[Catalyst] Provide AbstractKeyedDataObservable (29082769) · Commits · e / os / android_frameworks_base

packages/SettingsLib/DataStore/src/com/android/settingslib/datastore/KeyedObserver.kt

+60 −1

Original line number	Diff line number	Diff line
		@@ -22,6 +22,7 @@ import androidx.collection.MutableScatterMap
		import com.google.errorprone.annotations.CanIgnoreReturnValue
		import java.util.WeakHashMap
		import java.util.concurrent.Executor
		import java.util.concurrent.atomic.AtomicInteger

		/**
		* Callback to be informed of changes in [KeyedObservable] object.
		@@ -203,13 +204,71 @@ open class KeyedDataObservable<K> : KeyedObservable<K> {
		}
		}

		fun hasAnyObserver(): Boolean {
		open fun hasAnyObserver(): Boolean {
		synchronized(observers) { if (observers.isNotEmpty()) return true }
		synchronized(keyedObservers) { if (keyedObservers.isNotEmpty()) return true }
		return false
		}
		}

		/** [KeyedDataObservable] that maintains a counter for the observers. */
		abstract class AbstractKeyedDataObservable<K> : KeyedDataObservable<K>() {
		/**
		* Counter of observers.
		*
		* The value is accurate only when [addObserver] and [removeObserver] are invoked in pairs.
		*/
		private val counter = AtomicInteger()

		override fun addObserver(observer: KeyedObserver<K?>, executor: Executor) =
		if (super.addObserver(observer, executor)) {
		onObserverAdded()
		true
		} else {
		false
		}

		override fun addObserver(key: K, observer: KeyedObserver<K>, executor: Executor) =
		if (super.addObserver(key, observer, executor)) {
		onObserverAdded()
		true
		} else {
		false
		}

		private fun onObserverAdded() {
		if (counter.getAndIncrement() == 0) onFirstObserverAdded()
		}

		/** Callbacks when the first observer is just added. */
		protected abstract fun onFirstObserverAdded()

		override fun removeObserver(observer: KeyedObserver<K?>) =
		if (super.removeObserver(observer)) {
		onObserverRemoved()
		true
		} else {
		false
		}

		override fun removeObserver(key: K, observer: KeyedObserver<K>) =
		if (super.removeObserver(key, observer)) {
		onObserverRemoved()
		true
		} else {
		false
		}

		private fun onObserverRemoved() {
		if (counter.decrementAndGet() == 0) onLastObserverRemoved()
		}

		/** Callbacks when the last observer is just removed. */
		protected abstract fun onLastObserverRemoved()

		override fun hasAnyObserver() = counter.get() > 0
		}

		/** [KeyedObservable] with no-op implementations for all interfaces. */
		open class NoOpKeyedObservable<K> : KeyedObservable<K> {

packages/SettingsLib/DataStore/src/com/android/settingslib/datastore/SettingsStore.kt

+5 −50

Original line number	Diff line number	Diff line
		@@ -20,21 +20,10 @@ import android.content.ContentResolver
		import android.database.ContentObserver
		import android.net.Uri
		import android.util.Log
		import java.util.concurrent.Executor
		import java.util.concurrent.atomic.AtomicInteger

		/** Base class of the Settings provider data stores. */
		abstract class SettingsStore(protected val contentResolver: ContentResolver) :
		KeyedDataObservable<String>(), KeyValueStore {

		/**
		* Counter of observers.
		*
		* The value is accurate only when [addObserver] and [removeObserver] are called correctly. When
		* an observer is not removed (and its weak reference is garbage collected), the content
		* observer is not unregistered but this is not a big deal.
		*/
		private val counter = AtomicInteger()
		AbstractKeyedDataObservable<String>(), KeyValueStore {

		private val contentObserver =
		object : ContentObserver(HandlerExecutor.main) {
		@@ -48,49 +37,15 @@ abstract class SettingsStore(protected val contentResolver: ContentResolver) :
		}
		}

		override fun addObserver(observer: KeyedObserver<String?>, executor: Executor) =
		if (super.addObserver(observer, executor)) {
		onObserverAdded()
		true
		} else {
		false
		}

		override fun addObserver(key: String, observer: KeyedObserver<String>, executor: Executor) =
		if (super.addObserver(key, observer, executor)) {
		onObserverAdded()
		true
		} else {
		false
		}

		private fun onObserverAdded() {
		if (counter.getAndIncrement() != 0) return
		Log.i(tag, "registerContentObserver")
		contentResolver.registerContentObserver(uri, true, contentObserver)
		}

		/** The URI to watch for any key change. */
		protected abstract val uri: Uri

		override fun removeObserver(observer: KeyedObserver<String?>) =
		if (super.removeObserver(observer)) {
		onObserverRemoved()
		true
		} else {
		false
		}

		override fun removeObserver(key: String, observer: KeyedObserver<String>) =
		if (super.removeObserver(key, observer)) {
		onObserverRemoved()
		true
		} else {
		false
		override fun onFirstObserverAdded() {
		Log.i(tag, "registerContentObserver")
		contentResolver.registerContentObserver(uri, true, contentObserver)
		}

		private fun onObserverRemoved() {
		if (counter.decrementAndGet() != 0) return
		override fun onLastObserverRemoved() {
		Log.i(tag, "unregisterContentObserver")
		contentResolver.unregisterContentObserver(contentObserver)
		}