下面列出了java.util.concurrent.ThreadLocalRandom#nextSecondarySeed ( ) 实例代码，或者点击链接到github查看源代码，也可以在右侧发表评论。
/**
* Returns a (probably) non-empty steal queue, if one is found
* during a scan, else null. This method must be retried by
* caller if, by the time it tries to use the queue, it is empty.
*/
private WorkQueue findNonEmptyStealQueue() {
WorkQueue[] ws; int m; // one-shot version of scan loop
int r = ThreadLocalRandom.nextSecondarySeed();
if ((ws = workQueues) != null && (m = ws.length - 1) >= 0) {
for (int origin = r & m, k = origin, oldSum = 0, checkSum = 0;;) {
WorkQueue q; int b;
if ((q = ws[k]) != null) {
if ((b = q.base) - q.top < 0)
return q;
checkSum += b;
}
if ((k = (k + 1) & m) == origin) {
if (oldSum == (oldSum = checkSum))
break;
checkSum = 0;
}
}
}
return null;
}
/**
* Returns a (probably) non-empty steal queue, if one is found
* during a scan, else null. This method must be retried by
* caller if, by the time it tries to use the queue, it is empty.
*/
private WorkQueue findNonEmptyStealQueue() {
int r = ThreadLocalRandom.nextSecondarySeed();
for (;;) {
int ps = plock, m; WorkQueue[] ws; WorkQueue q;
if ((ws = workQueues) != null && (m = ws.length - 1) >= 0) {
for (int j = (m + 1) << 2; j >= 0; --j) {
if ((q = ws[(((r - j) << 1) | 1) & m]) != null &&
q.base - q.top < 0)
return q;
}
}
if (plock == ps)
return null;
}
}
/**
* Returns a (probably) non-empty steal queue, if one is found
* during a scan, else null. This method must be retried by
* caller if, by the time it tries to use the queue, it is empty.
*/
private WorkQueue findNonEmptyStealQueue() {
WorkQueue[] ws; int m; // one-shot version of scan loop
int r = ThreadLocalRandom.nextSecondarySeed();
if ((ws = workQueues) != null && (m = ws.length - 1) >= 0) {
for (int origin = r & m, k = origin, oldSum = 0, checkSum = 0;;) {
WorkQueue q; int b;
if ((q = ws[k]) != null) {
if ((b = q.base) - q.top < 0)
return q;
checkSum += b;
}
if ((k = (k + 1) & m) == origin) {
if (oldSum == (oldSum = checkSum))
break;
checkSum = 0;
}
}
}
return null;
}
/**
* Returns a (probably) non-empty steal queue, if one is found
* during a scan, else null. This method must be retried by
* caller if, by the time it tries to use the queue, it is empty.
*/
private WorkQueue findNonEmptyStealQueue() {
WorkQueue[] ws; int m; // one-shot version of scan loop
int r = ThreadLocalRandom.nextSecondarySeed();
if ((ws = workQueues) != null && (m = ws.length - 1) >= 0) {
for (int origin = r & m, k = origin, oldSum = 0, checkSum = 0;;) {
WorkQueue q; int b;
if ((q = ws[k]) != null) {
if ((b = q.base) - q.top < 0)
return q;
checkSum += b;
}
if ((k = (k + 1) & m) == origin) {
if (oldSum == (oldSum = checkSum))
break;
checkSum = 0;
}
}
}
return null;
}
/**
* Returns a (probably) non-empty steal queue, if one is found
* during a scan, else null. This method must be retried by
* caller if, by the time it tries to use the queue, it is empty.
*/
private WorkQueue findNonEmptyStealQueue() {
WorkQueue[] ws; int m; // one-shot version of scan loop
int r = ThreadLocalRandom.nextSecondarySeed();
if ((ws = workQueues) != null && (m = ws.length - 1) >= 0) {
for (int origin = r & m, k = origin, oldSum = 0, checkSum = 0;;) {
WorkQueue q; int b;
if ((q = ws[k]) != null) {
if ((b = q.base) - q.top < 0)
return q;
checkSum += b;
}
if ((k = (k + 1) & m) == origin) {
if (oldSum == (oldSum = checkSum))
break;
checkSum = 0;
}
}
}
return null;
}
/**
* Returns a (probably) non-empty steal queue, if one is found
* during a scan, else null. This method must be retried by
* caller if, by the time it tries to use the queue, it is empty.
