~bzr-pqm/bzr/bzr.dev

# Copyright (C) 2006, 2007 Canonical Ltd

#

# This program is free software; you can redistribute it and/or modify

# it under the terms of the GNU General Public License as published by

# the Free Software Foundation; either version 2 of the License, or

# (at your option) any later version.

#

# This program is distributed in the hope that it will be useful,

# but WITHOUT ANY WARRANTY; without even the implied warranty of

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

# GNU General Public License for more details.

#

# You should have received a copy of the GNU General Public License

# along with this program; if not, write to the Free Software

# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

"""Server for smart-server protocol."""

import errno

import socket

import threading

from bzrlib.hooks import Hooks

from bzrlib import (

    errors,

    trace,

    transport,

)

from bzrlib.smart.medium import SmartServerSocketStreamMedium

class SmartTCPServer(object):

    """Listens on a TCP socket and accepts connections from smart clients.

    Each connection will be served by a SmartServerSocketStreamMedium running in

    a thread.

    hooks: An instance of SmartServerHooks.

    """

    def __init__(self, backing_transport, host='127.0.0.1', port=0):

        """Construct a new server.

        To actually start it running, call either start_background_thread or

        serve.

        :param host: Name of the interface to listen on.

        :param port: TCP port to listen on, or 0 to allocate a transient port.

        """

        # let connections timeout so that we get a chance to terminate

        # Keep a reference to the exceptions we want to catch because the socket

        # module's globals get set to None during interpreter shutdown.

        from socket import timeout as socket_timeout

        from socket import error as socket_error

        self._socket_error = socket_error

        self._socket_timeout = socket_timeout

        self._server_socket = socket.socket()

        self._server_socket.bind((host, port))

        self._sockname = self._server_socket.getsockname()

        self.port = self._sockname[1]

        self._server_socket.listen(1)

        self._server_socket.settimeout(1)

        self.backing_transport = backing_transport

        self._started = threading.Event()

        self._stopped = threading.Event()

    def serve(self):

        self._should_terminate = False

        # for hooks we are letting code know that a server has started (and

        # later stopped).

        # There are three interesting urls:

        # The URL the server can be contacted on. (e.g. bzr://host/)

        # The URL that a commit done on the same machine as the server will

        # have within the servers space. (e.g. file:///home/user/source)

        # The URL that will be given to other hooks in the same process -

        # the URL of the backing transport itself. (e.g. chroot+:///)

        # We need all three because:

        #  * other machines see the first

        #  * local commits on this machine should be able to be mapped to

        #    this server 

        #  * commits the server does itself need to be mapped across to this

        #    server.

        # The latter two urls are different aliases to the servers url,

        # so we group those in a list - as there might be more aliases 

        # in the future.

        backing_urls = [self.backing_transport.base]

        try:

            backing_urls.append(self.backing_transport.external_url())

        except errors.InProcessTransport:

            pass

        for hook in SmartTCPServer.hooks['server_started']:

            hook(backing_urls, self.get_url())

        self._started.set()

        try:

            try:

                while not self._should_terminate:

                    try:

                        conn, client_addr = self._server_socket.accept()

                    except self._socket_timeout:

                        # just check if we're asked to stop

                        pass

                    except self._socket_error, e:

                        # if the socket is closed by stop_background_thread

                        # we might get a EBADF here, any other socket errors

                        # should get logged.

                        if e.args[0] != errno.EBADF:

                            trace.warning("listening socket error: %s", e)

                    else:

                        self.serve_conn(conn)

            except KeyboardInterrupt:

                # dont log when CTRL-C'd.

                raise

            except Exception, e:

                trace.error("Unhandled smart server error.")

                trace.log_exception_quietly()

                raise

        finally:

            self._stopped.set()

            try:

                # ensure the server socket is closed.

                self._server_socket.close()

            except self._socket_error:

                # ignore errors on close

                pass

            for hook in SmartTCPServer.hooks['server_stopped']:

                hook(backing_urls, self.get_url())

    def get_url(self):

        """Return the url of the server"""

        return "bzr://%s:%d/" % self._sockname

    def serve_conn(self, conn):

        # For WIN32, where the timeout value from the listening socket

        # propogates to the newly accepted socket.

        conn.setblocking(True)

        conn.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)

        handler = SmartServerSocketStreamMedium(conn, self.backing_transport)

        connection_thread = threading.Thread(None, handler.serve, name='smart-server-child')

        connection_thread.setDaemon(True)

        connection_thread.start()

    def start_background_thread(self):

        self._started.clear()

        self._server_thread = threading.Thread(None,

                self.serve,

                name='server-' + self.get_url())

        self._server_thread.setDaemon(True)

        self._server_thread.start()

        self._started.wait()

    def stop_background_thread(self):

        self._stopped.clear()

        # tell the main loop to quit on the next iteration.

        self._should_terminate = True

        # close the socket - gives error to connections from here on in,

        # rather than a connection reset error to connections made during

        # the period between setting _should_terminate = True and 

        # the current request completing/aborting. It may also break out the

        # main loop if it was currently in accept() (on some platforms).

        try:

            self._server_socket.close()

        except self._socket_error:

            # ignore errors on close

            pass

        if not self._stopped.isSet():

            # server has not stopped (though it may be stopping)

            # its likely in accept(), so give it a connection

            temp_socket = socket.socket()

            temp_socket.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)

            if not temp_socket.connect_ex(self._sockname):

                # and close it immediately: we dont choose to send any requests.

                temp_socket.close()

        self._stopped.wait()

        self._server_thread.join()

class SmartServerHooks(Hooks):

    """Hooks for the smart server."""

    def __init__(self):

        """Create the default hooks.

        These are all empty initially, because by default nothing should get

        notified.

        """

        Hooks.__init__(self)

        # Introduced in 0.16:

        # invoked whenever the server starts serving a directory.

        # The api signature is (backing urls, public url).

        self['server_started'] = []

        # Introduced in 0.16:

        # invoked whenever the server stops serving a directory.

        # The api signature is (backing urls, public url).

        self['server_stopped'] = []

SmartTCPServer.hooks = SmartServerHooks()

class SmartTCPServer_for_testing(SmartTCPServer):

    """Server suitable for use by transport tests.

    This server is backed by the process's cwd.

    """

    def __init__(self):

        SmartTCPServer.__init__(self, None)

    def get_backing_transport(self, backing_transport_server):

        """Get a backing transport from a server we are decorating."""

        return transport.get_transport(backing_transport_server.get_url())

    def setUp(self, backing_transport_server=None):

        """Set up server for testing"""

        from bzrlib.transport.chroot import ChrootServer

        if backing_transport_server is None:

            from bzrlib.transport.local import LocalURLServer

            backing_transport_server = LocalURLServer()

        self.chroot_server = ChrootServer(

            self.get_backing_transport(backing_transport_server))

        self.chroot_server.setUp()

        self.backing_transport = transport.get_transport(

            self.chroot_server.get_url())

        self.start_background_thread()

    def tearDown(self):

        self.stop_background_thread()

        self.chroot_server.tearDown()

    def get_bogus_url(self):

        """Return a URL which will fail to connect"""

        return 'bzr://127.0.0.1:1/'

class ReadonlySmartTCPServer_for_testing(SmartTCPServer_for_testing):

    """Get a readonly server for testing."""

    def get_backing_transport(self, backing_transport_server):

        """Get a backing transport from a server we are decorating."""

        url = 'readonly+' + backing_transport_server.get_url()

        return transport.get_transport(url)