io.aeron

Class Image

java.lang.Object

io.aeron.Image

public class Image
extends java.lang.Object

Represents a replicated publication Image from a publisher to a Subscription. Each Image identifies a source publisher by session id.

Constructor Summary

Constructors

Constructor and Description
Image(Subscription subscription, int sessionId, org.agrona.concurrent.status.Position subscriberPosition, LogBuffers logBuffers, org.agrona.ErrorHandler errorHandler, java.lang.String sourceIdentity, long correlationId) Construct a new image over a log to represent a stream of messages from a Publication.

Method Summary

Modifier and Type	Method and Description
int	blockPoll(BlockHandler blockHandler, int blockLengthLimit) Poll for new messages in a stream.
int	controlledPoll(ControlledFragmentHandler fragmentHandler, int fragmentLimit) Poll for new messages in a stream.
long	correlationId() The correlationId for identification of the image with the media driver.
java.nio.channels.FileChannel	fileChannel() The FileChannel to the raw log of the Image.
int	initialTermId() The initial term at which the stream started for this session.
boolean	isClosed() Has this object been closed and should no longer be used?
int	poll(FragmentHandler fragmentHandler, int fragmentLimit) Poll for new messages in a stream.
long	position() The position this Image has been consumed to by the subscriber.
int	rawPoll(RawBlockHandler rawBlockHandler, int blockLengthLimit) Poll for new messages in a stream.
int	sessionId() The sessionId for the steam of messages.
java.lang.String	sourceIdentity() The source identity of the sending publisher as an abstract concept appropriate for the media.
Subscription	subscription() Get the Subscription to which this Image belongs.
int	termBufferLength() Get the length in bytes for each term partition in the log buffer.

Methods inherited from class java.lang.Object

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

Constructor Detail

Image

public Image(Subscription subscription,
             int sessionId,
             org.agrona.concurrent.status.Position subscriberPosition,
             LogBuffers logBuffers,
             org.agrona.ErrorHandler errorHandler,
             java.lang.String sourceIdentity,
             long correlationId)

Construct a new image over a log to represent a stream of messages from a Publication.

Parameters:

subscription - to which this Image belongs.

sessionId - of the stream of messages.

subscriberPosition - for indicating the position of the subscriber in the stream.

logBuffers - containing the stream of messages.

errorHandler - to be called if an error occurs when polling for messages.

sourceIdentity - of the source sending the stream of messages.

correlationId - of the request to the media driver.

Method Detail

termBufferLength

public int termBufferLength()

Get the length in bytes for each term partition in the log buffer.

Returns:

the length in bytes for each term partition in the log buffer.

sessionId

public int sessionId()

The sessionId for the steam of messages.

Returns:

the sessionId for the steam of messages.

sourceIdentity

public java.lang.String sourceIdentity()

The source identity of the sending publisher as an abstract concept appropriate for the media.

Returns:

source identity of the sending publisher as an abstract concept appropriate for the media.

initialTermId

public int initialTermId()

The initial term at which the stream started for this session.

Returns:

the initial term id.

correlationId

public long correlationId()

The correlationId for identification of the image with the media driver.

Returns:

the correlationId for identification of the image with the media driver.

subscription

public Subscription subscription()

Get the Subscription to which this Image belongs.

Returns:

the Subscription to which this Image belongs.

isClosed

public boolean isClosed()

Has this object been closed and should no longer be used?

Returns:

true if it has been closed otherwise false.

position

public long position()

The position this Image has been consumed to by the subscriber.

Returns:

the position this Image has been consumed to by the subscriber.

fileChannel

public java.nio.channels.FileChannel fileChannel()

The FileChannel to the raw log of the Image.

Returns:

the FileChannel to the raw log of the Image.

poll

public int poll(FragmentHandler fragmentHandler,
                int fragmentLimit)

Poll for new messages in a stream. If new messages are found beyond the last consumed position then they will be delivered to the FragmentHandler up to a limited number of fragments as specified. To assemble messages that span multiple fragments then use FragmentAssembler.

Parameters:

fragmentHandler - to which message fragments are delivered.

fragmentLimit - for the number of fragments to be consumed during one polling operation.

Returns:

the number of fragments that have been consumed.

See Also:

FragmentAssembler

controlledPoll

public int controlledPoll(ControlledFragmentHandler fragmentHandler,
                          int fragmentLimit)

Poll for new messages in a stream. If new messages are found beyond the last consumed position then they will be delivered to the ControlledFragmentHandler up to a limited number of fragments as specified. To assemble messages that span multiple fragments then use ControlledFragmentAssembler.

Parameters:

fragmentHandler - to which message fragments are delivered.

fragmentLimit - for the number of fragments to be consumed during one polling operation.

Returns:

the number of fragments that have been consumed.

See Also:

ControlledFragmentAssembler

blockPoll

public int blockPoll(BlockHandler blockHandler,
                     int blockLengthLimit)

Poll for new messages in a stream. If new messages are found beyond the last consumed position then they will be delivered to the BlockHandler up to a limited number of bytes.

Parameters:

blockHandler - to which block is delivered.

blockLengthLimit - up to which a block may be in length.

Returns:

the number of bytes that have been consumed.

rawPoll

public int rawPoll(RawBlockHandler rawBlockHandler,
                   int blockLengthLimit)

Poll for new messages in a stream. If new messages are found beyond the last consumed position then they will be delivered to the RawBlockHandler up to a limited number of bytes. This method is useful for operations like bulk archiving a stream to file.

Parameters:

rawBlockHandler - to which block is delivered.

blockLengthLimit - up to which a block may be in length.

Returns:

the number of bytes that have been consumed.