| 219 |
|
* progress. Resizing proceeds by transferring bins, one by one, |
| 220 |
|
* from the table to the next table. However, threads claim small |
| 221 |
|
* blocks of indices to transfer (via field transferIndex) before |
| 222 |
< |
* doing so, reducing contention. Because we are using |
| 223 |
< |
* power-of-two expansion, the elements from each bin must either |
| 224 |
< |
* stay at same index, or move with a power of two offset. We |
| 225 |
< |
* eliminate unnecessary node creation by catching cases where old |
| 226 |
< |
* nodes can be reused because their next fields won't change. On |
| 227 |
< |
* average, only about one-sixth of them need cloning when a table |
| 228 |
< |
* doubles. The nodes they replace will be garbage collectable as |
| 229 |
< |
* soon as they are no longer referenced by any reader thread that |
| 230 |
< |
* may be in the midst of concurrently traversing table. Upon |
| 231 |
< |
* transfer, the old table bin contains only a special forwarding |
| 232 |
< |
* node (with hash field "MOVED") that contains the next table as |
| 233 |
< |
* its key. On encountering a forwarding node, access and update |
| 234 |
< |
* operations restart, using the new table. |
| 222 |
> |
* doing so, reducing contention. A generation stamp in field |
| 223 |
> |
* sizeCtl ensures that resizings do not overlap. Because we are |
| 224 |
> |
* using power-of-two expansion, the elements from each bin must |
| 225 |
> |
* either stay at same index, or move with a power of two |
| 226 |
> |
* offset. We eliminate unnecessary node creation by catching |
| 227 |
> |
* cases where old nodes can be reused because their next fields |
| 228 |
> |
* won't change. On average, only about one-sixth of them need |
| 229 |
> |
* cloning when a table doubles. The nodes they replace will be |
| 230 |
> |
* garbage collectable as soon as they are no longer referenced by |
| 231 |
> |
* any reader thread that may be in the midst of concurrently |
| 232 |
> |
* traversing table. Upon transfer, the old table bin contains |
| 233 |
> |
* only a special forwarding node (with hash field "MOVED") that |
| 234 |
> |
* contains the next table as its key. On encountering a |
| 235 |
> |
* forwarding node, access and update operations restart, using |
| 236 |
> |
* the new table. |
| 237 |
|
* |
| 238 |
|
* Each bin transfer requires its bin lock, which can stall |
| 239 |
|
* waiting for locks while resizing. However, because other |
| 411 |
|
*/ |
| 412 |
|
private static final int MIN_TRANSFER_STRIDE = 16; |
| 413 |
|
|
| 414 |
+ |
/** |
| 415 |
+ |
* The number of bits used for generation stamp in sizeCtl. |
| 416 |
+ |
* Must be at least 6 for 32bit arrays. |
| 417 |
+ |
*/ |
| 418 |
+ |
private static int RESIZE_STAMP_BITS = 16; |
| 419 |
+ |
|
| 420 |
+ |
/** |
| 421 |
+ |
* The maximum number of threads that can help resize. |
| 422 |
+ |
* Must fit in 32 - RESIZE_STAMP_BITS bits. |
| 423 |
+ |
*/ |
| 424 |
+ |
private static final int MAX_RESIZERS = (1 << (32 - RESIZE_STAMP_BITS)) - 1; |
