io.aeron.logbuffer

Class TermAppender

java.lang.Object

io.aeron.logbuffer.TermAppender

public final class TermAppender
extends java.lang.Object

Term buffer appender which supports many producers concurrently writing an append-only log.

Note: This class is threadsafe.

Messages are appended to a term using a framing protocol as described in FrameDescriptor.

A default message header is applied to each message with the fields filled in for fragment flags, type, term number, as appropriate.

A message of type FrameDescriptor.PADDING_FRAME_TYPE is appended at the end of the buffer if claimed space is not sufficiently large to accommodate the message about to be written.

Field Summary

Fields

Modifier and Type	Field and Description
static int	FAILED The append operation failed because it was past the end of the buffer.

Constructor Summary

Constructors

Constructor and Description
TermAppender(org.agrona.concurrent.UnsafeBuffer termBuffer, org.agrona.concurrent.UnsafeBuffer metaDataBuffer, int partitionIndex) Construct a view over a term buffer and state buffer for appending frames.

Method Summary

Modifier and Type	Method and Description
int	appendFragmentedMessage(HeaderWriter header, org.agrona.DirectBuffer bufferOne, int offsetOne, int lengthOne, org.agrona.DirectBuffer bufferTwo, int offsetTwo, int lengthTwo, int maxPayloadLength, ReservedValueSupplier reservedValueSupplier, int activeTermId) Append a fragmented message to the the term buffer.
int	appendFragmentedMessage(HeaderWriter header, org.agrona.DirectBuffer buffer, int offset, int length, int maxPayloadLength, ReservedValueSupplier reservedValueSupplier, int activeTermId) Append a fragmented message to the the term buffer.
int	appendFragmentedMessage(HeaderWriter header, DirectBufferVector[] vectors, int length, int maxPayloadLength, ReservedValueSupplier reservedValueSupplier, int activeTermId) Append a fragmented message to the the term buffer.
int	appendUnfragmentedMessage(HeaderWriter header, org.agrona.DirectBuffer bufferOne, int offsetOne, int lengthOne, org.agrona.DirectBuffer bufferTwo, int offsetTwo, int lengthTwo, ReservedValueSupplier reservedValueSupplier, int activeTermId) Append an unfragmented message to the the term buffer.
int	appendUnfragmentedMessage(HeaderWriter header, org.agrona.DirectBuffer buffer, int offset, int length, ReservedValueSupplier reservedValueSupplier, int activeTermId) Append an unfragmented message to the the term buffer.
int	appendUnfragmentedMessage(HeaderWriter header, DirectBufferVector[] vectors, int length, ReservedValueSupplier reservedValueSupplier, int activeTermId) Append an unfragmented message to the the term buffer as a gathering of vectors.
int	claim(HeaderWriter header, int length, BufferClaim bufferClaim, int activeTermId) Claim length of a the term buffer for writing in the message with zero copy semantics.
long	rawTailVolatile() Get the raw current tail value in a volatile memory ordering fashion.

Methods inherited from class java.lang.Object

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

Field Detail

FAILED

public static final int FAILED

The append operation failed because it was past the end of the buffer.

See Also:

Constant Field Values

Constructor Detail

TermAppender

public TermAppender(org.agrona.concurrent.UnsafeBuffer termBuffer,
                    org.agrona.concurrent.UnsafeBuffer metaDataBuffer,
                    int partitionIndex)

Construct a view over a term buffer and state buffer for appending frames.

Parameters:

termBuffer - for where messages are stored.

metaDataBuffer - for where the state of writers is stored manage concurrency.

partitionIndex - for this will be the active appender.

Method Detail

rawTailVolatile

public long rawTailVolatile()

Get the raw current tail value in a volatile memory ordering fashion.

Returns:

the current tail value.

claim

public int claim(HeaderWriter header,
                 int length,
                 BufferClaim bufferClaim,
                 int activeTermId)

Claim length of a the term buffer for writing in the message with zero copy semantics.

Parameters:

header - for writing the default header.

length - of the message to be written.

bufferClaim - to be updated with the claimed region.

activeTermId - used for flow control.

Returns:

the resulting offset of the term after the append on success otherwise FAILED.

appendUnfragmentedMessage

public int appendUnfragmentedMessage(HeaderWriter header,
                                     org.agrona.DirectBuffer bufferOne,
                                     int offsetOne,
                                     int lengthOne,
                                     org.agrona.DirectBuffer bufferTwo,
                                     int offsetTwo,
                                     int lengthTwo,
                                     ReservedValueSupplier reservedValueSupplier,
                                     int activeTermId)

Append an unfragmented message to the the term buffer.

