io.aeron.logbuffer

Class LogBufferDescriptor

java.lang.Object

io.aeron.logbuffer.LogBufferDescriptor

public class LogBufferDescriptor
extends java.lang.Object

Layout description for log buffers which contains partitions of terms with associated term meta data, plus ending with overall log meta data.

  +----------------------------+
  |           Term 0           |
  +----------------------------+
  |           Term 1           |
  +----------------------------+
  |           Term 2           |
  +----------------------------+
  |        Log Meta Data       |
  +----------------------------+
 

Field Summary

Fields

Modifier and Type	Field and Description
static int	LOG_ACTIVE_PARTITION_INDEX_OFFSET Offset within the log meta data where the active partition index is stored.
static int	LOG_CORRELATION_ID_OFFSET Offset within the log meta data which the
static int	LOG_DEFAULT_FRAME_HEADER_LENGTH_OFFSET Offset within the log meta data which the length field for the frame header is stored.
static int	LOG_DEFAULT_FRAME_HEADER_MAX_LENGTH Maximum length of a frame header.
static int	LOG_DEFAULT_FRAME_HEADER_OFFSET Offset at which the default frame headers begin.
static int	LOG_INITIAL_TERM_ID_OFFSET Offset within the log meta data where the active term id is stored.
static int	LOG_META_DATA_LENGTH Total length of the log meta data buffer in bytes.
static int	LOG_META_DATA_SECTION_INDEX Section index for which buffer contains the log meta data.
static int	LOG_MTU_LENGTH_OFFSET Offset within the log meta data which the MTU length is stored;
static int	LOG_TIME_OF_LAST_SM_OFFSET Offset within the log meta data where the time of last SM is stored.
static int	PARTITION_COUNT The number of partitions the log is divided into.
static int	TERM_MIN_LENGTH Minimum buffer length for a log term
static int	TERM_TAIL_COUNTERS_OFFSET Offset within the meta data where the tail values are stored.

Constructor Summary

Constructors

Constructor and Description
LogBufferDescriptor()

Method Summary

Modifier and Type	Method and Description
static int	activePartitionIndex(org.agrona.concurrent.UnsafeBuffer logMetaDataBuffer) Get the value of the active partition index used by the producer of this log.
static void	activePartitionIndex(org.agrona.concurrent.UnsafeBuffer logMetaDataBuffer, int activePartitionIndex) Set the value of the current active partition index for the producer using memory ordered semantics.
static void	applyDefaultHeader(org.agrona.concurrent.UnsafeBuffer logMetaDataBuffer, org.agrona.concurrent.UnsafeBuffer termBuffer, int termOffset) Apply the default header for a message in a term.
static void	checkTermLength(int termLength) Check that term length is valid and alignment is valid.
static long	computeLogLength(int termLength) Compute the total length of a log file given the term length.
static long	computePosition(int activeTermId, int termOffset, int positionBitsToShift, int initialTermId) Compute the current position in absolute number of bytes.
static long	computeTermBeginPosition(int activeTermId, int positionBitsToShift, int initialTermId) Compute the current position in absolute number of bytes for the beginning of a term.
static int	computeTermIdFromPosition(long position, int positionBitsToShift, int initialTermId) Compute the term id from a position.
static int	computeTermLength(long logLength) Compute the term length based on the total length of the log.
static int	computeTermOffsetFromPosition(long position, int positionBitsToShift) Compute the term offset from a given position.
static long	correlationId(org.agrona.concurrent.UnsafeBuffer logMetaDataBuffer) Get the value of the correlation ID for this log.
static void	correlationId(org.agrona.concurrent.UnsafeBuffer logMetaDataBuffer, long id) Set the correlation ID used for this log.
static org.agrona.concurrent.UnsafeBuffer	defaultFrameHeader(org.agrona.concurrent.UnsafeBuffer logMetaDataBuffer) Get a wrapper around the default frame header from the log meta data.
static int	indexByPosition(long position, int positionBitsToShift) Determine the partition index given a stream position.
static int	indexByTerm(int initialTermId, int activeTermId) Determine the partition index to be used given the initial term and active term ids.
static int	indexByTermCount(long termCount) Determine the partition index based on number of terms that have passed.
static void	initialiseTailWithTermId(org.agrona.concurrent.UnsafeBuffer logMetaData, int partitionIndex, int termId) Set the initial value for the termId in the upper bits of the tail counter.
static int	initialTermId(org.agrona.concurrent.UnsafeBuffer logMetaDataBuffer) Get the value of the initial Term id used for this log.
static void	initialTermId(org.agrona.concurrent.UnsafeBuffer logMetaDataBuffer, int initialTermId) Set the initial term at which this log begins.
static int	mtuLength(org.agrona.concurrent.UnsafeBuffer logMetaDataBuffer) Get the value of the MTU length used for this log.
static void	mtuLength(org.agrona.concurrent.UnsafeBuffer logMetaDataBuffer, int mtuLength) Set the MTU length used for this log.
static int	nextPartitionIndex(int currentIndex) Rotate to the next partition in sequence for the term id.
static long	rawTailVolatile(org.agrona.concurrent.UnsafeBuffer logMetaDataBuffer) Get the raw value of the tail for the current active partition.
static long	rawTailVolatile(org.agrona.concurrent.UnsafeBuffer logMetaDataBuffer, int partitionIndex) Get the raw value of the tail for the given partition.
static void	rotateLog(org.agrona.concurrent.UnsafeBuffer logMetaDataBuffer, int activePartitionIndex, int termId) Rotate the log and update the default headers for the new term.
static void	storeDefaultFrameHeader(org.agrona.concurrent.UnsafeBuffer logMetaDataBuffer, org.agrona.DirectBuffer defaultHeader) Store the default frame header to the log meta data buffer.
static int	termId(long rawTail) Get the termId from a packed raw tail value.
static int	termOffset(long rawTail, long termLength) Read the termOffset from a packed raw tail value.
static long	timeOfLastStatusMessage(org.agrona.concurrent.UnsafeBuffer logMetaDataBuffer) Get the value of the time of last SM in System.currentTimeMillis().
static void	timeOfLastStatusMessage(org.agrona.concurrent.UnsafeBuffer logMetaDataBuffer, long timeInMillis) Set the value of the time of last SM used by the producer of this log.

