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BatteryStats custom buckets: don't revive dead Uids

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It is possible for old uids to be reported to BatteryStats
in updateCustomMeasuredEnergyDataLocked().
This can happen, e.g., if a uid was uninstalled between
successive custom energy updates, so that the uid did use non-zero
energy but BatteryStats doesn't care anymore since the uid is gone.
If this happens,
we don't want to recreate any removed Uid objects, so we need
to be careful to only consider Uids that aren't removed.

In practice, this method will only be called after the CPU update,
which means that BatteryStats should already know about all active
uids (assuming they used CPU). Therefore, there shouldn't be any
unknown uids actively using custom energy buckets at this point.
We therefore simply ignore any unknown uids (just log them), on
the assumption that they refer to removed uids or stopped users.

Test: atest BatteryStatsTests
Bug: 180030409
Change-Id: If4fee7a1d11b148ca16d464d6ce4720c5a251130
This commit is contained in:
Adam Bookatz
2021-02-24 01:35:16 +00:00
parent 0088eefaac
commit 5bb1ec89d3
1 changed files with 15 additions and 4 deletions
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19
core/java/com/android/internal/os/BatteryStatsImpl.java
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@@ -12520,6 +12520,7 @@ public class BatteryStatsImpl extends BatteryStats {
* @param totalEnergyUJ energy (microjoules) used for this bucket since this was last called.
* @param uidEnergies map of uid->energy (microjoules) for this bucket since last called.
* Data inside uidEnergies will not be modified (treated immutable).
* Uids not already known to BatteryStats will be ignored.
*/
public void updateCustomMeasuredEnergyDataLocked(int customEnergyBucket,
long totalEnergyUJ, @Nullable SparseLongArray uidEnergies) {
@@ -12540,10 +12541,20 @@ public class BatteryStatsImpl extends BatteryStats {
final int uidInt = mapUid(uidEnergies.keyAt(i));
final long uidEnergyUJ = uidEnergies.valueAt(i);
if (uidEnergyUJ == 0) continue;
// TODO(b/180030409): Worry about dead Uids (no longer in BSI) being revived by this,
// or converse problem of not creating a new Uid if its first blame is recorded here.
final Uid uidObj = getUidStatsLocked(uidInt);
uidObj.addEnergyToCustomBucketLocked(uidEnergyUJ, customEnergyBucket, true);
final Uid uidObj = getAvailableUidStatsLocked(uidInt);
if (uidObj != null) {
uidObj.addEnergyToCustomBucketLocked(uidEnergyUJ, customEnergyBucket, true);
} else {
// Ignore any uid not already known to BatteryStats, rather than creating a new Uid.
// Otherwise we could end up reviving dead Uids. Note that the CPU data is updated
// first, so any uid that has used any CPU should already be known to BatteryStats.
// Recently removed uids (especially common for isolated uids) can reach this path
// and are ignored.
if (!Process.isIsolated(uidInt)) {
Slog.w(TAG, "Received measured energy " + totalEnergyUJ + " for custom bucket "
+ customEnergyBucket + " for non-existent uid " + uidInt);
}
}
}
}