*/
private WorkQueue findNonEmptyStealQueue() {
WorkQueue[] ws; int m; // one-shot version of scan loop
int r = ThreadLocalRandom.nextSecondarySeed();
if ((ws = workQueues) != null && (m = ws.length - 1) >= 0) {
for (int origin = r & m, k = origin, oldSum = 0, checkSum = 0;;) {
WorkQueue q; int b;
if ((q = ws[k]) != null) {
if ((b = q.base) - q.top < 0)
return q;
checkSum += b;
}
if ((k = (k + 1) & m) == origin) {
if (oldSum == (oldSum = checkSum))
break;
checkSum = 0;
}
}
}
return null;
}
/**
* Returns a (probably) non-empty steal queue, if one is found
* during a scan, else null. This method must be retried by
* caller if, by the time it tries to use the queue, it is empty.
*/
private WorkQueue findNonEmptyStealQueue() {
WorkQueue[] ws; int m; // one-shot version of scan loop
int r = ThreadLocalRandom.nextSecondarySeed();
if ((ws = workQueues) != null && (m = ws.length - 1) >= 0) {
for (int origin = r & m, k = origin, oldSum = 0, checkSum = 0;;) {
WorkQueue q; int b;
if ((q = ws[k]) != null) {
if ((b = q.base) - q.top < 0)
return q;
checkSum += b;
}
if ((k = (k + 1) & m) == origin) {
if (oldSum == (oldSum = checkSum))
break;
checkSum = 0;
}
}
}
return null;
}
/**
* Acquires the plock lock to protect worker array and related
* updates. This method is called only if an initial CAS on plock
* fails. This acts as a spinlock for normal cases, but falls back
* to builtin monitor to block when (rarely) needed. This would be
* a terrible idea for a highly contended lock, but works fine as
* a more conservative alternative to a pure spinlock.
*/
private int acquirePlock() {
int spins = PL_SPINS, ps, nps;
for (;;) {
if (((ps = plock) & PL_LOCK) == 0 &&
U.compareAndSwapInt(this, PLOCK, ps, nps = ps + PL_LOCK))
return nps;
else if (spins >= 0) {
if (ThreadLocalRandom.nextSecondarySeed() >= 0)
--spins;
}
else if (U.compareAndSwapInt(this, PLOCK, ps, ps | PL_SIGNAL)) {
synchronized (this) {
if ((plock & PL_SIGNAL) != 0) {
try {
wait();
} catch (InterruptedException ie) {
try {
Thread.currentThread().interrupt();
} catch (SecurityException ignore) {
}
}
}
else
notifyAll();
}
}
}
}
/**
* Spins and/or blocks until runstate lock is available. See
* above for explanation.
*/
private int awaitRunStateLock() {
Object lock;
boolean wasInterrupted = false;
for (int spins = SPINS, r = 0, rs, ns;;) {
if (((rs = runState) & RSLOCK) == 0) {
if (U.compareAndSwapInt(this, RUNSTATE, rs, ns = rs | RSLOCK)) {
if (wasInterrupted) {
try {
Thread.currentThread().interrupt();
} catch (SecurityException ignore) {
}
}
return ns;
}
}
else if (r == 0)
r = ThreadLocalRandom.nextSecondarySeed();
else if (spins > 0) {
r ^= r << 6; r ^= r >>> 21; r ^= r << 7; // xorshift
if (r >= 0)
--spins;
}
else if ((rs & STARTED) == 0 || (lock = stealCounter) == null)
Thread.yield(); // initialization race
else if (U.compareAndSwapInt(this, RUNSTATE, rs, rs | RSIGNAL)) {
synchronized (lock) {
if ((runState & RSIGNAL) != 0) {
try {
lock.wait();
} catch (InterruptedException ie) {
if (!(Thread.currentThread() instanceof
ForkJoinWorkerThread))
wasInterrupted = true;
}
}
else
lock.notifyAll();
}
}
}
}
/**
* Spins and/or blocks until runstate lock is available. See
* above for explanation.
