| /* |
| * Copyright (C) 2020 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 com.android.server.utils; |
| |
| import android.annotation.NonNull; |
| import android.annotation.Nullable; |
| import android.util.SparseArray; |
| |
| import java.util.ArrayList; |
| |
| /** |
| * A watched variant of SparseArray. If a {@link Watchable} is stored in the array, the |
| * array registers with the {@link Watchable}. The array registers only once with each |
| * {@link Watchable} no matter how many times the {@link Watchable} is stored in the |
| * array. |
| * @param <E> The element type, stored in the array. |
| */ |
| public class WatchedSparseArray<E> extends WatchableImpl |
| implements Snappable { |
| |
| // The storage |
| private final SparseArray<E> mStorage; |
| |
| // If true, the array is watching its children |
| private volatile boolean mWatching = false; |
| |
| // The local observer |
| private final Watcher mObserver = new Watcher() { |
| @Override |
| public void onChange(@Nullable Watchable o) { |
| WatchedSparseArray.this.dispatchChange(o); |
| } |
| }; |
| |
| /** |
| * A private convenience function that notifies registered listeners that an element |
| * has been added to or removed from the array. The what parameter is the array itself. |
| */ |
| private void onChanged() { |
| dispatchChange(this); |
| } |
| |
| /** |
| * A convenience function. Register the object if it is {@link Watchable} and if the |
| * array is currently watching. Note that the watching flag must be true if this |
| * function is to succeed. |
| */ |
| private void registerChild(Object o) { |
| if (mWatching && o instanceof Watchable) { |
| ((Watchable) o).registerObserver(mObserver); |
| } |
| } |
| |
| /** |
| * A convenience function. Unregister the object if it is {@link Watchable} and if |
| * the array is currently watching. Note that the watching flag must be true if this |
| * function is to succeed. |
| */ |
| private void unregisterChild(Object o) { |
| if (mWatching && o instanceof Watchable) { |
| ((Watchable) o).unregisterObserver(mObserver); |
| } |
| } |
| |
| /** |
| * A convenience function. Unregister the object if it is {@link Watchable}, if the array is |
| * currently watching, and if the storage does not contain the object. Note that the watching |
| * flag must be true if this function is to succeed. This must be called after an object has |
| * been removed from the storage. |
| */ |
| private void unregisterChildIf(Object o) { |
| if (mWatching && o instanceof Watchable) { |
| if (mStorage.indexOfValue((E) o) == -1) { |
| ((Watchable) o).unregisterObserver(mObserver); |
| } |
| } |
| } |
| |
| /** |
| * Register a {@link Watcher} with the array. If this is the first Watcher than any |
| * array values that are {@link Watchable} are registered to the array itself. |
| */ |
| @Override |
| public void registerObserver(@NonNull Watcher observer) { |
| super.registerObserver(observer); |
| if (registeredObserverCount() == 1) { |
| // The watching flag must be set true before any children are registered. |
| mWatching = true; |
| final int end = mStorage.size(); |
| for (int i = 0; i < end; i++) { |
| registerChild(mStorage.valueAt(i)); |
| } |
| } |
| } |
| |
| /** |
| * Unregister a {@link Watcher} from the array. If this is the last Watcher than any |
| * array values that are {@link Watchable} are unregistered to the array itself. |
| */ |
| @Override |
| public void unregisterObserver(@NonNull Watcher observer) { |
| super.unregisterObserver(observer); |
| if (registeredObserverCount() == 0) { |
| final int end = mStorage.size(); |
| for (int i = 0; i < end; i++) { |
| unregisterChild(mStorage.valueAt(i)); |
| } |
| // The watching flag must be true while children are unregistered. |
| mWatching = false; |
| } |
| } |
| |
| /** |
| * Creates a new WatchedSparseArray containing no mappings. |
| */ |
