#!/usr/bin/env python

"""Threaded Application Server

The AppServer is the main process of WebKit. It handles requests for
servlets from webservers.

ThreadedAppServer uses a threaded model for handling multiple requests.

At one time there were other experimental execution models for AppServer,
but none of these were successful and have been removed.
The ThreadedAppServer/AppServer distinction is thus largely historical.

ThreadedAppServer takes the following command line arguments:

start: start the AppServer (default argument)
stop: stop the currently running Apperver
daemon: run as a daemon
ClassName.SettingName=value: change configuration settings

When started, the app server records its pid in appserver.pid.

"""

import threading, Queue, select, socket, errno, traceback
from threading import Thread, currentThread
from marshal import dumps, loads

try:
	from ctypes import pythonapi, py_object
except ImportError:
	py_object = pythonapi = None
try:
	PyThreadState_SetAsyncExc = pythonapi.PyThreadState_SetAsyncExc
except (TypeError, AttributeError):
	PyThreadState_SetAsyncExc = None
try: # for Python < 2.5
	BaseException
except NameError:
	BaseException = Exception

from Common import *
import AppServer as AppServerModule
from PidFile import ProcessRunning
from AutoReloadingAppServer import AutoReloadingAppServer as AppServer
from ASStreamOut import ASStreamOut, ConnectionAbortedError
from HTTPExceptions import HTTPServiceUnavailable
from WebUtils.Funcs import requestURI

debug = False

defaultConfig = {
	'Host': 'localhost', # same as '127.0.0.1'
	'EnableAdapter': True, # enable WebKit adapter
	'AdapterPort': 8086,
	'EnableMonitor': False, # disable status monitoring
	'SCGIPort': 8084,
	'EnableSCGI': False, # disable SCGI adapter
	'MonitorPort': 8085,
	'EnableHTTP': True, # enable built-in HTTP server
	'HTTPPort': 8080,
	'StartServerThreads': 10, # initial number of server threads
	'MinServerThreads': 5, # minimum number
	'MaxServerThreads': 20, # maxium number
	'MaxRequestTime': 300, # maximum request execution time in seconds
	'RequestQueueSize': 0, # means twice the maximum number of threads
	'RequestBufferSize': 8*1024, # 8 kBytes
	'ResponseBufferSize': 8*1024, # 8 kBytes
	'AddressFiles': '%s.address', # %s stands for the protocol name
	# @@ the following setting is not yet implemented
	# 'SocketType': 'inet', # inet, inet6, unix
}

# Need to know this value for communications
# (note that this limits the size of the dictionary we receive
# from the AppServer to 2,147,483,647 bytes):
intLength = len(dumps(int(1)))

# Initialize global variables
server = None
exitStatus = 0


class NotEnoughDataError(Exception):
	pass

class ProtocolError(Exception):
	pass

class ThreadAbortedError(HTTPServiceUnavailable):
	pass

class RequestAbortedError(ThreadAbortedError):
	pass

class RequestTooLongError(RequestAbortedError):
	pass

class ServerShutDownError(ThreadAbortedError):
	pass


class WorkerThread(Thread):
	"""Base class for Webware worker threads that can be aborted.

	(Idea taken from: http://sebulba.wikispaces.com/recipe+thread2)

	"""

	_canAbort = PyThreadState_SetAsyncExc is not None

	def threadID(self):
		"""Return the thread's internal id."""
		try:
			return self._threadID
		except AttributeError:
			for threadID, t in threading._active.items():
				if t is self:
					self._threadID = threadID
					return threadID

	def abort(self, exception=ThreadAbortedError):
		"""Abort the current thread by raising an exception in its context.

		A return value of one means the thread was successfully aborted,
		a value of zero means the thread could not be found,
		any other value indicates that an error has occurred.

		"""
		if not self._canAbort:
			if debug:
				print "Error: Aborting threads is not possible"
			return -1
		if debug:
			print "Aborting worker thread..."
		try:
			processing = self.isAlive() and self._processing
		except AttributeError:
			processing = False
		if not processing:
			if debug:
				print "Error: Thread is not working."
		threadID = self.threadID()
		if threadID is None:
			if debug:
				print "Error: Worker thread id not found"
			return 0
		if debug:
			print "Worker thread id is", threadID
		try:
			ret = PyThreadState_SetAsyncExc(threadID, py_object(exception))
			# If it returns a number greater than one, we're in trouble,
			# and should call it again with exc=NULL to revert the effect
			if ret > 1:
				PyThreadState_SetAsyncExc(threadID, 0)
		except Exception:
			ret = -1
		if debug:
			if ret == 0:
				print "Error: Could not find thread", threadID
			elif ret != 1:
				print "Error: Could not abort thread", threadID
		return ret


class ThreadedAppServer(AppServer):
	"""Threaded Application Server.

	`ThreadedAppServer` accepts incoming socket requests, spawns a
	new thread or reuses an existing one, then dispatches the request
	to the appropriate handler (e.g., an Adapter handler, HTTP handler,
	etc., one for each protocol).

	The transaction is connected directly to the socket, so that the
	response is sent directly (if streaming is used, like if you call
	`response.flush()`). Thus the ThreadedAppServer packages the
	socket/response, rather than value being returned up the call chain.