| 425 |
+ |
|
| 426 |
+ |
/** |
| 427 |
+ |
* The bit shift for recording size stamp in sizeCtl. |
| 428 |
+ |
*/ |
| 429 |
+ |
private static final int RESIZE_STAMP_SHIFT = 32 - RESIZE_STAMP_BITS; |
| 430 |
+ |
|
| 431 |
|
/* |
| 432 |
|
* Encodings for Node hash fields. See above for explanation. |
| 433 |
|
*/ |
| 1558 |
|
/* ---------------- Table Initialization and Resizing -------------- */ |
| 1559 |
|
|
| 1560 |
|
/** |
| 1561 |
+ |
* Returns the stamp bits for resizing a table of size n. |
| 1562 |
+ |
* Must be negative when shifted left by RESIZE_STAMP_SHIFT. |
| 1563 |
+ |
*/ |
| 1564 |
+ |
static final int resizeStamp(int n) { |
| 1565 |
+ |
return Integer.numberOfLeadingZeros(n) | (1 << (RESIZE_STAMP_BITS - 1)); |
| 1566 |
+ |
} |
| 1567 |
+ |
|
| 1568 |
+ |
/** |
| 1569 |
|
* Initializes table, using the size recorded in sizeCtl. |
| 1570 |
|
*/ |
| 1571 |
|
private final Node<K,V>[] initTable() { |
| 1578 |
|
if ((tab = table) == null || tab.length == 0) { |
| 1579 |
|
int n = (sc > 0) ? sc : DEFAULT_CAPACITY; |
| 1580 |
|
@SuppressWarnings("unchecked") |
| 1581 |
< |
Node<K,V>[] nt = (Node<K,V>[])new Node<?,?>[n]; |
| 1581 |
> |
Node<K,V>[] nt = (Node<K,V>[])new Node<?,?>[n]; |
| 1582 |
|
table = tab = nt; |
| 1583 |
|
sc = n - (n >>> 2); |
| 1584 |
|
} |
| 1620 |
|
s = sumCount(); |
| 1621 |
|
} |
| 1622 |
|
if (check >= 0) { |
| 1623 |
< |
Node<K,V>[] tab, nt; int sc; |
| 1623 |
> |
Node<K,V>[] tab, nt; int n, sc; |
| 1624 |
|
while (s >= (long)(sc = sizeCtl) && (tab = table) != null && |
| 1625 |
< |
tab.length < MAXIMUM_CAPACITY) { |
| 1625 |
> |
(n = tab.length) < MAXIMUM_CAPACITY) { |
| 1626 |
> |
int rs = resizeStamp(n); |
| 1627 |
|
if (sc < 0) { |
| 1628 |
< |
if (sc == -1 || transferIndex <= 0 || |
| 1629 |
< |
(nt = nextTable) == null) |
| 1628 |
> |
if ((sc >>> RESIZE_STAMP_SHIFT) != rs || sc == rs + 1 || |
| 1629 |
> |
sc == rs + MAX_RESIZERS || (nt = nextTable) == null || |
| 1630 |
> |
transferIndex <= 0) |
| 1631 |
|
break; |
| 1632 |
< |
if (U.compareAndSwapInt(this, SIZECTL, sc, sc - 1)) |
| 1632 |
> |
if (U.compareAndSwapInt(this, SIZECTL, sc, sc + 1)) |
| 1633 |
|
transfer(tab, nt); |
| 1634 |
|
} |
| 1635 |
< |
else if (U.compareAndSwapInt(this, SIZECTL, sc, -2)) |
| 1635 |
> |
else if (U.compareAndSwapInt(this, SIZECTL, sc, |
| 1636 |
> |
(rs << RESIZE_STAMP_SHIFT) + 2)) |
| 1637 |
|
transfer(tab, null); |
| 1638 |
|
s = sumCount(); |
| 1639 |
|
} |
| 1645 |
|
*/ |
| 1646 |
|
final Node<K,V>[] helpTransfer(Node<K,V>[] tab, Node<K,V> f) { |
| 1647 |
|
Node<K,V>[] nextTab; int sc; |
| 1648 |
< |
if ((f instanceof ForwardingNode) && |
| 1648 |
> |
if (tab != null && (f instanceof ForwardingNode) && |
| 1649 |
|
(nextTab = ((ForwardingNode<K,V>)f).nextTable) != null) { |
| 1650 |
< |
while (transferIndex > 0 && nextTab == nextTable && |
| 1651 |
< |
(sc = sizeCtl) < -1) { |
| 1652 |
< |
if (U.compareAndSwapInt(this, SIZECTL, sc, sc - 1)) { |
| 1650 |
> |
int rs = resizeStamp(tab.length); |
| 1651 |
> |
while (nextTab == nextTable && table == tab && |
