MeeGo Touch Homescreen startup signalling

MeeGo Touch Homescreen integrates to upstart scripts by stopping its execution after it is drawn and responsive. MeeGo Touch Homescreen also sends a D-Bus signal that tells other interested parties that the home screen is up and running.

Integration with upstart scripts

MeeGo Touch Homescreen has two modes in which it operates:

1. upstart mode, where duihome stops itself after it has initialized and is responsive
2. non-upstart mode, where duihome doesn't stop.

The latter mode is used for functional tests and such, the former mode is what will run on production devices. Using the upstart mode practically causes duihome to stop itself with a SIGSTOP signal, which tells the controlling upstart script to send a SIGCONT and run the dependent scripts. This is practically achieved by using a proper command line argument, and adding a proper expect-stop-stanza to the upstart script of duihome. An example script is below:

start on started xsession-default/mission-control
expect stop
stop on stopping xsession

console none
script
   exec su - user -c "exec /usr/bin/duihome --upstart"
end script

post-start script
   initctl emit --quiet --no-wait DESKTOP_READY
end script

respawn
respawn limit 3 30
reboot

Note the "--upstart" parameter, and the "expect stop" stanza.

D-Bus notification of MeeGo Touch Homescreen readiness

Regardless of the use of upstart mode, duihome sends a D-Bus signal when it has initialized and is responsive. The D-Bus signal details are as follows:

Signal property	Value
Interface	com.nokia.duihome.readyNotifier
Path	/com/nokia/duihome
Name	ready