Add support for lazy conditions (b0e25804) · Commits · e / os / android_frameworks_base

packages/SystemUI/shared/src/com/android/systemui/shared/condition/CombinedCondition.kt

+162 −10

Original line number	Diff line number	Diff line
		@@ -16,27 +16,179 @@

		package com.android.systemui.shared.condition

		import kotlinx.coroutines.CoroutineScope
		import kotlinx.coroutines.ExperimentalCoroutinesApi
		import kotlinx.coroutines.Job
		import kotlinx.coroutines.channels.awaitClose
		import kotlinx.coroutines.flow.Flow
		import kotlinx.coroutines.flow.callbackFlow
		import kotlinx.coroutines.flow.distinctUntilChanged
		import kotlinx.coroutines.flow.flatMapLatest
		import kotlinx.coroutines.flow.flowOf
		import kotlinx.coroutines.launch

		/**
		* A higher order [Condition] which combines multiple conditions with a specified
		* [Evaluator.ConditionOperand].
		* [Evaluator.ConditionOperand]. Conditions are executed lazily as-needed.
		*
		* @param scope The [CoroutineScope] to execute in.
		* @param conditions The list of conditions to evaluate. Since conditions are executed lazily, the
		* ordering is important here.
		* @param operand The [Evaluator.ConditionOperand] to apply to the conditions.
		*/
		internal class CombinedCondition
		@OptIn(ExperimentalCoroutinesApi::class)
		class CombinedCondition
		constructor(
		private val scope: CoroutineScope,
		private val conditions: Collection<Condition>,
		@Evaluator.ConditionOperand private val operand: Int
		) : Condition(null, false), Condition.Callback {
		) : Condition(scope, null, false) {

		private var job: Job? = null
		private val _startStrategy by lazy { calculateStartStrategy() }

		override fun start() {
		onConditionChanged(this)
		conditions.forEach { it.addCallback(this) }
		}
		job =
		scope.launch {
		val groupedConditions = conditions.groupBy { it.isOverridingCondition }

		override fun onConditionChanged(condition: Condition) {
		Evaluator.evaluate(conditions, operand)?.also { value -> updateCondition(value) }
		?: clearCondition()
		lazilyEvaluate(
		conditions = groupedConditions.getOrDefault(true, emptyList()),
		filterUnknown = true
		)
		.distinctUntilChanged()
		.flatMapLatest { overriddenValue ->
		// If there are overriding conditions with values set, they take precedence.
		if (overriddenValue == null) {
		lazilyEvaluate(
		conditions = groupedConditions.getOrDefault(false, emptyList()),
		filterUnknown = false
		)
		} else {
		flowOf(overriddenValue)
		}
		}
		.collect { conditionMet ->
		if (conditionMet == null) {
		clearCondition()
		} else {
		updateCondition(conditionMet)
		}
		}
		}
		}

		override fun stop() {
		conditions.forEach { it.removeCallback(this) }
		job?.cancel()
		job = null
		}

		/**
		* Evaluates a list of conditions lazily with support for short-circuiting. Conditions are
		* executed serially in the order provided. At any point if the result can be determined, we
		* short-circuit and return the result without executing all conditions.
		*/
		private fun lazilyEvaluate(
		conditions: Collection<Condition>,
		filterUnknown: Boolean,
		): Flow<Boolean?> = callbackFlow {
		val jobs = MutableList<Job?>(conditions.size) { null }
		val values = MutableList<Boolean?>(conditions.size) { null }
		val flows = conditions.map { it.toFlow() }

		fun cancelAllExcept(indexToSkip: Int) {
		for (index in 0 until jobs.size) {
		if (index == indexToSkip) {
		continue
		}
		if (
		indexToSkip == -1 \|\|
		conditions.elementAt(index).startStrategy == START_WHEN_NEEDED
		) {
		jobs[index]?.cancel()
		jobs[index] = null
		values[index] = null
		}
		}
		}

		fun collectFlow(index: Int) {
		// Base case which is triggered once we have collected all the flows. In this case,
		// we never short-circuited and therefore should return the fully evaluated
		// conditions.
		if (flows.isEmpty() \|\| index == -1) {
		val filteredValues =
		if (filterUnknown) {
		values.filterNotNull()
		} else {
		values
		}
		trySend(Evaluator.evaluate(filteredValues, operand))
		return
		}
		jobs[index] =
		scope.launch {
		flows.elementAt(index).collect { value ->
		values[index] = value
		if (shouldEarlyReturn(value)) {
		trySend(value)
		// The overall result is contingent on this condition, so we don't need
		// to monitor any other conditions.
		cancelAllExcept(index)
		} else {
		collectFlow(jobs.indexOfFirst { it == null })
		}
		}
		}
		}

