#!/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.

"""

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

from Common import *
import AppServer as AppServerModule
from PidFile import ProcessRunning
from AutoReloadingAppServer import AutoReloadingAppServer as AppServer
from ASStreamOut import ASStreamOut, ConnectionAbortedError
from MiscUtils.Funcs import timestamp
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
    '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
    '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 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._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)

            out = sys.stdout
            out.write('Creating %d threads' % threadCount)
            for i in range(threadCount):
                self.spawnThread()
                out.write(".")
                out.flush()
            out.write("\n")

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

            self.readyForRequests()
        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

    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] == errno.EINTR:
                        continue
                    else:
                        raise

                for sock in input:
                    self._requestID += 1
                    client, addr = sock.accept()
                    serverAddress = sock.getsockname()
                    try:
                        handler = self._handlerCache[serverAddress].pop()
                    except IndexError:
                        handler = self._socketHandlers[serverAddress](self,
                            serverAddress)
                    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.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 i in self._threadPool:
            if i._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 = threading.Thread(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
            # disapear, but they will eventually.
            self._threadCount -= 1
        for i 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 i.isAlive():
                rv = i.join() # Don't need a timeout, it isn't alive
                self._threadPool.remove(i)
                if debug:
                    print "Thread absorbed, real threadCount =", len(self._threadPool)


    ## 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 = threading.currentThread()
        t._processing = False

        try:
            while 1:
                try:
                    handler = self._requestQueue.get()
                    if handler is None: # None means time to quit
                        if debug:
                            print "Thread retrieved None, quitting."
                        break
                    t._processing = True
                    try:
                        handler.handleRequest()
                    except Exception:
                        traceback.print_exc(file=sys.stderr)
                    t._processing = False
                    handler.close()
                except Queue.Empty:
                    pass
        finally:
            self.delThread()
        if debug:
            print threading.currentThread(), "Quitting."

    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)
        for i in self._threadPool:
            try:
                i.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

    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 handleRequest(self):
        """
        Subclasses should override this -- this is where
        work gets done.
        """
        pass

    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:
            # Common error: client is speaking HTTP.
            if chunk[:3] == 'GET':
                self._sock.sendall('''\
HTTP/1.0 505 HTTP Version Not Supported\r
Content-type: text/plain\r
\r
Error: Invalid AppServer protocol: %s.\r
Sorry, I don't speak HTTP.  You must connect via an adapter.\r
See the Troubleshooting section of the WebKit Install Guide.\r
''' % msg)
                self._sock.close()
                return None
            print "ERROR:", msg
            print "ERROR: you can only connect to", self._serverAddress[1], \
                "via an adapter,"
            print "       like mod_webkit or wkcgi, not with a browser."
            raise
        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 = dictLength - len(chunk)
        return loads(chunk)


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):
        verbose = self._server._verbose
        startTime = time.time()
        if verbose:
            print "BEGIN REQUEST"
            print asclocaltime(startTime)
        conn = self._sock
        if verbose:
            print "receiving request from", conn
        requestDict = self.receiveDict()
        if requestDict['format'] == "STATUS":
            conn.send(str(self._server._requestID))
        elif requestDict['format'] == 'QUIT':
            conn.send("OK")
            conn.close()
            self._server.shutDown()


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


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.

    """

    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 silentErrnos:
                        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).

        """
        verbose = self._server._verbose
        self._startTime = time.time()

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

        if verbose:
            uri = requestDict.has_key('environ') \
                and requestURI(requestDict['environ']) or '-'
            sys.stdout.write('%5i  %s  %s\n'
                % (self._requestID, timestamp()['pretty'], uri))

        requestDict['input'] = self.makeInput()
        requestDict['requestID'] = self._requestID

        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

        if verbose:
            duration = ('%0.2f secs' % (time.time() - self._startTime)).ljust(19)
            sys.stdout.write('%5i  %s  %s\n\n' % (self._requestID, duration,
                aborted and '*connection aborted*' or uri))

        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)


# 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 = threading.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 i in args[:]:
        if settingRE.match(i):
            match = settingRE.match(i)
            name = match.group(1)
            value = i[match.end():]
            Configurable.addCommandLineSetting(name, value)
        elif i == "stop":
            function = AppServerModule.stop
        elif i == "daemon":
            daemon = True
        elif i == "start":
            pass
        elif i[:8] == "workdir=":
            workDir = i[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)