	"""


	## Init ##

	def __init__(self, path=None):
		"""Setup the AppServer.

		Create an initial thread pool (threads created with `spawnThread`),
		and the request queue, record the PID in a file, and add any enabled
		handlers (Adapter, HTTP, Monitor).

		"""
		self._threadPool = []
		self._threadCount = 0
		self._threadUseCounter = []
		self._addr = {}
		self._requestID = 0
		self._socketHandlers = {}
		self._handlerCache = {}
		self._threadHandler = {}
		self._sockets = {}

		self._defaultConfig = None
		AppServer.__init__(self, path)

		try:
			threadCount = self.setting('StartServerThreads')
			self._maxServerThreads = self.setting('MaxServerThreads')
			self._minServerThreads = self.setting('MinServerThreads')
			self._requestQueueSize = self.setting('RequestQueueSize')
			if not self._requestQueueSize:
				# if not set, make queue size twice the max number of threads
				self._requestQueueSize = 2 * self._maxServerThreads
			elif self._requestQueueSize < self._maxServerThreads:
				# otherwise do not make it smaller than the max number of threads
				self._requestQueueSize = self._maxServerThreads
			self._requestBufferSize = self.setting('RequestBufferSize')
			self._responseBufferSize = self.setting('ResponseBufferSize')

			self._requestQueue = Queue.Queue(self._requestQueueSize)

			maxRequestTime = self.setting('MaxRequestTime') or None
			if maxRequestTime and not self._canAbortRequest:
				print "Warning: MaxRequestTime setting ineffective" \
					" (cannot abort requests)"
				maxRequestTime = None
			self._maxRequestTime = maxRequestTime
			self._checkRequestTime = None

			out = sys.stdout
			out.write('Creating %d threads' % threadCount)
			for i in range(threadCount):
				self.spawnThread()
				if not debug:
					out.write(".")
				out.flush()
			out.write("\n")

			if self.setting('EnableAdapter'):
				self.addSocketHandler(AdapterHandler)
			if self.setting('EnableMonitor'):
				self.addSocketHandler(MonitorHandler)
			if self.setting('EnableSCGI'):
				self.addSocketHandler(SCGIHandler)
			if self.setting('EnableHTTP'):
				from HTTPServer import HTTPAppServerHandler
				self.addSocketHandler(HTTPAppServerHandler)

			self.readyForRequests()

			if maxRequestTime:
				self._checkRequestTime = time.time() + maxRequestTime
		except:
			AppServer.initiateShutdown(self)
			raise

	def addSocketHandler(self, handlerClass, serverAddress=None):
		"""Add socket handler.

		Adds a socket handler for `serverAddress` -- `serverAddress`
		is a tuple ``(host, port)``, where ``host`` is the interface
		to connect to (for instance, the IP address on a machine with
		multiple IP numbers), and ``port`` is the port (e.g. HTTP is on
		80 by default, and Webware adapters use 8086 by default).

		The `handlerClass` is a subclass of `Handler`, and is used to
		handle the actual request -- usually returning control back
		to ThreadedAppServer in some fashion. See `Handler` for more.

		"""

		if serverAddress is None:
			serverAddress = self.address(handlerClass.settingPrefix)
		sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
		sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
		try:
			sock.bind(serverAddress)
			sock.listen(1024)
		except:
			print "Error: Can not listen for %s on %s" % (
				handlerClass.settingPrefix, str(serverAddress))
			sys.stdout.flush()
			raise
		serverAddress = sock.getsockname() # resolve/normalize
		self._socketHandlers[serverAddress] = handlerClass
		self._handlerCache[serverAddress] = []
		self._sockets[serverAddress] = sock
		adrStr = ':'.join(map(str, serverAddress))
		print "Listening for %s on %s" % (handlerClass.settingPrefix, adrStr)
		# write text file with server address
		adrFile = self.addressFileName(handlerClass)
		if os.path.exists(adrFile):
			print "Warning: %s already exists" % adrFile
			try:
				os.unlink(adrFile)
			except OSError: # we cannot remove the file
				if open(adrFile).read() == adrStr:
					return # same content, so never mind
				else:
					print "Error: Could not remove", adrFile
					sys.stdout.flush()
					raise
		try:
			f = open(adrFile, 'w')
			f.write(adrStr)
			f.close()
		except IOError:
			print "Error: Could not write", adrFile
			sys.stdout.flush()
			raise

	def isPersistent(self):
		return True

	def defaultConfig(self):
		"""The default AppServer.config."""
		if self._defaultConfig is None:
			self._defaultConfig = AppServer.defaultConfig(self).copy()
			# Update with ThreadedAppServer specific settings
			# as defined in defaultConfig on the module level:
			self._defaultConfig.update(defaultConfig)
		return self._defaultConfig

	_ignoreErrnos = [] # silently ignore these errors:
	for e in 'EAGAIN', 'EWOULDBLOCK', 'EINTR', 'ECONNABORTED', 'EPROTO':
		try:
			_ignoreErrnos.append(getattr(errno, e))
		except AttributeError:
			pass

	def mainloop(self, timeout=1):
		"""Main thread loop.

