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Java example source code file (CacheTesting.java)

This example Java source code file (CacheTesting.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

annotation, expiration, faketicker, integer, localcache, localloadingcache, map, object, referenceentry, segment, set, suppresswarnings, threading, threads, util

The CacheTesting.java Java example source code

/*
 * Copyright (C) 2011 The Guava Authors
 *
 * 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 com.google.common.cache;

import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.truth.Truth.assertThat;
import static junit.framework.Assert.assertEquals;
import static junit.framework.Assert.assertFalse;
import static junit.framework.Assert.assertNotNull;
import static junit.framework.Assert.assertNotSame;
import static junit.framework.Assert.assertNull;
import static junit.framework.Assert.assertSame;
import static junit.framework.Assert.assertTrue;

import com.google.common.base.Preconditions;
import com.google.common.cache.LocalCache.LocalLoadingCache;
import com.google.common.cache.LocalCache.ReferenceEntry;
import com.google.common.cache.LocalCache.Segment;
import com.google.common.cache.LocalCache.ValueReference;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Maps;
import com.google.common.collect.Sets;
import com.google.common.testing.EqualsTester;
import com.google.common.testing.FakeTicker;

import java.lang.ref.Reference;
import java.util.Collection;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicReferenceArray;

import javax.annotation.Nullable;

/**
 * A collection of utilities for {@link Cache} testing.
 *
 * @author mike nonemacher
 */
class CacheTesting {

  /**
   * Poke into the Cache internals to simulate garbage collection of the value associated with the
   * given key. This assumes that the associated entry is a WeakValueReference or a
   * SoftValueReference (and not a LoadingValueReference), and throws an IllegalStateException
   * if that assumption does not hold.
   */
  @SuppressWarnings("unchecked")  // the instanceof check and the cast generate this warning
  static <K, V> void simulateValueReclamation(Cache cache, K key) {
    ReferenceEntry<K, V> entry = getReferenceEntry(cache, key);
    if (entry != null) {
      ValueReference<K, V> valueRef = entry.getValueReference();
      // fail on strong/computing refs
      Preconditions.checkState(valueRef instanceof Reference);
      Reference<V> ref = (Reference) valueRef;
      if (ref != null) {
        ref.clear();
      }
    }
  }

  /**
   * Poke into the Cache internals to simulate garbage collection of the given key. This assumes
   * that the given entry is a weak or soft reference, and throws an IllegalStateException if that
   * assumption does not hold.
   */
  @SuppressWarnings("unchecked")  // the instanceof check and the cast generate this warning
  static <K, V> void simulateKeyReclamation(Cache cache, K key) {
    ReferenceEntry<K, V> entry = getReferenceEntry(cache, key);

    Preconditions.checkState(entry instanceof Reference);
    Reference<?> ref = (Reference) entry;
    if (ref != null) {
      ref.clear();
    }
  }

  static <K, V> ReferenceEntry getReferenceEntry(Cache cache, K key) {
    checkNotNull(cache);
    checkNotNull(key);
    LocalCache<K, V> map = toLocalCache(cache);
    return map.getEntry(key);
  }

  /**
   * Forces the segment containing the given {@code key} to expand (see
   * {@link Segment#expand()}.
   */
  static <K, V> void forceExpandSegment(Cache cache, K key) {
    checkNotNull(cache);
    checkNotNull(key);
    LocalCache<K, V> map = toLocalCache(cache);
    int hash = map.hash(key);
    Segment<K, V> segment = map.segmentFor(hash);
    segment.expand();
  }

  /**
   * Gets the {@link LocalCache} used by the given {@link Cache}, if any, or throws an
   * IllegalArgumentException if this is a Cache type that doesn't have a LocalCache.
   */
  static <K, V> LocalCache toLocalCache(Cache cache) {
    if (cache instanceof LocalLoadingCache) {
      return ((LocalLoadingCache<K, V>) cache).localCache;
    }
    throw new IllegalArgumentException("Cache of type " + cache.getClass()
        + " doesn't have a LocalCache.");
  }

