io.aeron

Class FragmentAssembler

java.lang.Object

io.aeron.FragmentAssembler

All Implemented Interfaces:

FragmentHandler

public class FragmentAssembler
extends java.lang.Object
implements FragmentHandler

A FragmentHandler that sits in a chain-of-responsibility pattern that reassembles fragmented messages so that the next handler in the chain only sees whole messages.

Unfragmented messages are delegated without copy. Fragmented messages are copied to a temporary buffer for reassembly before delegation.

The Header passed to the delegate on assembling a message will be that of the last fragment.

Session based buffers will be allocated and grown as necessary based on the length of messages to be assembled. When sessions go inactive see UnavailableImageHandler, it is possible to free the buffer by calling freeSessionBuffer(int).

See Also:

Subscription.poll(FragmentHandler, int), Image.poll(FragmentHandler, int)

Constructor Summary

Constructors

Constructor and Description
FragmentAssembler(FragmentHandler delegate) Construct an adapter to reassemble message fragments and delegate on whole messages.
FragmentAssembler(FragmentHandler delegate, int initialBufferLength) Construct an adapter to reassemble message fragments and delegate on whole messages.
FragmentAssembler(FragmentHandler delegate, int initialBufferLength, boolean isDirectByteBuffer) Construct an adapter to reassemble message fragments and delegate on whole messages.

Method Summary

Modifier and Type	Method and Description
void	clear() Clear down the cache of buffers by session for reassembling messages.
FragmentHandler	delegate() Get the delegate unto which assembled messages are delegated.
boolean	freeSessionBuffer(int sessionId) Free an existing session buffer to reduce memory pressure when an image goes inactive or no more large messages are expected.
boolean	isDirectByteBuffer() Is the underlying buffer used to assemble fragments a direct ByteBuffer?
void	onFragment(org.agrona.DirectBuffer buffer, int offset, int length, Header header) The implementation of FragmentHandler that reassembles and forwards whole messages.

Methods inherited from class java.lang.Object

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

Constructor Detail

FragmentAssembler

public FragmentAssembler(FragmentHandler delegate)

Construct an adapter to reassemble message fragments and delegate on whole messages.

Parameters:

delegate - onto which whole messages are forwarded.

FragmentAssembler

public FragmentAssembler(FragmentHandler delegate,
                         int initialBufferLength)

Construct an adapter to reassemble message fragments and delegate on whole messages.

Parameters:

delegate - onto which whole messages are forwarded.

initialBufferLength - to be used for each session.

FragmentAssembler

public FragmentAssembler(FragmentHandler delegate,
                         int initialBufferLength,
                         boolean isDirectByteBuffer)

Construct an adapter to reassemble message fragments and delegate on whole messages.

Parameters:

delegate - onto which whole messages are forwarded.

initialBufferLength - to be used for each session.

isDirectByteBuffer - is the underlying buffer to be a direct ByteBuffer?

Method Detail

delegate

public FragmentHandler delegate()

Get the delegate unto which assembled messages are delegated.

Returns:

the delegate unto which assembled messages are delegated.

isDirectByteBuffer

public boolean isDirectByteBuffer()

Is the underlying buffer used to assemble fragments a direct ByteBuffer?

Returns:

true if the underlying buffer used to assemble fragments is a direct ByteBuffer

onFragment

public void onFragment(org.agrona.DirectBuffer buffer,
                       int offset,
                       int length,
                       Header header)

The implementation of FragmentHandler that reassembles and forwards whole messages.

Specified by:

onFragment in interface FragmentHandler

Parameters:

buffer - containing the data.

offset - at which the data begins.

length - of the data in bytes.

header - representing the meta data for the data.

freeSessionBuffer

public boolean freeSessionBuffer(int sessionId)

Free an existing session buffer to reduce memory pressure when an image goes inactive or no more large messages are expected.

Parameters:

sessionId - to have its buffer freed

Returns:

true if a buffer has been freed otherwise false.

clear

public void clear()

Clear down the cache of buffers by session for reassembling messages.