| /* |
| * Copyright (C) 2018 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.util; |
| |
| import android.annotation.NonNull; |
| import android.annotation.Nullable; |
| import android.os.Parcel; |
| import android.os.SystemClock; |
| |
| import java.util.Objects; |
| |
| /** |
| * A value with an associated reference time. The reference time will typically be provided by the |
| * elapsed realtime clock. The elapsed realtime clock can be obtained using methods like |
| * {@link SystemClock#elapsedRealtime()} or {@link SystemClock#elapsedRealtimeClock()}. |
| * If a suitable clock is used the reference time can be used to identify the age of a value or |
| * ordering between values. |
| * |
| * <p>To read and write a timestamped value from / to a Parcel see |
| * {@link #readFromParcel(Parcel, ClassLoader, Class)} and |
| * {@link #writeToParcel(Parcel, TimestampedValue)}. |
| * |
| * @param <T> the type of the value with an associated timestamp |
| * @hide |
| */ |
| public final class TimestampedValue<T> { |
| private final long mReferenceTimeMillis; |
| private final T mValue; |
| |
| public TimestampedValue(long referenceTimeMillis, T value) { |
| mReferenceTimeMillis = referenceTimeMillis; |
| mValue = value; |
| } |
| |
| public long getReferenceTimeMillis() { |
| return mReferenceTimeMillis; |
| } |
| |
| public T getValue() { |
| return mValue; |
| } |
| |
| @Override |
| public boolean equals(Object o) { |
| if (this == o) { |
| return true; |
| } |
| if (o == null || getClass() != o.getClass()) { |
| return false; |
| } |
| TimestampedValue<?> that = (TimestampedValue<?>) o; |
| return mReferenceTimeMillis == that.mReferenceTimeMillis |
| && Objects.equals(mValue, that.mValue); |
| } |
| |
| @Override |
| public int hashCode() { |
| return Objects.hash(mReferenceTimeMillis, mValue); |
| } |
| |
| @Override |
| public String toString() { |
| return "TimestampedValue{" |
| + "mReferenceTimeMillis=" + mReferenceTimeMillis |
| + ", mValue=" + mValue |
| + '}'; |
| } |
| |
| /** |
| * Read a {@link TimestampedValue} from a parcel that was stored using |
| * {@link #writeToParcel(Parcel, TimestampedValue)}. |
| * |
| * <p>The marshalling/unmarshalling of the value relies upon {@link Parcel#writeValue(Object)} |
| * and {@link Parcel#readValue(ClassLoader)} and so this method can only be used with types |
| * supported by those methods. |
| * |
| * @param in the Parcel to read from |
| * @param classLoader the ClassLoader to pass to {@link Parcel#readValue(ClassLoader)} |
| * @param valueClass the expected type of the value, typically the same as {@code <T>} but can |
| * also be a subclass |
| * @throws RuntimeException if the value read is not compatible with {@code valueClass} or the |
| * object could not be read |
| */ |
| @SuppressWarnings("unchecked") |
| @NonNull |
| public static <T> TimestampedValue<T> readFromParcel( |
| @NonNull Parcel in, @Nullable ClassLoader classLoader, Class<? extends T> valueClass) { |
| long referenceTimeMillis = in.readLong(); |
| T value = (T) in.readValue(classLoader); |
| // Equivalent to static code: if (!(value.getClass() instanceof {valueClass})) { |
| if (value != null && !valueClass.isAssignableFrom(value.getClass())) { |
| throw new RuntimeException("Value was of type " + value.getClass() |
| + " is not assignable to " + valueClass); |
| } |
| return new TimestampedValue<>(referenceTimeMillis, value); |
| } |
| |
| /** |
| * Write a {@link TimestampedValue} to a parcel so that it can be read using |
| * {@link #readFromParcel(Parcel, ClassLoader, Class)}. |
| * |
| * <p>The marshalling/unmarshalling of the value relies upon {@link Parcel#writeValue(Object)} |
| * and {@link Parcel#readValue(ClassLoader)} and so this method can only be used with types |
| * supported by those methods. |
| * |
| * @param dest the Parcel |
| * @param timestampedValue the value |
| * @throws RuntimeException if the value could not be written to the Parcel |
| */ |
| public static void writeToParcel( |
| @NonNull Parcel dest, @NonNull TimestampedValue<?> timestampedValue) { |
| dest.writeLong(timestampedValue.mReferenceTimeMillis); |
| dest.writeValue(timestampedValue.mValue); |
| } |
| |
| /** |
| * Returns the difference in milliseconds between two instance's reference times. |
| */ |
| public static long referenceTimeDifference( |
| @NonNull TimestampedValue<?> one, @NonNull TimestampedValue<?> two) { |
| return one.mReferenceTimeMillis - two.mReferenceTimeMillis; |
| } |
| } |