  /**
   * Determines whether the given cache can be converted to a LocalCache by
   * {@link #toLocalCache} without throwing an exception.
   */
  static boolean hasLocalCache(Cache<?, ?> cache) {
    return (checkNotNull(cache) instanceof LocalLoadingCache);
  }

  static void drainRecencyQueues(Cache<?, ?> cache) {
    if (hasLocalCache(cache)) {
      LocalCache<?, ?> map = toLocalCache(cache);
      for (Segment<?, ?> segment : map.segments) {
        drainRecencyQueue(segment);
      }
    }
  }

  static void drainRecencyQueue(Segment<?, ?> segment) {
    segment.lock();
    try {
      segment.cleanUp();
    } finally {
      segment.unlock();
    }
  }

  static void drainReferenceQueues(Cache<?, ?> cache) {
    if (hasLocalCache(cache)) {
      drainReferenceQueues(toLocalCache(cache));
    }
  }

  static void drainReferenceQueues(LocalCache<?, ?> cchm) {
    for (LocalCache.Segment<?, ?> segment : cchm.segments) {
      drainReferenceQueue(segment);
    }
  }

  static void drainReferenceQueue(LocalCache.Segment<?, ?> segment) {
    segment.lock();
    try {
      segment.drainReferenceQueues();
    } finally {
      segment.unlock();
    }
  }

  static int getTotalSegmentSize(Cache<?, ?> cache) {
    LocalCache<?, ?> map = toLocalCache(cache);
    int totalSize = 0;
    for (Segment<?, ?> segment : map.segments) {
      totalSize += segment.maxSegmentWeight;
    }
    return totalSize;
  }

  /**
   * Peeks into the cache's internals to check its internal consistency. Verifies that each
   * segment's count matches its #elements (after cleanup), each segment is unlocked, each entry
   * contains a non-null key and value, and the eviction and expiration queues are consistent
   * (see {@link #checkEviction}, {@link #checkExpiration}).
   */
  static void checkValidState(Cache<?, ?> cache) {
    if (hasLocalCache(cache)) {
      checkValidState(toLocalCache(cache));
    }
  }

  static void checkValidState(LocalCache<?, ?> cchm) {
    for (Segment<?, ?> segment : cchm.segments) {
      segment.cleanUp();
      assertFalse(segment.isLocked());
      Map<?, ?> table = segmentTable(segment);
      // cleanup and then check count after we have a strong reference to all entries
      segment.cleanUp();
      // under high memory pressure keys/values may be nulled out but not yet enqueued
      assertThat(table.size()).isAtMost(segment.count);
      for (Entry<?, ?> entry : table.entrySet()) {
        assertNotNull(entry.getKey());
        assertNotNull(entry.getValue());
        assertSame(entry.getValue(), cchm.get(entry.getKey()));
      }
    }
    checkEviction(cchm);
    checkExpiration(cchm);
  }

  /**
   * Peeks into the cache's internals to verify that its expiration queue is consistent. Verifies
   * that the next/prev links in the expiration queue are correct, and that the queue is ordered
   * by expiration time.
   */
  static void checkExpiration(Cache<?, ?> cache) {
    if (hasLocalCache(cache)) {
      checkExpiration(toLocalCache(cache));
    }
  }

  static void checkExpiration(LocalCache<?, ?> cchm) {
    for (Segment<?, ?> segment : cchm.segments) {
      if (cchm.usesWriteQueue()) {
        Set<ReferenceEntry entries = Sets.newIdentityHashSet();

        ReferenceEntry<?, ?> prev = null;
        for (ReferenceEntry<?, ?> current : segment.writeQueue) {
          assertTrue(entries.add(current));
          if (prev != null) {
            assertSame(prev, current.getPreviousInWriteQueue());
            assertSame(prev.getNextInWriteQueue(), current);
            assertThat(prev.getWriteTime()).isAtMost(current.getWriteTime());
          }
          Object key = current.getKey();
          if (key != null) {
            assertSame(current, segment.getEntry(key, current.getHash()));
          }
          prev = current;
        }
        assertEquals(segment.count, entries.size());
      } else {
        assertTrue(segment.writeQueue.isEmpty());
      }

      if (cchm.usesAccessQueue()) {
        Set<ReferenceEntry entries = Sets.newIdentityHashSet();

