bitbake: server: Rework the server API so process and xmlrpc servers coexist

This changes the way bitbake server works quite radically. Now, the
server is always a process based server with the option of starting
an XMLRPC listener on a specific inferface/port.

Behind the scenes this is done with a "bitbake.sock" file alongside
the bitbake.lock file. If we can obtain the lock, we know we need
to start a server. The server always listens on the socket and UIs
can then connect to this. UIs connect by sending a set of three file
descriptors over the domain socket, one for sending commands, one for
receiving command results and the other for receiving events.

These changes meant we can throw away all the horrid server abstraction
code, the plugable transport option to bitbake and the code becomes
much more readable and debuggable. It also likely removes a ton of
ways you could hang the UI/cooker in weird ways due to all the race
conditions that existed with previous processes.

Changes:

 * The foreground option for bitbake-server was dropped. Just tail
   the log if you really want this, the codepaths were complicated enough
   without adding one for this.
 * BBSERVER="autodetect" was dropped. The server will autostart and
   autoconnect in process mode. You have to specify an xmlrpc server
   address since that can't be autodetected. I can't see a use case
   for autodetect now.
 * The transport/servetype option to bitbake was dropped.
 * A BB_SERVER_TIMEOUT variable is added which allows the server
   to stay resident for a period of time after the last client
   disconnects before unloading. This is used if the -T/--idle-timeout
   option is not passed to bitbake.

This change is invasive and may well introduce new issues however I
believe the codebase is in a much better position for further
development and debugging.

(Bitbake rev: 72a3dbe13a23588e24c0baca6d58c35cdeba3f63)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

1 files changed, 158 insertions, 0 deletions

diff --git a/bitbake/lib/bb/server/xmlrpcserver.py b/bitbake/lib/bb/server/xmlrpcserver.py
new file mode 100644
index 0000000000..875b1282e5
--- /dev/null
+++ b/bitbake/lib/bb/server/xmlrpcserver.py
@@ -0,0 +1,158 @@
+#
+# BitBake XMLRPC Server Interface
+#
+# Copyright (C) 2006 - 2007  Michael 'Mickey' Lauer
+# Copyright (C) 2006 - 2008  Richard Purdie
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License version 2 as
+# published by the Free Software Foundation.
+#
+# 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.,
+# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+
+import os
+import sys
+
+import hashlib
+import time
+import inspect
+from xmlrpc.server import SimpleXMLRPCServer, SimpleXMLRPCRequestHandler
+
+import bb
+
+# This request handler checks if the request has a "Bitbake-token" header
+# field (this comes from the client side) and compares it with its internal
+# "Bitbake-token" field (this comes from the server). If the two are not
+# equal, it is assumed that a client is trying to connect to the server
+# while another client is connected to the server. In this case, a 503 error
+# ("service unavailable") is returned to the client.
+class BitBakeXMLRPCRequestHandler(SimpleXMLRPCRequestHandler):
+    def __init__(self, request, client_address, server):
+        self.server = server
+        SimpleXMLRPCRequestHandler.__init__(self, request, client_address, server)
+
+    def do_POST(self):
+        try:
+            remote_token = self.headers["Bitbake-token"]
+        except:
+            remote_token = None
+        if 0 and remote_token != self.server.connection_token and remote_token != "observer":
+            self.report_503()
+        else:
+            if remote_token == "observer":
+                self.server.readonly = True
+            else:
+                self.server.readonly = False
+            SimpleXMLRPCRequestHandler.do_POST(self)
+
+    def report_503(self):
+        self.send_response(503)
+        response = 'No more client allowed'
+        self.send_header("Content-type", "text/plain")
+        self.send_header("Content-length", str(len(response)))
+        self.end_headers()
+        self.wfile.write(bytes(response, 'utf-8'))
+
+class BitBakeXMLRPCServer(SimpleXMLRPCServer):
+    # remove this when you're done with debugging
+    # allow_reuse_address = True
+
+    def __init__(self, interface, cooker, parent):
+        # Use auto port configuration
+        if (interface[1] == -1):
+            interface = (interface[0], 0)
+        SimpleXMLRPCServer.__init__(self, interface,
+                                    requestHandler=BitBakeXMLRPCRequestHandler,
+                                    logRequests=False, allow_none=True)
+        self.host, self.port = self.socket.getsockname()
+        self.interface = interface
+
+        self.connection_token = None
+        self.commands = BitBakeXMLRPCServerCommands(self)
+        self.register_functions(self.commands, "")
+
+        self.cooker = cooker
+        self.parent = parent
+
+
+    def register_functions(self, context, prefix):
+        """
+        Convenience method for registering all functions in the scope
+        of this class that start with a common prefix
+        """
+        methodlist = inspect.getmembers(context, inspect.ismethod)
+        for name, method in methodlist:
+            if name.startswith(prefix):
+                self.register_function(method, name[len(prefix):])
+
+    def get_timeout(self, delay):
+        socktimeout = self.socket.gettimeout() or delay
+        return min(socktimeout, delay)
+
+    def handle_requests(self):
+        self._handle_request_noblock()
+
+class BitBakeXMLRPCServerCommands():
+
+    def __init__(self, server):
+        self.server = server
+        self.has_client = False
+
+    def registerEventHandler(self, host, port):
+        """
+        Register a remote UI Event Handler
+        """
+        s, t = bb.server.xmlrpcclient._create_server(host, port)
+
+        # we don't allow connections if the cooker is running
+        if (self.server.cooker.state in [bb.cooker.state.parsing, bb.cooker.state.running]):
+            return None, "Cooker is busy: %s" % bb.cooker.state.get_name(self.server.cooker.state)
+
+        self.event_handle = bb.event.register_UIHhandler(s, True)
+        return self.event_handle, 'OK'
+
+    def unregisterEventHandler(self, handlerNum):
+        """
+        Unregister a remote UI Event Handler
+        """
+        ret = bb.event.unregister_UIHhandler(handlerNum, True)
+        self.event_handle = None
+        return ret
+
+    def runCommand(self, command):
+        """
+        Run a cooker command on the server
+        """
+        return self.server.cooker.command.runCommand(command, self.server.readonly)
+
+    def getEventHandle(self):
+        return self.event_handle
+
+    def terminateServer(self):
+        """
+        Trigger the server to quit
+        """
+        self.server.parent.quit = True
+        print("XMLRPC Server triggering exit")
+        return
+
+    def addClient(self):
+        if self.server.parent.haveui:
+            return None
+        token = hashlib.md5(str(time.time()).encode("utf-8")).hexdigest()
+        self.server.connection_token = token
+        self.server.parent.haveui = True
+        return token
+
+    def removeClient(self):
+        if self.server.parent.haveui:
+            self.server.connection_token = None
+            self.server.parent.haveui = False
+