		// Collect any eager conditions immediately.
		var started = false
		for ((index, condition) in conditions.withIndex()) {
		if (condition.startStrategy == START_EAGERLY) {
		collectFlow(index)
		started = true
		}
		}

		// If no eager conditions started, start the first condition to kick off evaluation.
		if (!started) {
		collectFlow(0)
		}
		awaitClose { cancelAllExcept(-1) }
		}

		private fun shouldEarlyReturn(conditionMet: Boolean?): Boolean {
		return when (operand) {
		Evaluator.OP_AND -> conditionMet == false
		Evaluator.OP_OR -> conditionMet == true
		else -> false
		}
		}

		/**
		* Calculate the start strategy for this condition. This depends on the strategies of the child
		* conditions. If there are any eager conditions, we must also start this condition eagerly. In
		* the absence of eager conditions, we check for lazy conditions. In the absence of either, we
		* make the condition only start when needed.
		*/
		private fun calculateStartStrategy(): Int {
		var startStrategy = START_WHEN_NEEDED
		for (condition in conditions) {
		when (condition.startStrategy) {
		START_EAGERLY -> return START_EAGERLY
		START_LAZILY -> {
		startStrategy = START_LAZILY
		}
		START_WHEN_NEEDED -> {
		// this is the default, so do nothing
		}
		}
		}
		return startStrategy
		}

		override fun getStartStrategy(): Int {
		return _startStrategy
		}
		}

packages/SystemUI/shared/src/com/android/systemui/shared/condition/Condition.java

+46 −12

Original line number	Diff line number	Diff line
		@@ -18,11 +18,14 @@ package com.android.systemui.shared.condition;

		import android.util.Log;

		import androidx.annotation.IntDef;
		import androidx.annotation.NonNull;
		import androidx.lifecycle.Lifecycle;
		import androidx.lifecycle.LifecycleEventObserver;
		import androidx.lifecycle.LifecycleOwner;

		import java.lang.annotation.Retention;
		import java.lang.annotation.RetentionPolicy;
		import java.lang.ref.WeakReference;
		import java.util.ArrayList;
		import java.util.Arrays;
		@@ -30,6 +33,8 @@ import java.util.Collection;
		import java.util.Iterator;
		import java.util.List;

		import kotlinx.coroutines.CoroutineScope;

		/**
		* Base class for a condition that needs to be fulfilled in order for {@link Monitor} to inform
		* its callbacks.
		@@ -39,24 +44,27 @@ public abstract class Condition {

		private final ArrayList<WeakReference<Callback>> mCallbacks = new ArrayList<>();
		private final boolean mOverriding;
		private final CoroutineScope mScope;
		private Boolean mIsConditionMet;
		private boolean mStarted = false;

		/**
		* By default, conditions have an initial value of false and are not overriding.
		*/
		public Condition() {
		this(false, false);
		public Condition(CoroutineScope scope) {
		this(scope, false, false);
		}

		/**
		* Constructor for specifying initial state and overriding condition attribute.
		*
		* @param initialConditionMet Initial state of the condition.
		* @param overriding Whether this condition overrides others.
		*/
		protected Condition(Boolean initialConditionMet, boolean overriding) {
		protected Condition(CoroutineScope scope, Boolean initialConditionMet, boolean overriding) {
		mIsConditionMet = initialConditionMet;
		mOverriding = overriding;
		mScope = scope;
		}

		/**
		@@ -69,6 +77,29 @@ public abstract class Condition {
		*/
		protected abstract void stop();

		/**
		* Condition should be started as soon as there is an active subscription.
		*/
		public static final int START_EAGERLY = 0;
		/**
		* Condition should be started lazily only if needed. But once started, it will not be cancelled
		* unless there are no more active subscriptions.
		*/
		public static final int START_LAZILY = 1;
		/**
		* Condition should be started lazily only if needed, and can be stopped when not needed. This
		* should be used for conditions which are expensive to keep running.
		*/
		public static final int START_WHEN_NEEDED = 2;

