A uint64 array wrapper for optimized allocation and copying

Bug: 315052795
Bug: 357697495
Test: atest libbattery_test; atest FrameworksCoreTests
Flag: EXEMPT bugfix
Change-Id: I3c09c438131b3f67ef04436667e589d1d86aff71

5 files changed, 231 insertions, 100 deletions

diff --git a/libs/battery/LongArrayMultiStateCounter.cpp b/libs/battery/LongArrayMultiStateCounter.cpp
index 125cfaffa4..35c40ab7e6 100644
--- a/libs/battery/LongArrayMultiStateCounter.cpp
+++ b/libs/battery/LongArrayMultiStateCounter.cpp
@@ -21,58 +21,134 @@
 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;
+Uint64ArrayRW::Uint64ArrayRW(const Uint64Array &copy) : Uint64Array(copy.size()) {
+    if (mSize != 0 && copy.data() != nullptr) {
+        mData = new uint64_t[mSize];
+        memcpy(mData, copy.data(), mSize * sizeof(uint64_t));
+    } else {
+        mData = nullptr;
     }
+}
 
-    bool is_delta_valid = true;
-    for (int i = size - 1; i >= 0; i--) {
-        if (newValue[i] >= previousValue[i]) {
-            (*outValue)[i] = newValue[i] - previousValue[i];
+uint64_t *Uint64ArrayRW::dataRW() {
+    if (mData == nullptr) {
+        mData = new uint64_t[mSize];
+        memset(mData, 0, mSize * sizeof(uint64_t));
+    }
+    return mData;
+}
+
+Uint64ArrayRW &Uint64ArrayRW::operator=(const Uint64Array &t) {
+    if (t.size() != mSize) {
+        delete[] mData;
+        mSize = t.size();
+        mData = nullptr;
+    }
+    if (mSize != 0) {
+        if (t.data() != nullptr) {
+            mData = new uint64_t[mSize];
+            memcpy(mData, t.data(), mSize * sizeof(uint64_t));
         } else {
-            (*outValue)[i] = 0;
-            is_delta_valid = false;
+            mData = nullptr;
         }
     }
-    return is_delta_valid;
+    return *this;
+}
+
+std::ostream &operator<<(std::ostream &os, const Uint64Array &v) {
+    os << "{";
+    const uint64_t *data = v.data();
+    if (data != nullptr) {
+        bool first = true;
+        for (size_t i = 0; i < v.size(); i++) {
+            if (!first) {
+                os << ", ";
+            }
+            os << data[i];
+            first = false;
+        }
+    }
+    os << "}";
+    return os;
+}
+
+// Convenience constructor for tests
+Uint64ArrayRW::Uint64ArrayRW(std::initializer_list<uint64_t> init) : Uint64Array(init.size()) {
+    mData = new uint64_t[mSize];
+    memcpy(mData, init.begin(), mSize * sizeof(uint64_t));
+}
+
+// Used in tests only.
+bool Uint64Array::operator==(const Uint64Array &other) const {
+    if (size() != other.size()) {
+        return false;
+    }
+    const uint64_t* thisData = data();
+    const uint64_t* thatData = other.data();
+    for (size_t i = 0; i < mSize; i++) {
+        const uint64_t v1 = thisData != nullptr ? thisData[i] : 0;
+        const uint64_t v2 = thatData != nullptr ? thatData[i] : 0;
+        if (v1 != v2) {
+            return false;
+        }
+    }
+    return true;
 }
 
 template <>
-void LongArrayMultiStateCounter::add(std::vector<uint64_t>* value1,
-                                     const std::vector<uint64_t>& value2, const uint64_t numerator,
-                                     const uint64_t denominator) const {
+void LongArrayMultiStateCounter::add(Uint64ArrayRW *value1, const Uint64Array &value2,
+                                     const uint64_t numerator, const uint64_t denominator) const {
+    const uint64_t* data2 = value2.data();
+    if (data2 == nullptr) {
+        return;
+    }
+
+    uint64_t* data1 = value1->dataRW();
+    size_t size = value2.size();
     if (numerator != denominator) {
-        for (int i = value2.size() - 1; i >= 0; i--) {
+        for (size_t i = 0; i < size; i++) {
             // The caller ensures that denominator != 0
-            (*value1)[i] += value2[i] * numerator / denominator;
+            data1[i] += data2[i] * numerator / denominator;
         }
     } else {
-        for (int i = value2.size() - 1; i >= 0; i--) {
-            (*value1)[i] += value2[i];
+        for (size_t i = 0; i < size; i++) {
+            data1[i] += data2[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 << ", ";
+template<>
+bool LongArrayMultiStateCounter::delta(const Uint64ArrayRW &previousValue,
+                                       const Uint64Array &newValue, Uint64ArrayRW *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;
+    }
+    if (outValue->size() != size) {
+        ALOGE("Incorrect outValue size: %d, should be %d", (int) outValue->size(), (int) size);
+        return false;
+    }
+
+    bool is_delta_valid = true;
+    const uint64_t *prevData = previousValue.data();
+    const uint64_t *newData = newValue.data();
+    uint64_t *outData = outValue->dataRW();
+    for (size_t i = 0; i < size; i++) {
+        if (prevData == nullptr) {
+            if (newData == nullptr) {
+                outData[i] = 0;
+            } else {
+                outData[i] = newData[i];
+            }
+        } else if (newData == nullptr || newData[i] < prevData[i]) {
+            outData[i] = 0;
+            is_delta_valid = false;
+        } else {
+            outData[i] = newData[i] - prevData[i];
         }
-        s << n;
-        first = false;
     }
-    s << "}";
-    return s.str();
+    return is_delta_valid;
 }
 