Parameters:

header - for writing the default header.

bufferOne - containing the first part of the message.

offsetOne - at which the first part of the message begins.

lengthOne - of the first part of the message.

bufferTwo - containing the second part of the message.

offsetTwo - at which the second part of the message begins.

lengthTwo - of the second part of the message.

reservedValueSupplier - ReservedValueSupplier for the frame.

activeTermId - used for flow control.

Returns:

the resulting offset of the term after the append on success otherwise FAILED

appendUnfragmentedMessage

public int appendUnfragmentedMessage(HeaderWriter header,
                                     org.agrona.DirectBuffer buffer,
                                     int offset,
                                     int length,
                                     ReservedValueSupplier reservedValueSupplier,
                                     int activeTermId)

Append an unfragmented message to the the term buffer.

Parameters:

header - for writing the default header.

buffer - containing the message.

offset - at which the message begins.

length - of the message in the source buffer.

reservedValueSupplier - ReservedValueSupplier for the frame.

activeTermId - used for flow control.

Returns:

the resulting offset of the term after the append on success otherwise FAILED

appendUnfragmentedMessage

public int appendUnfragmentedMessage(HeaderWriter header,
                                     DirectBufferVector[] vectors,
                                     int length,
                                     ReservedValueSupplier reservedValueSupplier,
                                     int activeTermId)

Append an unfragmented message to the the term buffer as a gathering of vectors.

Parameters:

header - for writing the default header.

vectors - to the buffers.

length - of the message as a sum of the vectors.

reservedValueSupplier - ReservedValueSupplier for the frame.

activeTermId - used for flow control.

Returns:

the resulting offset of the term after the append on success otherwise FAILED.

appendFragmentedMessage

public int appendFragmentedMessage(HeaderWriter header,
                                   org.agrona.DirectBuffer buffer,
                                   int offset,
                                   int length,
                                   int maxPayloadLength,
                                   ReservedValueSupplier reservedValueSupplier,
                                   int activeTermId)

Append a fragmented message to the the term buffer. The message will be split up into fragments of MTU length minus header.

Parameters:

header - for writing the default header.

buffer - containing the message.

offset - at which the message begins.

length - of the message in the source buffer.

maxPayloadLength - that the message will be fragmented into.

reservedValueSupplier - ReservedValueSupplier for the frame.

activeTermId - used for flow control.

Returns:

the resulting offset of the term after the append on success otherwise FAILED.

appendFragmentedMessage

public int appendFragmentedMessage(HeaderWriter header,
                                   org.agrona.DirectBuffer bufferOne,
                                   int offsetOne,
                                   int lengthOne,
                                   org.agrona.DirectBuffer bufferTwo,
                                   int offsetTwo,
                                   int lengthTwo,
                                   int maxPayloadLength,
                                   ReservedValueSupplier reservedValueSupplier,
                                   int activeTermId)

Append a fragmented message to the the term buffer. The message will be split up into fragments of MTU length minus header.

Parameters:

header - for writing the default header.

bufferOne - containing the first part of the message.

offsetOne - at which the first part of the message begins.

lengthOne - of the first part of the message.

bufferTwo - containing the second part of the message.

offsetTwo - at which the second part of the message begins.

lengthTwo - of the second part of the message.

maxPayloadLength - that the message will be fragmented into.

reservedValueSupplier - ReservedValueSupplier for the frame.

activeTermId - used for flow control.

Returns:

the resulting offset of the term after the append on success otherwise FAILED.

appendFragmentedMessage

public int appendFragmentedMessage(HeaderWriter header,
                                   DirectBufferVector[] vectors,
                                   int length,
                                   int maxPayloadLength,
                                   ReservedValueSupplier reservedValueSupplier,
                                   int activeTermId)

Append a fragmented message to the the term buffer. The message will be split up into fragments of MTU length minus header.

Parameters:

header - for writing the default header.

vectors - to the buffers.

length - of the message as a sum of the vectors.

maxPayloadLength - that the message will be fragmented into.

reservedValueSupplier - ReservedValueSupplier for the frame.

activeTermId - used for flow control.

Returns:

the resulting offset of the term after the append on success otherwise FAILED.