Class Sequence

java.lang.Object
com.lmax.disruptor.Sequence
Direct Known Subclasses:
FixedSequenceGroup, SequenceGroup
public class Sequence extends Object

Concurrent sequence class used for tracking the progress of the ring buffer and event processors. Support a number of concurrent operations including CAS and order writes.

Also attempts to be more efficient with regards to false sharing by adding padding around the volatile field.

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    protected long
    p1
     
    protected long
    p10
     
    protected long
    p11
     
    protected long
    p12
     
    protected long
    p13
     
    protected long
    p14
     
    protected long
    p15
     
    protected long
    p2
     
    protected long
    p3
     
    protected long
    p4
     
    protected long
    p5
     
    protected long
    p6
     
    protected long
    p7
     
    protected long
    p9
     
    protected long
    value
     

  • Constructor Summary

    Constructors
    Constructor
    Description
    Sequence()
    Create a sequence initialised to -1.
    Sequence(long initialValue)
    Create a sequence with a specified initial value.

  • Method Summary

    Modifier and Type
    Method
    Description
    long
    addAndGet(long increment)
    Atomically add the supplied value.
    boolean
    compareAndSet(long expectedValue, long newValue)
    Perform a compare and set operation on the sequence.
    long
    get()
    Perform a volatile read of this sequence's value.
    long
    incrementAndGet()
    Atomically increment the sequence by one.
    void
    set(long value)
    Perform an ordered write of this sequence.
    void
    setVolatile(long value)
    Performs a volatile write of this sequence.
    String
    toString()
     

    Methods inherited from class Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

  • Field Details

    • p9

      protected long p9

    • p10

      protected long p10

    • p11

      protected long p11

    • p12

      protected long p12

    • p13

      protected long p13

    • p14

      protected long p14

    • p15

      protected long p15

    • value

      protected volatile long value

    • p1

      protected long p1

    • p2

      protected long p2

    • p3

      protected long p3

    • p4

      protected long p4

    • p5

      protected long p5

    • p6

      protected long p6

    • p7

      protected long p7

  • Constructor Details

    • Sequence

      public Sequence()
      Create a sequence initialised to -1.

    • Sequence

      public Sequence(long initialValue)
      Create a sequence with a specified initial value.
      Parameters:
      initialValue - The initial value for this sequence.

  • Method Details

    • get

      public long get()
      Perform a volatile read of this sequence's value.
      Returns:
      The current value of the sequence.

    • set

      public void set(long value)
      Perform an ordered write of this sequence. The intent is a Store/Store barrier between this write and any previous store.
      Parameters:
      value - The new value for the sequence.

    • setVolatile

      public void setVolatile(long value)
      Performs a volatile write of this sequence. The intent is a Store/Store barrier between this write and any previous write and a Store/Load barrier between this write and any subsequent volatile read.
      Parameters:
      value - The new value for the sequence.

    • compareAndSet

      public boolean compareAndSet(long expectedValue, long newValue)
      Perform a compare and set operation on the sequence.
      Parameters:
      expectedValue - The expected current value.
      newValue - The value to update to.
      Returns:
      true if the operation succeeds, false otherwise.

    • incrementAndGet

      public long incrementAndGet()
      Atomically increment the sequence by one.
      Returns:
      The value after the increment

    • addAndGet

      public long addAndGet(long increment)
      Atomically add the supplied value.
      Parameters:
      increment - The value to add to the sequence.
      Returns:
      The value after the increment.

    • toString

      public String toString()
      Overrides:
      toString in class Object