 } // namespace battery
diff --git a/libs/battery/LongArrayMultiStateCounter.h b/libs/battery/LongArrayMultiStateCounter.h
index f3439f6a0c..e00c96898e 100644
--- a/libs/battery/LongArrayMultiStateCounter.h
+++ b/libs/battery/LongArrayMultiStateCounter.h
@@ -23,7 +23,66 @@
 namespace android {
 namespace battery {
 
-typedef MultiStateCounter<std::vector<uint64_t>> LongArrayMultiStateCounter;
+/**
+ * Wrapper for an array of uint64's.
+ */
+class Uint64Array {
+  protected:
+    size_t mSize;
+
+  public:
+    Uint64Array() : Uint64Array(0) {}
+
+    Uint64Array(size_t size) : mSize(size) {}
+
+    virtual ~Uint64Array() {}
+
+    size_t size() const { return mSize; }
+
+    /**
+     * Returns the wrapped array.
+     *
+     * Nullable! Null should be interpreted the same as an array of zeros
+     */
+    virtual const uint64_t *data() const { return nullptr; }
+
+    friend std::ostream &operator<<(std::ostream &os, const Uint64Array &v);
+
+    // Test API
+    bool operator==(const Uint64Array &other) const;
+};
+
+/**
+ * Mutable version of Uint64Array.
+ */
+class Uint64ArrayRW: public Uint64Array {
+    uint64_t* mData;
+
+public:
+    Uint64ArrayRW() : Uint64ArrayRW(0) {}
+
+    Uint64ArrayRW(size_t size) : Uint64Array(size), mData(nullptr) {}
+
+    Uint64ArrayRW(const Uint64Array &copy);
+
+    // Need an explicit copy constructor. In the initialization context C++ does not understand that
+    // a Uint64ArrayRW is a Uint64Array.
+    Uint64ArrayRW(const Uint64ArrayRW &copy) : Uint64ArrayRW((const Uint64Array &) copy) {}
+
+    // Test API
+    Uint64ArrayRW(std::initializer_list<uint64_t> init);
+
+    ~Uint64ArrayRW() override { delete[] mData; }
+
+    const uint64_t *data() const override { return mData; }
+
+    // NonNull. Will initialize the wrapped array if it is null.
+    uint64_t *dataRW();
+
+    Uint64ArrayRW &operator=(const Uint64Array &t);
+};
+
+typedef MultiStateCounter<Uint64ArrayRW, Uint64Array> LongArrayMultiStateCounter;
 
 } // namespace battery
 } // namespace android
diff --git a/libs/battery/LongArrayMultiStateCounterTest.cpp b/libs/battery/LongArrayMultiStateCounterTest.cpp
index e4e6b2a49f..1c74e3fd14 100644
--- a/libs/battery/LongArrayMultiStateCounterTest.cpp
+++ b/libs/battery/LongArrayMultiStateCounterTest.cpp
@@ -24,25 +24,25 @@ namespace battery {
 class LongArrayMultiStateCounterTest : public testing::Test {};
 
 TEST_F(LongArrayMultiStateCounterTest, stateChange) {
-    LongArrayMultiStateCounter testCounter(2, std::vector<uint64_t>(4));
-    testCounter.updateValue(std::vector<uint64_t>({0, 0, 0, 0}), 1000);
+    LongArrayMultiStateCounter testCounter(2, Uint64Array(4));
+    testCounter.updateValue(Uint64ArrayRW({0, 0, 0, 0}), 1000);
     testCounter.setState(0, 1000);
     testCounter.setState(1, 2000);
-    testCounter.updateValue(std::vector<uint64_t>({100, 200, 300, 400}), 3000);
+    testCounter.updateValue(Uint64ArrayRW({100, 200, 300, 400}), 3000);
 
