8023463: Improvements to HashMap/LinkedHashMap use of bins/buckets and trees (red/black)

8012913: LinkedHashMap key/value/entry spliterators should report ORDERED
Reviewed-by: mduigou, forax, bchristi, alanb
Contributed-by: NDoug Lea &lt;dl@cs.oswego.edu&gt;, Paul Sandoz <paul.sandoz@oracle.com>

test/java/lang/reflect/Generics/Probe.java

@@ -50,9 +50,9 @@ import static java.util.Arrays.*;
           "java.util.HashMap$EntryIterator",
           "java.util.HashMap$KeyIterator",
           "java.util.HashMap$ValueIterator",
-          "java.util.LinkedHashMap$EntryIterator",
-          "java.util.LinkedHashMap$KeyIterator",
-          "java.util.LinkedHashMap$ValueIterator"})
+          "java.util.LinkedHashMap$LinkedEntryIterator",
+          "java.util.LinkedHashMap$LinkedKeyIterator",
+          "java.util.LinkedHashMap$LinkedValueIterator"})
 public class Probe {
     public static void main (String... args) throws Throwable {
         Classes classesAnnotation = (Probe.class).getAnnotation(Classes.class);

test/java/util/Map/CheckRandomHashSeed.java

@@ -53,8 +53,6 @@ public class CheckRandomHashSeed {
             throw new Error("Error in test setup: " + (expectRandom ? "" : "not " ) + "expecting random hashSeed, but " + PROP_NAME + " is " + (propSet ? "" : "not ") + "enabled");
         }
 
-        testMap(new HashMap());
-        testMap(new LinkedHashMap());
         testMap(new WeakHashMap());
         testMap(new Hashtable());
     }

test/java/util/Map/InPlaceOpsCollisions.java

@@ -25,7 +25,6 @@
  * @test
  * @bug 8005698
  * @run main InPlaceOpsCollisions -shortrun
- * @run main/othervm -Djdk.map.randomseed=true InPlaceOpsCollisions -shortrun
  * @summary Ensure overrides of in-place operations in Maps behave well with lots of collisions.
  * @author Brent Christian
  */

