diff -r 2954aa6b7e34 -r bb827716b9b9 jdk/src/share/classes/java/util/IdentityHashMap.java --- a/jdk/src/share/classes/java/util/IdentityHashMap.java Fri Jul 11 14:06:42 2014 -0700 +++ b/jdk/src/share/classes/java/util/IdentityHashMap.java Sat Jul 12 04:15:56 2014 +0400 @@ -1,5 +1,5 @@ /* - * Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved. + * Copyright (c) 2000, 2014, 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 @@ -25,7 +25,6 @@ package java.util; -import java.io.*; import java.lang.reflect.Array; import java.util.function.BiConsumer; import java.util.function.BiFunction; @@ -74,7 +73,7 @@ * maximum size and the number of buckets is unspecified. * *

If the size of the map (the number of key-value mappings) sufficiently - * exceeds the expected maximum size, the number of buckets is increased + * exceeds the expected maximum size, the number of buckets is increased. * Increasing the number of buckets ("rehashing") may be fairly expensive, so * it pays to create identity hash maps with a sufficiently large expected * maximum size. On the other hand, iteration over collection views requires @@ -160,6 +159,10 @@ * The maximum capacity, used if a higher value is implicitly specified * by either of the constructors with arguments. * MUST be a power of two <= 1<<29. + * + * In fact, the map can hold no more than MAXIMUM_CAPACITY-1 items + * because it has to have at least one slot with the key == null + * in order to avoid infinite loops in get(), put(), remove() */ private static final int MAXIMUM_CAPACITY = 1 << 29; @@ -181,11 +184,6 @@ transient int modCount; /** - * The next size value at which to resize (capacity * load factor). - */ - private transient int threshold; - - /** * Value representing null keys inside tables. */ static final Object NULL_KEY = new Object(); @@ -229,27 +227,18 @@ } /** - * Returns the appropriate capacity for the specified expected maximum - * size. Returns the smallest power of two between MINIMUM_CAPACITY - * and MAXIMUM_CAPACITY, inclusive, that is greater than - * (3 * expectedMaxSize)/2, if such a number exists. Otherwise - * returns MAXIMUM_CAPACITY. If (3 * expectedMaxSize)/2 is negative, it - * is assumed that overflow has occurred, and MAXIMUM_CAPACITY is returned. + * Returns the appropriate capacity for the given expected maximum size. + * Returns the smallest power of two between MINIMUM_CAPACITY and + * MAXIMUM_CAPACITY, inclusive, that is greater than (3 * + * expectedMaxSize)/2, if such a number exists. Otherwise returns + * MAXIMUM_CAPACITY. */ - private int capacity(int expectedMaxSize) { - // Compute min capacity for expectedMaxSize given a load factor of 2/3 - int minCapacity = (3 * expectedMaxSize)/2; - - // Compute the appropriate capacity - int result; - if (minCapacity > MAXIMUM_CAPACITY || minCapacity < 0) { - result = MAXIMUM_CAPACITY; - } else { - result = MINIMUM_CAPACITY; - while (result < minCapacity) - result <<= 1; - } - return result; + private static int capacity(int expectedMaxSize) { + // assert expectedMaxSize >= 0; + return + (expectedMaxSize > MAXIMUM_CAPACITY / 3) ? MAXIMUM_CAPACITY : + (expectedMaxSize <= 2 * MINIMUM_CAPACITY / 3) ? MINIMUM_CAPACITY : + Integer.highestOneBit(expectedMaxSize + (expectedMaxSize << 1)); } /** @@ -262,7 +251,6 @@ // assert initCapacity >= MINIMUM_CAPACITY; // assert initCapacity <= MAXIMUM_CAPACITY; - threshold = (initCapacity * 2)/3; table = new Object[2 * initCapacity]; } @@ -429,52 +417,58 @@ * @see #containsKey(Object) */ public V put(K key, V value) { - Object k = maskNull(key); - Object[] tab = table; - int len = tab.length; - int i = hash(k, len); + final Object k = maskNull(key); + + retryAfterResize: for (;;) { + final Object[] tab = table; + final int len = tab.length; + int i = hash(k, len); - Object item; - while ( (item = tab[i]) != null) { - if (item == k) { - @SuppressWarnings("unchecked") - V oldValue = (V) tab[i + 1]; - tab[i + 1] = value; - return oldValue; + for (Object item; (item = tab[i]) != null; + i = nextKeyIndex(i, len)) { + if (item == k) { + @SuppressWarnings("unchecked") + V oldValue = (V) tab[i + 1]; + tab[i + 1] = value; + return oldValue; + } } - i = nextKeyIndex(i, len); - } + + final int s = size + 1; + // Use optimized form of 3 * s. + // Next capacity is len, 2 * current capacity. + if (s + (s << 1) > len && resize(len)) + continue retryAfterResize; - modCount++; - tab[i] = k; - tab[i + 1] = value; - if (++size >= threshold) - resize(len); // len == 2 * current capacity. - return null; + modCount++; + tab[i] = k; + tab[i + 1] = value; + size = s; + return null; + } } /** - * Resize the table to hold given capacity. + * Resizes the table if necessary to hold given capacity. * * @param newCapacity the new capacity, must be a power of two. + * @return whether a resize did in fact take place */ - private void resize(int newCapacity) { + private boolean resize(int newCapacity) { // assert (newCapacity & -newCapacity) == newCapacity; // power of 2 int newLength = newCapacity * 2; Object[] oldTable = table; int oldLength = oldTable.length; - if (oldLength == 2*MAXIMUM_CAPACITY) { // can't expand any further - if (threshold == MAXIMUM_CAPACITY-1) + if (oldLength == 2 * MAXIMUM_CAPACITY) { // can't expand any further + if (size == MAXIMUM_CAPACITY - 1) throw new IllegalStateException("Capacity exhausted."); - threshold = MAXIMUM_CAPACITY-1; // Gigantic map! - return; + return false; } if (oldLength >= newLength) - return; + return false; Object[] newTable = new Object[newLength]; - threshold = newLength / 3; for (int j = 0; j < oldLength; j += 2) { Object key = oldTable[j]; @@ -490,6 +484,7 @@ } } table = newTable; + return true; } /** @@ -504,8 +499,8 @@ int n = m.size(); if (n == 0) return; - if (n > threshold) // conservatively pre-expand - resize(capacity(n)); + if (n > size) + resize(capacity(n)); // conservatively pre-expand for (Entry e : m.entrySet()) put(e.getKey(), e.getValue()); @@ -542,7 +537,6 @@ return null; i = nextKeyIndex(i, len); } - } /** @@ -1266,8 +1260,8 @@ private static final long serialVersionUID = 8188218128353913216L; /** - * Save the state of the IdentityHashMap instance to a stream - * (i.e., serialize it). + * Saves the state of the IdentityHashMap instance to a stream + * (i.e., serializes it). * * @serialData The size of the HashMap (the number of key-value * mappings) (int), followed by the key (Object) and @@ -1295,8 +1289,8 @@ } /** - * Reconstitute the IdentityHashMap instance from a stream (i.e., - * deserialize it). + * Reconstitutes the IdentityHashMap instance from a stream (i.e., + * deserializes it). */ private void readObject(java.io.ObjectInputStream s) throws java.io.IOException, ClassNotFoundException { @@ -1305,9 +1299,10 @@ // Read in size (number of Mappings) int size = s.readInt(); - - // Allow for 33% growth (i.e., capacity is >= 2* size()). - init(capacity((size*4)/3)); + if (size < 0) + throw new java.io.StreamCorruptedException + ("Illegal mappings count: " + size); + init(capacity(size)); // Read the keys and values, and put the mappings in the table for (int i=0; i