		@Retention(RetentionPolicy.SOURCE)
		@IntDef({START_EAGERLY, START_LAZILY, START_WHEN_NEEDED})
		@interface StartStrategy {
		}

		@StartStrategy
		protected abstract int getStartStrategy();

		/**
		* Returns whether the current condition overrides
		*/
		@@ -183,6 +214,7 @@ public abstract class Condition {
		/**
		* Returns whether the condition is set. This method should be consulted to understand the
		* value of {@link #isConditionMet()}.
		*
		* @return {@code true} if value is present, {@code false} otherwise.
		*/
		public boolean isConditionSet() {
		@@ -210,17 +242,18 @@ public abstract class Condition {
		* conditions are true.
		*/
		public Condition and(@NonNull Collection<Condition> others) {
		final List<Condition> conditions = new ArrayList<>(others);
		final List<Condition> conditions = new ArrayList<>();
		conditions.add(this);
		return new CombinedCondition(conditions, Evaluator.OP_AND);
		conditions.addAll(others);
		return new CombinedCondition(mScope, conditions, Evaluator.OP_AND);
		}

		/**
		* Creates a new condition which will only be true when both this condition and the provided
		* condition is true.
		*/
		public Condition and(@NonNull Condition other) {
		return new CombinedCondition(Arrays.asList(this, other), Evaluator.OP_AND);
		public Condition and(@NonNull Condition... others) {
		return and(Arrays.asList(others));
		}

		/**
		@@ -228,17 +261,18 @@ public abstract class Condition {
		* provided conditions are true.
		*/
		public Condition or(@NonNull Collection<Condition> others) {
		final List<Condition> conditions = new ArrayList<>(others);
		final List<Condition> conditions = new ArrayList<>();
		conditions.add(this);
		return new CombinedCondition(conditions, Evaluator.OP_OR);
		conditions.addAll(others);
		return new CombinedCondition(mScope, conditions, Evaluator.OP_OR);
		}

		/**
		* Creates a new condition which will only be true when either this condition or the provided
		* condition is true.
		*/
		public Condition or(@NonNull Condition other) {
		return new CombinedCondition(Arrays.asList(this, other), Evaluator.OP_OR);
		public Condition or(@NonNull Condition... others) {
		return or(Arrays.asList(others));
		}

		/**

packages/SystemUI/shared/src/com/android/systemui/shared/condition/ConditionExtensions.kt

+30 −2

Original line number	Diff line number	Diff line
		package com.android.systemui.shared.condition

		import com.android.systemui.shared.condition.Condition.StartStrategy
		import kotlinx.coroutines.CoroutineScope
		import kotlinx.coroutines.Job
		import kotlinx.coroutines.channels.awaitClose
		import kotlinx.coroutines.flow.Flow
		import kotlinx.coroutines.flow.callbackFlow
		import kotlinx.coroutines.flow.distinctUntilChanged
		import kotlinx.coroutines.launch

		/** Converts a boolean flow to a [Condition] object which can be used with a [Monitor] */
		@JvmOverloads
		fun Flow<Boolean>.toCondition(scope: CoroutineScope, initialValue: Boolean? = null): Condition {
		return object : Condition(initialValue, false) {
		fun Flow<Boolean>.toCondition(
		scope: CoroutineScope,
		@StartStrategy strategy: Int,
		initialValue: Boolean? = null
		): Condition {
		return object : Condition(scope, initialValue, false) {
		var job: Job? = null

		override fun start() {
		@@ -19,5 +27,25 @@ fun Flow<Boolean>.toCondition(scope: CoroutineScope, initialValue: Boolean? = nu
		job?.cancel()
		job = null
		}

		override fun getStartStrategy() = strategy
		}
		}

		/** Converts a [Condition] to a boolean flow */
		fun Condition.toFlow(): Flow<Boolean?> {
		return callbackFlow {
		val callback =
		Condition.Callback { condition ->
		if (condition.isConditionSet) {
		trySend(condition.isConditionMet)
		} else {
		trySend(null)
		}
		}
		addCallback(callback)
		callback.onConditionChanged(this@toFlow)
		awaitClose { removeCallback(callback) }
		}
		.distinctUntilChanged()
		}