*/
private int awaitRunStateLock() {
Object lock;
boolean wasInterrupted = false;
for (int spins = SPINS, r = 0, rs, ns;;) {
if (((rs = runState) & RSLOCK) == 0) {
if (U.compareAndSwapInt(this, RUNSTATE, rs, ns = rs | RSLOCK)) {
if (wasInterrupted) {
try {
Thread.currentThread().interrupt();
} catch (SecurityException ignore) {
}
}
return ns;
}
}
else if (r == 0)
r = ThreadLocalRandom.nextSecondarySeed();
else if (spins > 0) {
r ^= r << 6; r ^= r >>> 21; r ^= r << 7; // xorshift
if (r >= 0)
--spins;
}
else if ((rs & STARTED) == 0 || (lock = stealCounter) == null)
Thread.yield(); // initialization race
else if (U.compareAndSwapInt(this, RUNSTATE, rs, rs | RSIGNAL)) {
synchronized (lock) {
if ((runState & RSIGNAL) != 0) {
try {
lock.wait();
} catch (InterruptedException ie) {
if (!(Thread.currentThread() instanceof
ForkJoinWorkerThread))
wasInterrupted = true;
}
}
else
lock.notifyAll();
}
}
}
}
/**
* Returns raw result after waiting, or null if interruptible and
* interrupted.
*/
private Object waitingGet(boolean interruptible) {
Signaller q = null;
boolean queued = false;
int spins = -1;
Object r;
while ((r = result) == null) {
if (spins < 0)
spins = SPINS;
else if (spins > 0) {
if (ThreadLocalRandom.nextSecondarySeed() >= 0)
--spins;
}
else if (q == null)
q = new Signaller(interruptible, 0L, 0L);
else if (!queued)
queued = tryPushStack(q);
else if (interruptible && q.interruptControl < 0) {
q.thread = null;
cleanStack();
return null;
}
else if (q.thread != null && result == null) {
try {
ForkJoinPool.managedBlock(q);
} catch (InterruptedException ie) {
q.interruptControl = -1;
}
}
}
if (q != null) {
q.thread = null;
if (q.interruptControl < 0) {
if (interruptible)
r = null; // report interruption
else
Thread.currentThread().interrupt();
}
}
postComplete();
return r;
}
/**
* Spins and/or blocks until runstate lock is available. See
* above for explanation.
*/
private int awaitRunStateLock() {
Object lock;
boolean wasInterrupted = false;
for (int spins = SPINS, r = 0, rs, ns;;) {
if (((rs = runState) & RSLOCK) == 0) {
if (U.compareAndSwapInt(this, RUNSTATE, rs, ns = rs | RSLOCK)) {
if (wasInterrupted) {
try {
Thread.currentThread().interrupt();
} catch (SecurityException ignore) {
}
}
return ns;
}
}
else if (r == 0)
r = ThreadLocalRandom.nextSecondarySeed();
else if (spins > 0) {
r ^= r << 6; r ^= r >>> 21; r ^= r << 7; // xorshift
if (r >= 0)
--spins;
}
else if ((rs & STARTED) == 0 || (lock = stealCounter) == null)
Thread.yield(); // initialization race
else if (U.compareAndSwapInt(this, RUNSTATE, rs, rs | RSIGNAL)) {
synchronized (lock) {
if ((runState & RSIGNAL) != 0) {
try {
lock.wait();
} catch (InterruptedException ie) {
if (!(Thread.currentThread() instanceof
ForkJoinWorkerThread))
wasInterrupted = true;
}
}
else
lock.notifyAll();
}
}
}
}
/**
* Returns raw result after waiting, or null if interruptible and
* interrupted.
*/
private Object waitingGet(boolean interruptible) {
WaitNode q = null;
boolean queued = false;
int spins = SPINS;
for (Object r;;) {
if ((r = result) != null) {
if (q != null) { // suppress unpark
q.thread = null;
if (q.interruptControl < 0) {
if (interruptible) {
removeWaiter(q);
return null;
}
Thread.currentThread().interrupt();
}
}
postComplete(); // help release others
return r;
}
else if (spins > 0) {
int rnd = ThreadLocalRandom.nextSecondarySeed();
if (rnd == 0)
rnd = ThreadLocalRandom.current().nextInt();
if (rnd >= 0)
--spins;
}
else if (q == null)
q = new WaitNode(interruptible, 0L, 0L);
else if (!queued)
queued = UNSAFE.compareAndSwapObject(this, WAITERS,
q.next = waiters, q);
else if (interruptible && q.interruptControl < 0) {
removeWaiter(q);
return null;
}
else if (q.thread != null && result == null) {
try {
ForkJoinPool.managedBlock(q);
} catch (InterruptedException ex) {
q.interruptControl = -1;
}
}
}
}
/**
* Spins and/or blocks until runstate lock is available. See
* above for explanation.