test/java/util/Map/MapBinToFromTreeTest.java

+/*
+ * Copyright (c) 2013, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+import org.testng.annotations.DataProvider;
+import org.testng.annotations.Test;
+
+import java.util.Collection;
+import java.util.HashMap;
+import java.util.LinkedHashMap;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.function.BiConsumer;
+import java.util.stream.Collector;
+import java.util.stream.Collectors;
+import java.util.stream.IntStream;
+
+import static org.testng.Assert.assertEquals;
+
+/*
+ * @test
+ * @bug 8023463
+ * @summary Test the case where a bin is treeified and vice verser
+ * @run testng MapBinToFromTreeTest
+ */
+
+@Test
+public class MapBinToFromTreeTest {
+
+    // Initial capacity of map
+    // Should be >= the map capacity for treeifiying, see HashMap/ConcurrentMap.MIN_TREEIFY_CAPACITY
+    static final int INITIAL_CAPACITY = 64;
+
+    // Maximum size of map
+    // Should be > the treeify threshold, see HashMap/ConcurrentMap.TREEIFY_THRESHOLD
+    // Should be > INITIAL_CAPACITY to ensure resize occurs
+    static final int SIZE = 256;
+
+    // Load factor of map
+    // A value 1.0 will ensure that a new threshold == capacity
+    static final float LOAD_FACTOR = 1.0f;
+
+    @DataProvider(name = "maps")
+    static Object[][] mapProvider() {
+        return new Object[][] {
+                // Pass in the class name as a description for test reporting
+                // purposes
+                { HashMap.class.getName(), new HashMap(INITIAL_CAPACITY, LOAD_FACTOR) },
+                { LinkedHashMap.class.getName(), new LinkedHashMap(INITIAL_CAPACITY, LOAD_FACTOR) },
+                { ConcurrentHashMap.class.getName(), new ConcurrentHashMap(INITIAL_CAPACITY, LOAD_FACTOR) },
+        };
+    }
+
+    @Test(dataProvider = "maps")
+    public void testPutThenGet(String d, Map<HashCodeInteger, Integer> m) {
+        put(SIZE, m, (i, s) -> {
+            for (int j = 0; j < s; j++) {
+                assertEquals(m.get(new HashCodeInteger(j)).intValue(), j,
+                             String.format("Map.get(%d)", j));
+            }
+        });
+    }
+
+    @Test(dataProvider = "maps")
+    public void testPutThenTraverse(String d, Map<HashCodeInteger, Integer> m) {
+        Collector<Integer, ?, ? extends Collection<Integer>> c = getCollector(m);
+
+        put(SIZE, m, (i, s) -> {
+            // Note that it is OK to collect to a Set (HashSet) as long as
+            // integer values are used since these tests only check for
+            // collisions and other tests will verify more general functionality
+            Collection<Integer> actual = m.keySet().stream().map(e -> e.value).collect(c);
+            Collection<Integer> expected = IntStream.range(0, s).boxed().collect(c);
+            assertEquals(actual, expected, "Map.keySet()");
+        });
+    }
+
+    @Test(dataProvider = "maps")
+    public void testRemoveThenGet(String d, Map<HashCodeInteger, Integer> m) {
+        put(SIZE, m, (i, s) -> { });
+
+        remove(m, (i, s) -> {
+            for (int j = i + 1; j < SIZE; j++) {
+                assertEquals(m.get(new HashCodeInteger(j)).intValue(), j,
+                             String.format("Map.get(%d)", j));
+            }
+        });
+    }
+
+    @Test(dataProvider = "maps")
+    public void testRemoveThenTraverse(String d, Map<HashCodeInteger, Integer> m) {
+        put(SIZE, m, (i, s) -> { });
+
+        Collector<Integer, ?, ? extends Collection<Integer>> c = getCollector(m);
+
+        remove(m, (i, s) -> {
+            Collection<Integer> actual = m.keySet().stream().map(e -> e.value).collect(c);
+            Collection<Integer> expected = IntStream.range(i + 1, SIZE).boxed().collect(c);
+            assertEquals(actual, expected, "Map.keySet()");
+        });
+    }
+
+    @Test(dataProvider = "maps")
+    public void testUntreeifyOnResizeWithGet(String d, Map<HashCodeInteger, Integer> m) {
+        // Fill the map with 64 entries grouped into 4 buckets
+        put(INITIAL_CAPACITY, m, (i, s) -> { });
+
+        for (int i = INITIAL_CAPACITY; i < SIZE; i++) {
+            // Add further entries in the 0'th bucket so as not to disturb
+            // other buckets, entries of which may be distributed and/or
+            // the bucket untreeified on resize
+            m.put(new HashCodeInteger(i, 0), i);
+
+            for (int j = 0; j < INITIAL_CAPACITY; j++) {
+                assertEquals(m.get(new HashCodeInteger(j)).intValue(), j,
+                             String.format("Map.get(%d) < INITIAL_CAPACITY", j));
+            }
+            for (int j = INITIAL_CAPACITY; j <= i; j++) {
+                assertEquals(m.get(new HashCodeInteger(j, 0)).intValue(), j,
+                             String.format("Map.get(%d) >= INITIAL_CAPACITY", j));
+            }
+        }
+    }
+
+    @Test(dataProvider = "maps")
+    public void testUntreeifyOnResizeWithTraverse(String d, Map<HashCodeInteger, Integer> m) {
+        // Fill the map with 64 entries grouped into 4 buckets
+        put(INITIAL_CAPACITY, m, (i, s) -> { });
+
+        Collector<Integer, ?, ? extends Collection<Integer>> c = getCollector(m);
+
+        for (int i = INITIAL_CAPACITY; i < SIZE; i++) {
+            // Add further entries in the 0'th bucket so as not to disturb
+            // other buckets, entries of which may be distributed and/or
+            // the bucket untreeified on resize
+            m.put(new HashCodeInteger(i, 0), i);
+
+            Collection<Integer> actual = m.keySet().stream().map(e -> e.value).collect(c);
+            Collection<Integer> expected = IntStream.rangeClosed(0, i).boxed().collect(c);
+            assertEquals(actual, expected, "Key set");
+        }
+    }
+
+    Collector<Integer, ?, ? extends Collection<Integer>> getCollector(Map<?, ?> m) {
+        Collector<Integer, ?, ? extends Collection<Integer>> collector = m instanceof LinkedHashMap
+                                                                         ? Collectors.toList()
+                                                                         : Collectors.toSet();
+        return collector;
+    }
+
+    void put(int size, Map<HashCodeInteger, Integer> m, BiConsumer<Integer, Integer> c) {
+        for (int i = 0; i < size; i++) {
+            m.put(new HashCodeInteger(i), i);
+
+            c.accept(i, m.size());
+        }
+    }
+
+    void remove(Map<HashCodeInteger, Integer> m, BiConsumer<Integer, Integer> c) {
+        int size = m.size();
+        // Remove all elements thus ensuring at some point trees will be
+        // converting back to bins
+        for (int i = 0; i < size; i++) {
+            m.remove(new HashCodeInteger(i));
+
+            c.accept(i, m.size());
+        }
+    }
+
+    final static class HashCodeInteger implements Comparable<HashCodeInteger> {
+        final int value;
+
+        final int hashcode;
+
+        HashCodeInteger(int value) {
+            this(value, hash(value));
+        }
+
+        HashCodeInteger(int value, int hashcode) {
+            this.value = value;
+            this.hashcode = hashcode;
+        }
+
+        static int hash(int i) {
+            // Assuming 64 entries with keys from 0 to 63 then a map:
+            // - of capacity 64 will have 4 buckets with 16 entries per-bucket
+            // - of capacity 128 will have 8 buckets with 8 entries per-bucket
+            // - of capacity 256 will have 16 buckets with 4 entries per-bucket
+            //
+            // Re-sizing will result in re-distribution, doubling the buckets
+            // and reducing the entries by half. This will result in
+            // untreeifying when the number of entries is less than untreeify
+            // threshold (see HashMap/ConcurrentMap.UNTREEIFY_THRESHOLD)
+            return (i % 4) + (i / 4) * INITIAL_CAPACITY;
+        }
+
+        @Override
+        public boolean equals(Object obj) {
+            if (obj instanceof HashCodeInteger) {
+                HashCodeInteger other = (HashCodeInteger) obj;
+                return other.value == value;
+            }
+            return false;
+        }
+
+        @Override
+        public int hashCode() {
+            return hashcode;
+        }
+
+        @Override
+        public int compareTo(HashCodeInteger o) {
+            return value - o.value;
+        }
+
+        @Override
+        public String toString() {
+            return Integer.toString(value);
+        }
+    }
+}