		This is the main thread loop that accepts and dispatches
		socket requests.

		It goes through a loop as long as ``self._running > 2``.
		Setting ``self._running = 2`` asks the the main loop to end.
		When the main loop is finished, it sets ``self._running = 1``.
		When the AppServer is completely down, it sets ``self._running = 0``.

		The loop waits for connections, then based on the connecting
		port it initiates the proper Handler (e.g.,
		AdapterHandler, HTTPHandler). Handlers are reused when possible.

		The initiated handlers are put into a queue, and
		worker threads poll that queue to look for requests that
		need to be handled (worker threads use `threadloop`).

		Every so often (every 5 loops) it updates thread usage
		information (`updateThreadUsage`), and every
		``MaxServerThreads * 2`` loops it it will manage
		threads (killing or spawning new ones, in `manageThreadCount`).

		"""

		threadCheckInterval = self._maxServerThreads * 2
		threadUpdateDivisor = 5 # grab stat interval
		threadCheck = 0

		self._running = 3 # server is in the main loop now

		try:
			while self._running > 2:

				# block for timeout seconds waiting for connections
				try:
					input, output, exc = select.select(
						self._sockets.values(), [], [], timeout)
				except select.error, e:
					if e[0] not in self._ignoreErrnos:
						raise
					if debug:
						print "Socket select error:", e
					continue

				for sock in input:

					try:
						client, addr = sock.accept()
					except select.error, e:
						if e[0] not in self._ignoreErrnos:
							raise
						if debug:
							print "Socket accept error:", e
						continue

					serverAddress = sock.getsockname()
					try:
						handler = self._handlerCache[serverAddress].pop()
					except IndexError:
						handler = self._socketHandlers[serverAddress](self,
							serverAddress)
					self._requestID += 1
					handler.activate(client, self._requestID)
					self._requestQueue.put(handler)

				if threadCheck % threadUpdateDivisor == 0:
					self.updateThreadUsage()

				if threadCheck > threadCheckInterval:
					threadCheck = 0
					self.manageThreadCount()
				else:
					threadCheck += 1

				self.abortLongRequests()
				self.restartIfNecessary()

		finally:
			self._running = 1


	## Thread Management ##

	# These methods handle the thread pool. The AppServer pre-allocates
	# threads, and reuses threads for requests. So as more threads
	# are needed with varying load, new threads are spawned, and if there
	# are excess threads, then threads are removed.

	def updateThreadUsage(self):
		"""Update the threadUseCounter list.

		Called periodically	from `mainloop`.

		"""
		count = self.activeThreadCount()
		if len(self._threadUseCounter) > self._maxServerThreads:
			self._threadUseCounter.pop(0)
		self._threadUseCounter.append(count)

	def activeThreadCount(self):
		"""Get a snapshot of the number of threads currently in use.

		Called from `updateThreadUsage`.

		"""
		count = 0
		for t in self._threadPool:
			if t._processing:
				count += 1
		return count

	def manageThreadCount(self):
		"""Adjust the number of threads in use.

		From information gleened from `updateThreadUsage`, we see about how
		many threads are being used, to see if we have too many threads or
		too few. Based on this we create or absorb threads.

		"""

		# @@: This algorithm needs work. The edges (i.e. at the
		# minserverthreads) are tricky. When working with this,
		# remember thread creation is *cheap*.

		average = max = 0

		if debug:
			print "ThreadUse Samples:", self._threadUseCounter
		for i in self._threadUseCounter:
			average += i
			if i > max:
				max = i
		average /= len(self._threadUseCounter)
		if debug:
			print "Average Thread Use: ", average
			print "Max Thread Use: ", max
			print "ThreadCount: ", self._threadCount

		if len(self._threadUseCounter) < self._maxServerThreads:
			return # not enough samples

		margin = self._threadCount / 2 # smoothing factor
		if debug:
			print "Margin:", margin

		if average > self._threadCount - margin and \
			self._threadCount < self._maxServerThreads:
			# Running low: double thread count
			n = min(self._threadCount,
				self._maxServerThreads - self._threadCount)
			if debug:
				print "Adding %s threads" % n
			for i in range(n):
				self.spawnThread()
		elif average < self._threadCount - margin and \
			self._threadCount > self._minServerThreads:
			n = min(self._threadCount - self._minServerThreads,
				self._threadCount - max)
			self.absorbThread(n)
		else:
			# cleanup any stale threads that we killed but haven't joined
			self.absorbThread(0)

	def spawnThread(self):
		"""Create a new worker thread.

		Worker threads poll with the `threadloop` method.

		"""
		if debug:
			print "Spawning new thread"
		t = WorkerThread(target=self.threadloop)
		t._processing = False
		t.start()
		self._threadPool.append(t)
		self._threadCount += 1
		if debug:
			print "New thread spawned, threadCount =", self._threadCount

	def absorbThread(self, count=1):
		"""Absorb a thread.

		We do this by putting a None on the Queue.
		When a thread gets it, that tells it to exit.

		We also keep track of the threads, so after killing
		threads we go through all the threads and find the
		thread(s) that have exited, so that we can take them
		out of the thread pool.

