B08b: Try Monitor App

Install

First build the application

m -j24 UserSwitchMonitorApp

Then see the output on the console. It's built and put into the directory

out/target/product/vsoc_x86_64_only/system/priv-app/UserSwitchMonitorApp/UserSwitchMonitorApp.apk

Install the application and grant the necessary runtime permission:

adb install --user 0 $OUT/system/priv-app/UserSwitchMonitorApp/UserSwitchMonitorApp.apk
adb shell pm grant --user 0 com.google.android.car.userswitchmonitor android.permission.INTERACT_ACROSS_USERS

Run

Start the (foreground) service

adb shell am start-foreground-service --user 0 com.google.android.car.userswitchmonitor/.UserSwitchMonitorService

Now the app is running and the service within the application has started. See the tag mentioned in the logcat output

adb logcat -s UserSwitchMonitor

Also, see the dumpsys output of the service.

adb shell dumpsys activity service com.google.android.car.userswitchmonitor/.UserSwitchMonitorService

Try it Out

Next, try a user switch in the running Android system. In the top right corner you can switch between the Driver and the Guest user.

Do this now and re-execute the logcat and dumpsys commands. You should see additional log messages and events.

Extra Tasks

Locate the source code of the application in the source tree. E.g., the function that prints the output seen in the dumpsys command. Use both: cs.android.com and the local source tree.

Also, try to use the mgrep and godir commands in the AOSP build environment.

Also, locate the AndroidManifest.xml and review the (foreground) service definition used for am start-foreground-service.

And question: What is the difference between the folder /system/priv-app and /system/app/ in the system partition?