| public WatchedSparseArray() { |
| mStorage = new SparseArray(); |
| } |
| |
| /** |
| * Creates a new WatchedSparseArray containing no mappings that |
| * will not require any additional memory allocation to store the |
| * specified number of mappings. If you supply an initial capacity of |
| * 0, the sparse array will be initialized with a light-weight |
| * representation not requiring any additional array allocations. |
| */ |
| public WatchedSparseArray(int initialCapacity) { |
| mStorage = new SparseArray(initialCapacity); |
| } |
| |
| /** |
| * Create a {@link WatchedSparseArray} from a {@link SparseArray} |
| */ |
| public WatchedSparseArray(@NonNull SparseArray<E> c) { |
| mStorage = c.clone(); |
| } |
| |
| /** |
| * The copy constructor does not copy the watcher data. |
| */ |
| public WatchedSparseArray(@NonNull WatchedSparseArray<E> r) { |
| mStorage = r.mStorage.clone(); |
| } |
| |
| /** |
| * Make <this> a copy of src. Any data in <this> is discarded. |
| */ |
| public void copyFrom(@NonNull SparseArray<E> src) { |
| clear(); |
| final int end = src.size(); |
| for (int i = 0; i < end; i++) { |
| put(src.keyAt(i), src.valueAt(i)); |
| } |
| } |
| |
| /** |
| * Make dst a copy of <this>. Any previous data in dst is discarded. |
| */ |
| public void copyTo(@NonNull SparseArray<E> dst) { |
| dst.clear(); |
| final int end = size(); |
| for (int i = 0; i < end; i++) { |
| dst.put(keyAt(i), valueAt(i)); |
| } |
| } |
| |
| /** |
| * Return the underlying storage. This breaks the wrapper but is necessary when |
| * passing the array to distant methods. |
| */ |
| public SparseArray<E> untrackedStorage() { |
| return mStorage; |
| } |
| |
| /** |
| * Returns true if the key exists in the array. This is equivalent to |
| * {@link #indexOfKey(int)} >= 0. |
| * |
| * @param key Potential key in the mapping |
| * @return true if the key is defined in the mapping |
| */ |
| public boolean contains(int key) { |
| return mStorage.contains(key); |
| } |
| |
| /** |
| * Gets the Object mapped from the specified key, or <code>null</code> |
| * if no such mapping has been made. |
| */ |
| public E get(int key) { |
| return mStorage.get(key); |
| } |
| |
| /** |
| * Gets the Object mapped from the specified key, or the specified Object |
| * if no such mapping has been made. |
| */ |
| public E get(int key, E valueIfKeyNotFound) { |
| return mStorage.get(key, valueIfKeyNotFound); |
| } |
| |
| /** |
| * Removes the mapping from the specified key, if there was any. |
| */ |
| public void delete(int key) { |
| final E child = mStorage.get(key); |
| mStorage.delete(key); |
| unregisterChildIf(child); |
| onChanged(); |
| } |
| |
| /** |
| * @hide |
| * Removes the mapping from the specified key, if there was any, returning the old value. |
| */ |
| public E removeReturnOld(int key) { |
| final E result = mStorage.removeReturnOld(key); |
| unregisterChildIf(result); |
| return result; |
| } |
| |
| /** |
| * Alias for {@link #delete(int)}. |
| */ |
| public void remove(int key) { |
| delete(key); |
| } |
| |
| /** |
| * Removes the mapping at the specified index. |
| * |
| * <p>For indices outside of the range <code>0...size()-1</code>, an |
| * {@link ArrayIndexOutOfBoundsException} is thrown.</p> |
| */ |
| public void removeAt(int index) { |
| final E child = mStorage.valueAt(index); |
| mStorage.removeAt(index); |
| unregisterChildIf(child); |
| onChanged(); |
| } |
| |
| /** |
| * Remove a range of mappings as a batch. |
| * |
| * @param index Index to begin at |
| * @param size Number of mappings to remove |
| * |
| * <p>For indices outside of the range <code>0...size()-1</code>, |
| * the behavior is undefined.</p> |
| */ |
| public void removeAtRange(int index, int size) { |
| final ArrayList<E> children = new ArrayList<>(); |
| try { |
| for (int i = 0; i < size; i++) { |
| children.add(mStorage.valueAt(i + index)); |
