| 236 |
|
* @param <K> the type of keys maintained by this map |
| 237 |
|
* @param <V> the type of mapped values |
| 238 |
|
*/ |
| 239 |
< |
public class ConcurrentHashMap<K,V> extends AbstractMap<K,V> implements ConcurrentMap<K,V>, Serializable { |
| 239 |
> |
public class ConcurrentHashMap<K,V> extends AbstractMap<K,V> |
| 240 |
> |
implements ConcurrentMap<K,V>, Serializable { |
| 241 |
|
private static final long serialVersionUID = 7249069246763182397L; |
| 242 |
|
|
| 243 |
|
/* |
| 411 |
|
* related operations (which is the main reason we cannot use |
| 412 |
|
* existing collections such as TreeMaps). TreeBins contain |
| 413 |
|
* Comparable elements, but may contain others, as well as |
| 414 |
< |
* elements that are Comparable but not necessarily Comparable |
| 415 |
< |
* for the same T, so we cannot invoke compareTo among them. To |
| 416 |
< |
* handle this, the tree is ordered primarily by hash value, then |
| 417 |
< |
* by Comparable.compareTo order if applicable. On lookup at a |
| 418 |
< |
* node, if elements are not comparable or compare as 0 then both |
| 419 |
< |
* left and right children may need to be searched in the case of |
| 420 |
< |
* tied hash values. (This corresponds to the full list search |
| 421 |
< |
* that would be necessary if all elements were non-Comparable and |
| 422 |
< |
* had tied hashes.) The red-black balancing code is updated from |
| 423 |
< |
* pre-jdk-collections |
| 414 |
> |
* elements that are Comparable but not necessarily Comparable for |
| 415 |
> |
* the same T, so we cannot invoke compareTo among them. To handle |
| 416 |
> |
* this, the tree is ordered primarily by hash value, then by |
| 417 |
> |
* Comparable.compareTo order if applicable. On lookup at a node, |
| 418 |
> |
* if elements are not comparable or compare as 0 then both left |
| 419 |
> |
* and right children may need to be searched in the case of tied |
| 420 |
> |
* hash values. (This corresponds to the full list search that |
| 421 |
> |
* would be necessary if all elements were non-Comparable and had |
| 422 |
> |
* tied hashes.) On insertion, to keep a total ordering (or as |
| 423 |
> |
* close as is required here) across rebalancings, we compare |
| 424 |
> |
* classes and identityHashCodes as tie-breakers. The red-black |
| 425 |
> |
* balancing code is updated from pre-jdk-collections |
| 426 |
|
* (http://gee.cs.oswego.edu/dl/classes/collections/RBCell.java) |
| 427 |
|
* based in turn on Cormen, Leiserson, and Rivest "Introduction to |
| 428 |
|
* Algorithms" (CLR). |
| 452 |
|
* unused "Segment" class that is instantiated in minimal form |
| 453 |
|
* only when serializing. |
| 454 |
|
* |
| 455 |
+ |
* Also, solely for compatibility with previous versions of this |
| 456 |
+ |
* class, it extends AbstractMap, even though all of its methods |
| 457 |
+ |
* are overridden, so it is just useless baggage. |
| 458 |
+ |
* |
| 459 |
|
* This file is organized to make things a little easier to follow |
| 460 |
|
* while reading than they might otherwise: First the main static |
| 461 |
|
* declarations and utilities, then fields, then main public |
| 2627 |
|
p = pr; |
| 2628 |
|
else if ((pk = p.key) == k || (pk != null && k.equals(pk))) |
| 2629 |
|
return p; |
| 2630 |
< |
else if (pl == null && pr == null) |
| 2631 |
< |
break; |
| 2630 |
> |
else if (pl == null) |
| 2631 |
> |
p = pr; |
| 2632 |
> |
else if (pr == null) |
| 2633 |
> |
p = pl; |
| 2634 |
|
else if ((kc != null || |
| 2635 |
|
(kc = comparableClassFor(k)) != null) && |
| 2636 |
|
(dir = compareComparables(kc, k, pk)) != 0) |
| 2637 |
|
p = (dir < 0) ? pl : pr; |
| 2638 |
< |
else if (pl == null) |
| 2630 |
< |
p = pr; |
| 2631 |
< |
else if (pr == null || |
| 2632 |
< |
(q = pr.findTreeNode(h, k, kc)) == null) |
| 2633 |
< |
p = pl; |
| 2634 |
< |
else |
| 2638 |
> |
else if ((q = pr.findTreeNode(h, k, kc)) != null) |
| 2639 |
|
return q; |
| 2640 |
+ |
else |
| 2641 |
+ |
p = pl; |
| 2642 |
