java.lang.Object
- org.jgroups.nio.Buffers

All Implemented Interfaces:

java.lang.Iterable<java.nio.ByteBuffer>
```
public class Buffers
extends java.lang.Object
implements java.lang.Iterable<java.nio.ByteBuffer>
```
Class to do scattering reads or gathering writes on a sequence of ByteBuffer instances. The buffers are kept in an array with fixed capacity (max Short.MAX_VALUE). Buffers can be added and removed dynamically, but they're dropped when the capacity is exceeded. This means that, if a we have configured a capacity of 5 buffers, and want to add 6, none of the 6 buffers will be added!
A read is successful when all non-null buffers from left to right are filled, i.e. all Buffer.remaining() methods return 0.
Same for writes: when all non-null buffers (from left to right) have been written (Buffer.remaining() == 0), a write is considered successful; otherwise it is partial.
Individual buffers can be accessed; e.g. for reading its value after a read. It is also possible to add buffers dynamically, e.g. after reading a 'length' buffer, a user may want to add a new buffer allocated for reading 'length' bytes.
This class is not synchronized.

Since:

3.6.5

Author:

Bela Ban

Nested Class Summary

Nested Classes
Modifier and Type Class Description

protected class Buffers.BuffersIterator
Iterates over the non-null buffers

Field Summary

Fields
Modifier and Type	Field	Description
`protected java.nio.ByteBuffer[]`	`bufs`
`protected short`	`limit`
`protected int`	`max_length`
`protected short`	`next_to_copy`
`protected short`	`position`

Constructor Summary

Constructors
Constructor Description

Buffers(int capacity)
Creates a new instance with an array of capacity buffers

Buffers(java.nio.ByteBuffer... data)

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`Buffers`	`add(java.nio.ByteBuffer buf)`	Adds a buffer.
`Buffers`	`add(java.nio.ByteBuffer... buffers)`	Adds a number of buffers.
`protected boolean`	`adjustPosition(boolean null_complete_data)`
`protected static int`	`assertPositiveUnsignedShort(int num)`
`Buffers`	`copy()`	Copies the data that has not yet been written and moves last_copied.
`static java.nio.ByteBuffer`	`copyBuffer(java.nio.ByteBuffer buf)`	Copies a ByteBuffer by copying and wrapping the underlying array of a heap-based buffer.
`java.nio.ByteBuffer`	`get(int index)`
`boolean`	`hasRemaining()`
`java.util.Iterator<java.nio.ByteBuffer>`	`iterator()`
`int`	`limit()`
`Buffers`	`limit(int new_limit)`
`protected boolean`	`makeSpace()`
`int`	`maxLength()`
`Buffers`	`maxLength(int len)`
`int`	`nextToCopy()`
`Buffers`	`nextToCopy(int next)`
`protected boolean`	`nullData()`	Looks at all buffers in range [position ..
`int`	`position()`
`Buffers`	`position(int new_pos)`
`boolean`	`read(java.nio.channels.SocketChannel ch)`	Performs a scattering read into all (contiguous) non-null buffers in range [position ..
`java.nio.ByteBuffer`	`readLengthAndData(java.nio.channels.SocketChannel ch)`	Reads length and then length bytes into the data buffer, which is grown if needed.
`int`	`remaining()`
`Buffers`	`remove(int index)`	Nulls the buffer at index
`Buffers`	`set(int index, java.nio.ByteBuffer buf)`
`int`	`size()`	Returns the number of elements that have not yet been read or written
`protected boolean`	`spaceAvailable(int num_buffers)`
`protected static short`	`toPositiveUnsignedShort(int num)`
`java.lang.String`	`toString()`
`boolean`	`write(java.nio.channels.GatheringByteChannel ch)`	Writes the buffers from position to limit to the given channel.
`boolean`	`write(java.nio.channels.GatheringByteChannel ch, java.nio.ByteBuffer... buffers)`	Helper method which adds the buffers passed as arguments and then calls write()

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, spliterator

- Field Detail
  - bufs
```
protected final java.nio.ByteBuffer[] bufs
```
  - position
```
protected short position
```
  - limit
```
protected short limit
```
  - next_to_copy
```
protected short next_to_copy
```
  - max_length
```
protected int max_length
```
- Constructor Detail
  - Buffers
```
public Buffers(int capacity)
```
    Creates a new instance with an array of capacity buffers
    
