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Commit a34c31db authored by Neil Fuller's avatar Neil Fuller Committed by Automerger Merge Worker
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Merge "Make ReferenceWithHistory output easier to use" into sc-dev am: 0fb5c795 

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/13462306

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: I15ac15813169c89eeed5938176b6894357ebcf4a
parents f78016d9 0fb5c795

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;

    }

}