		"""
		for i in range(count):
			self._requestQueue.put(None)
			# _threadCount is an estimate, just because we
			# put None in the queue, the threads don't immediately
			# disappear, but they will eventually.
			self._threadCount -= 1
		for t in self._threadPool:
			# There may still be a None in the queue, and some
			# of the threads we want gone may not yet be gone.
			# But we'll pick them up later -- they'll wait.
			if not t.isAlive():
				t.join() # Don't need a timeout, it isn't alive
				self._threadPool.remove(t)
				if debug:
					print "Thread absorbed, real threadCount =", len(self._threadPool)

	_canAbortRequest = WorkerThread._canAbort

	def abortRequest(self, requestID, exception=RequestAbortedError):
		"""Abort a request by raising an exception in its worker thread.

		A return value of one means the thread was successfully aborted,
		a value of zero means the thread could not be found,
		any other value indicates that an error has occurred.

		"""
		verbose = self._verbose
		if verbose:
			print "Aborting request", requestID
		if not self._canAbortRequest:
			if verbose:
				print "Error: Cannot abort requests"
			return -1
		for t, h in self._threadHandler.items():
			try:
				handlerRequestID = h._requestID
			except AttributeError:
				handlerRequestID = None
			if requestID == handlerRequestID:
				t._abortHandler = h
				try:
					if self._threadHandler[t] is not h:
						# request already finished in the meantime
						raise KeyError
					ret = t.abort(exception)
				except Exception:
					ret = 0
				t._abortHandler = None
				break
		else:
			ret = 0
		if verbose:
			if ret == 0:
				print "Error: Could not find thread for this request"
			elif ret == 1:
				print "The worker thread for this request has been aborted"
			else:
				print "Error: Could not abort thread for this request"
		return ret

	def abortLongRequests(self):
		"""Check for long-running requests and cancel these.

		The longest allowed execution time for requests is controlled
		by the MaxRequestTime setting.

		"""
		if self._checkRequestTime is None:
			return
		currentTime = time.time()
		if currentTime > self._checkRequestTime:
			if debug:
				print "Checking for long-running requests"
			verbose = self._verbose
			minRequestTime = currentTime - self._maxRequestTime
			for t, h in self._threadHandler.items():
				try:
					requestDict = h._requestDict
					requestID = requestDict['requestID']
					requestTime = requestDict['time']
				except (AttributeError, KeyError):
					continue
				if requestTime < minRequestTime:
					t._abortHandler = h
					try:
						if self._threadHandler[t] is not h:
							# request already finished in the meantime
							raise KeyError
						if verbose:
							print "Aborting long-running request", requestID
						t.abort(RequestTooLongError)
					except Exception:
						pass
					t._abortHandler = None
				elif requestTime < currentTime:
					currentTime = requestTime
			self._checkRequestTime = currentTime + self._maxRequestTime


	## Worker Threads ##

	def threadloop(self):
		"""The main loop for worker threads.

		Worker threads poll the `_requestQueue` to find a request handler
		waiting to run. If they find a None in the queue, this thread has
		been selected to die, which is the way the loop ends.

		The handler object does all the work when its `handleRequest` method
		is called.

		`initThread` and `delThread` methods are called at the beginning and
		end of the thread loop, but they aren't being used for anything
		(future use as a hook).

		"""
		self.initThread()
		t = currentThread()
		t._processing = False
		t._abortHandler = None
		try:
			while 1:
				try:
					handler = self._requestQueue.get()
				except Queue.Empty:
					continue
				if handler is None:
					# None means time to quit
					break
				try:
					t._processing = True
					self._threadHandler[t] = handler
					try:
						handler.handleRequest()
					except ThreadAbortedError:
						print "Worker thread has been aborted"
					except Exception:
						print "Exception in worker thread"
						traceback.print_exc(file=sys.stderr)
					del self._threadHandler[t]
					t._processing = False
				finally:
					handler.close()
				while t._abortHandler is handler:
					# this handler is to be aborted,
					# so don't handle another request now
					time.sleep(0.1)
		finally:
			try:
				del self._threadHandler[t]
				t._processing = False
			except KeyError:
				pass
			self.delThread()
		if debug:
			print "Quitting", t

	def initThread(self):
		"""Initialize thread.

		Invoked immediately by threadloop() as a hook for subclasses.
		This implementation does nothing and subclasses need not invoke super.

		"""
		pass

	def delThread(self):
		"""Delete thread.

		Invoked immediately by threadloop() as a hook for subclasses.
		This implementation does nothing and subclasses need not invoke super.

		"""
		pass


	## Shutting Down ##

	def shutDown(self):
		"""Called on shutdown.

		Also calls `AppServer.shutDown`, but first closes all sockets
		and tells all the threads to die.