| } |
| } catch (Exception e) { |
| // Ignore any exception and proceed with removal. |
| } |
| try { |
| mStorage.removeAtRange(index, size); |
| } finally { |
| // Even on exception, make sure to deregister children that have been |
| // removed. |
| for (int i = 0; i < size; i++) { |
| unregisterChildIf(children.get(i)); |
| } |
| } |
| onChanged(); |
| } |
| |
| /** |
| * Adds a mapping from the specified key to the specified value, |
| * replacing the previous mapping from the specified key if there |
| * was one. |
| */ |
| public void put(int key, E value) { |
| final E old = mStorage.get(key); |
| mStorage.put(key, value); |
| unregisterChildIf(old); |
| registerChild(value); |
| onChanged(); |
| } |
| |
| /** |
| * Returns the number of key-value mappings that this SparseArray |
| * currently stores. |
| */ |
| public int size() { |
| return mStorage.size(); |
| } |
| |
| /** |
| * Given an index in the range <code>0...size()-1</code>, returns |
| * the key from the <code>index</code>th key-value mapping that this |
| * SparseArray stores. |
| * |
| * <p>The keys corresponding to indices in ascending order are guaranteed to |
| * be in ascending order, e.g., <code>keyAt(0)</code> will return the |
| * smallest key and <code>keyAt(size()-1)</code> will return the largest |
| * key.</p> |
| * |
| * <p>For indices outside of the range <code>0...size()-1</code>, |
| * the behavior is undefined for apps targeting {@link android.os.Build.VERSION_CODES#P} and |
| * earlier, and an {@link ArrayIndexOutOfBoundsException} is thrown for apps targeting |
| * {@link android.os.Build.VERSION_CODES#Q} and later.</p> |
| */ |
| public int keyAt(int index) { |
| return mStorage.keyAt(index); |
| } |
| |
| /** |
| * Given an index in the range <code>0...size()-1</code>, returns |
| * the value from the <code>index</code>th key-value mapping that this |
| * SparseArray stores. |
| * |
| * <p>The values corresponding to indices in ascending order are guaranteed |
| * to be associated with keys in ascending order, e.g., |
| * <code>valueAt(0)</code> will return the value associated with the |
| * smallest key and <code>valueAt(size()-1)</code> will return the value |
| * associated with the largest key.</p> |
| * |
| * <p>For indices outside of the range <code>0...size()-1</code>, |
| * the behavior is undefined for apps targeting {@link android.os.Build.VERSION_CODES#P} and |
| * earlier, and an {@link ArrayIndexOutOfBoundsException} is thrown for apps targeting |
| * {@link android.os.Build.VERSION_CODES#Q} and later.</p> |
| */ |
| public E valueAt(int index) { |
| return mStorage.valueAt(index); |
| } |
| |
| /** |
| * Given an index in the range <code>0...size()-1</code>, sets a new |
| * value for the <code>index</code>th key-value mapping that this |
| * SparseArray stores. |
| * |
| * <p>For indices outside of the range <code>0...size()-1</code>, the behavior is undefined for |
| * apps targeting {@link android.os.Build.VERSION_CODES#P} and earlier, and an |
| * {@link ArrayIndexOutOfBoundsException} is thrown for apps targeting |
| * {@link android.os.Build.VERSION_CODES#Q} and later.</p> |
| */ |
| public void setValueAt(int index, E value) { |
| final E old = mStorage.valueAt(index); |
| mStorage.setValueAt(index, value); |
| if (value != old) { |
| unregisterChildIf(old); |
| registerChild(value); |
| onChanged(); |
| } |
| } |
| |
| /** |
| * Returns the index for which {@link #keyAt} would return the |
| * specified key, or a negative number if the specified |
| * key is not mapped. |
| */ |
| public int indexOfKey(int key) { |
| return mStorage.indexOfKey(key); |
| } |
| |
| /** |
| * Returns an index for which {@link #valueAt} would return the |
| * specified value, or a negative number if no keys map to the |
| * specified value. |
| * <p>Beware that this is a linear search, unlike lookups by key, |
