src/share/classes/java/util/concurrent/ConcurrentMap.java

rev 7360 : 8016446: Improve forEach/replaceAll for Map, HashMap, Hashtable, IdentityHashMap, WeakHashMap, TreeMap
Reviewed-by: forax, duigou, psandoz
Contributed-by: Mike Duigou <mike.duigou@oracle.com>, Remi Forax <forax@univ-mlv.fr>

*** 33,42 ****
--- 33,44 ----
   * http://creativecommons.org/publicdomain/zero/1.0/
   */
  
  package java.util.concurrent;
  import java.util.Map;
+ import java.util.Objects;
+ import java.util.function.BiFunction;
  
  /**
   * A {@link java.util.Map} providing additional atomic
   * {@code putIfAbsent}, {@code remove}, and {@code replace} methods.
   *
*** 181,186 ****
--- 183,220 ----
       *         and this map does not permit null keys or values
       * @throws IllegalArgumentException if some property of the specified key
       *         or value prevents it from being stored in this map
       */
      V replace(K key, V value);
+ 
+     /**
+      * {@inheritDoc}
+      *
+      * @implNote This implementation assumes that the ConcurrentMap cannot
+      * contain null values and get() returning null unambiguously means the key
+      * is absent. Implementations which support null values
+      * <strong>must</strong> override this default implementation.
+      */
+     @Override
+     default void replaceAll(BiFunction<? super K, ? super V, ? extends V> function) {
+         Objects.requireNonNull(function);
+         for (Map.Entry<K, V> entry : entrySet()) {
+             K k;
+             V v;
+             try {
+                 k = entry.getKey();
+                 v = entry.getValue();
+             } catch(IllegalStateException ise) {
+                 // this usually means the entry is no longer in the map.
+                 continue;
+             }
+ 
+             while(!replace(k, v, function.apply(k, v))) {
+                 // v changed or k is gone
+                 if( (v = get(k)) == null) {
+                     // k is no longer in the map.
+                     break;
+                 }
+             }
+         }
+     }
  }