Add MultiStateCounter

This native object is used to track values per-state. For example,
if the state changes from 0 to 1 between two updateValue calls,
the delta between the values is distributed to the states 0 and 1
in accordance with the time spent in those states.

Bug: 197162116
Test: atest libbattery_test

Change-Id: Ie304db5c93f4aa9676d12d0a8ab53b6867b24fff

1 files changed, 79 insertions, 0 deletions

diff --git a/libs/battery/LongArrayMultiStateCounter.cpp b/libs/battery/LongArrayMultiStateCounter.cpp
new file mode 100644
index 0000000000..68e088394a
--- /dev/null
+++ b/libs/battery/LongArrayMultiStateCounter.cpp
@@ -0,0 +1,79 @@
+/*
+ * Copyright (C) 2021 The Android Open Source Project
+ * Android BPF library - public API
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "LongArrayMultiStateCounter.h"
+#include <log/log.h>
+
+namespace android {
+namespace battery {
+
+template <>
+bool LongArrayMultiStateCounter::delta(const std::vector<uint64_t>& previousValue,
+                                       const std::vector<uint64_t>& newValue,
+                                       std::vector<uint64_t>* outValue) const {
+    size_t size = previousValue.size();
+    if (newValue.size() != size) {
+        ALOGE("Incorrect array size: %d, should be %d", (int)newValue.size(), (int)size);
+        return false;
+    }
+
+    bool is_delta_valid = true;
+    for (int i = size - 1; i >= 0; i--) {
+        if (newValue[i] >= previousValue[i]) {
+            (*outValue)[i] = newValue[i] - previousValue[i];
+        } else {
+            (*outValue)[i] = 0;
+            is_delta_valid = false;
+        }
+    }
+    return is_delta_valid;
+}
+
+template <>
+void LongArrayMultiStateCounter::add(std::vector<uint64_t>* value1,
+                                     const std::vector<uint64_t>& value2, const uint64_t numerator,
+                                     const uint64_t denominator) const {
+    if (numerator != denominator) {
+        for (int i = value2.size() - 1; i >= 0; i--) {
+            // The caller ensures that denominator != 0
+            (*value1)[i] += value2[i] * numerator / denominator;
+        }
+    } else {
+        for (int i = value2.size() - 1; i >= 0; i--) {
+            (*value1)[i] += value2[i];
+        }
+    }
+}
+
+template <>
+std::string LongArrayMultiStateCounter::valueToString(const std::vector<uint64_t>& v) const {
+    std::stringstream s;
+    s << "{ ";
+    bool first = true;
+    for (uint64_t n : v) {
+        if (!first) {
+            s << ", ";
+        }
+        s << n;
+        first = false;
+    }
+    s << "}";
+    return s.str();
+}
+
+} // namespace battery
+} // namespace android