|
} while (p != null); |
| 2643 |
|
} |
| 2644 |
|
return null; |
| 2665 |
|
static final int READER = 4; // increment value for setting read lock |
| 2666 |
|
|
| 2667 |
|
/** |
| 2668 |
+ |
* Tie-breaking utility for ordering insertions when equal |
| 2669 |
+ |
* hashCodes and non-comparable. We don't require a total |
| 2670 |
+ |
* order, just a consistent insertion rule to maintain |
| 2671 |
+ |
* equivalence across rebalancings. Tie-breaking further than |
| 2672 |
+ |
* necessary simplifies testing a bit. |
| 2673 |
+ |
*/ |
| 2674 |
+ |
static int tieBreakOrder(Object a, Object b) { |
| 2675 |
+ |
int d; |
| 2676 |
+ |
if (a == null || b == null || |
| 2677 |
+ |
(d = a.getClass().getName(). |
| 2678 |
+ |
compareTo(b.getClass().getName())) == 0) |
| 2679 |
+ |
d = (System.identityHashCode(a) <= System.identityHashCode(b) ? |
| 2680 |
+ |
-1 : 1); |
| 2681 |
+ |
return d; |
| 2682 |
+ |
} |
| 2683 |
+ |
|
| 2684 |
+ |
/** |
| 2685 |
|
* Creates bin with initial set of nodes headed by b. |
| 2686 |
|
*/ |
| 2687 |
|
TreeBin(TreeNode<K,V> b) { |
| 2697 |
|
r = x; |
| 2698 |
|
} |
| 2699 |
|
else { |
| 2700 |
< |
Object key = x.key; |
| 2701 |
< |
int hash = x.hash; |
| 2700 |
> |
K k = x.key; |
| 2701 |
> |
int h = x.hash; |
| 2702 |
|
Class<?> kc = null; |
| 2703 |
|
for (TreeNode<K,V> p = r;;) { |
| 2704 |
|
int dir, ph; |
| 2705 |
< |
if ((ph = p.hash) > hash) |
| 2705 |
> |
K pk = p.key; |
| 2706 |
> |
if ((ph = p.hash) > h) |
| 2707 |
|
dir = -1; |
| 2708 |
< |
else if (ph < hash) |
| 2708 |
> |
else if (ph < h) |
| 2709 |
|
dir = 1; |
| 2710 |
< |
else if ((kc != null || |
| 2711 |
< |
(kc = comparableClassFor(key)) != null)) |
| 2712 |
< |
dir = compareComparables(kc, key, p.key); |
| 2713 |
< |
else |
| 2714 |
< |
dir = 0; |
| 2691 |
< |
TreeNode<K,V> xp = p; |
| 2710 |
> |
else if ((kc == null && |
| 2711 |
> |
(kc = comparableClassFor(k)) == null) || |
| 2712 |
> |
(dir = compareComparables(kc, k, pk)) == 0) |
| 2713 |
> |
dir = tieBreakOrder(k, pk); |
| 2714 |
> |
TreeNode<K,V> xp = p; |
| 2715 |
|
if ((p = (dir <= 0) ? p.left : p.right) == null) { |
| 2716 |
|
x.parent = xp; |
| 2717 |
|
if (dir <= 0) |
| 2725 |
|
} |
| 2726 |
|
} |
| 2727 |
|
this.root = r; |
| 2728 |
+ |
assert checkInvariants(root); |
| 2729 |
|
} |
| 2730 |
|
|
| 2731 |
|
/** |
| 2806 |
|
*/ |
| 2807 |
|
final TreeNode<K,V> putTreeVal(int h, K k, V v) { |
| 2808 |
|
Class<?> kc = null; |
| 2809 |
+ |
boolean searched = false; |
| 2810 |
|
for (TreeNode<K,V> p = root;;) { |
| 2811 |
< |
int dir, ph; K pk; TreeNode<K,V> q, pr; |
| 2811 |
> |
int dir, ph; K pk; |
| 2812 |
|
if (p == null) { |
| 2813 |
|
first = root = new TreeNode<K,V>(h, k, v, null, null); |
| 2814 |
|
break; |
| 2822 |
|
else if ((kc == null && |
| 2823 |
|
(kc = comparableClassFor(k)) == null) || |
| 2824 |
|
(dir = compareComparables(kc, k, pk)) == 0) { |
| 2825 |
< |
if (p.left == null) |
| 2826 |
< |
dir = 1; |
| 2827 |
< |
else if ((pr = p.right) == null || |
| 2828 |
< |
(q = pr.findTreeNode(h, k, kc)) == null) |
| 2829 |
< |
dir = -1; |
| 2830 |
< |
else |
| 2831 |
< |
return q; |
| 2825 |
> |
if (!searched) { |
| 2826 |
> |
TreeNode<K,V> q, ch; |
| 2827 |
> |
searched = true; |
| 2828 |
> |
if (((ch = p.left) != null && |
| 2829 |
> |
(q = ch.findTreeNode(h, k, kc)) != null) || |
| 2830 |
> |
((ch = p.right) != null && |
| 2831 |
> |
(q = ch.findTreeNode(h, k, kc)) != null)) |
| 2832 |
> |
return q; |
| 2833 |
> |
} |
| 2834 |
> |
dir = tieBreakOrder(k, pk); |
| 2835 |
|
} |
| 2836 |
+ |
|
| 2837 |
|
TreeNode<K,V> xp = p; |
| 2838 |
< |
if ((p = (dir < 0) ? p.left : p.right) == null) { |
| 2838 |
> |
if ((p = (dir <= 0) ? p.left : p.right) == null) { |
| 2839 |
|
TreeNode<K,V> x, f = first; |
| 2840 |
|
first = x = new TreeNode<K,V>(h, k, v, f, xp); |
| 2841 |
|
if (f != null) |
| 2842 |
|
f.prev = x; |
| 2843 |
< |
if (dir < 0) |
| 2843 |
> |
if (dir <= 0) |
| 2844 |
|
xp.left = x; |
| 2845 |
|
else |
| 2846 |
|
xp.right = x; |
