Merge "Make ReferenceWithHistory output easier to use" into sc-dev (0fb5c795) · Commits · e / os / android_frameworks_base

services/core/java/com/android/server/timezonedetector/ReferenceWithHistory.java

+21 −35

Original line number	Diff line number	Diff line
		@@ -19,8 +19,11 @@ package com.android.server.timezonedetector;
		import android.annotation.IntRange;
		import android.annotation.NonNull;
		import android.annotation.Nullable;
		import android.os.SystemClock;
		import android.os.TimestampedValue;
		import android.util.IndentingPrintWriter;

		import java.time.Duration;
		import java.util.ArrayDeque;

		/**
		@@ -49,18 +52,15 @@ import java.util.ArrayDeque;
		*/
		public final class ReferenceWithHistory<V> {

		private static final Object NULL_MARKER = "{null marker}";

		/** The maximum number of references to store. */
		private final int mMaxHistorySize;

		/**
		* The history storage. Note that ArrayDeque doesn't support {@code null} so this stores Object
		* and not V. Use {@link #packNullIfRequired(Object)} and {@link #unpackNullIfRequired(Object)}
		* to convert to / from the storage object.
		*/
		/** The number of times {@link #set(Object)} has been called. */
		private int mSetCount;

		/** The history storage. */
		@Nullable
		private ArrayDeque<Object> mValues;
		private ArrayDeque<TimestampedValue<V>> mValues;

		/**
		* Creates an instance that records, at most, the specified number of values.
		@@ -78,8 +78,8 @@ public final class ReferenceWithHistory<V> {
		if (mValues == null \|\| mValues.isEmpty()) {
		return null;
		}
		Object value = mValues.getFirst();
		return unpackNullIfRequired(value);
		TimestampedValue<V> valueHolder = mValues.getFirst();
		return valueHolder.getValue();
		}

		/**
		@@ -98,8 +98,10 @@ public final class ReferenceWithHistory<V> {

		V previous = get();

		Object nullSafeValue = packNullIfRequired(newValue);
		mValues.addFirst(nullSafeValue);
		TimestampedValue<V> valueHolder =
		new TimestampedValue<>(SystemClock.elapsedRealtime(), newValue);
		mValues.addFirst(valueHolder);
		mSetCount++;
		return previous;
		}

		@@ -110,10 +112,13 @@ public final class ReferenceWithHistory<V> {
		if (mValues == null) {
		ipw.println("{Empty}");
		} else {
		int i = 0;
		for (Object value : mValues) {
		ipw.println(i + ": " + unpackNullIfRequired(value));
		i++;
		int i = mSetCount;
		for (TimestampedValue<V> valueHolder : mValues) {
		ipw.print(--i);
		ipw.print("@");
		ipw.print(Duration.ofMillis(valueHolder.getReferenceTimeMillis()).toString());
		ipw.print(": ");
		ipw.println(valueHolder.getValue());
		}
		}
		ipw.flush();
		@@ -130,23 +135,4 @@ public final class ReferenceWithHistory<V> {
		public String toString() {
		return String.valueOf(get());
		}

		/**
		* Turns a non-nullable Object into a nullable value. See also
		* {@link #packNullIfRequired(Object)}.
		*/
		@SuppressWarnings("unchecked")
		@Nullable
		private V unpackNullIfRequired(@NonNull Object value) {
		return value == NULL_MARKER ? null : (V) value;
		}

		/**
		* Turns a nullable value into a non-nullable Object. See also
		* {@link #unpackNullIfRequired(Object)}.
		*/
		@NonNull
		private Object packNullIfRequired(@Nullable V value) {
		return value == null ? NULL_MARKER : value;
		}
		}