		"""
		print "ThreadedAppServer is shutting down..."
		if self._running > 2:
			self._running = 2 # ask main loop to finish
			self.awakeSelect() # unblock select call in mainloop()
			sys.stdout.flush()
			for i in range(30): # wait at most 3 seconds for shutdown
				if self._running < 2:
					break
				time.sleep(0.1)
		if self._sockets:
			# Close all sockets now:
			for sock in self._sockets.values():
				sock.close()
		if self._socketHandlers:
			# Remove the text files with the server addresses:
			for handler in self._socketHandlers.values():
				adrFile = self.addressFileName(handler)
				if os.path.exists(adrFile):
					try:
						os.unlink(adrFile)
					except OSError:
						print "Warning: Could not remove", adrFile
		# Tell all threads to end:
		for i in range(self._threadCount):
			self._requestQueue.put(None)
		if self._canAbortRequest:
			for t in self._threadHandler.keys():
				t.abort(ServerShutDownError)
		for t in self._threadPool:
			try:
				t.join()
			except Exception:
				pass
		# Call super's shutdown:
		AppServer.shutDown(self)

	def awakeSelect(self):
		"""Awake the select() call.

		The `select()` in `mainloop()` is blocking, so when
		we shut down we have to make a connect to unblock it.
		Here's where we do that.

		"""
		for host, port in self._sockets.keys():
			if host == '0.0.0.0':
				# Can't connect to 0.0.0.0; use 127.0.0.1 instead
				host = '127.0.0.1'
			sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
			try:
				sock.connect((host, port))
				sock.close()
			except Exception:
				pass


	## Misc ##

	def address(self, settingPrefix):
		"""Get host address.

		The address for the Adapter (Host/interface, and port),
		as taken from ``Configs/AppServer.config``,
		settings ``Host`` and ``AdapterPort``.

		"""
		try:
			return self._addr[settingPrefix]
		except KeyError:
			host = self.setting(settingPrefix + 'Host', self.setting('Host'))
			if settingPrefix == 'Adapter':
				# jdh 2004-12-01:
				# 'Port' has been renamed to 'AdapterPort'. However, we don't
				# want the the default AdapterPort in DefaultConfig above to
				# be used if a user still has 'Port' in their config file.
				# So for now, we prefer the 'Port' setting if it exists.
				# After a few releases we can remove this special case.
				port = self.setting('Port', None)
				if port is None:
					port = self.setting(settingPrefix + 'Port')
				else:
					print "WARNING:", \
						"The 'Port' setting has been renamed to 'AdapterPort'."
					print "Please update your AppServer.config file."
			else:
				port = self.setting(settingPrefix + 'Port')
			self._addr[settingPrefix] = (host, port)
			return self._addr[settingPrefix]

	def addressFileName(self, handlerClass):
		"""Get the name of the text file with the server address."""
		return self.serverSidePath(
			self.setting('AddressFiles') % handlerClass.protocolName)


class Handler:
	"""A very general socket handler.

	Handler is an abstract superclass -- specific protocol implementations
	will subclass this. A Handler takes a socket to interact with, and
	creates a raw request.

	Handlers will be reused. When a socket is received `activate` will be
	called -- but the handler should not do anything, as it is still running
	in the main thread. The handler is put into a queue, and a worker thread
	picks it up and runs `handleRequest`, which subclasses should override.

	Several methods are provided which are typically used by subclasses.

	"""

	def __init__(self, server, serverAddress):
		"""Create a new socket handler.

		Each handler is attached to a specific host and port,
		and of course to the AppServer.

		"""
		self._server = server
		self._serverAddress = serverAddress
		self._verbose = server._verbose

	def activate(self, sock, requestID):
		"""Activate the handler for processing the request.

		`sock` is the incoming socket that this handler will work with,
		and `requestID` is a serial number unique for each request.

		This isn't where work gets done -- the handler is queued after this,
		and work is done when `handleRequest` is called.

		"""
		self._requestID = requestID
		self._sock = sock

	def close(self):
		"""Close the socket.

		Called when the handler is finished. Closes the socket and
		returns the handler to the pool of inactive handlers.

		"""
		self._sock = None
		self._server._handlerCache[self._serverAddress].append(self)

	def receiveDict(self):
		"""Receive a dictionary from the socket.

		Utility function to receive a marshalled dictionary from the socket.
		Returns None if the request was empty.

		"""
		chunk = ''
		missing = intLength
		while missing > 0:
			block = self._sock.recv(missing)
			if not block:
				self._sock.close()
				if len(chunk) == 0:
					# We probably awakened due to awakeSelect being called.
					return None
				else:
					# We got a partial request -- something went wrong.
					raise NotEnoughDataError, 'received only %d of %d bytes' \
						' when receiving dictLength' % (len(chunk), intLength)
			chunk += block
			missing = intLength - len(chunk)
		try:
			dictLength = loads(chunk)
		except ValueError, msg:
			if chunk[:3] == 'GET':
				# Common error: client is speaking HTTP.
				while msg and len(chunk) < 8192:
					block = self._sock.recv(1)
					if not block:
						break
					chunk += block
					if chunk.endswith('\r\r') or chunk.endswith('\n\n') \
							or chunk.endswith('\r\n\r\n'):
						msg = None
			if msg:
				print "ERROR:", msg
			else:
				print "ERROR: HTTP GET from WebKit adapter port."
				self._sock.sendall('''\
HTTP/1.0 505 HTTP Version Not Supported\r
Content-type: text/plain\r
\r
Error: Invalid AppServer protocol.\r
Sorry, I don't speak HTTP. You must connect via an adapter.\r
See the Troubleshooting section of the WebKit Install Guide.\r''')
			self._sock.close()
			print "       You can only connect to", self._serverAddress[1], \
				"via an adapter like mod_webkit or wkcgi."
			return None
		if type(dictLength) != type(1):
			self._sock.close()
			raise ProtocolError, "Invalid AppServer protocol"
		chunk = ''
		missing = dictLength
		while missing > 0:
			block = self._sock.recv(missing)
			if not block:
				self._sock.close()
				raise NotEnoughDataError, 'received only %d of %d bytes' \
					' when receiving dict' % (len(chunk), dictLength)
			chunk += block
			missing -= len(chunk)
		return loads(chunk)

	def handleRequest(self):
		"""Handle a raw request.

