8176894: Provide specialized implementation for default methods putIf…

…Absent, computeIfAbsent, computeIfPresent, compute, merge in TreeMap

Co-authored-by: Sergey Kuksenko <sergey.kuksenko@oracle.com>
Reviewed-by: martin, stuefe, rriggs

src/java.base/share/classes/java/util/TreeMap.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2020, 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
@@ -29,6 +29,7 @@
 import java.util.function.BiConsumer;
 import java.util.function.BiFunction;
 import java.util.function.Consumer;
+import java.util.function.Function;
 
 /**
  * A Red-Black tree based {@link NavigableMap} implementation.
@@ -341,8 +342,7 @@ public void putAll(Map<? extends K, ? extends V> map) {
         // Offload comparator-based version for sake of performance
         if (comparator != null)
             return getEntryUsingComparator(key);
-        if (key == null)
-            throw new NullPointerException();
+        Objects.requireNonNull(key);
         @SuppressWarnings("unchecked")
             Comparable<? super K> k = (Comparable<? super K>) key;
         Entry<K,V> p = root;
@@ -531,15 +531,121 @@ else if (cmp > 0)
      *         does not permit null keys
      */
     public V put(K key, V value) {
+        return put(key, value, true);
+    }
+
+    @Override
+    public V putIfAbsent(K key, V value) {
+        return put(key, value, false);
+    }
+
+    /**
+     * {@inheritDoc}
+     *
+     * <p>This method will, on a best-effort basis, throw a
+     * {@link ConcurrentModificationException} if it is detected that the
+     * mapping function modifies this map during computation.
+     *
+     * @throws ConcurrentModificationException if it is detected that the
+     * mapping function modified this map
+     */
+    @Override
+    public V computeIfAbsent(K key, Function<? super K, ? extends V> mappingFunction) {
+        Objects.requireNonNull(mappingFunction);
+        V newValue;
         Entry<K,V> t = root;
         if (t == null) {
-            compare(key, key); // type (and possibly null) check
+            newValue = callMappingFunctionWithCheck(key, mappingFunction);
+            if (newValue != null) {
+                addEntryToEmptyMap(key, newValue);
+                return newValue;
+            } else {
+                return null;
+            }
+        }
+        int cmp;
+        Entry<K,V> parent;
+        // split comparator and comparable paths
+        Comparator<? super K> cpr = comparator;
+        if (cpr != null) {
+            do {
+                parent = t;
+                cmp = cpr.compare(key, t.key);
+                if (cmp < 0)
+                    t = t.left;
+                else if (cmp > 0)
+                    t = t.right;
+                else
+                    return t.value;
+            } while (t != null);
+        } else {
+            Objects.requireNonNull(key);
+            @SuppressWarnings("unchecked")
+            Comparable<? super K> k = (Comparable<? super K>) key;
+            do {
+                parent = t;
+                cmp = k.compareTo(t.key);
+                if (cmp < 0)
+                    t = t.left;
+                else if (cmp > 0)
+                    t = t.right;
+                else
+                    return t.value;
+            } while (t != null);
+        }
+        newValue = callMappingFunctionWithCheck(key, mappingFunction);
+        if (newValue != null) {
+            addEntry(key, newValue, parent, cmp < 0);
+            return newValue;
+        }
+        return null;
+    }
 
