knotty, xmlrpc: add observer-only mode

I add an observer only mode for the knotty UI and
the XMLRPC server that will allow the UI to register
a callback with a server in order to receive events.

The observer-UI is able to send read-only commands to the
server, and also is able to register as an event handler.

Read-only commands are the commands that do not change
the state of the server and have been marked as such in
the command module.

The observer can switch to a full client if it calls addClient
at any time, and the server has no other client running.

Signed-off-by: Alexandru DAMIAN <alexandru.damian@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

4 files changed, 42 insertions, 21 deletions

diff --git a/lib/bb/command.py b/lib/bb/command.py
index ab6950111..5f696c2ae 100644
--- a/lib/bb/command.py
+++ b/lib/bb/command.py
@@ -59,11 +59,14 @@ class Command:
         # FIXME Add lock for this
         self.currentAsyncCommand = None
 
-    def runCommand(self, commandline):
+    def runCommand(self, commandline, ro_only = False):
         command = commandline.pop(0)
         if hasattr(CommandsSync, command):
             # Can run synchronous commands straight away
             command_method = getattr(self.cmds_sync, command)
+            if ro_only:
+                if not hasattr(command_method, 'readonly') or False == getattr(command_method, 'readonly'):
+                    return None, "Not able to execute not readonly commands in readonly mode"
             try:
                 result = command_method(self, commandline)
             except CommandError as exc:
@@ -153,6 +156,7 @@ class CommandsSync:
             expand = params[1]
 
         return command.cooker.data.getVar(varname, expand)
+    getVariable.readonly = True
 
     def setVariable(self, command, params):
         """
@@ -200,6 +204,7 @@ class CommandsSync:
         Get the CPU count on the bitbake server
         """
         return bb.utils.cpu_count()
+    getCpuCount.readonly = True
 
     def matchFile(self, command, params):
         fMatch = params[0]
diff --git a/lib/bb/server/xmlrpc.py b/lib/bb/server/xmlrpc.py
index 5045e55ae..026415efd 100644
--- a/lib/bb/server/xmlrpc.py
+++ b/lib/bb/server/xmlrpc.py
@@ -93,7 +93,7 @@ class BitBakeServerCommands():
         """
         Run a cooker command on the server
         """
-        return self.cooker.command.runCommand(command)
+        return self.cooker.command.runCommand(command, self.server.readonly)
 
     def terminateServer(self):
         """
@@ -124,7 +124,7 @@ class BitBakeServerCommands():
 # ("service unavailable") is returned to the client.
 class BitBakeXMLRPCRequestHandler(SimpleXMLRPCRequestHandler):
     def __init__(self, request, client_address, server):
-        self.connection_token = server.connection_token
+        self.server = server
         SimpleXMLRPCRequestHandler.__init__(self, request, client_address, server)
 
     def do_POST(self):
@@ -132,9 +132,13 @@ class BitBakeXMLRPCRequestHandler(SimpleXMLRPCRequestHandler):
             remote_token = self.headers["Bitbake-token"]
         except:
             remote_token = None
-        if remote_token != self.connection_token:
+        if 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):
@@ -283,13 +287,17 @@ class XMLRPCServer(SimpleXMLRPCServer, BaseImplServer):
         self.connection_token = token
 
 class BitBakeXMLRPCServerConnection(BitBakeBaseServerConnection):
-    def __init__(self, serverImpl, clientinfo=("localhost", 0)):
+    def __init__(self, serverImpl, clientinfo=("localhost", 0), observer_only = False):
         self.connection, self.transport = _create_server(serverImpl.host, serverImpl.port)
         self.clientinfo = clientinfo
         self.serverImpl = serverImpl
+        self.observer_only = observer_only
 
     def connect(self):
-        token = self.connection.addClient()
+        if not self.observer_only:
+            token = self.connection.addClient()
+        else:
+            token = "observer"
         if token is None:
             return None
         self.transport.set_connection_token(token)
@@ -299,7 +307,8 @@ class BitBakeXMLRPCServerConnection(BitBakeBaseServerConnection):
         return self
 
     def removeClient(self):
-        self.connection.removeClient()
+        if not self.observer_only:
+            self.connection.removeClient()
 
     def terminate(self):
         # Don't wait for server indefinitely
@@ -331,7 +340,8 @@ class BitBakeServer(BitBakeBaseServer):
 
 class BitBakeXMLRPCClient(BitBakeBaseServer):
 
