Package org.jgroups.util

Class Buffer<T>

java.lang.Object

org.jgroups.util.Buffer<T>

All Implemented Interfaces:

java.lang.Iterable<T>

Direct Known Subclasses:

DynamicBuffer, FixedBuffer

public abstract class Buffer<T>
extends java.lang.Object
implements java.lang.Iterable<T>

Base class for message buffers. Used on the senders (keeping track of sent messages and purging delivered messages) and receivers (delivering messages in the correct order and asking senders for missing messages).

Since:

5.4

Author:

Bela Ban

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
protected class	Buffer.HighestDeliverable
protected class	Buffer.Missing
protected class	Buffer.NumDeliverable
static class	Buffer.Options
protected class	Buffer.Remover<R>
static interface	Buffer.Visitor<T>

Field Summary

Fields

Modifier and Type	Field	Description
protected java.util.concurrent.atomic.AtomicInteger	adders
protected long	hd	The highest delivered (=removed) seqno
protected long	high	The highest received/sent seqno.
protected java.util.concurrent.locks.Lock	lock
protected long	low	sender: highest seqno seen by everyone, receiver: highest delivered seqno
protected long	offset
protected int	size	The number of non-null elements

Constructor Summary

Constructors

Constructor	Description
Buffer()

Method Summary

Modifier and Type	Method	Description
abstract T	_get(long seqno)
boolean	add(long seqno, T element)	Adds an element if the element at the given index is null.
abstract boolean	add(long seqno, T element, java.util.function.Predicate<T> remove_filter, Buffer.Options options)	Adds an element if the element at the given index is null.
abstract boolean	add(MessageBatch batch, java.util.function.Function<T,java.lang.Long> seqno_getter, boolean remove_from_batch, T const_value)
abstract int	capacity()	Returns the current capacity in the buffer.
int	computeSize()	Iterates from hd to high and adds up non-null values.
java.lang.String	dump()	Dumps all non-null messages (used for testing)
abstract void	forEach(long from, long to, Buffer.Visitor<T> visitor, boolean nullify)
void	forEach(Buffer.Visitor<T> visitor, boolean nullify)
abstract T	get(long seqno)
java.util.concurrent.atomic.AtomicInteger	getAdders()
long[]	getDigest()
long	getHighestDeliverable()	Returns the highest deliverable (= removable) seqno.
SeqnoList	getMissing()	Returns a list of missing (= null) elements
SeqnoList	getMissing(int max_msgs)	Returns a list of missing messages
int	getNumDeliverable()	Returns the number of messages that can be delivered
long	hd()
long	high()
long	highestDelivered()
Buffer<T>	highestDelivered(long seqno)	Only used internally on a state transfer (setting the digest).
boolean	isEmpty()
abstract java.util.Iterator<T>	iterator(long from, long to)
java.util.concurrent.locks.Lock	lock()
long	low()
int	numMissing()	Returns the number of null elements in the range [hd+1 ..
long	offset()
int	purge(long seqno)	Removes all elements <= seqno from the buffer.
abstract int	purge(long seqno, boolean force)	Purges (nulls) all elements <= seqno.
T	remove()
abstract T	remove(boolean nullify)
java.util.List<T>	removeMany(boolean nullify, int max_results)
abstract java.util.List<T>	removeMany(boolean nullify, int max_results, java.util.function.Predicate<T> filter)
abstract <R> R	removeMany(boolean nullify, int max_results, java.util.function.Predicate<T> filter, java.util.function.Supplier<R> result_creator, java.util.function.BiConsumer<R,T> accumulator)
void	resetStats()
int	size()
abstract java.util.stream.Stream<T>	stream()
abstract java.util.stream.Stream<T>	stream(long from, long to)
java.lang.String	toString()

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.lang.Iterable

forEach, iterator, spliterator

Field Detail

lock

protected final java.util.concurrent.locks.Lock lock

adders

protected final java.util.concurrent.atomic.AtomicInteger adders

offset

protected long offset

low

protected long low

sender: highest seqno seen by everyone, receiver: highest delivered seqno

hd

protected long hd

The highest delivered (=removed) seqno

high

protected long high

The highest received/sent seqno. Moved forward by add(). The next message to be added is high+1. low <= hd <= high always holds

size

protected int size

The number of non-null elements

Constructor Detail

Buffer

public Buffer()

Method Detail

lock

public java.util.concurrent.locks.Lock lock()

getAdders

public java.util.concurrent.atomic.AtomicInteger getAdders()

offset

public long offset()

low

public long low()

highestDelivered

public long highestDelivered()

hd

public long hd()

high

public long high()

size

public int size()

isEmpty

public boolean isEmpty()

capacity

public abstract int capacity()

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)

resetStats

public void resetStats()

add

public boolean add(long seqno,
                   T element)

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.

Parameters:

seqno -

element -

Returns:

True if the element at the computed index was null, else false

add

public abstract boolean add(long seqno,
                            T element,
                            java.util.function.Predicate<T> remove_filter,
                            Buffer.Options options)

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.

Parameters:

seqno -

element -

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.

options -

Returns:

True if the element at the computed index was null, else false

add

public abstract boolean add(MessageBatch batch,
                            java.util.function.Function<T,java.lang.Long> seqno_getter,
                            boolean remove_from_batch,
                            T const_value)

get

public abstract T get(long seqno)

_get

public abstract T _get(long seqno)

remove

public T remove()

remove

public abstract T remove(boolean nullify)

removeMany

public java.util.List<T> removeMany(boolean nullify,
                                    int max_results)

removeMany

public abstract java.util.List<T> removeMany(boolean nullify,
                                             int max_results,
                                             java.util.function.Predicate<T> filter)

removeMany

public abstract <R> R removeMany(boolean nullify,
                                 int max_results,
                                 java.util.function.Predicate<T> filter,
                                 java.util.function.Supplier<R> result_creator,
                                 java.util.function.BiConsumer<R,T> accumulator)

purge

public int purge(long seqno)

Removes all elements <= seqno from the buffer. Does this by nulling all elements < index(seqno)

purge

public abstract int purge(long seqno,
                          boolean force)

Purges (nulls) all elements <= seqno.

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

forEach

public void forEach(Buffer.Visitor<T> visitor,
                    boolean nullify)

forEach

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

iterator

public abstract java.util.Iterator<T> iterator(long from,
                                               long to)

stream

public abstract java.util.stream.Stream<T> stream()

stream

public abstract java.util.stream.Stream<T> stream(long from,
                                                  long to)

computeSize

public int computeSize()

Iterates from hd to high and adds up non-null values. Caller must hold the lock.

numMissing

public int numMissing()

Returns the number of null elements in the range [hd+1 .. hr-1] excluding hd and hr

getMissing

public SeqnoList getMissing()

Returns a list of missing (= null) elements

Returns:

A SeqnoList of missing messages, or null if no messages are missing

getMissing

public SeqnoList getMissing(int max_msgs)

Returns a list of missing messages

Parameters:

max_msgs - If > 0, the max number of missing messages to be returned (oldest first), else no limit

Returns:

A SeqnoList of missing messages, or null if no messages are missing

getNumDeliverable

public int getNumDeliverable()

Returns the number of messages that can be delivered

getHighestDeliverable

public long getHighestDeliverable()

Returns the highest deliverable (= removable) seqno. This may be higher than highestDelivered(), e.g. if elements have been added but not yet removed

getDigest

public long[] getDigest()

highestDelivered

public Buffer<T> highestDelivered(long seqno)

Only used internally on a state transfer (setting the digest). Don't use this in application code!

dump

public java.lang.String dump()

Dumps all non-null messages (used for testing)

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object