Android/frameworks_base
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Hold wakeup alarms for as long as possible

Browse Source 
If the screen is off, but the CPU is awake and epoll_wait returns for a
non-wakeup alarm, sending any wakeup alarm within its eligibility window
would cause all the held non-wakeup alarms to also fire, which could:
1. Elongate the length of the time the CPU is awake.
2. Cause apps to wake up and perform work.

This change defers sending any wakeup alarm as long as it is possible to
defer all such eligible alarms to later.

Also, fixed a bug in sorting after adding multiple alarms to the store.

Test: atest CtsAlarmManagerTestCases
atest FrameworksMockingServicesTests:com.android.server.alarm

Bug: 161497385
Change-Id: I01f98255091baddf4e7529f88733776e27d090d7
This commit is contained in:
Suprabh Shukla
2021-05-03 19:46:34 -07:00
parent 54df750079
commit 74b85211fa
1 changed files with 32 additions and 9 deletions
Download Patch File Download Diff File Expand all files Collapse all files

41
apex/jobscheduler/service/java/com/android/server/alarm/LazyAlarmStore.java
View File

@@ -40,6 +40,7 @@ import java.util.function.Predicate;
public class LazyAlarmStore implements AlarmStore {
@VisibleForTesting
static final String TAG = LazyAlarmStore.class.getSimpleName();
private static final long ALARM_DEADLINE_SLOP = 500;
private final ArrayList<Alarm> mAlarms = new ArrayList<>();
private Runnable mOnAlarmClockRemoved;
@@ -75,7 +76,7 @@ public class LazyAlarmStore implements AlarmStore {
return;
}
mAlarms.addAll(alarms);
Collections.sort(alarms, sDecreasingTimeOrder);
Collections.sort(mAlarms, sDecreasingTimeOrder);
}
@Override
@@ -163,25 +164,47 @@ public class LazyAlarmStore implements AlarmStore {
@Override
public ArrayList<Alarm> removePendingAlarms(long nowElapsed) {
final ArrayList<Alarm> pending = new ArrayList<>();
final ArrayList<Alarm> standAlones = new ArrayList<>();
// Only send wake-up alarms if this is the absolutely latest time we can evaluate
// for at least one wakeup alarm. This prevents sending other non-wakeup alarms when the
// screen is off but the CPU is awake for some reason.
boolean sendWakeups = false;
// If any alarm with FLAG_STANDALONE is present, we cannot send any alarms without that flag
// in the present batch.
boolean standalonesOnly = false;
for (int i = mAlarms.size() - 1; i >= 0; i--) {
final Alarm alarm = mAlarms.get(i);
if (alarm.getWhenElapsed() > nowElapsed) {
break;
}
mAlarms.remove(i);
pending.add(alarm);
if (alarm.wakeup && alarm.getMaxWhenElapsed() <= nowElapsed + ALARM_DEADLINE_SLOP) {
// Using some slop as it is better to send the wakeup alarm now, rather than
// waking up again a short time later, just to send it.
sendWakeups = true;
}
if ((alarm.flags & AlarmManager.FLAG_STANDALONE) != 0) {
standAlones.add(alarm);
standalonesOnly = true;
}
}
if (!standAlones.isEmpty()) {
// If there are deliverable standalone alarms, others must not go out yet.
mAlarms.removeAll(standAlones);
return standAlones;
final ArrayList<Alarm> toSend = new ArrayList<>();
for (int i = pending.size() - 1; i >= 0; i--) {
final Alarm pendingAlarm = pending.get(i);
if (!sendWakeups && pendingAlarm.wakeup) {
continue;
}
if (standalonesOnly && (pendingAlarm.flags & AlarmManager.FLAG_STANDALONE) == 0) {
continue;
}
pending.remove(i);
toSend.add(pendingAlarm);
}
mAlarms.removeAll(pending);
return pending;
// Perhaps some alarms could not be sent right now. Adding them back for later.
addAll(pending);
return toSend;
}
@Override