-            root = new Entry<>(key, value, null);
-            size = 1;
-            modCount++;
+    /**
+     * {@inheritDoc}
+     *
+     * <p>This method will, on a best-effort basis, throw a
+     * {@link ConcurrentModificationException} if it is detected that the
+     * remapping function modifies this map during computation.
+     *
+     * @throws ConcurrentModificationException if it is detected that the
+     * remapping function modified this map
+     */
+    @Override
+    public V computeIfPresent(K key, BiFunction<? super K, ? super V, ? extends V> remappingFunction) {
+        Objects.requireNonNull(remappingFunction);
+        Entry<K,V> oldEntry = getEntry(key);
+        if (oldEntry != null && oldEntry.value != null) {
+            return remapValue(oldEntry, key, remappingFunction);
+        } else {
             return null;
         }
+    }
+
+    /**
+     * {@inheritDoc}
+     *
+     * <p>This method will, on a best-effort basis, throw a
+     * {@link ConcurrentModificationException} if it is detected that the
+     * remapping function modifies this map during computation.
+     *
+     * @throws ConcurrentModificationException if it is detected that the
+     * remapping function modified this map
+     */
+    @Override
+    public V compute(K key, BiFunction<? super K, ? super V, ? extends V> remappingFunction) {
+        Objects.requireNonNull(remappingFunction);
+        V newValue;
+        Entry<K,V> t = root;
+        if (t == null) {
+            newValue = callRemappingFunctionWithCheck(key, null, remappingFunction);
+            if (newValue != null) {
+                addEntryToEmptyMap(key, newValue);
+                return newValue;
+            } else {
+                return null;
+            }
+        }
         int cmp;
         Entry<K,V> parent;
         // split comparator and comparable paths
@@ -553,14 +659,12 @@ public V put(K key, V value) {
                 else if (cmp > 0)
                     t = t.right;
                 else
-                    return t.setValue(value);
+                    return remapValue(t, key, remappingFunction);
             } while (t != null);
-        }
-        else {
-            if (key == null)
-                throw new NullPointerException();
+        } else {
+            Objects.requireNonNull(key);
             @SuppressWarnings("unchecked")
-                Comparable<? super K> k = (Comparable<? super K>) key;
+            Comparable<? super K> k = (Comparable<? super K>) key;
             do {
                 parent = t;
                 cmp = k.compareTo(t.key);
@@ -569,20 +673,188 @@ else if (cmp > 0)
                 else if (cmp > 0)
                     t = t.right;
                 else
-                    return t.setValue(value);
+                    return remapValue(t, key, remappingFunction);
             } while (t != null);
         }
+        newValue = callRemappingFunctionWithCheck(key, null, remappingFunction);
+        if (newValue != null) {
+            addEntry(key, newValue, parent, cmp < 0);
+            return newValue;
+        }
+        return null;
+    }
+
+    /**
+     * {@inheritDoc}
+     *
+     * <p>This method will, on a best-effort basis, throw a
+     * {@link ConcurrentModificationException} if it is detected that the
+     * remapping function modifies this map during computation.
+     *
+     * @throws ConcurrentModificationException if it is detected that the
+     * remapping function modified this map
+     */
+    @Override
+    public V merge(K key, V value, BiFunction<? super V, ? super V, ? extends V> remappingFunction) {
+        Objects.requireNonNull(remappingFunction);
+        Objects.requireNonNull(value);
+        Entry<K,V> t = root;
+        if (t == null) {
+            addEntryToEmptyMap(key, value);
+            return value;
+        }
+        int cmp;
+        Entry<K,V> parent;
+        // split comparator and comparable paths
+        Comparator<? super K> cpr = comparator;
+        if (cpr != null) {
+            do {
+                parent = t;
+                cmp = cpr.compare(key, t.key);
+                if (cmp < 0)
+                    t = t.left;
+                else if (cmp > 0)
+                    t = t.right;
+                else return mergeValue(t, value, remappingFunction);
+            } while (t != null);
+        } else {
+            Objects.requireNonNull(key);
+            @SuppressWarnings("unchecked")
+            Comparable<? super K> k = (Comparable<? super K>) key;
+            do {
+                parent = t;
+                cmp = k.compareTo(t.key);
+                if (cmp < 0)
+                    t = t.left;
+                else if (cmp > 0)
+                    t = t.right;
+                else return mergeValue(t, value, remappingFunction);
+            } while (t != null);
+        }
+        addEntry(key, value, parent, cmp < 0);
+        return value;
+    }
+
+    private V callMappingFunctionWithCheck(K key, Function<? super K, ? extends V> mappingFunction) {
+        int mc = modCount;
+        V newValue = mappingFunction.apply(key);
+        if (mc != modCount) {
+            throw new ConcurrentModificationException();
+        }
+        return newValue;
+    }
+
+    private V callRemappingFunctionWithCheck(K key, V oldValue, BiFunction<? super K, ? super V, ? extends V> remappingFunction) {
+        int mc = modCount;
+        V newValue = remappingFunction.apply(key, oldValue);
+        if (mc != modCount) {
+            throw new ConcurrentModificationException();
+        }
+        return newValue;
+    }
+
+    private void addEntry(K key, V value, Entry<K, V> parent, boolean addToLeft) {
         Entry<K,V> e = new Entry<>(key, value, parent);
-        if (cmp < 0)
+        if (addToLeft)
             parent.left = e;
         else
             parent.right = e;
         fixAfterInsertion(e);
         size++;
         modCount++;
+    }
+
+    private void addEntryToEmptyMap(K key, V value) {
+        compare(key, key); // type (and possibly null) check
+        root = new Entry<>(key, value, null);
+        size = 1;
+        modCount++;
+    }
+
+    private V put(K key, V value, boolean replaceOld) {
+        Entry<K,V> t = root;
+        if (t == null) {
+            addEntryToEmptyMap(key, value);
+            return null;
+        }
+        int cmp;
+        Entry<K,V> parent;
+        // split comparator and comparable paths
+        Comparator<? super K> cpr = comparator;
+        if (cpr != null) {
+            do {
+                parent = t;
+                cmp = cpr.compare(key, t.key);
+                if (cmp < 0)
+                    t = t.left;
+                else if (cmp > 0)
+                    t = t.right;
+                else {
+                    V oldValue = t.value;
+                    if (replaceOld || oldValue == null) {
+                        t.value = value;
+                    }
+                    return oldValue;
+                }
+            } while (t != null);
+        } else {
+            Objects.requireNonNull(key);
+            @SuppressWarnings("unchecked")
+            Comparable<? super K> k = (Comparable<? super K>) key;
+            do {
+                parent = t;
+                cmp = k.compareTo(t.key);
+                if (cmp < 0)
+                    t = t.left;
+                else if (cmp > 0)
+                    t = t.right;
+                else {
+                    V oldValue = t.value;
+                    if (replaceOld || oldValue == null) {
+                        t.value = value;
+                    }
+                    return oldValue;
+                }
+            } while (t != null);
+        }
+        addEntry(key, value, parent, cmp < 0);
         return null;
     }
 
