Periodic Threads and Timers

The scrubber and stats-gathering threads must wake up periodically to do their work.

AlarmClock::Pause (int howlong); /* called by waiting threads */

Puts calling thread to sleep.

Maintains a collection of threads waiting for time to pass.

AlarmClock::Tick(); /* called by clock interrupt handler */

Wake up any waiting threads whose wait times have elapsed.

scrubber

stats

while (systemActive) {

do my work;

alarm->Pause(10000);

}