guava

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/*
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 * Copyright (C) 2008 The Guava Authors
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 *
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 * Licensed under the Apache License, Version 2.0 (the "License");
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 * you may not use this file except in compliance with the License.
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 * You may obtain a copy of the License at
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 *
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 * http://www.apache.org/licenses/LICENSE-2.0
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 *
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 * Unless required by applicable law or agreed to in writing, software
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 * distributed under the License is distributed on an "AS IS" BASIS,
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 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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 * See the License for the specific language governing permissions and
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 * limitations under the License.
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 */
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package com.google.common.testing;
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import static com.google.common.base.Preconditions.checkArgument;
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import com.google.common.annotations.GwtCompatible;
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import com.google.common.annotations.GwtIncompatible;
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import com.google.common.annotations.J2ktIncompatible;
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import com.google.common.base.Ticker;
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import com.google.errorprone.annotations.CanIgnoreReturnValue;
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import java.time.Duration;
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import java.util.concurrent.TimeUnit;
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import java.util.concurrent.atomic.AtomicLong;
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/**
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 * A Ticker whose value can be advanced programmatically in test.
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 *
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 * <p>The ticker can be configured so that the time is incremented whenever {@link #read} is called:
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 * see {@link #setAutoIncrementStep}.
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 *
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 * <p>This class is thread-safe.
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 *
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 * @author Jige Yu
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 * @since 10.0
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 */
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@ElementTypesAreNonnullByDefault
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@GwtCompatible
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public class FakeTicker extends Ticker {
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  private final AtomicLong nanos = new AtomicLong();
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  private volatile long autoIncrementStepNanos;
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  /** Advances the ticker value by {@code time} in {@code timeUnit}. */
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  @SuppressWarnings("GoodTime") // should accept a java.time.Duration
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  @CanIgnoreReturnValue
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  public FakeTicker advance(long time, TimeUnit timeUnit) {
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    return advance(timeUnit.toNanos(time));
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  }
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  /** Advances the ticker value by {@code nanoseconds}. */
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  @SuppressWarnings("GoodTime") // should accept a java.time.Duration
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  @CanIgnoreReturnValue
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  public FakeTicker advance(long nanoseconds) {
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    nanos.addAndGet(nanoseconds);
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    return this;
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  }
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  /**
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   * Advances the ticker value by {@code duration}.
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   *
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   * @since 28.0
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   */
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  @GwtIncompatible
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  @J2ktIncompatible
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  @CanIgnoreReturnValue
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  @SuppressWarnings("Java7ApiChecker") // guava-android can rely on library desugaring now.
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  public FakeTicker advance(Duration duration) {
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    return advance(duration.toNanos());
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  }
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  /**
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   * Sets the increment applied to the ticker whenever it is queried.
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   *
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   * <p>The default behavior is to auto increment by zero. i.e: The ticker is left unchanged when
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   * queried.
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   */
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  @SuppressWarnings("GoodTime") // should accept a java.time.Duration
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  @CanIgnoreReturnValue
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  public FakeTicker setAutoIncrementStep(long autoIncrementStep, TimeUnit timeUnit) {
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    checkArgument(autoIncrementStep >= 0, "May not auto-increment by a negative amount");
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    this.autoIncrementStepNanos = timeUnit.toNanos(autoIncrementStep);
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    return this;
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  }
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  /**
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   * Sets the increment applied to the ticker whenever it is queried.
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   *
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   * <p>The default behavior is to auto increment by zero. i.e: The ticker is left unchanged when
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   * queried.
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   *
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   * @since 28.0
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   */
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  @GwtIncompatible
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  @J2ktIncompatible
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  @CanIgnoreReturnValue
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  @SuppressWarnings("Java7ApiChecker") // guava-android can rely on library desugaring now.
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  public FakeTicker setAutoIncrementStep(Duration autoIncrementStep) {
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    return setAutoIncrementStep(autoIncrementStep.toNanos(), TimeUnit.NANOSECONDS);
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  }
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  @Override
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  public long read() {
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    return nanos.getAndAdd(autoIncrementStepNanos);
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  }
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}
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