| * and that multiple keys can map to the same value and this will |
| * find only one of them. |
| * <p>Note also that unlike most collections' {@code indexOf} methods, |
| * this method compares values using {@code ==} rather than {@code equals}. |
| */ |
| public int indexOfValue(E value) { |
| return mStorage.indexOfValue(value); |
| } |
| |
| /** |
| * Returns an index for which {@link #valueAt} would return the |
| * specified value, or a negative number if no keys map to the |
| * specified value. |
| * <p>Beware that this is a linear search, unlike lookups by key, |
| * and that multiple keys can map to the same value and this will |
| * find only one of them. |
| * <p>Note also that this method uses {@code equals} unlike {@code indexOfValue}. |
| * @hide |
| */ |
| public int indexOfValueByValue(E value) { |
| return mStorage.indexOfValueByValue(value); |
| } |
| |
| /** |
| * Removes all key-value mappings from this SparseArray. |
| */ |
| public void clear() { |
| // The storage cannot be simply cleared. Each element in the storage must be |
| // unregistered. Deregistration is only needed if the array is actually |
| // watching. |
| if (mWatching) { |
| final int end = mStorage.size(); |
| for (int i = 0; i < end; i++) { |
| unregisterChild(mStorage.valueAt(i)); |
| } |
| } |
| mStorage.clear(); |
| onChanged(); |
| } |
| |
| /** |
| * Puts a key/value pair into the array, optimizing for the case where |
| * the key is greater than all existing keys in the array. |
| */ |
| public void append(int key, E value) { |
| mStorage.append(key, value); |
| registerChild(value); |
| onChanged(); |
| } |
| |
| @Override |
| public int hashCode() { |
| return mStorage.hashCode(); |
| } |
| |
| @Override |
| public boolean equals(@Nullable Object o) { |
| if (o instanceof WatchedSparseArray) { |
| WatchedSparseArray w = (WatchedSparseArray) o; |
| return mStorage.equals(w.mStorage); |
| } else { |
| return false; |
| } |
| } |
| |
| /** |
| * <p>This implementation composes a string by iterating over its mappings. If |
| * this map contains itself as a value, the string "(this Map)" |
| * will appear in its place. |
| */ |
| @Override |
| public String toString() { |
| return mStorage.toString(); |
| } |
| |
| /** |
| * Create a copy of the array. If the element is a subclass of Snapper then the copy |
| * contains snapshots of the elements. Otherwise the copy contains references to the |
| * elements. The returned snapshot is immutable. |
| * @return A new array whose elements are the elements of <this>. |
| */ |
| public WatchedSparseArray<E> snapshot() { |
| WatchedSparseArray<E> l = new WatchedSparseArray<>(size()); |
| snapshot(l, this); |
| return l; |
| } |
| |
| /** |
| * Make <this> a snapshot of the argument. Note that <this> is immutable when the |
| * method returns. <this> must be empty when the function is called. |
| * @param r The source array, which is copied into <this> |
| */ |
| public void snapshot(@NonNull WatchedSparseArray<E> r) { |
| snapshot(this, r); |
| } |
| |
| /** |
| * Make the destination a copy of the source. If the element is a subclass of Snapper then the |
| * copy contains snapshots of the elements. Otherwise the copy contains references to the |
| * elements. The destination must be initially empty. Upon return, the destination is |
| * immutable. |
| * @param dst The destination array. It must be empty. |
| * @param src The source array. It is not modified. |
| */ |
| public static <E> void snapshot(@NonNull WatchedSparseArray<E> dst, |
| @NonNull WatchedSparseArray<E> src) { |
| if (dst.size() != 0) { |
| throw new IllegalArgumentException("snapshot destination is not empty"); |
| } |
| final int end = src.size(); |
| for (int i = 0; i < end; i++) { |
| final E val = Snapshots.maybeSnapshot(src.valueAt(i)); |
| final int key = src.keyAt(i); |
| dst.put(key, val); |
| } |
| dst.seal(); |
| } |
| |
| } |