		This is where the work gets done. Subclasses should override.

		"""
		pass

	def startRequest(self, requestDict=None):
		"""Track start of a raw request.

		Subclasses can use and override this method.

		"""
		requestDict = requestDict or {}
		requestID = self._requestID
		requestTime = requestDict.get('time') or time.time()
		requestDict['requestID'] = requestID
		requestDict['time'] = requestTime
		# The request object is stored for tracking/debugging purposes.
		self._requestDict = requestDict
		if self._verbose:
			requestTime = time.localtime(requestTime)[:6]
			env = requestDict.get('environ')
			uri = env and requestURI(env) or '-'
			print '%5d  %4d-%02d-%02d %02d:%02d:%02d  %s' % (
				(requestID,) + requestTime + (uri,))

	def endRequest(self, error=None):
		"""Track end of a raw request.

		Subclasses can use and override this method.

		"""
		if self._verbose:
			requestDict = self._requestDict
			requestID = requestDict['requestID']
			duration = round((time.time() - requestDict['time'])*1000)
			env = requestDict.get('environ')
			if not error:
				error = env and requestURI(env) or '-'
			print '%5d  %14.0f msec  %s\n' % (
				requestID, duration, error)


class MonitorHandler(Handler):
	"""Monitor server status.

	Monitor is a minimal service that accepts a simple protocol,
	and returns a value indicating the status of the server.

	The protocol passes a marshalled dict, much like the Adapter
	interface, which looks like ``{'format': 'CMD'}``, where CMD
	is a command (``STATUS`` or ``QUIT``). Responds with a simple
	string, either the number of requests we've received (for
	``STATUS``) or ``OK`` for ``QUIT`` (which also stops the server).

	"""
	# @@ 2003-03 ib: we should have a RESTART command, and
	# perhaps better status indicators (number of threads, etc).

	protocolName = 'monitor'
	settingPrefix = 'Monitor'

	def handleRequest(self):
		requestDict = self.receiveDict()
		if not requestDict:
			return

		requestDict['environ'] = { 'REQUEST_URI': '*%s %s*'
			% (self.settingPrefix, requestDict['format'])}
		self.startRequest(requestDict)

		conn = self._sock
		if requestDict['format'] == "STATUS":
			conn.send(str(self._server._requestID))
		elif requestDict['format'] == 'QUIT':
			conn.send("OK")
			conn.close()
			self._server.shutDown()


class TASStreamOut(ASStreamOut):
	"""Response stream for ThreadedAppServer.

	The `TASStreamOut` class streams to a given socket, so that when `flush`
	is called and the buffer is ready to be written, it sends the data from the
	buffer out on the socket. This is the response stream used for requests
	generated by ThreadedAppServer.

	"""

	_ignoreErrnos = [] # silently ignore these errors:
	for e in 'EPIPE', 'ECONNABORTED', 'ECONNRESET':
		try:
			_ignoreErrnos.append(getattr(errno, e))
		except AttributeError:
			pass

	def __init__(self, sock, autoCommit=False, bufferSize=8192):
		"""Create stream.

		We get an extra `sock` argument, which is the socket which we'll
		stream output to (if we're streaming).

		"""
		ASStreamOut.__init__(self, autoCommit, bufferSize)
		self._socket = sock

	def flush(self):
		"""Flush stream.

		Calls `ASStreamOut.ASStreamOut.flush`, and if that returns True
		(indicating the buffer is full enough) then we send data from
		the buffer out on the socket.

		"""
		result = ASStreamOut.flush(self)
		if result: # a true return value means we can send
			reslen = len(self._buffer)
			sent = 0
			bufferSize = self._bufferSize
			while sent < reslen:
				try:
					sent += self._socket.send(
						self._buffer[sent:sent+bufferSize])
				except socket.error, e:
					if debug or e[0] not in self._ignoreErrnos:
						print "StreamOut Error:", e
					self._closed = True
					raise ConnectionAbortedError
			self.pop(sent)


class AdapterHandler(Handler):
	"""Adapter handler.

	Handles the Adapter protocol (as used in mod_webkit, wkcgi,
	WebKit.cgi, HTTPAdapter, etc). This protocol passes a marshalled
	dictionary which contains the keys ``format`` and ``environ``.
	``format`` is currently always the string ``CGI``, and ``environ``
	is a dictionary of string: string, with values like those passed
	in the environment to a CGI request (QUERY_STRING, HTTP_HOST, etc).

	The handler adds one more key, ``input``, which contains a file
	object based off the socket, which contains the body of the
	request (the POST data, for instance). It's left to Application
	to handle that data.