*/
private int awaitRunStateLock() {
Object lock;
boolean wasInterrupted = false;
for (int spins = SPINS, r = 0, rs, ns;;) {
if (((rs = runState) & RSLOCK) == 0) {
if (U.compareAndSwapInt(this, RUNSTATE, rs, ns = rs | RSLOCK)) {
if (wasInterrupted) {
try {
Thread.currentThread().interrupt();
} catch (SecurityException ignore) {
}
}
return ns;
}
}
else if (r == 0)
r = ThreadLocalRandom.nextSecondarySeed();
else if (spins > 0) {
r ^= r << 6; r ^= r >>> 21; r ^= r << 7; // xorshift
if (r >= 0)
--spins;
}
else if ((rs & STARTED) == 0 || (lock = stealCounter) == null)
Thread.yield(); // initialization race
else if (U.compareAndSwapInt(this, RUNSTATE, rs, rs | RSIGNAL)) {
synchronized (lock) {
if ((runState & RSIGNAL) != 0) {
try {
lock.wait();
} catch (InterruptedException ie) {
if (!(Thread.currentThread() instanceof
ForkJoinWorkerThread))
wasInterrupted = true;
}
}
else
lock.notifyAll();
}
}
}
}
/**
* Returns raw result after waiting, or null if interruptible and
* interrupted.
*/
private Object waitingGet(boolean interruptible) {
Signaller q = null;
boolean queued = false;
int spins = -1;
Object r;
while ((r = result) == null) {
if (spins < 0)
spins = (Runtime.getRuntime().availableProcessors() > 1) ?
1 << 8 : 0; // Use brief spin-wait on multiprocessors
else if (spins > 0) {
if (ThreadLocalRandom.nextSecondarySeed() >= 0)
--spins;
}
else if (q == null)
q = new Signaller(interruptible, 0L, 0L);
else if (!queued)
queued = tryPushStack(q);
else if (interruptible && q.interruptControl < 0) {
q.thread = null;
cleanStack();
return null;
}
else if (q.thread != null && result == null) {
try {
ForkJoinPool.managedBlock(q);
} catch (InterruptedException ie) {
q.interruptControl = -1;
}
}
}
if (q != null) {
q.thread = null;
if (q.interruptControl < 0) {
if (interruptible)
r = null; // report interruption
else
Thread.currentThread().interrupt();
}
}
postComplete();
return r;
}
/**
* Returns raw result after waiting, or null if interruptible and
* interrupted.
*/
private Object waitingGet(boolean interruptible) {
Signaller q = null;
boolean queued = false;
int spins = -1;
Object r;
while ((r = result) == null) {
if (spins < 0)
spins = (Runtime.getRuntime().availableProcessors() > 1) ?
1 << 8 : 0; // Use brief spin-wait on multiprocessors
else if (spins > 0) {
if (ThreadLocalRandom.nextSecondarySeed() >= 0)
--spins;
}
else if (q == null)
q = new Signaller(interruptible, 0L, 0L);
else if (!queued)
queued = tryPushStack(q);
else if (interruptible && q.interruptControl < 0) {
q.thread = null;
cleanStack();
return null;
}
else if (q.thread != null && result == null) {
try {
ForkJoinPool.managedBlock(q);
} catch (InterruptedException ie) {
q.interruptControl = -1;
}
}
}
if (q != null) {
q.thread = null;
if (q.interruptControl < 0) {
if (interruptible)
r = null; // report interruption
else
Thread.currentThread().interrupt();
}
}
postComplete();
return r;
}
/**
* Spins and/or blocks until runstate lock is available. See
* above for explanation.
*/
private int awaitRunStateLock() {
Object lock;
boolean wasInterrupted = false;
for (int spins = SPINS, r = 0, rs, ns;;) {
if (((rs = runState) & RSLOCK) == 0) {
if (U.compareAndSwapInt(this, RUNSTATE, rs, ns = rs | RSLOCK)) {
if (wasInterrupted) {
try {
Thread.currentThread().interrupt();
} catch (SecurityException ignore) {
}
}
return ns;
}
}
else if (r == 0)
r = ThreadLocalRandom.nextSecondarySeed();
else if (spins > 0) {
r ^= r << 6; r ^= r >>> 21; r ^= r << 7; // xorshift
if (r >= 0)
--spins;
}
else if ((rs & STARTED) == 0 || (lock = stealCounter) == null)
Thread.yield(); // initialization race
else if (U.compareAndSwapInt(this, RUNSTATE, rs, rs | RSIGNAL)) {
synchronized (lock) {
if ((runState & RSIGNAL) != 0) {
try {
lock.wait();
} catch (InterruptedException ie) {
if (!(Thread.currentThread() instanceof
ForkJoinWorkerThread))
wasInterrupted = true;
}
}
else
lock.notifyAll();
}
}
}
}
/**
* Spins and/or blocks until runstate lock is available. See
* above for explanation.
