--- old/src/java.base/share/classes/java/util/TreeMap.java	2017-03-17 12:36:26.816171045 -0700
+++ new/src/java.base/share/classes/java/util/TreeMap.java	2017-03-17 12:36:26.632171037 -0700
@@ -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.
@@ -531,17 +532,35 @@
      *         does not permit null keys
      */
     public V put(K key, V value) {
-        Entry<K,V> t = root;
-        if (t == null) {
-            compare(key, key); // type (and possibly null) check
+        return put(key, value, true);
+    }
+
+    private void addEntry(K key, V value, int cmp, Entry<K, V> parent) {
+        Entry<K, V> e = new Entry<>(key, value, parent);
+        if (cmp < 0)
+            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++;
+    }
 
-            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;
+        Entry<K, V> parent;
         // split comparator and comparable paths
         Comparator<? super K> cpr = comparator;
         if (cpr != null) {
@@ -552,15 +571,203 @@
                     t = t.left;
                 else if (cmp > 0)
                     t = t.right;
+                else {
+                    V oldValue = t.value;
+                    if (replaceOld) {
+                        t.value = value;
+                    }
+                    return oldValue;
+                }
+            } while (t != null);
+        } else {
+            if (key == null)
+                throw new NullPointerException();
+            @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) {
+                        t.value = value;
+                    }
+                    return oldValue;
+                }
+            } while (t != null);
+        }
+        addEntry(key, value, cmp, parent);
+        return null;
+    }
+
+    @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
+     * remapping function modifies this map during computation.
+     *
+     * @throws ConcurrentModificationException if it is detected that the
+     * remapping 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) {
+            newValue = getNewValueAndCheckModification(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 {
+            if (key == null)
+                throw new NullPointerException();
+            @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.setValue(value);
+                    return t.value;
             } while (t != null);
         }
-        else {
+        newValue = getNewValueAndCheckModification(key, mappingFunction);
+        if (newValue != null) {
+            addEntry(key, newValue, cmp, parent);
+            return newValue;
+        }
+        return null;
+    }
+
+    private V getNewValueAndCheckModification(K key, Function<? super K, ? extends V> mappingFunction) {
+        V newValue;
+        int mc = modCount;
+        newValue = mappingFunction.apply(key);
+        if (mc != modCount) {
+            throw new ConcurrentModificationException();
+        }
+        return newValue;
+    }
+
+    /**
+     * {@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;
+        }
+    }
+
+    private V remapValue(Entry<K, V> t, K key, BiFunction<? super K, ? super V, ? extends V> remappingFunction) {
+        V newValue = getNewValueAndCheckModification(key, t.value, remappingFunction);
+        if (newValue == null) {
+            deleteEntry(t);
+            return null;
+        } else {
+            // replace old mapping
+            t.value = newValue;
+            return newValue;
+        }
+    }
+
+    private V getNewValueAndCheckModification(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;
+    }
+
+    /**
+     * {@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 = getNewValueAndCheckModification(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
+        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 remapValue(t, key, remappingFunction);
+            } while (t != null);
+        } else {
             if (key == null)
                 throw new NullPointerException();
             @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);
@@ -569,17 +776,14 @@
                 else if (cmp > 0)
                     t = t.right;
                 else
-                    return t.setValue(value);
+                    return remapValue(t, key, remappingFunction);
             } while (t != null);
         }
-        Entry<K,V> e = new Entry<>(key, value, parent);
-        if (cmp < 0)
-            parent.left = e;
-        else
-            parent.right = e;
-        fixAfterInsertion(e);
-        size++;
-        modCount++;
+        newValue = getNewValueAndCheckModification(key, null, remappingFunction);
+        if (newValue != null) {
+            addEntry(key, newValue, cmp, parent);
+            return newValue;
+        }
         return null;
     }