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package co.paralleluniverse.strands.channels.disruptor;
import co.paralleluniverse.fibers.SuspendExecution;
import co.paralleluniverse.strands.Timeout;
import co.paralleluniverse.strands.channels.ReceivePort;
import com.lmax.disruptor.AbstractSequencer;
import com.lmax.disruptor.AlertException;
import com.lmax.disruptor.RingBuffer;
import com.lmax.disruptor.Sequence;
import com.lmax.disruptor.Sequencer;
import com.lmax.disruptor.WaitStrategy;
import java.lang.reflect.Field;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
/**
*
* @author pron
*/
public class DisruptorReceiveChannel<Message> implements ReceivePort<Message> {
private final SequenceBarrier barrier;
private final RingBuffer<Message> buffer;
private final Sequence sequence = new Sequence(Sequencer.INITIAL_CURSOR_VALUE);
private long availableSequence;
private volatile boolean closed;
public DisruptorReceiveChannel(RingBuffer<Message> buffer, Sequence... dependentSequences) {
this.buffer = buffer;
final Sequencer sequencer = getSequencer(buffer);
final WaitStrategy waitStrategy = getWaitStrategy(sequencer);
final Sequence cursor = getCursor(sequencer);
if (!(waitStrategy instanceof StrandBlockingWaitStrategy))
throw new IllegalArgumentException("Channel can only be created from RingBuffer with StrandBlockingWaitStrategy");
this.barrier = new ProcessingSequenceBarrier(sequencer, waitStrategy, cursor, dependentSequences);
barrier.clearAlert();
}
@Override
public Message receive() throws SuspendExecution, InterruptedException {
if (closed)
return null;
long nextSequence = sequence.get() + 1L;
while (nextSequence > availableSequence) {
try {
availableSequence = barrier.waitFor1(nextSequence);
} catch (AlertException ex) {
// ???
}
}
Message message = buffer.get(nextSequence);
return message;
}
@Override
public Message receive(long timeout, TimeUnit unit) throws SuspendExecution, InterruptedException {
if (unit == null)
return receive();
if (timeout <= 0)
return tryReceive();
if (closed)
return null;
try {
long nextSequence = sequence.get() + 1L;
if (nextSequence > availableSequence) {
final long start = System.nanoTime();
long left = unit.toNanos(timeout);
final long deadline = start + unit.toNanos(timeout);
while (nextSequence > availableSequence) {
try {
availableSequence = barrier.waitFor1(nextSequence, left, TimeUnit.NANOSECONDS);
} catch (AlertException ex) {
// ???
}
if (nextSequence > availableSequence) {
left = deadline - System.nanoTime();
if (left <= 0)
return null;
}
}
}
Message message = buffer.get(nextSequence);
return message;
} catch (TimeoutException e) {
return null;
}
}
@Override
public Message receive(Timeout timeout) throws SuspendExecution, InterruptedException {
return receive(timeout.nanosLeft(), TimeUnit.NANOSECONDS);
}
@Override
public Message tryReceive() {
if (closed)
return null;
long nextSequence = sequence.get() + 1L;
if (nextSequence > availableSequence)
return null;
return buffer.get(nextSequence);
}
private static Sequencer getSequencer(RingBuffer<?> buffer) {
try {
return (Sequencer) sequencerField.get(buffer);
} catch (IllegalArgumentException ex) {
throw new AssertionError(ex);
} catch (IllegalAccessException ex) {
throw new Error(ex);
}
}
private static Sequence getCursor(Sequencer sequencer) {
try {
return (Sequence) cursorField.get(sequencer);
} catch (IllegalArgumentException ex) {
throw new AssertionError(ex);
} catch (IllegalAccessException ex) {
throw new Error(ex);
}
}
private static WaitStrategy getWaitStrategy(Sequencer sequencer) {
try {
return (WaitStrategy) waitStrategyField.get(sequencer);
} catch (IllegalArgumentException ex) {
throw new AssertionError(ex);
} catch (IllegalAccessException ex) {
throw new Error(ex);
}
}
@Override
public void close() {
this.closed = true;
}
@Override
public boolean isClosed() {
return closed;
}
private static final Field sequencerField;
private static final Field cursorField;
private static final Field waitStrategyField;
static {
try {
sequencerField = RingBuffer.class.getDeclaredField("sequencer");
sequencerField.setAccessible(true);
cursorField = AbstractSequencer.class.getDeclaredField("cursor");
cursorField.setAccessible(true);
waitStrategyField = AbstractSequencer.class.getDeclaredField("waitStrategy");
waitStrategyField.setAccessible(true);
} catch (NoSuchFieldException ex) {
throw new AssertionError(ex);
} catch (SecurityException ex) {
throw new Error(ex);
}
}
}