     // Time was split in half between the two states, so the counts will be split 50:50 too
-    EXPECT_EQ(std::vector<uint64_t>({50, 100, 150, 200}), testCounter.getCount(0));
-    EXPECT_EQ(std::vector<uint64_t>({50, 100, 150, 200}), testCounter.getCount(1));
+    EXPECT_EQ(Uint64ArrayRW({50, 100, 150, 200}), testCounter.getCount(0));
+    EXPECT_EQ(Uint64ArrayRW({50, 100, 150, 200}), testCounter.getCount(1));
 }
 
 TEST_F(LongArrayMultiStateCounterTest, accumulation) {
-    LongArrayMultiStateCounter testCounter(2, std::vector<uint64_t>(4));
-    testCounter.updateValue(std::vector<uint64_t>({0, 0, 0, 0}), 1000);
+    LongArrayMultiStateCounter testCounter(2, Uint64Array(4));
+    testCounter.updateValue(Uint64ArrayRW({0, 0, 0, 0}), 1000);
     testCounter.setState(0, 1000);
     testCounter.setState(1, 2000);
-    testCounter.updateValue(std::vector<uint64_t>({100, 200, 300, 400}), 3000);
+    testCounter.updateValue(Uint64ArrayRW({100, 200, 300, 400}), 3000);
     testCounter.setState(0, 4000);
-    testCounter.updateValue(std::vector<uint64_t>({200, 300, 400, 500}), 8000);
+    testCounter.updateValue(Uint64ArrayRW({200, 300, 400, 500}), 8000);
 
     // The first delta is split 50:50:
     //   0: {50, 100, 150, 200}
@@ -50,16 +50,16 @@ TEST_F(LongArrayMultiStateCounterTest, accumulation) {
     // The second delta is split 4:1
     //   0: {80, 80, 80, 80}
     //   1: {20, 20, 20, 20}
-    EXPECT_EQ(std::vector<uint64_t>({130, 180, 230, 280}), testCounter.getCount(0));
-    EXPECT_EQ(std::vector<uint64_t>({70, 120, 170, 220}), testCounter.getCount(1));
+    EXPECT_EQ(Uint64ArrayRW({130, 180, 230, 280}), testCounter.getCount(0));
+    EXPECT_EQ(Uint64ArrayRW({70, 120, 170, 220}), testCounter.getCount(1));
 }
 
 TEST_F(LongArrayMultiStateCounterTest, toString) {
-    LongArrayMultiStateCounter testCounter(2, std::vector<uint64_t>(4));
-    testCounter.updateValue(std::vector<uint64_t>({0, 0, 0, 0}), 1000);
+    LongArrayMultiStateCounter testCounter(2, Uint64Array(4));
+    testCounter.updateValue(Uint64ArrayRW({0, 0, 0, 0}), 1000);
     testCounter.setState(0, 1000);
     testCounter.setState(1, 2000);
-    testCounter.updateValue(std::vector<uint64_t>({100, 200, 300, 400}), 3000);
+    testCounter.updateValue(Uint64ArrayRW({100, 200, 300, 400}), 3000);
 
     EXPECT_STREQ("[0: {50, 100, 150, 200}, 1: {50, 100, 150, 200}] updated: 3000 currentState: 1",
                  testCounter.toString().c_str());
diff --git a/libs/battery/MultiStateCounter.h b/libs/battery/MultiStateCounter.h
index 04b718698e..fadc4ffd41 100644
--- a/libs/battery/MultiStateCounter.h
+++ b/libs/battery/MultiStateCounter.h
@@ -35,12 +35,12 @@ namespace battery {
 
 typedef uint16_t state_t;
 
-template <class T>
+template <class T, class V>
 class MultiStateCounter {
-    uint16_t stateCount;
+    const uint16_t stateCount;
+    const V emptyValue;
     state_t currentState;
     time_t lastStateChangeTimestamp;
-    T emptyValue;
     T lastValue;
     time_t lastUpdateTimestamp;
     T deltaValue;
@@ -54,7 +54,7 @@ class MultiStateCounter {
     State* states;
 
 public:
-    MultiStateCounter(uint16_t stateCount, const T& emptyValue);
+    MultiStateCounter(uint16_t stateCount, const V& emptyValue);
 
     virtual ~MultiStateCounter();
 
