core/test/com/google/inject/internal/util/Jsr166HashMap.java

/*
 * Written by Doug Lea with assistance from members of JCP JSR-166
 * Expert Group and released to the public domain, as explained at
 * http://creativecommons.org/licenses/publicdomain
 * Other contributors include Andrew Wright, Jeffrey Hayes,
 * Pat Fisher, Mike Judd.
 */

package com.google.inject.internal.util;

import com.google.inject.internal.util.ForwardingConcurrentMap;
import com.google.inject.internal.util.CustomConcurrentHashMap;
import java.io.Serializable;
import java.util.Map;
import java.util.concurrent.ConcurrentMap;

/**
 * A copy of {@link java.util.concurrent.ConcurrentHashMap} used to test {@link
 * com.google.inject.internal.util.CustomConcurrentHashMap}. This also serves
 * as the examples in the CustomConcurrentHashMap Javadocs.
 */
public class Jsr166HashMap<K, V> extends ForwardingConcurrentMap<K, V>
    implements Serializable {

  static class ConcurrentHashMapStrategy<K, V>
      implements CustomConcurrentHashMap.Strategy<K, V,
      InternalEntry<K, V>>, Serializable {
    public InternalEntry<K, V> newEntry(K key, int hash,
        InternalEntry<K, V> next) {
      return new InternalEntry<K,V>(key, hash, null, next);
    }
    public InternalEntry<K, V> copyEntry(K key,
        InternalEntry<K, V> original, InternalEntry<K, V> next) {
      return new InternalEntry<K, V>(key, original.hash, original.value, next);
    }
    public void setValue(InternalEntry<K, V> entry, V value) {
      entry.value = value;
    }
    public V getValue(InternalEntry<K, V> entry) { return entry.value; }
    public boolean equalKeys(K a, Object b) { return a.equals(b); }
    public boolean equalValues(V a, Object b) { return a.equals(b); }
    public int hashKey(Object key) { return key.hashCode(); }
    public K getKey(InternalEntry<K, V> entry) { return entry.key; }
    public InternalEntry<K, V> getNext(InternalEntry<K, V> entry) {
      return entry.next;
    }
    public int getHash(InternalEntry<K, V> entry) { return entry.hash; }
    public void setInternals(CustomConcurrentHashMap.Internals<K, V,
        InternalEntry<K, V>> internals) {} // ignored
  }

  static class InternalEntry<K, V> {
    final K key;
    final int hash;
    final InternalEntry<K, V> next;
    volatile V value;
    InternalEntry(K key, int hash, V value, InternalEntry<K, V> next) {
      this.key = key;
      this.hash = hash;
      this.value = value;
      this.next = next;
    }
  }

  /* ---------------- Public operations -------------- */

  /**
   * The default initial capacity for this table,
   * used when not otherwise specified in a constructor.
   */
  static final int DEFAULT_INITIAL_CAPACITY = 16;

  /**
   * The default load factor for this table, used when not
   * otherwise specified in a constructor.
   */
  static final float DEFAULT_LOAD_FACTOR = 0.75f;

  /**
   * The default concurrency level for this table, used when not
   * otherwise specified in a constructor.
   */
  static final int DEFAULT_CONCURRENCY_LEVEL = 16;

  final ConcurrentMap<K, V> delegate;

  protected ConcurrentMap<K, V> delegate() {
    return delegate;
  }

  /**
   * Creates a new, empty map with the specified initial capacity, load factor
   * and concurrency level.
   *
   * @param initialCapacity  the initial capacity. The implementation performs
   *                         internal sizing to accommodate this many
   *                         elements.
   * @param loadFactor       the load factor threshold, used to control
   *                         resizing. Resizing may be performed when the
   *                         average number of elements per bin exceeds this
   *                         threshold.
   * @param concurrencyLevel the estimated number of concurrently updating
   *                         threads. The implementation performs internal
   *                         sizing to try to accommodate this many threads.
   * @throws IllegalArgumentException if the initial capacity is negative or
   *                                  the load factor or concurrencyLevel are
   *                                  nonpositive.
   */
  public Jsr166HashMap(int initialCapacity,
      float loadFactor, int concurrencyLevel) {
    this.delegate = new CustomConcurrentHashMap.Builder()
        .initialCapacity(initialCapacity)
        .loadFactor(loadFactor)
        .concurrencyLevel(concurrencyLevel)
        .buildMap(new ConcurrentHashMapStrategy<K, V>());
  }

  /**
   * Creates a new, empty map with the specified initial capacity and load
   * factor and with the default concurrencyLevel (16).
   *
   * @param initialCapacity The implementation performs internal sizing to
   *                        accommodate this many elements.
   * @param loadFactor      the load factor threshold, used to control
   *                        resizing. Resizing may be performed when the
   *                        average number of elements per bin exceeds this
   *                        threshold.
   * @throws IllegalArgumentException if the initial capacity of elements is
   *                                  negative or the load factor is
   *                                  nonpositive
   * @since 1.6
   */
  public Jsr166HashMap(int initialCapacity, float loadFactor) {
    this(initialCapacity, loadFactor, DEFAULT_CONCURRENCY_LEVEL);
  }

  /**
   * Creates a new, empty map with the specified initial capacity, and with
   * default load factor (0.75) and concurrencyLevel (16).
   *
   * @param initialCapacity the initial capacity. The implementation performs
   *                        internal sizing to accommodate this many
   *                        elements.
   * @throws IllegalArgumentException if the initial capacity of elements is
   *                                  negative.
   */
  public Jsr166HashMap(int initialCapacity) {
    this(initialCapacity, DEFAULT_LOAD_FACTOR, DEFAULT_CONCURRENCY_LEVEL);
  }

  /**
   * Creates a new, empty map with a default initial capacity (16), load
   * factor (0.75) and concurrencyLevel (16).
   */
  public Jsr166HashMap() {
    this(DEFAULT_INITIAL_CAPACITY, DEFAULT_LOAD_FACTOR,
        DEFAULT_CONCURRENCY_LEVEL);
  }

  /**
   * Creates a new map with the same mappings as the given map. The map is
   * created with a capacity of 1.5 times the number of mappings in the given
   * map or 16 (whichever is greater), and a default load factor (0.75) and
   * concurrencyLevel (16).
   *
   * @param m the map
   */
  public Jsr166HashMap(Map<? extends K, ? extends V> m) {
    this(Math.max((int) (m.size() / DEFAULT_LOAD_FACTOR) + 1,
        DEFAULT_INITIAL_CAPACITY),
        DEFAULT_LOAD_FACTOR, DEFAULT_CONCURRENCY_LEVEL);
    putAll(m);
  }
}