io.aeron

Class ControlledFragmentAssembler

java.lang.Object

io.aeron.ControlledFragmentAssembler

All Implemented Interfaces:

ControlledFragmentHandler

public class ControlledFragmentAssembler
extends java.lang.Object
implements ControlledFragmentHandler

A ControlledFragmentHandler 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.controlledPoll(ControlledFragmentHandler, int), Image.controlledPoll(ControlledFragmentHandler, int), Image.controlledPeek(long, ControlledFragmentHandler, long)

Nested Class Summary

Nested classes/interfaces inherited from interface io.aeron.logbuffer.ControlledFragmentHandler

ControlledFragmentHandler.Action

Constructor Summary

Constructors

Constructor and Description
ControlledFragmentAssembler(ControlledFragmentHandler delegate) Construct an adapter to reassemble message fragments and delegate on whole messages.
ControlledFragmentAssembler(ControlledFragmentHandler delegate, int initialBufferLength) Construct an adapter to reassemble message fragments and delegate on whole messages.
ControlledFragmentAssembler(ControlledFragmentHandler 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.
ControlledFragmentHandler	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?
ControlledFragmentHandler.Action	onFragment(org.agrona.DirectBuffer buffer, int offset, int length, Header header) The implementation of ControlledFragmentHandler 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

ControlledFragmentAssembler

public ControlledFragmentAssembler(ControlledFragmentHandler delegate)

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

Parameters:

delegate - onto which whole messages are forwarded.

ControlledFragmentAssembler

public ControlledFragmentAssembler(ControlledFragmentHandler 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.

ControlledFragmentAssembler

public ControlledFragmentAssembler(ControlledFragmentHandler 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 ControlledFragmentHandler 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 ControlledFragmentHandler.Action onFragment(org.agrona.DirectBuffer buffer,
                                                   int offset,
                                                   int length,
                                                   Header header)

The implementation of ControlledFragmentHandler that reassembles and forwards whole messages.

Specified by:

onFragment in interface ControlledFragmentHandler

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.

Returns:

The action to be taken with regard to the stream position after the callback.

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.