if not get_daemon(self.thread):
+                    self.bus.log("Joining %r" % name)
+                    self.thread.join()
+                self.bus.log("Stopped thread %r." % name)
+            self.thread = None
+    
+    def graceful(self):
+        """Stop the callback's background task thread and restart it."""
+        self.stop()
+        self.start()
+
+
+class Autoreloader(Monitor):
+    """Monitor which re-executes the process when files change.
+    
+    This :ref:`plugin<plugins>` restarts the process (via :func:`os.execv`)
+    if any of the files it monitors change (or is deleted). By default, the
+    autoreloader monitors all imported modules; you can add to the
+    set by adding to ``autoreload.files``::
+    
+        cherrypy.engine.autoreload.files.add(myFile)
+    
+    If there are imported files you do *not* wish to monitor, you can adjust the
+    ``match`` attribute, a regular expression. For example, to stop monitoring
+    cherrypy itself::
+    
+        cherrypy.engine.autoreload.match = r'^(?!cherrypy).+'
+    
+    Like all :class:`Monitor<cherrypy.process.plugins.Monitor>` plugins,
+    the autoreload plugin takes a ``frequency`` argument. The default is
+    1 second; that is, the autoreloader will examine files once each second.
+    """
+    
+    files = None
+    """The set of files to poll for modifications."""
+    
+    frequency = 1
+    """The interval in seconds at which to poll for modified files."""
+    
+    match = '.*'
+    """A regular expression by which to match filenames."""
+    
+    def __init__(self, bus, frequency=1, match='.*'):
+        self.mtimes = {}
+        self.files = set()
+        self.match = match
+        Monitor.__init__(self, bus, self.run, frequency)
+    
+    def start(self):
+        """Start our own background task thread for self.run."""
+        if self.thread is None:
+            self.mtimes = {}
+        Monitor.start(self)
+    start.priority = 70 
+    
+    def sysfiles(self):
+        """Return a Set of sys.modules filenames to monitor."""
+        files = set()
+        for k, m in sys.modules.items():
+            if re.match(self.match, k):
+                if hasattr(m, '__loader__') and hasattr(m.__loader__, 'archive'):
+                    f = m.__loader__.archive
+                else:
+                    f = getattr(m, '__file__', None)
+                    if f is not None and not os.path.isabs(f):
+                        # ensure absolute paths so a os.chdir() in the app doesn't break me
+                        f = os.path.normpath(os.path.join(_module__file__base, f))
+                files.add(f)
+        return files
+    
+    def run(self):
+        """Reload the process if registered files have been modified."""
+        for filename in self.sysfiles() | self.files:
+            if filename:
+                if filename.endswith('.pyc'):
+                    filename = filename[:-1]
+                
+                oldtime = self.mtimes.get(filename, 0)
+                if oldtime is None:
+                    # Module with no .py file. Skip it.
+                    continue
+                
+                try:
+                    mtime = os.stat(filename).st_mtime
+                except OSError:
+                    # Either a module with no .py file, or it's been deleted.
+                    mtime = None
+                
+                if filename not in self.mtimes:
+                    # If a module has no .py file, this will be None.
+                    self.mtimes[filename] = mtime
+                else:
+                    if mtime is None or mtime > oldtime:
+                        # The file has been deleted or modified.
+                        self.bus.log("Restarting because %s changed." % filename)
+                        self.thread.cancel()
+                        self.bus.log("Stopped thread %r." % self.thread.getName())
+                        self.bus.restart()
+                        return
+
+
+class ThreadManager(SimplePlugin):
+    """Manager for HTTP request threads.
+    
+    If you have control over thread creation and destruction, publish to
+    the 'acquire_thread' and 'release_thread' channels (for each thread).
+    This will register/unregister the current thread and publish to
+    'start_thread' and 'stop_thread' listeners in the bus as needed.
+    
+    If threads are created and destroyed by code you do not control
+    (e.g., Apache), then, at the beginning of every HTTP request,
+    publish to 'acquire_thread' only. You should not publish to
+    'release_thread' in this case, since you do not know whether
+    the thread will be re-used or not. The bus will call
+    'stop_thread' listeners for you when it stops.
+    """
+    
+    threads = None
+    """A map of {thread ident: index number} pairs."""
+    
+    def __init__(self, bus):
+        self.threads = {}
+        SimplePlugin.__init__(self, bus)
+        self.bus.listeners.setdefault('acquire_thread', set())
+        self.bus.listeners.setdefault('start_thread', set())
+        self.bus.listeners.setdefault('release_thread', set())
+        self.bus.listeners.setdefault('stop_thread', set())
+
+    def acquire_thread(self):
+        """Run 'start_thread' listeners for the current thread.
+        
+        If the current thread has already been seen, any 'start_thread'
+        listeners will not be run again.
+        """
+        thread_ident = get_thread_ident()
+        if thread_ident not in self.threads:
+            # We can't just use get_ident as the thread ID
+            # because some platforms reuse thread ID's.
+            i = len(self.threads) + 1
+            self.threads[thread_ident] = i
+            self.bus.publish('start_thread', i)
+    
+    def release_thread(self):
+        """Release the current thread and run 'stop_thread' listeners."""
+        thread_ident = get_thread_ident()
+        i = self.threads.pop(thread_ident, None)
+        if i is not None:
+            self.bus.publish('stop_thread', i)
+    
+    def stop(self):
+        """Release all threads and run all 'stop_thread' listeners."""
+        for thread_ident, i in self.threads.items():
+            self.bus.publish('stop_thread', i)
+        self.threads.clear()
+    graceful = stop
+