Watcher/Watchable classes for PackageManagerService (1c22ad15) · Commits · e / os / android_frameworks_base

services/core/java/com/android/server/utils/Watchable.java

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		/*
		* 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;

		/**
		* Notify registered {@link Watcher}s when the content changes.
		*/
		public interface Watchable {

		/**
		* Ensures an observer is in the list, exactly once. The observer cannot be null. The
		* function quietly returns if the observer is already in the list.
		*
		* @param observer The {@link Watcher} to be notified when the {@link Watchable} changes.
		*/
		public void registerObserver(@NonNull Watcher observer);

		/**
		* Ensures an observer is not in the list. The observer must not be null. The function
		* quietly returns if the objserver is not in the list.
		*
		* @param observer The {@link Watcher} that should not be in the notification list.
		*/
		public void unregisterObserver(@NonNull Watcher observer);

		/**
		* Invokes {@link Watcher#onChange} on each registered observer. The method can be called
		* with the {@link Watchable} that generated the event. In a tree of {@link Watchable}s, this
		* is generally the first (deepest) {@link Watchable} to detect a change.
		*
		* @param what The {@link Watchable} that generated the event.
		*/
		public void dispatchChange(@Nullable Watchable what);
		}

services/core/java/com/android/server/utils/WatchableImpl.java

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		/*
		* 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 java.util.ArrayList;
		import java.util.Objects;

		/**
		* A concrete implementation of {@link Watchable}
		*/
		public class WatchableImpl implements Watchable {
		/**
		* The list of observers.
		*/
		protected final ArrayList<Watcher> mObservers = new ArrayList<>();

		/**
		* Ensure the observer is the list. The observer cannot be null but it is okay if it
		* is already in the list.
		*
		* @param observer The {@link} Watcher to be added to the notification list.
		*/
		@Override
		public void registerObserver(@NonNull Watcher observer) {
		Objects.requireNonNull(observer, "observer may not be null");
		synchronized (mObservers) {
		if (!mObservers.contains(observer)) {
		mObservers.add(observer);
		}
		}
		}

		/**
		* Removes a previously registered observer. The observer must not be null and it
		* must already have been registered.
		*
		* @param observer The {@link} Watcher to be removed from the notification list.
		*/
		@Override
		public void unregisterObserver(@NonNull Watcher observer) {
		Objects.requireNonNull(observer, "observer may not be null");
		synchronized (mObservers) {
		mObservers.remove(observer);
		}
		}

		/**
		* Return the number of registered observers.
		*
		* @return The number of registered observers.
		*/
		public int registeredObserverCount() {
		return mObservers.size();
		}

		/**
		* Invokes {@link Watcher#onChange} on each observer.
		*
		* @param what The {@link Watchable} that generated the event
		*/
		@Override
		public void dispatchChange(@Nullable Watchable what) {
		synchronized (mObservers) {
		final int end = mObservers.size();
		for (int i = 0; i < end; i++) {
		mObservers.get(i).onChange(what);
		}
		}
		}
		}

services/core/java/com/android/server/utils/WatchedArrayMap.java

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		/*
		* 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.ArrayMap;
		import android.util.Log;

		import java.util.Collection;
		import java.util.Collections;
		import java.util.Map;
		import java.util.Set;

		/**
		* WatchedArrayMap is an {@link android.util.ArrayMap} that can report changes to itself. If its
		* values are {@link Watchable} then the WatchedArrayMap will also report changes to the values.
		* A {@link Watchable} is notified only once, no matter how many times it is stored in the array.
		*/
		public class WatchedArrayMap<K, V> extends WatchableImpl implements Map<K, V> {

		// The storage
		private final ArrayMap<K, V> mStorage;

		// If true, the array is watching its children
		private boolean mWatching = false;

		// The local observer
		private final Watcher mObserver = new Watcher() {
		@Override
		public void onChange(@Nullable Watchable what) {
		WatchedArrayMap.this.dispatchChange(what);
		}
		};

		/**
		* A convenience function called when the elements are added to or removed from the storage.
		* The watchable is always {@link this}.
		*/
		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. Also note that if this is called with the same object
		* twice, <this> is only registered once.
		*/
		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. This unconditionally removes the object from the
		* registered list.
		*/
		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 there are no other instances of this object in
		* the storage. Note that the watching flag must be true if this function is to
		* succeed. The object must already have been removed from the storage before this
		* method is called.
		*/
		private void unregisterChildIf(Object o) {
		if (mWatching && o instanceof Watchable) {
		if (!mStorage.containsValue(o)) {
		((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;
		}
		}

