Class FixedBuffer<T>

java.lang.Object
org.jgroups.util.Buffer<T>
org.jgroups.util.FixedBuffer<T>
Type Parameters:
T - T
All Implemented Interfaces:
Closeable, AutoCloseable, Iterable<T>
public class FixedBuffer<T> extends Buffer<T>
Ring buffer of fixed capacity. Indices low and high point to the beginning and end of the buffer. Sequence numbers (seqnos) are mapped to an index by 
seqno % capacity
. High can never pass low, and drops the element or blocks when that's the case.
Note that 'null' is not a valid element, but signifies a missing element
The design is described in doc/design/FixedBuffer.txt.
Since:
5.4
Author:
Bela Ban

  • Field Details

    • buf

      protected T[] buf
      Holds the elements

    • buffer_full

      protected final Condition buffer_full

    • open

      protected boolean open
      Used to unblock blocked senders on close(). When false, senders don't block when full but discard element

    • num_blockings

      protected final LongAdder num_blockings

    • avg_time_blocked

      protected final AverageMinMax avg_time_blocked

    • num_dropped_msgs

      protected final LongAdder num_dropped_msgs
      Number of received messages dropped due to full buffer

  • Constructor Details

    • FixedBuffer

      public FixedBuffer()

    • FixedBuffer

      public FixedBuffer(long offset)

    • FixedBuffer

      public FixedBuffer(int capacity, long offset)
      Creates a RingBuffer
      Parameters:
      capacity - The number of elements the ring buffer's array should hold.
      offset - The offset. The first element to be added has to be offset +1.

  • Method Details

    • capacity

      public int capacity()
      Description copied from class: Buffer
      Returns the current capacity in the buffer. This value is fixed in a fixed-size buffer (e.g. FixedBuffer), but can change in a dynamic buffer (DynamicBuffer)
      Specified by:
      capacity in class Buffer<T>

    • numBlockings

      public long numBlockings()

    • avgTimeBlocked

      public AverageMinMax avgTimeBlocked()

    • numDroppedMessages

      public long numDroppedMessages()

    • add

      public boolean add(long seqno, T element, Predicate<T> remove_filter, boolean block_if_full)
      Description copied from class: Buffer
      Adds an element if the element at the given index is null. Returns true if no element existed at the given index, else returns false and doesn't set the element.
      Specified by:
      add in class Buffer<T>
      Parameters:
      seqno - The seqno of the element
      element - The element to be added
      remove_filter - A filter used to remove all consecutive messages passing the filter (and non-null). This doesn't necessarily null a removed message, but may simply advance an index (e.g. highest delivered). Ignored if null.
      block_if_full - If true: blocks when an element is to be added to the buffer, else drops the element
      Returns:
      True if the element at the computed index was null, else false

    • add

      public boolean add(MessageBatch batch, Function<T,Long> seqno_getter, boolean remove_from_batch, T const_value)
      Specified by:
      add in class Buffer<T>

    • add

      public boolean add(List<LongTuple<T>> list, boolean remove_added_elements, T const_value)
      Description copied from class: Buffer
      Adds elements from the list
      Specified by:
      add in class Buffer<T>
      Parameters:
      list - The list of tuples of seqnos and elements. If remove_added_elements is true, if elements could not be added (e.g. because they were already present or the seqno was < HD), those elements will be removed from list
      remove_added_elements - If true, elements that could not be added to the table are removed from list
      const_value - If non-null, this value should be used rather than the values of the list tuples
      Returns:
      True if at least 1 element was added successfully, false otherwise.

    • remove

      public T remove(boolean nullify)
      Removes the next non-null element and advances hd
      Specified by:
      remove in class Buffer<T>
      Returns:
      T if there was a non-null element at hd+1, otherwise null

    • removeMany

      public List<T> removeMany(boolean nullify, int max_results, Predicate<T> filter)
      Specified by:
      removeMany in class Buffer<T>

    • removeMany

      public <R> R removeMany(boolean nullify, int max_results, Predicate<T> filter, Supplier<R> result_creator, BiConsumer<R,T> accumulator)
      Specified by:
      removeMany in class Buffer<T>

    • get

      public T get(long seqno)
      Specified by:
      get in class Buffer<T>

    • _get

      public T _get(long seqno)
      Only used for testing !!
      Specified by:
      _get in class Buffer<T>

    • purge

      public int purge(long seqno, boolean force)
      Description copied from class: Buffer
      Purges (nulls) all elements <= seqno.
      Specified by:
      purge in class Buffer<T>
      Parameters:
      seqno - All elements <= seqno will be purged.
      force - If false, seqno is max(seqno,hd), else max(seqno,high). In the latter case (seqno > hd), we might purge elements that have not yet been received
      Returns:
      0. The number of purged elements

    • changeCapacity

      public void changeCapacity(int new_capacity)
      Changes the size of the buffer. This method should NOT be used; it is only here to change config in perf tests dynamically!!

    • forEach

      public void forEach(long from, long to, Buffer.Visitor<T> visitor, boolean nullify)
      Specified by:
      forEach in class Buffer<T>

    • forEach

      public void forEach(long from, long to, Buffer.Visitor<T> visitor, boolean nullify, boolean respect_stop)

    • resetStats

      public void resetStats()
      Overrides:
      resetStats in class Buffer<T>

    • open

      public void open(boolean b)
      Overrides:
      open in class Buffer<T>

    • iterator

      public Iterator<T> iterator()
      Returns an iterator over the elements of the ring buffer in the range [LOW+1 .. HIGH]
      Returns:
      FixedBufferIterator
      Throws:
      NoSuchElementException - is HD is moved forward during the iteration

    • iterator

      public Iterator<T> iterator(long from, long to)
      Specified by:
      iterator in class Buffer<T>

    • stream

      public Stream<T> stream()
      Specified by:
      stream in class Buffer<T>

    • stream

      public Stream<T> stream(long from, long to)
      Specified by:
      stream in class Buffer<T>

    • index

      protected int index(long seqno)

    • block

      protected boolean block(long seqno)

    • increaseCapacity

      protected void increaseCapacity(int new_cap)

    • decreaseCapacity

      protected void decreaseCapacity(int new_cap)