Blocking suspend blockers

Blocking suspend blockers

The trick, in Android world, is that only a limited set of known processes can actually set suspend blockers (just as in POSIXy Linux world, only a limited set of processes can write to /dev/sd*). Everyone else who wants to block suspend has to ask one of the privileged processes to set a block for them, using Android's RPC mechanism. An Android app comes with a manifest file, and in that manifest file, you must declare if you wish to take out a suspend blocker. This translates in UI terms to a warning when the application is installed, telling you that the application can "prevent phone from sleeping", and to Android's "where's my battery gone" UI and APIs blaming applications that hold a suspend blocker for the resulting power consumption.

Thus, on a phone, if you take out a suspend blocker via the RPC mechanism, you get blamed whenever the user asks the phone "why's my battery life poor?", even if it's another app hammering the CPU and keeping you out of idle. The hope is that this will be enough to stop application writers from using suspend blockers when they're not needed.