/** @see Sequencer#next(int) */
@Override
public long next(int n) {
if (n < 1) {
throw new IllegalArgumentException("n must be > 0");
}
long nextValue = pad.nextValue;
long nextSequence = nextValue + n;
long wrapPoint = nextSequence - bufferSize;
long cachedGatingSequence = pad.cachedValue;
if (wrapPoint > cachedGatingSequence || cachedGatingSequence > nextValue) {
long minSequence;
while (wrapPoint > (minSequence = Util.getMinimumSequence(gatingSequences, nextValue))) {
Thread.yield();
// LockSupport.parkNanos(1L); // TODO: Use waitStrategy to spin?
}
pad.cachedValue = minSequence;
}
pad.nextValue = nextSequence;
return nextSequence;
}
@Test
public void shouldWaitForWorkCompleteWhereAllWorkersAreBlockedOnRingBuffer() throws Exception {
long expectedNumberMessages = 10;
fillRingBuffer(expectedNumberMessages);
final StubEventProcessor[] workers = new StubEventProcessor[3];
for (int i = 0, size = workers.length; i < size; i++) {
workers[i] = new StubEventProcessor();
workers[i].setSequence(expectedNumberMessages - 1);
}
final SequenceBarrier sequenceBarrier = ringBuffer.newBarrier(Util.getSequencesFor(workers));
Runnable runnable =
new Runnable() {
public void run() {
long sequence = ringBuffer.next();
StubEvent event = ringBuffer.getPreallocated(sequence);
event.setValue((int) sequence);
ringBuffer.publish(sequence);
for (StubEventProcessor stubWorker : workers) {
stubWorker.setSequence(sequence);
}
}
};
new Thread(runnable).start();
long expectedWorkSequence = expectedNumberMessages;
long completedWorkSequence = sequenceBarrier.waitFor(expectedNumberMessages);
assertTrue(completedWorkSequence >= expectedWorkSequence);
}
@Test
public void shouldWaitForWorkCompleteWhereCompleteWorkThresholdIsBehind() throws Exception {
long expectedNumberMessages = 10;
fillRingBuffer(expectedNumberMessages);
final StubEventProcessor[] eventProcessors = new StubEventProcessor[3];
for (int i = 0, size = eventProcessors.length; i < size; i++) {
eventProcessors[i] = new StubEventProcessor();
eventProcessors[i].setSequence(expectedNumberMessages - 2);
}
final SequenceBarrier sequenceBarrier =
ringBuffer.newBarrier(Util.getSequencesFor(eventProcessors));
Runnable runnable =
new Runnable() {
public void run() {
for (StubEventProcessor stubWorker : eventProcessors) {
stubWorker.setSequence(stubWorker.getSequence().get() + 1L);
}
}
};
Thread thread = new Thread(runnable);
thread.start();
thread.join();
long expectedWorkSequence = expectedNumberMessages - 1;
long completedWorkSequence = sequenceBarrier.waitFor(expectedWorkSequence);
assertTrue(completedWorkSequence >= expectedWorkSequence);
}
/** @see Sequencer#remainingCapacity() */
@Override
public long remainingCapacity() {
long nextValue = pad.nextValue;
long consumed = Util.getMinimumSequence(gatingSequences, nextValue);
long produced = nextValue;
return getBufferSize() - (produced - consumed);
}
static {
UNSAFE = Util.getUnsafe();
try {
VALUE_OFFSET = UNSAFE.objectFieldOffset(Value.class.getDeclaredField("value"));
} catch (final Exception e) {
throw new RuntimeException(e);
}
}
@Test
public void shouldInterruptDuringBusySpin() throws Exception {
final long expectedNumberMessages = 10;
fillRingBuffer(expectedNumberMessages);
final CountDownLatch latch = new CountDownLatch(3);
final Sequence sequence1 = new CountDownLatchSequence(8L, latch);
final Sequence sequence2 = new CountDownLatchSequence(8L, latch);
final Sequence sequence3 = new CountDownLatchSequence(8L, latch);
context.checking(
new Expectations() {
{
one(eventProcessor1).getSequence();
will(returnValue(sequence1));
one(eventProcessor2).getSequence();
will(returnValue(sequence2));
one(eventProcessor3).getSequence();
will(returnValue(sequence3));
}
});
final SequenceBarrier sequenceBarrier =
ringBuffer.newBarrier(
Util.getSequencesFor(eventProcessor1, eventProcessor2, eventProcessor3));
final boolean[] alerted = {false};
Thread t =
new Thread(
new Runnable() {
public void run() {
try {
sequenceBarrier.waitFor(expectedNumberMessages - 1);
} catch (AlertException e) {
alerted[0] = true;
} catch (InterruptedException e) {
// don't care
}
}
});
t.start();
latch.await(3, TimeUnit.SECONDS);
sequenceBarrier.alert();
t.join();
assertTrue("Thread was not interrupted", alerted[0]);
}
/** @see Sequencer#hasAvailableCapacity(int) */
@Override
public boolean hasAvailableCapacity(final int requiredCapacity) {
long nextValue = pad.nextValue;
long wrapPoint = (nextValue + requiredCapacity) - bufferSize;
long cachedGatingSequence = pad.cachedValue;
if (wrapPoint > cachedGatingSequence || cachedGatingSequence > nextValue) {
long minSequence = Util.getMinimumSequence(gatingSequences, nextValue);
pad.cachedValue = minSequence;
if (wrapPoint > minSequence) {
return false;
}
}
return true;
}
public long remainingCapacity() {
long l1 = Util.getMinimumSequence(this.gatingSequences);
long l2 = this.cursor.get();
return getBufferSize() - (l2 - l1);
}