Methods inherited from class java.lang.Object

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

Field Detail

PARTITION_COUNT

public static final int PARTITION_COUNT

The number of partitions the log is divided into.

See Also:

Constant Field Values

LOG_META_DATA_SECTION_INDEX

public static final int LOG_META_DATA_SECTION_INDEX

Section index for which buffer contains the log meta data.

See Also:

Constant Field Values

TERM_MIN_LENGTH

public static final int TERM_MIN_LENGTH

Minimum buffer length for a log term

See Also:

Constant Field Values

TERM_TAIL_COUNTERS_OFFSET

public static final int TERM_TAIL_COUNTERS_OFFSET

Offset within the meta data where the tail values are stored.

LOG_ACTIVE_PARTITION_INDEX_OFFSET

public static final int LOG_ACTIVE_PARTITION_INDEX_OFFSET

Offset within the log meta data where the active partition index is stored.

LOG_TIME_OF_LAST_SM_OFFSET

public static final int LOG_TIME_OF_LAST_SM_OFFSET

Offset within the log meta data where the time of last SM is stored.

LOG_INITIAL_TERM_ID_OFFSET

public static final int LOG_INITIAL_TERM_ID_OFFSET

Offset within the log meta data where the active term id is stored.

LOG_DEFAULT_FRAME_HEADER_LENGTH_OFFSET

public static final int LOG_DEFAULT_FRAME_HEADER_LENGTH_OFFSET

Offset within the log meta data which the length field for the frame header is stored.

LOG_MTU_LENGTH_OFFSET

public static final int LOG_MTU_LENGTH_OFFSET

Offset within the log meta data which the MTU length is stored;

LOG_CORRELATION_ID_OFFSET

public static final int LOG_CORRELATION_ID_OFFSET

Offset within the log meta data which the

LOG_DEFAULT_FRAME_HEADER_OFFSET

public static final int LOG_DEFAULT_FRAME_HEADER_OFFSET

Offset at which the default frame headers begin.

LOG_DEFAULT_FRAME_HEADER_MAX_LENGTH

public static final int LOG_DEFAULT_FRAME_HEADER_MAX_LENGTH

Maximum length of a frame header.

See Also:

Constant Field Values

LOG_META_DATA_LENGTH

public static final int LOG_META_DATA_LENGTH

Total length of the log meta data buffer in bytes.

   0                   1                   2                   3
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  |                       Tail Counter 0                          |
  |                                                               |
  +---------------------------------------------------------------+
  |                       Tail Counter 1                          |
  |                                                               |
  +---------------------------------------------------------------+
  |                       Tail Counter 2                          |
  |                                                               |
  +---------------------------------------------------------------+
  |                   Active Partition Index                      |
  +---------------------------------------------------------------+
  |                      Cache Line Padding                      ...
 ...                                                              |
  +---------------------------------------------------------------+
  |                 Time of Last Status Message                   |
  |                                                               |
  +---------------------------------------------------------------+
  |                      Cache Line Padding                      ...
 ...                                                              |
  +---------------------------------------------------------------+
  |                 Registration / Correlation ID                 |
  |                                                               |
  +---------------------------------------------------------------+
  |                        Initial Term Id                        |
  +---------------------------------------------------------------+
  |                  Default Frame Header Length                  |
  +---------------------------------------------------------------+
  |                          MTU Length                           |
  +---------------------------------------------------------------+
  |                      Cache Line Padding                      ...
 ...                                                              |
  +---------------------------------------------------------------+
  |                    Default Frame Header                      ...
 ...                                                              |
  +---------------------------------------------------------------+
 

Constructor Detail

LogBufferDescriptor

public LogBufferDescriptor()

Method Detail

checkTermLength

public static void checkTermLength(int termLength)

Check that term length is valid and alignment is valid.