+    private V remapValue(Entry<K,V> t, K key, BiFunction<? super K, ? super V, ? extends V> remappingFunction) {
+        V newValue = callRemappingFunctionWithCheck(key, t.value, remappingFunction);
+        if (newValue == null) {
+            deleteEntry(t);
+            return null;
+        } else {
+            // replace old mapping
+            t.value = newValue;
+            return newValue;
+        }
+    }
+
+    private V mergeValue(Entry<K,V> t, V value, BiFunction<? super V, ? super V, ? extends V> remappingFunction) {
+        V oldValue = t.value;
+        V newValue;
+        if (t.value == null) {
+            newValue = value;
+        } else {
+            int mc = modCount;
+            newValue = remappingFunction.apply(oldValue, value);
+            if (mc != modCount) {
+                throw new ConcurrentModificationException();
+            }
+        }
+        if (newValue == null) {
+            deleteEntry(t);
+            return null;
+        } else {
+            // replace old mapping
+            t.value = newValue;
+            return newValue;
+        }
+    }
+
     /**
      * Removes the mapping for this key from this TreeMap if present.
      *

test/jdk/java/util/Map/FunctionalCMEs.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2015, 2020, 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
@@ -30,6 +30,7 @@
 import java.util.Iterator;
 import java.util.LinkedHashMap;
 import java.util.Map;
+import java.util.TreeMap;
 import java.util.function.BiFunction;
 
 import org.testng.annotations.Test;
@@ -53,6 +54,7 @@
                 new Object[]{new HashMap<>(), true},
                 new Object[]{new Hashtable<>(), true},
                 new Object[]{new LinkedHashMap<>(), true},
+                new Object[]{new TreeMap<>(), true},
                 // Test default Map methods - no CME
                 new Object[]{new Defaults.ExtendsAbstractMap<>(), false}
         ).iterator();