A new Client-Side FeatureFlags library. (27f4ca52) · Commits · e / os / android_frameworks_base

core/java/android/flags/BooleanFlag.java

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		/*
		* Copyright (C) 2023 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.flags;

		import android.annotation.NonNull;

		/**
		* A flag representing a true or false value.
		*
		* The value will always be the same during the lifetime of the process it is read in.
		*
		* @hide
		*/
		public class BooleanFlag implements Flag<Boolean> {
		private final String mNamespace;
		private final String mName;
		private final boolean mDefault;

		/**
		* @param namespace A namespace for this flag. See {@link android.provider.DeviceConfig}.
		* @param name A name for this flag.
		* @param defaultValue The value of this flag if no other override is present.
		*/
		BooleanFlag(String namespace, String name, boolean defaultValue) {
		mNamespace = namespace;
		mName = name;
		mDefault = defaultValue;
		}

		@Override
		@NonNull
		public Boolean getDefault() {
		return mDefault;
		}

		@Override
		@NonNull
		public String getNamespace() {
		return mNamespace;
		}

		@Override
		@NonNull
		public String getName() {
		return mName;
		}

		@Override
		@NonNull
		public String toString() {
		return getNamespace() + "." + getName() + "[" + getDefault() + "]";
		}
		}

core/java/android/flags/DynamicBooleanFlag.java

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		/*
		* Copyright (C) 2023 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.flags;

		/**
		* A flag representing a true or false value.
		*
		* The value may be different from one read to the next.
		*
		* @hide
		*/
		public class DynamicBooleanFlag implements DynamicFlag<Boolean> {

		private final String mNamespace;
		private final String mName;
		private final boolean mDefault;

		/**
		* @param namespace A namespace for this flag. See {@link android.provider.DeviceConfig}.
		* @param name A name for this flag.
		* @param defaultValue The value of this flag if no other override is present.
		*/
		DynamicBooleanFlag(String namespace, String name, boolean defaultValue) {
		mNamespace = namespace;
		mName = name;
		mDefault = defaultValue;
		}

		@Override
		public String getNamespace() {
		return mNamespace;
		}

		@Override
		public String getName() {
		return mName;
		}

		@Override
		public Boolean getDefault() {
		return mDefault;
		}

		@Override
		public String toString() {
		return getNamespace() + "." + getName() + "[" + getDefault() + "]";
		}
		}

core/java/android/flags/DynamicFlag.java

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		/*
		* Copyright (C) 2023 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.flags;

		/**
		* A flag for which the value may be different from one read to the next.
		*
		* @param <T> The type of value that this flag stores. E.g. Boolean or String.
		*
		* @hide
		*/
		public interface DynamicFlag<T> extends Flag<T> {
		}

core/java/android/flags/FeatureFlags.java

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		/*
		* Copyright (C) 2023 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.flags;

		import android.annotation.NonNull;

		import java.util.HashSet;
		import java.util.Set;

		/**
		* A class for querying constants from the system - primarily booleans.
		*
		* Clients using this class can define their flags and their default values in one place,
		* can override those values on running devices for debugging and testing purposes, and can control
		* what flags are available to be used on release builds.
		*
		* TODO(b/279054964): A lot. This is skeleton code right now.
		* @hide
		*/
		public class FeatureFlags {
		private static FeatureFlags sInstance;
		private static final Object sInstanceLock = new Object();

		private final Set<ChangeListener> mListeners = new HashSet<>();

		/**
		* Obtain a per-process instance of FeatureFlags.
		* @return
		*/
		@NonNull
		public static FeatureFlags getInstance() {
		synchronized (sInstanceLock) {
		if (sInstance == null) {
		sInstance = new FeatureFlags();
		}
		}

		return sInstance;
		}

		FeatureFlags() {
		}

		/**
		* Returns whether the supplied flag is true or not.
		*
		* {@link BooleanFlag} should only be used in debug builds. They do not get optimized out.
		*
		* The first time a flag is read, its value is cached for the lifetime of the process.
		*/
		public boolean isEnabled(@NonNull BooleanFlag flag) {
		return flag.getDefault();
		}

		/**
		* Returns whether the supplied flag is true or not.
		*
		* Always returns false.
		*/
		public boolean isEnabled(@NonNull FusedOffFlag flag) {
		return false;
		}

		/**
		* Returns whether the supplied flag is true or not.
		*
		* Always returns true;
		*/
		public boolean isEnabled(@NonNull FusedOnFlag flag) {
		return true;
		}

		/**
		* Returns whether the supplied flag is true or not.
		*
		* Can return a different value for the flag each time it is called if an override comes in.
		*/
		public boolean isCurrentlyEnabled(@NonNull DynamicBooleanFlag flag) {
		return flag.getDefault();
		}

		/**
		* Add a listener to be alerted when a {@link DynamicFlag} changes.
		*
		* See also {@link #removeChangeListener(ChangeListener)}.
		*
		* @param listener The listener to add.
		*/
		public void addChangeListener(@NonNull ChangeListener listener) {
		mListeners.add(listener);
		}

		/**
		* Remove a listener that was added earlier.
		*
		* See also {@link #addChangeListener(ChangeListener)}.
		*
		* @param listener The listener to remove.
		*/
		public void removeChangeListener(@NonNull ChangeListener listener) {
		mListeners.remove(listener);
		}

		/**
		* A simpler listener that is alerted when a {@link DynamicFlag} changes.
		*
		* See {@link #addChangeListener(ChangeListener)}
		*/
		public interface ChangeListener {
		/**
		* Called when a {@link DynamicFlag} changes.
		*
		* @param flag The flag that has changed.
		*/
		void onFlagChanged(DynamicFlag<?> flag);
		}
		}

core/java/android/flags/FeatureFlagsFake.java

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		/*
		* Copyright (C) 2023 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.flags;

		import android.annotation.NonNull;

		/**
		* An implementation of {@link FeatureFlags} for testing.
		* @hide
		*/
		public class FeatureFlagsFake extends FeatureFlags {
		public FeatureFlagsFake() {
		super();
		}

		@Override
		public boolean isEnabled(@NonNull BooleanFlag flag) {
		return flag.getDefault();
		}

		@Override
		public boolean isEnabled(@NonNull FusedOffFlag flag) {
		return false;
		}

		@Override
		public boolean isEnabled(@NonNull FusedOnFlag flag) {
		return true;
		}

		@Override
		public boolean isCurrentlyEnabled(@NonNull DynamicBooleanFlag flag) {
		return flag.getDefault();
		}
		}