* one of three states:
   *   - Active: shutdown == false
   *   - Shutdown: runningTasks > 0 and shutdown == true
   *   - Terminated: runningTasks == 0 and shutdown == true
   */
  @GuardedBy("lock")
  private int runningTasks = 0;

  @GuardedBy("lock")
  private boolean shutdown = false;

  @Override
  public void execute(Runnable command) {
    startTask();
    try {
      command.run();
    } finally {

import static com.google.common.base.Throwables.throwIfUnchecked;

import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.VisibleForTesting;
import com.google.errorprone.annotations.concurrent.GuardedBy;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Deque;
import java.util.List;
import java.util.logging.Level;
import java.util.logging.Logger;
import org.jspecify.annotations.NullMarked;

import static com.google.common.base.Throwables.throwIfUnchecked;

import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.VisibleForTesting;
import com.google.errorprone.annotations.concurrent.GuardedBy;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Deque;
import java.util.List;
import java.util.logging.Level;
import java.util.logging.Logger;
import org.jspecify.annotations.NullMarked;

 */

package com.google.common.util.concurrent;

import static com.google.common.truth.Truth.assertThat;
import static org.junit.Assert.assertThrows;

import com.google.errorprone.annotations.concurrent.GuardedBy;
import java.lang.reflect.Method;
import java.net.URLClassLoader;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.CancellationException;
import java.util.concurrent.Executor;

     * tail of the queue on write.
     */
    @GuardedBy("this")
    final Queue<ReferenceEntry<K, V>> writeQueue;

    /**
     * A queue of elements currently in the map, ordered by access time. Elements are added to the
     * tail of the queue on access (note that writes count as accesses).
     */
    @GuardedBy("this")
    final Queue<ReferenceEntry<K, V>> accessQueue;

    final Monitor monitor = new Monitor();

    @GuardedBy("monitor")
    final SetMultimap<State, Service> servicesByState =
        MultimapBuilder.enumKeys(State.class).linkedHashSetValues().build();

    @GuardedBy("monitor")
    final Multiset<State> states = servicesByState.keys();

    @GuardedBy("monitor")
    final IdentityHashMap<Service, Stopwatch> startupTimers = new IdentityHashMap<>();

    final Monitor monitor = new Monitor();

    @GuardedBy("monitor")
    final SetMultimap<State, Service> servicesByState =
        MultimapBuilder.enumKeys(State.class).linkedHashSetValues().build();

    @GuardedBy("monitor")
    final Multiset<State> states = servicesByState.keys();

    @GuardedBy("monitor")
    final IdentityHashMap<Service, Stopwatch> startupTimers = new IdentityHashMap<>();

import com.google.common.collect.MapMaker.Dummy;
import com.google.common.primitives.Ints;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import com.google.errorprone.annotations.concurrent.GuardedBy;
import com.google.errorprone.annotations.concurrent.LazyInit;
import com.google.j2objc.annotations.Weak;
import com.google.j2objc.annotations.WeakOuter;
import java.io.IOException;
import java.io.InvalidObjectException;

    oldValueRef.clear();
    assertFalse(segment.remove(key, hash, oldValue));
    assertEquals(0, segment.count);
    assertThat(segment.get(key, hash)).isNull();
  }

  @SuppressWarnings("GuardedBy")
  public void testExpand() {
    MapMakerInternalMap<Object, Object, ?, ?> map =
        makeMap(createMapMaker().concurrencyLevel(1).initialCapacity(1));
    Segment<Object, Object, ?, ?> segment = map.segments[0];

    oldValueRef.clear();
    assertFalse(segment.remove(key, hash, oldValue));
    assertEquals(0, segment.count);
    assertThat(segment.get(key, hash)).isNull();
  }

  @SuppressWarnings("GuardedBy")
  public void testExpand() {
    MapMakerInternalMap<Object, Object, ?, ?> map =
        makeMap(createMapMaker().concurrencyLevel(1).initialCapacity(1));
    Segment<Object, Object, ?, ?> segment = map.segments[0];