Parameters:

termLength - to be checked.

Throws:

java.lang.IllegalStateException - if the length is not as expected.

initialTermId

public static int initialTermId(org.agrona.concurrent.UnsafeBuffer logMetaDataBuffer)

Get the value of the initial Term id used for this log.

Parameters:

logMetaDataBuffer - containing the meta data.

Returns:

the value of the initial Term id used for this log.

initialTermId

public static void initialTermId(org.agrona.concurrent.UnsafeBuffer logMetaDataBuffer,
                                 int initialTermId)

Set the initial term at which this log begins. Initial should be randomised so that stream does not get reused accidentally.

Parameters:

logMetaDataBuffer - containing the meta data.

initialTermId - value to be set.

mtuLength

public static int mtuLength(org.agrona.concurrent.UnsafeBuffer logMetaDataBuffer)

Get the value of the MTU length used for this log.

Parameters:

logMetaDataBuffer - containing the meta data.

Returns:

the value of the MTU length used for this log.

mtuLength

public static void mtuLength(org.agrona.concurrent.UnsafeBuffer logMetaDataBuffer,
                             int mtuLength)

Set the MTU length used for this log.

Parameters:

logMetaDataBuffer - containing the meta data.

mtuLength - value to be set.

correlationId

public static long correlationId(org.agrona.concurrent.UnsafeBuffer logMetaDataBuffer)

Get the value of the correlation ID for this log.

Parameters:

logMetaDataBuffer - containing the meta data.

Returns:

the value of the correlation ID used for this log.

correlationId

public static void correlationId(org.agrona.concurrent.UnsafeBuffer logMetaDataBuffer,
                                 long id)

Set the correlation ID used for this log.

Parameters:

logMetaDataBuffer - containing the meta data.

id - value to be set.

timeOfLastStatusMessage

public static long timeOfLastStatusMessage(org.agrona.concurrent.UnsafeBuffer logMetaDataBuffer)

Get the value of the time of last SM in System.currentTimeMillis().

Parameters:

logMetaDataBuffer - containing the meta data.

Returns:

the value of time of last SM

timeOfLastStatusMessage

public static void timeOfLastStatusMessage(org.agrona.concurrent.UnsafeBuffer logMetaDataBuffer,
                                           long timeInMillis)

Set the value of the time of last SM used by the producer of this log.

Parameters:

logMetaDataBuffer - containing the meta data.

timeInMillis - value of the time of last SM in System.currentTimeMillis()

activePartitionIndex

public static int activePartitionIndex(org.agrona.concurrent.UnsafeBuffer logMetaDataBuffer)

Get the value of the active partition index used by the producer of this log. Consumers may have a different active index if they are running behind. The read is done with volatile semantics.

Parameters:

logMetaDataBuffer - containing the meta data.

Returns:

the value of the active partition index used by the producer of this log.

activePartitionIndex

public static void activePartitionIndex(org.agrona.concurrent.UnsafeBuffer logMetaDataBuffer,
                                        int activePartitionIndex)

Set the value of the current active partition index for the producer using memory ordered semantics.

Parameters:

logMetaDataBuffer - containing the meta data.

activePartitionIndex - value of the active partition index used by the producer of this log.

nextPartitionIndex

public static int nextPartitionIndex(int currentIndex)

Rotate to the next partition in sequence for the term id.

Parameters:

currentIndex - partition index

Returns:

the next partition index

indexByTerm

public static int indexByTerm(int initialTermId,
                              int activeTermId)

Determine the partition index to be used given the initial term and active term ids.

Parameters:

initialTermId - at which the log buffer usage began

activeTermId - that is in current usage

Returns:

the index of which buffer should be used

indexByTermCount

public static int indexByTermCount(long termCount)

Determine the partition index based on number of terms that have passed.

Parameters:

termCount - for the number of terms that have passed.

Returns:

the partition index for the term count.

indexByPosition

public static int indexByPosition(long position,
                                  int positionBitsToShift)

Determine the partition index given a stream position.

Parameters:

position - in the stream in bytes.

positionBitsToShift - number of times to right shift the position for term count

Returns:

the partition index for the position

computePosition

public static long computePosition(int activeTermId,
                                   int termOffset,
                                   int positionBitsToShift,
                                   int initialTermId)

Compute the current position in absolute number of bytes.