		/**
		* Create a new empty {@link WatchedArrayMap}. The default capacity of an array map
		* is 0, and will grow once items are added to it.
		*/
		public WatchedArrayMap() {
		this(0, false);
		}

		/**
		* Create a new {@link WatchedArrayMap} with a given initial capacity.
		*/
		public WatchedArrayMap(int capacity) {
		this(capacity, false);
		}

		/** {@hide} */
		public WatchedArrayMap(int capacity, boolean identityHashCode) {
		mStorage = new ArrayMap<K, V>(capacity, identityHashCode);
		}

		/**
		* Create a new {@link WatchedArrayMap} with the mappings from the given {@link Map}.
		*/
		public WatchedArrayMap(@Nullable Map<? extends K, ? extends V> map) {
		mStorage = new ArrayMap<K, V>();
		if (map != null) {
		putAll(map);
		}
		}

		/**
		* Return the underlying storage. This breaks the wrapper but is necessary when
		* passing the array to distant methods.
		*/
		public ArrayMap untrackedMap() {
		return mStorage;
		}

		/**
		* {@inheritDoc}
		*/
		@Override
		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();
		}

		/**
		* {@inheritDoc}
		*/
		@Override
		public boolean containsKey(Object key) {
		return mStorage.containsKey(key);
		}

		/**
		* {@inheritDoc}
		*/
		@Override
		public boolean containsValue(Object value) {
		return mStorage.containsValue(value);
		}

		/**
		* {@inheritDoc}
		*/
		@Override
		public Set<Map.Entry<K, V>> entrySet() {
		return Collections.unmodifiableSet(mStorage.entrySet());
		}

		/**
		* {@inheritDoc}
		*/
		@Override
		public boolean equals(Object o) {
		if (o instanceof WatchedArrayMap) {
		WatchedArrayMap w = (WatchedArrayMap) o;
		return mStorage.equals(w.mStorage);
		} else {
		return false;
		}
		}

		/**
		* {@inheritDoc}
		*/
		@Override
		public V get(Object key) {
		return mStorage.get(key);
		}

		/**
		* {@inheritDoc}
		*/
		@Override
		public int hashCode() {
		return mStorage.hashCode();
		}

		/**
		* {@inheritDoc}
		*/
		@Override
		public boolean isEmpty() {
		return mStorage.isEmpty();
		}

		/**
		* {@inheritDoc}
		*/
		@Override
		public Set<K> keySet() {
		return Collections.unmodifiableSet(mStorage.keySet());
		}

		/**
		* {@inheritDoc}
		*/
		@Override
		public V put(K key, V value) {
		final V result = mStorage.put(key, value);
		registerChild(value);
		onChanged();
		return result;
		}

		/**
		* {@inheritDoc}
		*/
		@Override
		public void putAll(@NonNull Map<? extends K, ? extends V> map) {
		for (Map.Entry<? extends K, ? extends V> element : map.entrySet()) {
		put(element.getKey(), element.getValue());
		}
		}

		/**
		* {@inheritDoc}
		*/
		@Override
		public V remove(@NonNull Object key) {
		final V result = mStorage.remove(key);
		unregisterChildIf(result);
		onChanged();
		return result;
		}

		/**
		* {@inheritDoc}
		*/
		@Override
		public int size() {
		return mStorage.size();
		}

		/**
		* {@inheritDoc}
		*/
		@Override
		public Collection<V> values() {
		return Collections.unmodifiableCollection(mStorage.values());
		}

		// Methods supported by ArrayMap that are not part of Map

		/**
		* Return the key at the given index in the array.
		*
		* <p>For indices outside of the range <code>0...size()-1</code>, an
		* {@link ArrayIndexOutOfBoundsException} is thrown.</p>
		*
		* @param index The desired index, must be between 0 and {@link #size()}-1.
		* @return Returns the key stored at the given index.
		*/
		public K keyAt(int index) {
		return mStorage.keyAt(index);
		}

		/**
		* Return the value at the given index in the array.
		*
		* <p>For indices outside of the range <code>0...size()-1</code>, an
		* {@link ArrayIndexOutOfBoundsException} is thrown.</p>
		*
		* @param index The desired index, must be between 0 and {@link #size()}-1.
		* @return Returns the value stored at the given index.
		*/
		public V valueAt(int index) {
		return mStorage.valueAt(index);
		}

		/**
		* Remove an existing key from the array map.
		* @param key The key of the mapping to remove.
		* @return Returns the value that was stored under the key, or null if there
		* was no such key.
		*/
		public int indexOfKey(K 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.
		* 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.
		*/
		public int indexOfValue(V value) {
		return mStorage.indexOfValue(value);
		}

