Merge pull request #48 from Ultimaker/CES-2235-delay-dbus-publication

CES-2235 Delay DBus publication

Author: onnodb

Charon/Service/FileService.py

@@ -18,15 +18,31 @@
 #   Note: This class does not currently use type hinting since type hints,
 #   dbus-python decorators and Python 3.4 do not mix well.
 class FileService(dbus.service.Object):
+
     def __init__(self, dbus_bus: dbus.Bus) -> None:
+        self.__dbus_bus = dbus_bus
         super().__init__(
-            bus_name = dbus.service.BusName("nl.ultimaker.charon", dbus_bus),
-            object_path = "/nl/ultimaker/charon"
+            conn=self.__dbus_bus,
+            object_path="/nl/ultimaker/charon",
+            # Postpone claiming a well-known name until the class is fully initialized.
+            # If we do this right now, the DBus service will be published to the
+            # bus in an incomplete state, and clients connecting early on may
+            # encounter, for instance, emptry introspection data on this service.
+            bus_name=None,
         )
+        self.__bus_name = None
 
         log.debug("FileService initialized")
         self.__queue = RequestQueue.RequestQueue()
 
+    ## Publish the fully initialized DBus service to the bus
+    def publish(self) -> None:
+        # Store a reference to the BusName for as long as the DBus service is alive;
+        # otherwise it gets GC'd, and the well-known name gets released again.
+        # Taking ownership of this well-known name is also the trigger for other services
+        # to notice that we are alive & available.
+        self.__bus_name = dbus.service.BusName("nl.ultimaker.charon", self.__dbus_bus)
+
     ##  Start a request for data from a file.
     #
     #   This function will start a request for data from a certain file.

Charon/Service/main.py

@@ -31,5 +31,6 @@
     _bus = dbus.SystemBus(private=True, mainloop=dbus.mainloop.glib.DBusGMainLoop())
 
 _service = Charon.Service.FileService(_bus)
+_service.publish()
 
 _loop.run()

build.sh

@@ -1,4 +1,4 @@
-#!/bin/sh
+#!/bin/bash
 
 ARCH="armhf"
 
@@ -42,7 +42,7 @@ usage()
     echo "NOTE: This script requires root permissions to run."
 }
 
-while getopts ":hc" options; do
+while getopts ":hcs" options; do
     case "${options}" in
     c)
         cleanup
@@ -52,6 +52,9 @@ while getopts ":hc" options; do
         usage
         exit 0
         ;;
+    s)
+        # Ignore for compatibility with other build scripts
+        ;;
     :)
         echo "Option -${OPTARG} requires an argument."
         exit 1

build_for_ultimaker.sh

@@ -1,4 +1,4 @@
-#!/bin/sh
+#!/bin/bash
 #
 # Copyright (C) 2019 Ultimaker B.V.
 #
@@ -19,7 +19,7 @@ run_linters="yes"
 run_tests="yes"
 
 # Run the make_docker.sh script here, within the context of the build_for_ultimaker.sh script
-. ./make_docker.sh
+. ./make_docker.sh ""
 
 env_check()
 {
@@ -71,7 +71,7 @@ usage()
     echo "  -t   Skip tests"
 }
 
-while getopts ":chlt" options; do
+while getopts ":chlst" options; do
     case "${options}" in
     c)
         run_env_check="no"
@@ -86,6 +86,9 @@ while getopts ":chlt" options; do
     t)
         run_tests="no"
         ;;
+    s)
+        # Ignore for compatibility with other build scripts
+        ;;
     :)
         echo "Option -${OPTARG} requires an argument."
         exit 1

docker_env/buildenv_check.sh

@@ -1,4 +1,4 @@
-#!/bin/sh
+#!/bin/bash
 
 set -eu