Parameters:

activeTermId - active term id.

termOffset - in the term.

positionBitsToShift - number of times to left shift the term count

initialTermId - the initial term id that this stream started on

Returns:

the absolute position in bytes

computeTermBeginPosition

public static long computeTermBeginPosition(int activeTermId,
                                            int positionBitsToShift,
                                            int initialTermId)

Compute the current position in absolute number of bytes for the beginning of a term.

Parameters:

activeTermId - active term id.

positionBitsToShift - number of times to left shift the term count

initialTermId - the initial term id that this stream started on

Returns:

the absolute position in bytes

computeTermIdFromPosition

public static int computeTermIdFromPosition(long position,
                                            int positionBitsToShift,
                                            int initialTermId)

Compute the term id from a position.

Parameters:

position - to calculate from

positionBitsToShift - number of times to right shift the position

initialTermId - the initial term id that this stream started on

Returns:

the term id according to the position

computeTermOffsetFromPosition

public static int computeTermOffsetFromPosition(long position,
                                                int positionBitsToShift)

Compute the term offset from a given position.

Parameters:

position - to calculate from

positionBitsToShift - number of times to right shift the position

Returns:

the offset within the term that represents the position

computeLogLength

public static long computeLogLength(int termLength)

Compute the total length of a log file given the term length.

Parameters:

termLength - on which to base the calculation.

Returns:

the total length of the log file.

computeTermLength

public static int computeTermLength(long logLength)

Compute the term length based on the total length of the log.

Parameters:

logLength - the total length of the log.

Returns:

length of an individual term buffer in the log.

storeDefaultFrameHeader

public static void storeDefaultFrameHeader(org.agrona.concurrent.UnsafeBuffer logMetaDataBuffer,
                                           org.agrona.DirectBuffer defaultHeader)

Store the default frame header to the log meta data buffer.

Parameters:

logMetaDataBuffer - into which the default headers should be stored.

defaultHeader - to be stored.

Throws:

java.lang.IllegalArgumentException - if the default header is larger than LOG_DEFAULT_FRAME_HEADER_MAX_LENGTH

defaultFrameHeader

public static org.agrona.concurrent.UnsafeBuffer defaultFrameHeader(org.agrona.concurrent.UnsafeBuffer logMetaDataBuffer)

Get a wrapper around the default frame header from the log meta data.

Parameters:

logMetaDataBuffer - containing the raw bytes for the default frame header.

Returns:

a buffer wrapping the raw bytes.

applyDefaultHeader

public static void applyDefaultHeader(org.agrona.concurrent.UnsafeBuffer logMetaDataBuffer,
                                      org.agrona.concurrent.UnsafeBuffer termBuffer,
                                      int termOffset)

Apply the default header for a message in a term.

Parameters:

logMetaDataBuffer - containing the default headers.

termBuffer - to which the default header should be applied.

termOffset - at which the default should be applied.

rotateLog

public static void rotateLog(org.agrona.concurrent.UnsafeBuffer logMetaDataBuffer,
                             int activePartitionIndex,
                             int termId)

Rotate the log and update the default headers for the new term.

Parameters:

logMetaDataBuffer - for the meta data.

activePartitionIndex - current active index.

termId - to be used in the default headers.

initialiseTailWithTermId

public static void initialiseTailWithTermId(org.agrona.concurrent.UnsafeBuffer logMetaData,
                                            int partitionIndex,
                                            int termId)

Set the initial value for the termId in the upper bits of the tail counter.

Parameters:

logMetaData - contain the tail counter.

partitionIndex - to be initialised.

termId - to be set.

termId

public static int termId(long rawTail)

Get the termId from a packed raw tail value.

Parameters:

rawTail - containing the termId

Returns:

the termId from a packed raw tail value.

termOffset

public static int termOffset(long rawTail,
                             long termLength)

Read the termOffset from a packed raw tail value.

Parameters:

rawTail - containing the termOffset.

termLength - that the offset cannot exceed.

Returns:

the termOffset value.

rawTailVolatile

public static long rawTailVolatile(org.agrona.concurrent.UnsafeBuffer logMetaDataBuffer,
                                   int partitionIndex)

Get the raw value of the tail for the given partition.

Parameters:

logMetaDataBuffer - containing the tail counters.

partitionIndex - for the tail counter.

Returns:

the raw value of the tail for the current active partition.

rawTailVolatile

public static long rawTailVolatile(org.agrona.concurrent.UnsafeBuffer logMetaDataBuffer)

Get the raw value of the tail for the current active partition.

Parameters:

logMetaDataBuffer - containing the tail counters.

Returns:

the raw value of the tail for the current active partition.