		/**
		* Set the value at a given index in the array.
		*
		* <p>For indices outside of the range <code>0...size()-1</code>, an
		* {@link ArrayIndexOutOfBoundsException} is thrown.</p>
		*
		* @param index The desired index, must be between 0 and {@link #size()}-1.
		* @param value The new value to store at this index.
		* @return Returns the previous value at the given index.
		*/
		public V setValueAt(int index, V value) {
		final V result = mStorage.setValueAt(index, value);
		if (value != result) {
		unregisterChildIf(result);
		registerChild(value);
		onChanged();
		}
		return result;
		}

		/**
		* Remove the key/value mapping at the given index.
		*
		* <p>For indices outside of the range <code>0...size()-1</code>, an
		* {@link ArrayIndexOutOfBoundsException} is thrown.</p>
		*
		* @param index The desired index, must be between 0 and {@link #size()}-1.
		* @return Returns the value that was stored at this index.
		*/
		public V removeAt(int index) {
		final V result = mStorage.removeAt(index);
		unregisterChildIf(result);
		onChanged();
		return result;
		}
		}

services/core/java/com/android/server/utils/WatchedSparseArray.java

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services/core/java/com/android/server/utils/WatchedSparseBooleanArray.java

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		/*
		* 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.SparseBooleanArray;

		/**
		* A watched variant of SparseBooleanArray. Changes to the array are notified to
		* registered {@link Watcher}s.
		*/
		public class WatchedSparseBooleanArray extends WatchableImpl {

		// The storage
		private final SparseBooleanArray mStorage;

		// A private convenience function
		private void dispatchChange() {
		dispatchChange(this);
		}

		/**
		* Creates a new WatchedSparseBooleanArray containing no mappings.
		*/
		public WatchedSparseBooleanArray() {
		mStorage = new SparseBooleanArray();
		}

		/**
		* Creates a new WatchedSparseBooleanArray 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 WatchedSparseBooleanArray(int initialCapacity) {
		mStorage = new SparseBooleanArray(initialCapacity);
		}

		/**
		* The copy constructor does not copy the watcher data.
		*/
		public WatchedSparseBooleanArray(@NonNull WatchedSparseBooleanArray r) {
		mStorage = r.mStorage.clone();
		}

		/**
		* Gets the boolean mapped from the specified key, or <code>false</code>
		* if no such mapping has been made.
		*/
		public boolean get(int key) {
		return mStorage.get(key);
		}

		/**
		* Gets the boolean mapped from the specified key, or the specified value
		* if no such mapping has been made.
		*/
		public boolean get(int key, boolean valueIfKeyNotFound) {
		return mStorage.get(key, valueIfKeyNotFound);
		}

		/**
		* Removes the mapping from the specified key, if there was any.
		*/
		public void delete(int key) {
		mStorage.delete(key);
		dispatchChange();
		}

		/**
		* Removes the mapping at the specified index.
		* <p>
		* For indices outside of the range {@code 0...size()-1}, the behavior is undefined.
		*/
		public void removeAt(int index) {
		mStorage.removeAt(index);
		dispatchChange();
		}

		/**
		* 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, boolean value) {
		if (mStorage.get(key) != value) {
		mStorage.put(key, value);
		dispatchChange();
		}
		}

		/**
		* Returns the number of key-value mappings that this SparseBooleanArray
		* 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
		* SparseBooleanArray 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
		* SparseBooleanArray 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 boolean valueAt(int index) {
		return mStorage.valueAt(index);
		}

		/**
		* Directly set the value at a particular index.
		*
		* <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, boolean value) {
		if (mStorage.valueAt(index) != value) {
		mStorage.setValueAt(index, value);
		dispatchChange();
		}
		}

		/** @hide */
		public void setKeyAt(int index, int key) {
		if (mStorage.keyAt(index) != key) {
		mStorage.setKeyAt(index, key);
		dispatchChange();
		}
		}

		/**
		* 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 key, or a negative number if no keys map to the
		* specified value.
		* 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.
		*/
		public int indexOfValue(boolean value) {
		return mStorage.indexOfValue(value);
		}

		/**
		* Removes all key-value mappings from this SparseBooleanArray.
		*/
		public void clear() {
		mStorage.clear();
		dispatchChange();
		}

		/**
		* 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, boolean value) {
		mStorage.append(key, value);
		dispatchChange();
		}

		@Override
		public int hashCode() {
		return mStorage.hashCode();
		}

		@Override
		public boolean equals(Object that) {
		return this == that \|\| mStorage.equals(that);
		}

		/**
		* {@inheritDoc}
		*
		* <p>This implementation composes a string by iterating over its mappings.
		*/
		@Override
		public String toString() {
		return mStorage.toString();
		}
		}