	"""
	protocolName = 'adapter'
	settingPrefix = 'Adapter'

	def handleRequest(self):
		"""Handle request.

		Creates the request dictionary, and creates a `TASStreamOut` object
		for the response, then calls `Application.dispatchRawRequest`, which
		does the rest of the work (here we just clean up after).

		"""
		requestDict = self.receiveDict()
		if not requestDict:
			return

		self.startRequest(requestDict)
		requestDict['input'] = self.makeInput()

		streamOut = TASStreamOut(self._sock, bufferSize=self._server._responseBufferSize)
		transaction = self._server._app.dispatchRawRequest(requestDict, streamOut)
		try:
			streamOut.close()
			aborted = False
		except ConnectionAbortedError:
			aborted = True

		try:
			self._sock.shutdown(1)
			self._sock.close()
		except Exception:
			pass

		self.endRequest(aborted and '*connection aborted*')

		transaction._application = None
		transaction.die()
		del transaction

	def makeInput(self):
		"""Create a file-like object from the socket."""
		return self._sock.makefile("rb", self._server._requestBufferSize)


class SCGIHandler(AdapterHandler):
	"""SCGI handler.

	Modified Adapter handler speaking the SCGI protocol.

	"""
	protocolName = 'scgi'
	settingPrefix = 'SCGI'

	def receiveDict(self):
		"""Receive a dictionary from the socket.

		Utility function to receive the SCGI headers from the socket.
		Returns None if the request was empty.

		"""
		chunk = ''
		while 1:
			c = self._sock.recv(1)
			if not c and not chunk:
				self._sock.close()
				return None
			if c == ':':
				break
			else:
				chunk += c
			if len(chunk) > 12:
				break
		try:
			if len(chunk) > 12 or not chunk.isdigit():
				raise ValueError, 'Malformed SCGI netstring'
			dictLength = long(chunk)
		except ValueError, msg:
			if chunk[:3] == 'GET':
				# Common error: client is speaking HTTP.
				while msg and len(chunk) < 8192:
					block = self._sock.recv(1)
					if not block:
						break
					chunk += block
					if chunk.endswith('\r\r') or chunk.endswith('\n\n') \
							or chunk.endswith('\r\n\r\n'):
						msg = None
			if msg:
				print "ERROR:", msg
			else:
				print "ERROR: HTTP GET from SCGI adapter port."
				self._sock.sendall('''\
HTTP/1.0 505 HTTP Version Not Supported\r
Content-type: text/plain\r
\r
Error: Invalid AppServer protocol.\r
Sorry, I don't speak HTTP. You must connect via an SCGI adapter.\r
See the Troubleshooting section of the WebKit Install Guide.\r''')
			self._sock.close()
			print "       You can only connect to", self._serverAddress[1], \
				"via an adapter like mod_scgi or pyscgi."
			return None
		chunk = ''
		missing = dictLength
		while missing > 0:
			block = self._sock.recv(missing)
			if not block:
				self._sock.close()
				raise NotEnoughDataError, 'received only %d of %d bytes' \
					' when receiving netstring' % (len(chunk), dictLength)
			chunk += block
			missing -= len(chunk)
		if self._sock.recv(1) != ',':
			self._sock.close()
			raise ProtocolError, 'Missing SCGI netstring terminator'
		items = chunk.split('\0')[:-1]
		environ = {}
		try:
			for i in range(0, len(items), 2):
				environ[items[i]] = items[i+1]
		except IndexError:
			raise ProtocolError, 'Malformed SCGI headers'
		return { 'format': 'CGI', 'time': time.time(), 'environ': environ }


# Determines whether the main look should run in another thread.
# On Win NT/2K/XP, we run the mainloop in a different thread because
# it's not safe for Ctrl-C to be caught while manipulating the queues.
# It's not safe on Linux either, but there, it appears that Ctrl-C will
# trigger an exception in ANY thread, so this fix doesn't help.
def runMainLoopInThread():
	return os.name == 'nt'

# Set to False in DebugAppServer so Python debuggers can trap exceptions:
doesRunHandleExceptions = True


class RestartAppServerError(Exception):
	"""Raised by DebugAppServer when needed."""
	pass


_chdir = os.chdir

def chdir(path, force=False):
	"""Execute os.chdir() with safety provision."""
	assert force, \
		"You cannot reliably use os.chdir() in a threaded environment.\n" \
		+ 16*" " + "Set force=True if you want to do it anway (using a lock)."
	_chdir(path)


## Script usage ##

def run(workDir=None):
	"""Start the server (`ThreadedAppServer`).

	`workDir` is the server-side path for the server, which may not be
	the ``Webware/WebKit`` directory (though by default it is).

	After setting up the ThreadedAppServer we call `ThreadedAppServer.mainloop`
	to start the server main loop. It also catches exceptions as a last resort.