        ReferenceEntry<?, ?> prev = null;
        for (ReferenceEntry<?, ?> current : segment.accessQueue) {
          assertTrue(entries.add(current));
          if (prev != null) {
            assertSame(prev, current.getPreviousInAccessQueue());
            assertSame(prev.getNextInAccessQueue(), current);
            // read accesses may be slightly misordered
            assertTrue(prev.getAccessTime() <= current.getAccessTime()
                || prev.getAccessTime() - current.getAccessTime() < 1000);
          }
          Object key = current.getKey();
          if (key != null) {
            assertSame(current, segment.getEntry(key, current.getHash()));
          }
          prev = current;
        }
        assertEquals(segment.count, entries.size());
      } else {
        assertTrue(segment.accessQueue.isEmpty());
      }
    }
  }

  /**
   * Peeks into the cache's internals to verify that its eviction queue is consistent. Verifies
   * that the prev/next links are correct, and that all items in each segment are also in that
   * segment's eviction (recency) queue.
   */
  static void checkEviction(Cache<?, ?> cache) {
    if (hasLocalCache(cache)) {
      checkEviction(toLocalCache(cache));
    }
  }

  static void checkEviction(LocalCache<?, ?> map) {
    if (map.evictsBySize()) {
      for (Segment<?, ?> segment : map.segments) {
        drainRecencyQueue(segment);
        assertEquals(0, segment.recencyQueue.size());
        assertEquals(0, segment.readCount.get());

        ReferenceEntry<?, ?> prev = null;
        for (ReferenceEntry<?, ?> current : segment.accessQueue) {
          if (prev != null) {
            assertSame(prev, current.getPreviousInAccessQueue());
            assertSame(prev.getNextInAccessQueue(), current);
          }
          Object key = current.getKey();
          if (key != null) {
            assertSame(current, segment.getEntry(key, current.getHash()));
          }
          prev = current;
        }
      }
    } else {
      for (Segment<?, ?> segment : map.segments) {
        assertEquals(0, segment.recencyQueue.size());
      }
    }
  }

  static int segmentSize(Segment<?, ?> segment) {
    Map<?, ?> map = segmentTable(segment);
    return map.size();
  }

  static <K, V> Map segmentTable(Segment segment) {
    AtomicReferenceArray<? extends ReferenceEntry table = segment.table;
    Map<K, V> map = Maps.newLinkedHashMap();
    for (int i = 0; i < table.length(); i++) {
      for (ReferenceEntry<K, V> entry = table.get(i); entry != null; entry = entry.getNext()) {
        K key = entry.getKey();
        V value = entry.getValueReference().get();
        if (key != null && value != null) {
          assertNull(map.put(key, value));
        }
      }
    }
    return map;
  }

  static int writeQueueSize(Cache<?, ?> cache) {
    LocalCache<?, ?> cchm = toLocalCache(cache);

    int size = 0;
    for (Segment<?, ?> segment : cchm.segments) {
      size += writeQueueSize(segment);
    }
    return size;
  }

  static int writeQueueSize(Segment<?, ?> segment) {
    return segment.writeQueue.size();
  }

  static int accessQueueSize(Cache<?, ?> cache) {
    LocalCache<?, ?> cchm = toLocalCache(cache);
    int size = 0;
    for (Segment<?, ?> segment : cchm.segments) {
      size += accessQueueSize(segment);
    }
    return size;
  }

  static int accessQueueSize(Segment<?, ?> segment) {
    return segment.accessQueue.size();
  }

  static int expirationQueueSize(Cache<?, ?> cache) {
    return Math.max(accessQueueSize(cache), writeQueueSize(cache));
  }

  static void processPendingNotifications(Cache<?, ?> cache) {
    if (hasLocalCache(cache)) {
      LocalCache<?, ?> cchm = toLocalCache(cache);
      cchm.processPendingNotifications();
    }
  }

  interface Receiver<T> {
    void accept(@Nullable T object);
  }

  /**
   * Assuming the given cache has maximum size {@code maxSize}, this method populates the cache (by
   * getting a bunch of different keys), then makes sure all the items in the cache are also in the
   * eviction queue. It will invoke the given {@code operation} on the first element in the
   * eviction queue, and then reverify that all items in the cache are in the eviction queue, and
   * verify that the head of the eviction queue has changed as a result of the operation.
   */
  static void checkRecency(LoadingCache<Integer, Integer> cache, int maxSize,
      Receiver<ReferenceEntry operation) {
    checkNotNull(operation);
    if (hasLocalCache(cache)) {
      warmUp(cache, 0, 2 * maxSize);