*/
private int awaitRunStateLock() {
Object lock;
boolean wasInterrupted = false;
for (int spins = SPINS, r = 0, rs, ns;;) {
if (((rs = runState) & RSLOCK) == 0) {
if (U.compareAndSwapInt(this, RUNSTATE, rs, ns = rs | RSLOCK)) {
if (wasInterrupted) {
try {
Thread.currentThread().interrupt();
} catch (SecurityException ignore) {
}
}
return ns;
}
}
else if (r == 0)
r = ThreadLocalRandom.nextSecondarySeed();
else if (spins > 0) {
r ^= r << 6; r ^= r >>> 21; r ^= r << 7; // xorshift
if (r >= 0)
--spins;
}
else if ((rs & STARTED) == 0 || (lock = stealCounter) == null)
Thread.yield(); // initialization race
else if (U.compareAndSwapInt(this, RUNSTATE, rs, rs | RSIGNAL)) {
synchronized (lock) {
if ((runState & RSIGNAL) != 0) {
try {
lock.wait();
} catch (InterruptedException ie) {
if (!(Thread.currentThread() instanceof
ForkJoinWorkerThread))
wasInterrupted = true;
}
}
else
lock.notifyAll();
}
}
}
}
/**
* Spins and/or blocks until runstate lock is available. See
* above for explanation.
*/
private int awaitRunStateLock() {
Object lock;
boolean wasInterrupted = false;
for (int spins = SPINS, r = 0, rs, ns;;) {
if (((rs = runState) & RSLOCK) == 0) {
if (U.compareAndSwapInt(this, RUNSTATE, rs, ns = rs | RSLOCK)) {
if (wasInterrupted) {
try {
Thread.currentThread().interrupt();
} catch (SecurityException ignore) {
}
}
return ns;
}
}
else if (r == 0)
r = ThreadLocalRandom.nextSecondarySeed();
else if (spins > 0) {
r ^= r << 6; r ^= r >>> 21; r ^= r << 7; // xorshift
if (r >= 0)
--spins;
}
else if ((rs & STARTED) == 0 || (lock = stealCounter) == null)
Thread.yield(); // initialization race
else if (U.compareAndSwapInt(this, RUNSTATE, rs, rs | RSIGNAL)) {
synchronized (lock) {
if ((runState & RSIGNAL) != 0) {
try {
lock.wait();
} catch (InterruptedException ie) {
if (!(Thread.currentThread() instanceof
ForkJoinWorkerThread))
wasInterrupted = true;
}
}
else
lock.notifyAll();
}
}
}
}
/**
* Spins and/or blocks until runstate lock is available. See
* above for explanation.
*/
private int awaitRunStateLock() {
Object lock;
boolean wasInterrupted = false;
for (int spins = SPINS, r = 0, rs, ns;;) {
if (((rs = runState) & RSLOCK) == 0) {
if (U.compareAndSwapInt(this, RUNSTATE, rs, ns = rs | RSLOCK)) {
if (wasInterrupted) {
try {
Thread.currentThread().interrupt();
} catch (SecurityException ignore) {
}
}
return ns;
}
}
else if (r == 0)
r = ThreadLocalRandom.nextSecondarySeed();
else if (spins > 0) {
r ^= r << 6; r ^= r >>> 21; r ^= r << 7; // xorshift
if (r >= 0)
--spins;
}
else if ((rs & STARTED) == 0 || (lock = stealCounter) == null)
Thread.yield(); // initialization race
else if (U.compareAndSwapInt(this, RUNSTATE, rs, rs | RSIGNAL)) {
synchronized (lock) {
if ((runState & RSIGNAL) != 0) {
try {
lock.wait();
} catch (InterruptedException ie) {
if (!(Thread.currentThread() instanceof
ForkJoinWorkerThread))
wasInterrupted = true;
}
}
else
lock.notifyAll();
}
}
}
}