@@ -66,35 +66,35 @@ public:
      * Copies the current state and accumulated times-in-state from the source. Resets
      * the accumulated value.
      */
-    void copyStatesFrom(const MultiStateCounter<T>& source);
+    void copyStatesFrom(const MultiStateCounter<T, V> &source);
 
-    void setValue(state_t state, const T& value);
+    void setValue(state_t state, const V& value);
 
     /**
      * Updates the value by distributing the delta from the previously set value
      * among states according to their respective time-in-state.
      * Returns the delta from the previously set value.
      */
-    const T& updateValue(const T& value, time_t timestamp);
+    const V& updateValue(const V& value, time_t timestamp);
 
     /**
      * Updates the value by distributing the specified increment among states according
      * to their respective time-in-state.
      */
-    void incrementValue(const T& increment, time_t timestamp);
+    void incrementValue(const V& increment, time_t timestamp);
 
     /**
      * Adds the specified increment to the value for the current state, without affecting
      * the last updated value or timestamp.  Ignores partial time-in-state: the entirety of
      * the increment is given to the current state.
      */
-    void addValue(const T& increment);
+    void addValue(const V& increment);
 
     void reset();
 
     uint16_t getStateCount();
 
-    const T& getCount(state_t state);
+    const V& getCount(state_t state);
 
     std::string toString();
 
@@ -104,27 +104,25 @@ private:
      * Returns true iff the combination of previousValue and newValue is valid
      * (newValue >= prevValue)
      */
-    bool delta(const T& previousValue, const T& newValue, T* outValue) const;
+    bool delta(const T& previousValue, const V& newValue, T* outValue) const;
 
     /**
      * Adds value2 to value1 and stores the result in value1.  Denominator is
      * guaranteed to be non-zero.
      */
-    void add(T* value1, const T& value2, const uint64_t numerator,
+    void add(T* value1, const V& value2, const uint64_t numerator,
              const uint64_t denominator) const;
-
-    std::string valueToString(const T& value) const;
 };
 
 // ---------------------- MultiStateCounter Implementation -------------------------
 // Since MultiStateCounter is a template, the implementation must be inlined.
 
-template <class T>
-MultiStateCounter<T>::MultiStateCounter(uint16_t stateCount, const T& emptyValue)
+template <class T, class V>
+MultiStateCounter<T, V>::MultiStateCounter(uint16_t stateCount, const V& emptyValue)
       : stateCount(stateCount),
+        emptyValue(emptyValue),
         currentState(0),
         lastStateChangeTimestamp(-1),
-        emptyValue(emptyValue),
         lastValue(emptyValue),
         lastUpdateTimestamp(-1),
         deltaValue(emptyValue),
@@ -136,13 +134,13 @@ MultiStateCounter<T>::MultiStateCounter(uint16_t stateCount, const T& emptyValue
     }
 }
 
-template <class T>
-MultiStateCounter<T>::~MultiStateCounter() {
+template <class T, class V>
+MultiStateCounter<T, V>::~MultiStateCounter() {
     delete[] states;
 };
 
-template <class T>
-void MultiStateCounter<T>::setEnabled(bool enabled, time_t timestamp) {
+template <class T, class V>
+void MultiStateCounter<T, V>::setEnabled(bool enabled, time_t timestamp) {
     if (enabled == isEnabled) {
         return;
     }
@@ -167,8 +165,8 @@ void MultiStateCounter<T>::setEnabled(bool enabled, time_t timestamp) {
     }
 }
 
-template <class T>
-void MultiStateCounter<T>::setState(state_t state, time_t timestamp) {
+template <class T, class V>
+void MultiStateCounter<T, V>::setState(state_t state, time_t timestamp) {
     if (isEnabled && lastStateChangeTimestamp >= 0 && lastUpdateTimestamp >= 0) {
         // If the update arrived out-of-order, just push back the timestamp to
         // avoid having the situation where timeInStateSinceUpdate > timeSinceUpdate
@@ -198,8 +196,8 @@ void MultiStateCounter<T>::setState(state_t state, time_t timestamp) {
     lastStateChangeTimestamp = timestamp;
 }
 
-template <class T>
-void MultiStateCounter<T>::copyStatesFrom(const MultiStateCounter<T>& source) {
+template <class T, class V>
+void MultiStateCounter<T, V>::copyStatesFrom(const MultiStateCounter<T, V>& source) {
     if (stateCount != source.stateCount) {
         ALOGE("State count mismatch: %u vs. %u\n", stateCount, source.stateCount);
         return;
@@ -214,14 +212,14 @@ void MultiStateCounter<T>::copyStatesFrom(const MultiStateCounter<T>& source) {
     lastUpdateTimestamp = source.lastUpdateTimestamp;
 }
 