      LocalCache<Integer, Integer> cchm = toLocalCache(cache);
      Segment<?, ?> segment = cchm.segments[0];
      drainRecencyQueue(segment);
      assertEquals(maxSize, accessQueueSize(cache));
      assertEquals(maxSize, cache.size());

      ReferenceEntry<?, ?> originalHead = segment.accessQueue.peek();
      @SuppressWarnings("unchecked")
      ReferenceEntry<Integer, Integer> entry = (ReferenceEntry) originalHead;
      operation.accept(entry);
      drainRecencyQueue(segment);

      assertNotSame(originalHead, segment.accessQueue.peek());
      assertEquals(cache.size(), accessQueueSize(cache));
    }
  }

  /**
   * Warms the given cache by getting all values in {@code [start, end)}, in order.
   */
  static void warmUp(LoadingCache<Integer, Integer> map, int start, int end) {
    checkNotNull(map);
    for (int i = start; i < end; i++) {
      map.getUnchecked(i);
    }
  }

  static void expireEntries(Cache<?, ?> cache, long expiringTime, FakeTicker ticker) {
    checkNotNull(ticker);
    expireEntries(toLocalCache(cache), expiringTime, ticker);
  }

  static void expireEntries(
      LocalCache<?, ?> cchm, long expiringTime, FakeTicker ticker) {

    for (Segment<?, ?> segment : cchm.segments) {
      drainRecencyQueue(segment);
    }

    ticker.advance(2 * expiringTime, TimeUnit.MILLISECONDS);

    long now = ticker.read();
    for (Segment<?, ?> segment : cchm.segments) {
      expireEntries(segment, now);
      assertEquals("Expiration queue must be empty by now", 0, writeQueueSize(segment));
      assertEquals("Expiration queue must be empty by now", 0, accessQueueSize(segment));
      assertEquals("Segments must be empty by now", 0, segmentSize(segment));
    }
    cchm.processPendingNotifications();
  }

  static void expireEntries(Segment<?, ?> segment, long now) {
    segment.lock();
    try {
      segment.expireEntries(now);
      segment.cleanUp();
    } finally {
      segment.unlock();
    }
  }
  static void checkEmpty(Cache<?, ?> cache) {
    assertEquals(0, cache.size());
    assertFalse(cache.asMap().containsKey(null));
    assertFalse(cache.asMap().containsKey(6));
    assertFalse(cache.asMap().containsValue(null));
    assertFalse(cache.asMap().containsValue(6));
    checkEmpty(cache.asMap());
  }

  static void checkEmpty(ConcurrentMap<?, ?> map) {
    checkEmpty(map.keySet());
    checkEmpty(map.values());
    checkEmpty(map.entrySet());
    assertEquals(ImmutableMap.of(), map);
    assertEquals(ImmutableMap.of().hashCode(), map.hashCode());
    assertEquals(ImmutableMap.of().toString(), map.toString());

    if (map instanceof LocalCache) {
      LocalCache<?, ?> cchm = (LocalCache) map;

      checkValidState(cchm);
      assertTrue(cchm.isEmpty());
      assertEquals(0, cchm.size());
      for (LocalCache.Segment<?, ?> segment : cchm.segments) {
        assertEquals(0, segment.count);
        assertEquals(0, segmentSize(segment));
        assertTrue(segment.writeQueue.isEmpty());
        assertTrue(segment.accessQueue.isEmpty());
      }
    }
  }

  static void checkEmpty(Collection<?> collection) {
    assertTrue(collection.isEmpty());
    assertEquals(0, collection.size());
    assertFalse(collection.iterator().hasNext());
    assertThat(collection.toArray()).isEmpty();
    assertThat(collection.toArray(new Object[0])).isEmpty();
    if (collection instanceof Set) {
      new EqualsTester()
          .addEqualityGroup(ImmutableSet.of(), collection)
          .addEqualityGroup(ImmutableSet.of(""))
          .testEquals();
    } else if (collection instanceof List) {
      new EqualsTester()
          .addEqualityGroup(ImmutableList.of(), collection)
          .addEqualityGroup(ImmutableList.of(""))
          .testEquals();
    }
  }
}

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