io.aeron.logbuffer

Class ExclusiveTermAppender

java.lang.Object

io.aeron.logbuffer.ExclusiveTermAppender

public class ExclusiveTermAppender
extends java.lang.Object

Term buffer appender which supports a single exclusive producer writing an append-only log. Note: This class is NOT 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 went past the end of the buffer and failed.
static int	TRIPPED The append operation tripped the end of the buffer and needs to rotate.

Constructor Summary

Constructors

Constructor and Description
ExclusiveTermAppender(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(int termId, int termOffset, HeaderWriter header, org.agrona.DirectBuffer srcBuffer, int srcOffset, int length, int maxPayloadLength, ReservedValueSupplier reservedValueSupplier) Append a fragmented message to the the term buffer.
int	appendUnfragmentedMessage(int termId, int termOffset, HeaderWriter header, org.agrona.DirectBuffer srcBuffer, int srcOffset, int length, ReservedValueSupplier reservedValueSupplier) Append an unfragmented message to the the term buffer.
int	claim(int termId, int termOffset, HeaderWriter header, int length, ExclusiveBufferClaim bufferClaim) Claim length of a the term buffer for writing in the message with zero copy semantics.
long	rawTail() Get the raw value of the current tail.
void	tailTermId(int termId) Set the value for the tail counter.

Methods inherited from class java.lang.Object

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

Field Detail

TRIPPED

public static final int TRIPPED

The append operation tripped the end of the buffer and needs to rotate.

See Also:

Constant Field Values

FAILED

public static final int FAILED

The append operation went past the end of the buffer and failed.

See Also:

Constant Field Values

Constructor Detail

ExclusiveTermAppender

public ExclusiveTermAppender(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

rawTail

public long rawTail()

Get the raw value of the current tail.

Returns:

the current tail value.

tailTermId

public void tailTermId(int termId)

Set the value for the tail counter.

Parameters:

termId - for the tail counter

claim

public int claim(int termId,
                 int termOffset,
                 HeaderWriter header,
                 int length,
                 ExclusiveBufferClaim bufferClaim)

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

Parameters:

termId - for the current term.

termOffset - in the term at which to append.

header - for writing the default header.

length - of the message to be written.

bufferClaim - to be updated with the claimed region.

Returns:

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

appendUnfragmentedMessage

public int appendUnfragmentedMessage(int termId,
                                     int termOffset,
                                     HeaderWriter header,
                                     org.agrona.DirectBuffer srcBuffer,
                                     int srcOffset,
                                     int length,
                                     ReservedValueSupplier reservedValueSupplier)

Append an unfragmented message to the the term buffer.

Parameters:

termId - for the current term.

termOffset - in the term at which to append.

header - for writing the default header.

srcBuffer - containing the message.

srcOffset - at which the message begins.

length - of the message in the source buffer.

reservedValueSupplier - ReservedValueSupplier for the frame.

Returns:

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

appendFragmentedMessage

public int appendFragmentedMessage(int termId,
                                   int termOffset,
                                   HeaderWriter header,
                                   org.agrona.DirectBuffer srcBuffer,
                                   int srcOffset,
                                   int length,
                                   int maxPayloadLength,
                                   ReservedValueSupplier reservedValueSupplier)

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

Parameters:

termId - for the current term.

termOffset - in the term at which to append.

header - for writing the default header.

srcBuffer - containing the message.

srcOffset - 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.

Returns:

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