	"""
	global server
	server = None
	global exitStatus
	exitStatus = 0
	os.chdir = chdir # inhibit use of os.chdir()
	runAgain = True
	while runAgain: # looping in support of RestartAppServerError
		try:
			try:
				runAgain = False
				server = ThreadedAppServer(workDir)
				if runMainLoopInThread():
					# catch the exception raised by sys.exit so
					# that we can re-call it in the main thread.
					def _windowsmainloop():
						global exitStatus
						try:
							server.mainloop()
						except SystemExit, e:
							exitStatus = e[0]
					# Run the server thread
					t = Thread(target=_windowsmainloop)
					t.start()
					try:
						while server._running > 1:
							try:
								time.sleep(1) # wait for interrupt
							except Exception:
								if server._running < 3:
									raise # shutdown
					finally:
						t.join()
				else:
					server.mainloop()
				sys.exit(exitStatus)
			except RestartAppServerError:
				print
				print "Restarting AppServer:"
				sys.stdout.flush()
				sys.stderr.flush()
				runAgain = True
			except SystemExit, e:
				print
				print "Exiting AppServer%s." % (
					e[0] == 3 and ' for reload' or '')
				exitStatus = e[0]
			except KeyboardInterrupt:
				print
				print "Exiting AppServer due to keyboard interrupt."
				exitStatus = 0
			except Exception, e:
				if isinstance(e, IOError) and e[0] == errno.EINTR:
					print
					print "Exiting AppServer due to interrupt signal."
					exitStatus = 0
				else:
					if doesRunHandleExceptions:
						if not server and isinstance(e, ProcessRunning):
							print "Error:", str(e)
						else:
							print
							traceback.print_exc()
							print
							print "Exiting AppServer due to above exception."
						exitStatus = 1
					else:
						raise
		finally:
			sys.stdout.flush()
			sys.stderr.flush()
			if server and server._running:
				server.initiateShutdown()
				server._closeThread.join()
			AppServerModule.globalAppServer = None
	sys.stdout.flush()
	sys.stderr.flush()
	os.chdir = _chdir # allow use of os.chdir() again
	return exitStatus

# Signal handlers

def shutDown(signum, frame):
	"""Signal handler for shutting down the server."""
	print
	print "App server has been signaled to shutdown."
	if server and server._running > 2:
		print "Shutting down at", asclocaltime()
		sys.stdout.flush()
		server._running = 2
		if signum == SIGINT:
			raise KeyboardInterrupt
		elif signum == SIGHUP:
			sys.exit(3) # force reload
		else:
			sys.exit(0) # normal exit
	else:
		print "No running app server was found."

try:
	# Use the threadframe module for dumping thread stack frames:
	# http://www.majid.info/mylos/stories/2004/06/10/threadframe.html
	import threadframe

	def threadDump(signum, frame):
		"""Signal handler for dumping thread stack frames to stdout."""
		print
		print "App server has been signaled to attempt a thread dump."
		print
		print "Thread stack frame dump at", asclocaltime()
		sys.stdout.flush()
		frames = threadframe.dict()
		items = frames.items()
		items.sort()
		print
		print "-" * 79
		print
		for threadID, frame in items:
			print "Thread ID: %d (reference count = %d)" % (
				threadID, sys.getrefcount(frame))
			print ''.join(traceback.format_list(traceback.extract_stack(frame)))
		items.sort()
		print "-" * 79
		sys.stdout.flush()

except ImportError:
	# threadframe module not available
	threadDump = None

import signal

# Shutdown signals

try:
	SIGHUP = signal.SIGHUP
	signal.signal(SIGHUP, shutDown)
except AttributeError:
	SIGHUP = None
try:
	SIGTERM = signal.SIGTERM
	signal.signal(SIGTERM, shutDown)
except AttributeError:
	SIGTERM = None
try:
	# this is Ctrl-C on Windows
	SIGINT = signal.SIGINT
	signal.signal(SIGINT, shutDown)
except AttributeError:
	SIGINT = None

if threadDump:

	# Signals for creating a thread dump

	try:
		SIGQUIT = signal.SIGQUIT
		signal.signal(SIGQUIT, threadDump)
	except AttributeError:
		SIGQUIT = None
	try:
		# this is Ctrl-Break on Windows (not Cygwin)
		SIGBREAK = signal.SIGBREAK
		signal.signal(SIGBREAK, threadDump)
	except AttributeError:
		SIGBREAK = None


import re
settingRE = re.compile(r'^(?:--)?([a-zA-Z][a-zA-Z0-9]*\.[a-zA-Z][a-zA-Z0-9]*)=')
from MiscUtils import Configurable

usage = re.search('\n.* arguments:\n\n(.*\n)*?\n', __doc__).group(0)

def main(args):
	"""Command line interface.

	Run by `Launch`, this is the main entrance and command-line interface
	for ThreadedAppServer.

	"""
	function = run
	daemon = False
	workDir = None
	for a in args[:]:
		if settingRE.match(a):
			match = settingRE.match(a)
			name = match.group(1)
			value = a[match.end():]
			Configurable.addCommandLineSetting(name, value)
		elif a == "stop":
			function = AppServerModule.stop
		elif a == "daemon":
			daemon = True
		elif a == "start":
			pass
		elif a[:8] == "workdir=":
			workDir = a[8:]
		else:
			print usage
			return
	if daemon:
		if os.name == "posix":
			pid = os.fork()
			if pid:
				sys.exit()
		else:
			print "Daemon mode not available on your OS."
	return function(workDir=workDir)
