Reset time-since-update if the tracked value is nonmonotonic
The absence of this reset led to timeInStateSinceUpdate exceeding
total timeSinceUpdate. This resulted in inflated counts,
which are smeared using the `delta * timeInState / timeSinceUpdate` formula.
So, instead of assigning a portion of the time to a specific state
it would assign a multiple of the time to it.
Bug: 204087731
Test: atest libbattery_test
Change-Id: I7805d5c6aa314f4030c8a1ac9541f2d439a471cb
diff --git a/libs/battery/MultiStateCounterTest.cpp b/libs/battery/MultiStateCounterTest.cpp
index 848fd10..876bf74 100644
--- a/libs/battery/MultiStateCounterTest.cpp
+++ b/libs/battery/MultiStateCounterTest.cpp
@@ -176,7 +176,7 @@
testCounter.setState(0, 0);
testCounter.updateValue(6.0, 2000);
- // Time moves back. The negative delta from 2000 to 1000 is ignored
+ // Time moves back. The delta over the negative interval from 2000 to 1000 is ignored
testCounter.updateValue(8.0, 1000);
double delta = testCounter.updateValue(11.0, 3000);
@@ -189,6 +189,27 @@
EXPECT_DOUBLE_EQ(3.0, delta);
}
+TEST_F(MultiStateCounterTest, updateValue_nonmonotonic) {
+ DoubleMultiStateCounter testCounter(2, 0);
+ testCounter.updateValue(0, 0);
+ testCounter.setState(0, 0);
+ testCounter.updateValue(6.0, 2000);
+
+ // Value goes down. The negative delta from 6.0 to 4.0 is ignored
+ testCounter.updateValue(4.0, 3000);
+
+ // Value goes up again. The positive delta from 4.0 to 7.0 is accumulated.
+ double delta = testCounter.updateValue(7.0, 4000);
+
+ // The total accumulated count is:
+ // 6.0 // For the period 0-2000
+ // +(7.0-4.0) // For the period 3000-4000
+ EXPECT_DOUBLE_EQ(9.0, testCounter.getCount(0));
+
+ // 7.0-4.0
+ EXPECT_DOUBLE_EQ(3.0, delta);
+}
+
TEST_F(MultiStateCounterTest, addValue) {
DoubleMultiStateCounter testCounter(1, 0);
testCounter.updateValue(0, 0);