-template <class T>
-void MultiStateCounter<T>::setValue(state_t state, const T& value) {
+template <class T, class V>
+void MultiStateCounter<T, V>::setValue(state_t state, const V& value) {
     states[state].counter = value;
 }
 
-template <class T>
-const T& MultiStateCounter<T>::updateValue(const T& value, time_t timestamp) {
-    T* returnValue = &emptyValue;
+template <class T, class V>
+const V& MultiStateCounter<T, V>::updateValue(const V& value, time_t timestamp) {
+    const V* returnValue = &emptyValue;
 
     // If the counter is disabled, we ignore the update, except when the counter got disabled after
     // the previous update, in which case we still need to pick up the residual delta.
@@ -250,8 +248,8 @@ const T& MultiStateCounter<T>::updateValue(const T& value, time_t timestamp) {
                     }
                 } else {
                     std::stringstream str;
-                    str << "updateValue is called with a value " << valueToString(value)
-                        << ", which is lower than the previous value " << valueToString(lastValue)
+                    str << "updateValue is called with a value " << value
+                        << ", which is lower than the previous value " << lastValue
                         << "\n";
                     ALOGE("%s", str.str().c_str());
 
@@ -276,23 +274,25 @@ const T& MultiStateCounter<T>::updateValue(const T& value, time_t timestamp) {
     return *returnValue;
 }
 
-template <class T>
-void MultiStateCounter<T>::incrementValue(const T& increment, time_t timestamp) {
+template <class T, class V>
+void MultiStateCounter<T, V>::incrementValue(const V& increment, time_t timestamp) {
+//    T newValue;
+//    newValue = lastValue; // Copy assignment, not initialization.
     T newValue = lastValue;
     add(&newValue, increment, 1 /* numerator */, 1 /* denominator */);
     updateValue(newValue, timestamp);
 }
 
-template <class T>
-void MultiStateCounter<T>::addValue(const T& value) {
+template <class T, class V>
+void MultiStateCounter<T, V>::addValue(const V& value) {
     if (!isEnabled) {
         return;
     }
     add(&states[currentState].counter, value, 1 /* numerator */, 1 /* denominator */);
 }
 
-template <class T>
-void MultiStateCounter<T>::reset() {
+template <class T, class V>
+void MultiStateCounter<T, V>::reset() {
     lastStateChangeTimestamp = -1;
     lastUpdateTimestamp = -1;
     for (int i = 0; i < stateCount; i++) {
@@ -301,25 +301,26 @@ void MultiStateCounter<T>::reset() {
     }
 }
 
-template <class T>
-uint16_t MultiStateCounter<T>::getStateCount() {
+template <class T, class V>
+uint16_t MultiStateCounter<T, V>::getStateCount() {
     return stateCount;
 }
 
-template <class T>
-const T& MultiStateCounter<T>::getCount(state_t state) {
+template <class T, class V>
+const V& MultiStateCounter<T, V>::getCount(state_t state) {
     return states[state].counter;
 }
 
-template <class T>
-std::string MultiStateCounter<T>::toString() {
+template <class T, class V>
+std::string MultiStateCounter<T, V>::toString() {
     std::stringstream str;
+//    str << "LAST VALUE: " << valueToString(lastValue);
     str << "[";
     for (int i = 0; i < stateCount; i++) {
         if (i != 0) {
             str << ", ";
         }
-        str << i << ": " << valueToString(states[i].counter);
+        str << i << ": " << states[i].counter;
         if (states[i].timeInStateSinceUpdate > 0) {
             str << " timeInStateSinceUpdate: " << states[i].timeInStateSinceUpdate;
         }
diff --git a/libs/battery/MultiStateCounterTest.cpp b/libs/battery/MultiStateCounterTest.cpp
index a51a38a6c7..589b7fe4e3 100644
--- a/libs/battery/MultiStateCounterTest.cpp
+++ b/libs/battery/MultiStateCounterTest.cpp
@@ -21,7 +21,7 @@
 namespace android {
 namespace battery {
 
-typedef MultiStateCounter<double> DoubleMultiStateCounter;
+typedef MultiStateCounter<double, double> DoubleMultiStateCounter;
 
 template <>
 bool DoubleMultiStateCounter::delta(const double& previousValue, const double& newValue,
@@ -41,11 +41,6 @@ void DoubleMultiStateCounter::add(double* value1, const double& value2, const ui
     }
 }
 
-template <>
-std::string DoubleMultiStateCounter::valueToString(const double& v) const {
-    return std::to_string(v);
-}
-
 class MultiStateCounterTest : public testing::Test {};
 
 TEST_F(MultiStateCounterTest, constructor) {