    Parameters:
    
    capacity - Must be an unsigned positive short [1 .. Short.MAX_VALUE]
  - Buffers
```
public Buffers(java.nio.ByteBuffer... data)
```
- Method Detail
  - position
```
public int position()
```
  - position
```
public Buffers position(int new_pos)
```
  - limit
```
public int limit()
```
  - limit
```
public Buffers limit(int new_limit)
```
  - nextToCopy
```
public int nextToCopy()
```
  - nextToCopy
```
public Buffers nextToCopy(int next)
```
  - maxLength
```
public int maxLength()
```
  - maxLength
```
public Buffers maxLength(int len)
```
  - remaining
```
public int remaining()
```
  - hasRemaining
```
public boolean hasRemaining()
```
  - add
```
public Buffers add(java.nio.ByteBuffer... buffers)
```
    Adds a number of buffers. Note that if the buffers cannot be added as a whole, e.g. because of exceeding the capacity, none of them will be added!
  - add
```
public Buffers add(java.nio.ByteBuffer buf)
```
    Adds a buffer. If there's no capacity, the buffer will not be added and will be silently dropped
  - get
```
public java.nio.ByteBuffer get(int index)
```
  - set
```
public Buffers set(int index,
                   java.nio.ByteBuffer buf)
```
  - remove
```
public Buffers remove(int index)
```
    Nulls the buffer at index
  - readLengthAndData
```
public java.nio.ByteBuffer readLengthAndData(java.nio.channels.SocketChannel ch)
                                      throws java.lang.Exception
```
    Reads length and then length bytes into the data buffer, which is grown if needed.
    
    Parameters:
    
    ch - The channel to read data from
    
    Returns:
    
    The data buffer (position is 0 and limit is length), or null if not all data could be read.
    
    Throws:
    
    java.lang.Exception
  - read
```
public boolean read(java.nio.channels.SocketChannel ch)
             throws java.lang.Exception
```
    Performs a scattering read into all (contiguous) non-null buffers in range [position .. limit]. Returns true if the scattering read was successful, else false. Note that to read the contents of the individual buffers, ByteBuffer.clear() has to be called (all buffers have their position == limit on a successful read).
    
    Throws:
    
    java.lang.Exception
  - write
```
public boolean write(java.nio.channels.GatheringByteChannel ch,
                     java.nio.ByteBuffer... buffers)
              throws java.lang.Exception
```
    Helper method which adds the buffers passed as arguments and then calls write()
    
    Throws:
    
    java.lang.Exception
  - write
```
public boolean write(java.nio.channels.GatheringByteChannel ch)
              throws java.lang.Exception
```
    Writes the buffers from position to limit to the given channel. Note that all buffers need to have their Buffer.position() at the start of the data to be written
    
    Parameters:
    
    ch - The channel to write to
    
    Returns:
    
    True if all the bytes of the buffer were written successfully, false otherwise (partial write).
    
    Throws:
    
    java.lang.Exception - Thrown if the write failed
  - copy
```
public Buffers copy()
```
    Copies the data that has not yet been written and moves last_copied. Typically done after an unsuccessful write, if copying is required. This is typically needed if the output buffer is reused. Note that direct buffers will be converted to heap-based buffers
  - size
```
public int size()
```
    Returns the number of elements that have not yet been read or written
  - toString
```
public java.lang.String toString()
```
    Overrides:
    
    toString in class java.lang.Object
  - spaceAvailable
```
protected boolean spaceAvailable(int num_buffers)
```
  - makeSpace
```
protected boolean makeSpace()
```
  - nullData
```
protected boolean nullData()
```
    Looks at all buffers in range [position .. limit-1] and nulls buffers that have no remaining data. Returns true if all buffers could be nulled, and false otherwise
  - adjustPosition
```
protected boolean adjustPosition(boolean null_complete_data)
```
  - toPositiveUnsignedShort
```
protected static short toPositiveUnsignedShort(int num)
```
  - assertPositiveUnsignedShort
```
protected static int assertPositiveUnsignedShort(int num)
```
  - copyBuffer
```
public static java.nio.ByteBuffer copyBuffer(java.nio.ByteBuffer buf)
```
    Copies a ByteBuffer by copying and wrapping the underlying array of a heap-based buffer. Direct buffers are converted to heap-based buffers
  - iterator
```
public java.util.Iterator<java.nio.ByteBuffer> iterator()
```
    Specified by:
    
    iterator in interface java.lang.Iterable<java.nio.ByteBuffer>

Constructor	Description
`Buffers(int capacity)`	Creates a new instance with an array of capacity buffers
`Buffers(java.nio.ByteBuffer... data)`

Class Buffers

Nested Class Summary

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Methods inherited from interface java.lang.Iterable

Field Detail

bufs

position

limit

next_to_copy

max_length

Constructor Detail

Buffers

Buffers

Method Detail

position

position

limit

limit

nextToCopy

nextToCopy

maxLength

maxLength

remaining

hasRemaining

add

add

get

set

remove

readLengthAndData

read

write

write

copy

size

toString

spaceAvailable

makeSpace

nullData

adjustPosition

toPositiveUnsignedShort

assertPositiveUnsignedShort

copyBuffer

iterator