| 1652 |
> |
(sc = sizeCtl) < 0) { |
| 1653 |
> |
if ((sc >>> RESIZE_STAMP_SHIFT) != rs || sc == rs + 1 || |
| 1654 |
> |
sc == rs + MAX_RESIZERS || transferIndex <= 0) |
| 1655 |
> |
break; |
| 1656 |
> |
if (U.compareAndSwapInt(this, SIZECTL, sc, sc + 1)) { |
| 1657 |
|
transfer(tab, nextTab); |
| 1658 |
|
break; |
| 1659 |
|
} |
| 1680 |
|
try { |
| 1681 |
|
if (table == tab) { |
| 1682 |
|
@SuppressWarnings("unchecked") |
| 1683 |
< |
Node<K,V>[] nt = (Node<K,V>[])new Node<?,?>[n]; |
| 1683 |
> |
Node<K,V>[] nt = (Node<K,V>[])new Node<?,?>[n]; |
| 1684 |
|
table = nt; |
| 1685 |
|
sc = n - (n >>> 2); |
| 1686 |
|
} |
| 1691 |
|
} |
| 1692 |
|
else if (c <= sc || n >= MAXIMUM_CAPACITY) |
| 1693 |
|
break; |
| 1694 |
< |
else if (tab == table && |
| 1695 |
< |
U.compareAndSwapInt(this, SIZECTL, sc, -2)) |
| 1696 |
< |
transfer(tab, null); |
| 1694 |
> |
else if (tab == table) { |
| 1695 |
> |
int rs = resizeStamp(n); |
| 1696 |
> |
if (sc < 0) { |
| 1697 |
> |
Node<K,V>[] nt; |
| 1698 |
> |
if ((sc >>> RESIZE_STAMP_SHIFT) != rs || sc == rs + 1 || |
| 1699 |
> |
sc == rs + MAX_RESIZERS || (nt = nextTable) == null || |
| 1700 |
> |
transferIndex <= 0) |
| 1701 |
> |
break; |
| 1702 |
> |
if (U.compareAndSwapInt(this, SIZECTL, sc, sc + 1)) |
| 1703 |
> |
transfer(tab, nt); |
| 1704 |
> |
} |
| 1705 |
> |
else if (U.compareAndSwapInt(this, SIZECTL, sc, |
| 1706 |
> |
(rs << RESIZE_STAMP_SHIFT) + 2)) |
| 1707 |
> |
transfer(tab, null); |
| 1708 |
> |
} |
| 1709 |
|
} |
| 1710 |
|
} |
| 1711 |
|
|
| 1760 |
|
sizeCtl = (n << 1) - (n >>> 1); |
| 1761 |
|
return; |
| 1762 |
|
} |
| 1763 |
< |
if (U.compareAndSwapInt(this, SIZECTL, sc = sizeCtl, ++sc)) { |
| 1764 |
< |
if (sc != -1) |
| 1763 |
> |
if (U.compareAndSwapInt(this, SIZECTL, sc = sizeCtl, sc - 1)) { |
| 1764 |
> |
if ((sc - 2) != resizeStamp(n)) |
| 1765 |
|
return; |
| 1766 |
|
finishing = advance = true; |
| 1767 |
|
i = n; // recheck before commit |
| 1855 |
|
private final void treeifyBin(Node<K,V>[] tab, int index) { |
| 1856 |
|
Node<K,V> b; int n, sc; |
| 1857 |
|
if (tab != null) { |
| 1858 |
< |
if ((n = tab.length) < MIN_TREEIFY_CAPACITY) { |
| 1859 |
< |
if (tab == table && (sc = sizeCtl) >= 0 && |
| 1860 |
< |
U.compareAndSwapInt(this, SIZECTL, sc, -2)) |
| 1815 |
< |
transfer(tab, null); |
| 1816 |
< |
} |
| 1817 |
< |
else if ((b = tabAt(tab, index)) != null) { |
| 1858 |
> |
if ((n = tab.length) < MIN_TREEIFY_CAPACITY) |
| 1859 |
> |
tryPresize(n << 1); |
| 1860 |
> |
else if ((b = tabAt(tab, index)) != null && b.hash >= 0) { |
| 1861 |
|
synchronized (b) { |
| 1862 |
|
if (tabAt(tab, index) == b) { |
| 1863 |
|
TreeNode<K,V> hd = null, tl = null; |
| 2055 |
|
private final void contendedLock() { |
| 2056 |
|
boolean waiting = false; |
| 2057 |
|
for (int s;;) { |
| 2058 |
< |
if (((s = lockState) & WRITER) == 0) { |
| 2058 |
> |
if (((s = lockState) & ~WAITER) == 0) { |
| 2059 |
|
if (U.compareAndSwapInt(this, LOCKSTATE, s, WRITER)) { |
| 2060 |
|
if (waiting) |
| 2061 |
|
waiter = null; |