-    def __init__(self):
+    def __init__(self, observer_only = False):
+        self.observer_only = observer_only
         pass
 
     def saveConnectionDetails(self, remote):
@@ -354,7 +364,7 @@ class BitBakeXMLRPCClient(BitBakeBaseServer):
         except:
             return None
         self.serverImpl = XMLRPCProxyServer(host, port)
-        self.connection = BitBakeXMLRPCServerConnection(self.serverImpl, (ip, 0))
+        self.connection = BitBakeXMLRPCServerConnection(self.serverImpl, (ip, 0), self.observer_only)
         return self.connection.connect()
 
     def endSession(self):
diff --git a/lib/bb/ui/knotty.py b/lib/bb/ui/knotty.py
index 389c3cc64..c6a1d3f98 100644
--- a/lib/bb/ui/knotty.py
+++ b/lib/bb/ui/knotty.py
@@ -216,21 +216,25 @@ class TerminalFilter(object):
             fd = sys.stdin.fileno()
             self.termios.tcsetattr(fd, self.termios.TCSADRAIN, self.stdinbackup)
 
-def main(server, eventHandler, params, tf = TerminalFilter):
-
+def _log_settings_from_server(server):
     # Get values of variables which control our output
     includelogs, error = server.runCommand(["getVariable", "BBINCLUDELOGS"])
     if error:
         logger.error("Unable to get the value of BBINCLUDELOGS variable: %s" % error)
-        return 1
+        raise BaseException(error)
     loglines, error = server.runCommand(["getVariable", "BBINCLUDELOGS_LINES"])
     if error:
         logger.error("Unable to get the value of BBINCLUDELOGS_LINES variable: %s" % error)
-        return 1
+        raise BaseException(error)
     consolelogfile, error = server.runCommand(["getVariable", "BB_CONSOLELOG"])
     if error:
         logger.error("Unable to get the value of BB_CONSOLELOG variable: %s" % error)
-        return 1
+        raise BaseException(error)
+    return includelogs, loglines, consolelogfile
+
+def main(server, eventHandler, params, tf = TerminalFilter):
+
+    includelogs, loglines, consolelogfile = _log_settings_from_server(server)
 
     if sys.stdin.isatty() and sys.stdout.isatty():
         log_exec_tty = True
@@ -254,7 +258,7 @@ def main(server, eventHandler, params, tf = TerminalFilter):
         consolelog.setFormatter(conlogformat)
         logger.addHandler(consolelog)
 
-    try:
+    if not params.observe_only:
         params.updateFromServer(server)
         cmdline = params.parseActions()
         if not cmdline:
@@ -271,9 +275,7 @@ def main(server, eventHandler, params, tf = TerminalFilter):
         elif ret != True:
             logger.error("Command '%s' failed: returned %s" % (cmdline, ret))
             return 1
-    except xmlrpclib.Fault as x:
-        logger.error("XMLRPC Fault getting commandline:\n %s" % x)
-        return 1
+
 
     parseprogress = None
     cacheprogress = None
@@ -320,7 +322,7 @@ def main(server, eventHandler, params, tf = TerminalFilter):
                 elif event.levelno == format.WARNING:
                     warnings = warnings + 1
                 # For "normal" logging conditions, don't show note logs from tasks
-                # but do show them if the user has changed the default log level to 
+                # but do show them if the user has changed the default log level to
                 # include verbose/debug messages
                 if event.taskpid != 0 and event.levelno <= format.NOTE:
                     continue
@@ -469,12 +471,15 @@ def main(server, eventHandler, params, tf = TerminalFilter):
                 pass
         except KeyboardInterrupt:
             termfilter.clearFooter()
-            if main.shutdown == 1:
+            if params.observe_only:
+                print("\nKeyboard Interrupt, exiting observer...")
+                main.shutdown = 2
+            if not params.observe_only and main.shutdown == 1:
                 print("\nSecond Keyboard Interrupt, stopping...\n")
                 _, error = server.runCommand(["stateStop"])
                 if error:
                     logger.error("Unable to cleanly stop: %s" % error)
-            if main.shutdown == 0:
+            if not params.observe_only and main.shutdown == 0:
                 print("\nKeyboard Interrupt, closing down...\n")
                 interrupted = True
                 _, error = server.runCommand(["stateShutdown"])
diff --git a/lib/bb/ui/uievent.py b/lib/bb/ui/uievent.py
index 0b9a836d0..038029fcf 100644
--- a/lib/bb/ui/uievent.py
+++ b/lib/bb/ui/uievent.py
@@ -84,6 +84,7 @@ class BBUIEventQueue:
 
     def startCallbackHandler(self):
 
+        self.server.timeout = 1
         while not self.server.quit:
             self.server.handle_request()
         self.server.server_close()