Package com.lmax.disruptor

Class SingleProducerSequencer

java.lang.Object
com.lmax.disruptor.AbstractSequencer
com.lmax.disruptor.SingleProducerSequencerPad
com.lmax.disruptor.SingleProducerSequencerFields
com.lmax.disruptor.SingleProducerSequencer
All Implemented Interfaces:
Cursored, Sequenced, Sequencer
public final class SingleProducerSequencer extends SingleProducerSequencerFields
Coordinator for claiming sequences for access to a data structure while tracking dependent Sequences. Not safe for use from multiple threads as it does not implement any barriers.

* Note on Cursored.getCursor(): With this sequencer the cursor value is updated after the call to Sequenced.publish(long) is made.

  • Field Details

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  • Constructor Details

    • SingleProducerSequencer

      public SingleProducerSequencer(int bufferSize, WaitStrategy waitStrategy)
      Construct a Sequencer with the selected wait strategy and buffer size.
      Parameters:
      bufferSize - the size of the buffer that this will sequence over.
      waitStrategy - for those waiting on sequences.

  • Method Details

    • hasAvailableCapacity

      public boolean hasAvailableCapacity(int requiredCapacity)
      Description copied from interface: Sequenced
      Has the buffer got capacity to allocate another sequence. This is a concurrent method so the response should only be taken as an indication of available capacity.
      Parameters:
      requiredCapacity - in the buffer
      Returns:
      true if the buffer has the capacity to allocate the next sequence otherwise false.
      See Also:

    • hasAvailableCapacity

      private boolean hasAvailableCapacity(int requiredCapacity, boolean doStore)

    • next

      public long next()
      Description copied from interface: Sequenced
      Claim the next event in sequence for publishing.
      Returns:
      the claimed sequence value
      See Also:

    • next

      public long next(int n)
      Description copied from interface: Sequenced
      Claim the next n events in sequence for publishing. This is for batch event producing. Using batch producing requires a little care and some math. 
       int n = 10;
 long hi = sequencer.next(n);
 long lo = hi - (n - 1);
 for (long sequence = lo; sequence <= hi; sequence++) {
     // Do work.
 }
 sequencer.publish(lo, hi);
      Parameters:
      n - the number of sequences to claim
      Returns:
      the highest claimed sequence value
      See Also:

    • tryNext

      public long tryNext() throws InsufficientCapacityException
      Description copied from interface: Sequenced
      Attempt to claim the next event in sequence for publishing. Will return the number of the slot if there is at least requiredCapacity slots available.
      Returns:
      the claimed sequence value
      Throws:
      InsufficientCapacityException - thrown if there is no space available in the ring buffer.
      See Also:

    • tryNext

      public long tryNext(int n) throws InsufficientCapacityException
      Description copied from interface: Sequenced
      Attempt to claim the next n events in sequence for publishing. Will return the highest numbered slot if there is at least requiredCapacity slots available. Have a look at Sequenced.next() for a description on how to use this method.
      Parameters:
      n - the number of sequences to claim
      Returns:
      the claimed sequence value
      Throws:
      InsufficientCapacityException - thrown if there is no space available in the ring buffer.
      See Also:

    • remainingCapacity

      public long remainingCapacity()
      Description copied from interface: Sequenced
      Get the remaining capacity for this sequencer.
      Returns:
      The number of slots remaining.
      See Also:

    • claim

      public void claim(long sequence)
      Description copied from interface: Sequencer
      Claim a specific sequence. Only used if initialising the ring buffer to a specific value.
      Parameters:
      sequence - The sequence to initialise too.
      See Also:

    • publish

      public void publish(long sequence)
      Description copied from interface: Sequenced
      Publishes a sequence. Call when the event has been filled.
      Parameters:
      sequence - the sequence to be published.
      See Also:

    • publish

      public void publish(long lo, long hi)
      Description copied from interface: Sequenced
      Batch publish sequences. Called when all of the events have been filled.
      Parameters:
      lo - first sequence number to publish
      hi - last sequence number to publish
      See Also:

    • isAvailable

      public boolean isAvailable(long sequence)
      Description copied from interface: Sequencer
      Confirms if a sequence is published and the event is available for use; non-blocking.
      Parameters:
      sequence - of the buffer to check
      Returns:
      true if the sequence is available for use, false if not
      See Also:

    • getHighestPublishedSequence

      public long getHighestPublishedSequence(long lowerBound, long availableSequence)
      Description copied from interface: Sequencer
      Get the highest sequence number that can be safely read from the ring buffer. Depending on the implementation of the Sequencer this call may need to scan a number of values in the Sequencer. The scan will range from nextSequence to availableSequence. If there are no available values >= nextSequence the return value will be nextSequence - 1. To work correctly a consumer should pass a value that is 1 higher than the last sequence that was successfully processed.
      Parameters:
      lowerBound - The sequence to start scanning from.
      availableSequence - The sequence to scan to.
      Returns:
      The highest value that can be safely read, will be at least nextSequence - 1.

    • toString

      public String toString()
      Overrides:
      toString in class AbstractSequencer

    • sameThread

      private boolean sameThread()