io.aeron.logbuffer

Class Header

java.lang.Object

io.aeron.logbuffer.Header

public class Header
extends java.lang.Object

Represents the header of the data frame for accessing meta data fields.

Constructor Summary

Constructors

Constructor and Description
Header(int initialTermId, int positionBitsToShift) Construct a header that references a buffer for the log.
Header(int initialTermId, int positionBitsToShift, java.lang.Object context) Construct a header that references a buffer for the log.

Method Summary

Modifier and Type	Method and Description
org.agrona.DirectBuffer	buffer() The DirectBuffer containing the header.
void	buffer(org.agrona.DirectBuffer buffer) The DirectBuffer containing the header.
java.lang.Object	context() Context for storing state related to the context of the callback where the header is used.
byte	flags() The flags for this frame.
int	frameLength() The total length of the frame including the header.
int	initialTermId() Get the initial term id this stream started at.
int	offset() The offset at which the frame begins.
void	offset(int offset) Set the offset at which the header begins in the log.
long	position() Get the current position to which the image has advanced on reading this message.
long	reservedValue() Get the value stored in the reserve space at the end of a data frame header.
int	sessionId() The session ID to which the frame belongs.
int	streamId() The stream ID to which the frame belongs.
int	termId() The term ID to which the frame belongs.
int	termOffset() The offset in the term at which the frame begins.
int	type() The type of the the frame which should always be HeaderFlyweight.HDR_TYPE_DATA

Methods inherited from class java.lang.Object

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

Constructor Detail

Header

public Header(int initialTermId,
              int positionBitsToShift)

Construct a header that references a buffer for the log.

Parameters:

initialTermId - this stream started at.

positionBitsToShift - for calculating positions.

Header

public Header(int initialTermId,
              int positionBitsToShift,
              java.lang.Object context)

Construct a header that references a buffer for the log.

Parameters:

initialTermId - this stream started at.

positionBitsToShift - for calculating positions.

context - for storing state when which can be accessed with context().

Method Detail

context

public java.lang.Object context()

Context for storing state related to the context of the callback where the header is used.

Returns:

context for storing state related to the context of the callback where the header is used.

position

public final long position()

Get the current position to which the image has advanced on reading this message.

Returns:

the current position to which the image has advanced on reading this message.

initialTermId

public final int initialTermId()

Get the initial term id this stream started at.

Returns:

the initial term id this stream started at.

offset

public final void offset(int offset)

Set the offset at which the header begins in the log.

Parameters:

offset - at which the header begins in the log.

offset

public final int offset()

The offset at which the frame begins.

Returns:

offset at which the frame begins.

buffer

public final org.agrona.DirectBuffer buffer()

The DirectBuffer containing the header.

Returns:

DirectBuffer containing the header.

buffer

public final void buffer(org.agrona.DirectBuffer buffer)

The DirectBuffer containing the header.

Parameters:

buffer - DirectBuffer containing the header.

frameLength

public int frameLength()

The total length of the frame including the header.

Returns:

the total length of the frame including the header.

sessionId

public final int sessionId()

The session ID to which the frame belongs.

Returns:

the session ID to which the frame belongs.

streamId

public final int streamId()

The stream ID to which the frame belongs.

Returns:

the stream ID to which the frame belongs.

termId

public final int termId()

The term ID to which the frame belongs.

Returns:

the term ID to which the frame belongs.

termOffset

public int termOffset()

The offset in the term at which the frame begins. This will be the same as offset()

Returns:

the offset in the term at which the frame begins.

type

public final int type()

The type of the the frame which should always be HeaderFlyweight.HDR_TYPE_DATA

Returns:

type of the the frame which should always be HeaderFlyweight.HDR_TYPE_DATA

flags

public byte flags()

The flags for this frame. Valid flags are DataHeaderFlyweight.BEGIN_FLAG and DataHeaderFlyweight.END_FLAG. A convenience flag DataHeaderFlyweight.BEGIN_AND_END_FLAGS can be used for both flags.

Returns:

the flags for this frame.

reservedValue

public long reservedValue()

Get the value stored in the reserve space at the end of a data frame header.

Note: The value is in ByteOrder.LITTLE_ENDIAN format.

Returns:

the value stored in the reserve space at the end of a data frame header.

See Also:

DataHeaderFlyweight