Merge "Using a list to store usage events" into pi-dev

am: 10b77a39a2

Change-Id: I92f83289bd5a10b0a17012c2fd993ade0033375e

core/java/android/app/usage/EventList.java

@@ -0,0 +1,106 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * 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.
+ */
+
+package android.app.usage;
+
+import java.util.ArrayList;
+
+/**
+ * A container to keep {@link UsageEvents.Event usage events} in non-descending order of their
+ * {@link UsageEvents.Event#mTimeStamp timestamps}.
+ *
+ * @hide
+ */
+public class EventList {
+
+    private final ArrayList<UsageEvents.Event> mEvents;
+
+    /**
+     * Create a new event list with default capacity
+     */
+    public EventList() {
+        mEvents = new ArrayList<>();
+    }
+
+    /**
+     * Returns the size of the list
+     * @return the number of events in the list
+     */
+    public int size() {
+        return mEvents.size();
+    }
+
+    /**
+     * Removes all events from the list
+     */
+    public void clear() {
+        mEvents.clear();
+    }
+
+    /**
+     * Returns the {@link UsageEvents.Event event} at the specified position in this list.
+     * @param index the index of the event to return, such that {@code 0 <= index < size()}
+     * @return The {@link UsageEvents.Event event} at position {@code index}
+     */
+    public UsageEvents.Event get(int index) {
+        return mEvents.get(index);
+    }
+
+    /**
+     * Inserts the given {@link UsageEvents.Event event} into the list while keeping the list sorted
+     * based on the event {@link UsageEvents.Event#mTimeStamp timestamps}.
+     *
+     * @param event The event to insert
+     */
+    public void insert(UsageEvents.Event event) {
+        final int size = mEvents.size();
+        // fast case: just append if this is the latest event
+        if (size == 0 || event.mTimeStamp >= mEvents.get(size - 1).mTimeStamp) {
+            mEvents.add(event);
+            return;
+        }
+        // To minimize number of elements being shifted, insert at the first occurrence of the next
+        // greatest timestamp in the list.
+        final int insertIndex = firstIndexOnOrAfter(event.mTimeStamp + 1);
+        mEvents.add(insertIndex, event);
+    }
+
+    /**
+     * Finds the index of the first event whose timestamp is greater than or equal to the given
+     * timestamp.
+     *
+     * @param timeStamp The timestamp for which to search the list.
+     * @return The smallest {@code index} for which {@code (get(index).mTimeStamp >= timeStamp)} is
+     * {@code true}, or {@link #size() size} if no such {@code index} exists.
+     */
+    public int firstIndexOnOrAfter(long timeStamp) {
+        final int size = mEvents.size();
+        int result = size;
+        int lo = 0;
+        int hi = size - 1;
+        while (lo <= hi) {
+            final int mid = (lo + hi) >>> 1;
+            final long midTimeStamp = mEvents.get(mid).mTimeStamp;
+            if (midTimeStamp >= timeStamp) {
+                hi = mid - 1;
+                result = mid;
+            } else {
+                lo = mid + 1;
+            }
+        }
+        return result;
+    }
+}

core/java/android/app/usage/TimeSparseArray.java

@@ -27,14 +27,12 @@ import android.util.Slog;
 public class TimeSparseArray<E> extends LongSparseArray<E> {
     private static final String TAG = TimeSparseArray.class.getSimpleName();
 
+    private boolean mWtfReported;
+
     public TimeSparseArray() {
         super();
     }
 
-    public TimeSparseArray(int initialCapacity) {
-        super(initialCapacity);
-    }
-
     /**
      * Finds the index of the first element whose timestamp is greater or equal to
      * the given time.
@@ -75,22 +73,16 @@ public class TimeSparseArray<E> extends LongSparseArray<E> {
     /**
      * {@inheritDoc}
      *
-     * Overridden to ensure no collisions. The key (time in milliseconds) is incremented till an
-     * empty place is found.
+     * <p> As this container is being used only to keep {@link android.util.AtomicFile files},
+     * there should not be any collisions. Reporting a {@link Slog#wtf(String, String)} in case that
+     * happens, as that will lead to one whole file being dropped.
      */
     @Override
     public void put(long key, E value) {
-        final long origKey = key;
-        int keyIndex = indexOfKey(key);
-        if (keyIndex >= 0) {
-            final long sz = size();
-            while (keyIndex < sz && keyAt(keyIndex) == key) {
-                key++;
-                keyIndex++;
-            }
-            if (key >= origKey + 100) {
-                Slog.w(TAG, "Value " + value + " supposed to be inserted at " + origKey
-                        + " displaced to " + key);
+        if (indexOfKey(key) >= 0) {
+            if (!mWtfReported) {
+                Slog.wtf(TAG, "Overwriting value " + get(key) + " by " + value);
+                mWtfReported = true;
             }
         }
         super.put(key, value);