packages/SystemUI/shared/src/com/android/systemui/shared/condition/Evaluator.kt

+26 −10

Original line number	Diff line number	Diff line
		@@ -22,7 +22,7 @@ import android.annotation.IntDef
		* Helper for evaluating a collection of [Condition] objects with a given
		* [Evaluator.ConditionOperand]
		*/
		internal object Evaluator {
		object Evaluator {
		/** Operands for combining multiple conditions together */
		@Retention(AnnotationRetention.SOURCE)
		@IntDef(value = [OP_AND, OP_OR])
		@@ -70,15 +70,31 @@ internal object Evaluator {
		fun evaluate(conditions: Collection<Condition>, @ConditionOperand operand: Int): Boolean? {
		if (conditions.isEmpty()) return null
		// If there are overriding conditions with values set, they take precedence.
		val targetConditions =
		val values: Collection<Boolean?> =
		conditions
		.filter { it.isConditionSet && it.isOverridingCondition }
		.ifEmpty { conditions }
		.map { condition ->
		if (condition.isConditionSet) {
		condition.isConditionMet
		} else {
		null
		}
		}
		return evaluate(values = values, operand = operand)
		}

		/**
		* Evaluates a set of booleans with a given operand
		*
		* @param operand The operand to use when evaluating.
		* @return Either true or false if the value is known, or null if value is unknown
		*/
		internal fun evaluate(values: Collection<Boolean?>, @ConditionOperand operand: Int): Boolean? {
		if (values.isEmpty()) return null
		return when (operand) {
		OP_AND ->
		threeValuedAndOrOr(conditions = targetConditions, returnValueIfAnyMatches = false)
		OP_OR ->
		threeValuedAndOrOr(conditions = targetConditions, returnValueIfAnyMatches = true)
		OP_AND -> threeValuedAndOrOr(values = values, returnValueIfAnyMatches = false)
		OP_OR -> threeValuedAndOrOr(values = values, returnValueIfAnyMatches = true)
		else -> null
		}
		}
		@@ -90,16 +106,16 @@ internal object Evaluator {
		* any value is true.
		*/
		private fun threeValuedAndOrOr(
		conditions: Collection<Condition>,
		values: Collection<Boolean?>,
		returnValueIfAnyMatches: Boolean
		): Boolean? {
		var hasUnknown = false
		for (condition in conditions) {
		if (!condition.isConditionSet) {
		for (value in values) {
		if (value == null) {
		hasUnknown = true
		continue
		}
		if (condition.isConditionMet == returnValueIfAnyMatches) {
		if (value == returnValueIfAnyMatches) {
		return returnValueIfAnyMatches
		}
		}

packages/SystemUI/src/com/android/systemui/dreams/conditions/AssistantAttentionCondition.java

+10 −0

Original line number	Diff line number	Diff line
		@@ -18,11 +18,14 @@ package com.android.systemui.dreams.conditions;

		import com.android.internal.app.AssistUtils;
		import com.android.internal.app.IVisualQueryDetectionAttentionListener;
		import com.android.systemui.dagger.qualifiers.Application;
		import com.android.systemui.dreams.DreamOverlayStateController;
		import com.android.systemui.shared.condition.Condition;

		import javax.inject.Inject;

		import kotlinx.coroutines.CoroutineScope;

		/**
		* {@link AssistantAttentionCondition} provides a signal when assistant has the user's attention.
		*/
		@@ -58,8 +61,10 @@ public class AssistantAttentionCondition extends Condition {

		@Inject
		public AssistantAttentionCondition(
		@Application CoroutineScope scope,
		DreamOverlayStateController dreamOverlayStateController,
		AssistUtils assistUtils) {
		super(scope);
		mDreamOverlayStateController = dreamOverlayStateController;
		mAssistUtils = assistUtils;
		}
		@@ -75,6 +80,11 @@ public class AssistantAttentionCondition extends Condition {
		mDreamOverlayStateController.removeCallback(mCallback);
		}

		@Override
		protected int getStartStrategy() {
		return START_EAGERLY;
		}

		private void enableVisualQueryDetection() {
		if (mEnabled) {
		return;