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_TERM_COUNT_OFFSET Offset within the log metadata where the active partition index is stored.
static int	LOG_CORRELATION_ID_OFFSET Offset within the log metadata which the correlation id is stored.
static int	LOG_DEFAULT_FRAME_HEADER_LENGTH_OFFSET Offset within the log metadata 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_END_OF_STREAM_POSITION_OFFSET Offset within the log metadata where the position of the End of Stream is stored.
static int	LOG_INITIAL_TERM_ID_OFFSET Offset within the log metadata where the active term id is stored.
static int	LOG_IS_CONNECTED_OFFSET Offset within the log metadata where whether the log is connected or not is stored.
static int	LOG_META_DATA_LENGTH Total length of the log metadata 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 metadata which the MTU length is stored.
static int	LOG_PAGE_SIZE_OFFSET Offset within the log metadata which the page size is stored.
static int	LOG_TERM_LENGTH_OFFSET Offset within the log metadata which the term length is stored.
static int	PAGE_MAX_SIZE Maximum page size
static int	PAGE_MIN_SIZE Minimum page size
static int	PARTITION_COUNT The number of partitions the log is divided into.
static int	TERM_MAX_LENGTH Maximum buffer length for a log term
static int	TERM_MIN_LENGTH Minimum buffer length for a log term
static int	TERM_TAIL_COUNTERS_OFFSET Offset within the metadata where the tail values are stored.

Constructor Summary

Constructors

Constructor and Description
LogBufferDescriptor()

Method Summary

Modifier and Type	Method and Description
static int	activeTermCount(org.agrona.concurrent.UnsafeBuffer metadataBuffer) Get the value of the active term count used by the producer of this log.
static void	activeTermCount(org.agrona.concurrent.UnsafeBuffer metadataBuffer, int termCount) Set the value of the current active partition index for the producer.
static void	activeTermCountOrdered(org.agrona.concurrent.UnsafeBuffer metadataBuffer, int termCount) Set the value of the current active term count for the producer using memory ordered semantics.
static void	applyDefaultHeader(org.agrona.concurrent.UnsafeBuffer metadataBuffer, org.agrona.concurrent.UnsafeBuffer termBuffer, int termOffset) Apply the default header for a message in a term.
static boolean	casActiveTermCount(org.agrona.concurrent.UnsafeBuffer metadataBuffer, int expectedTermCount, int updateTermCount) Compare and set the value of the current active term count.
static boolean	casRawTail(org.agrona.concurrent.UnsafeBuffer metadataBuffer, int partitionIndex, long expectedRawTail, long updateRawTail) Compare and set the raw value of the tail for the given partition.
static void	checkPageSize(int pageSize) Check that page size is valid and alignment is valid.
static void	checkTermLength(int termLength) Check that term length is valid and alignment is valid.
static long	computeLogLength(int termLength, int filePageSize) 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 long	correlationId(org.agrona.concurrent.UnsafeBuffer metadataBuffer) Get the value of the correlation ID for this log relating to the command which created it.
static void	correlationId(org.agrona.concurrent.UnsafeBuffer metadataBuffer, long id) Set the correlation ID used for this log relating to the command which created it.
static org.agrona.concurrent.UnsafeBuffer	defaultFrameHeader(org.agrona.concurrent.UnsafeBuffer metadataBuffer) Get a wrapper around the default frame header from the log meta data.
static long	endOfStreamPosition(org.agrona.concurrent.UnsafeBuffer metadataBuffer) Get the value of the end of stream position.
static void	endOfStreamPosition(org.agrona.concurrent.UnsafeBuffer metadataBuffer, long position) Set the value of the end of stream position.
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 metadataBuffer, 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 metadataBuffer) Get the value of the initial Term id used for this log.
static void	initialTermId(org.agrona.concurrent.UnsafeBuffer metadataBuffer, int initialTermId) Set the initial term at which this log begins.
static boolean	isConnected(org.agrona.concurrent.UnsafeBuffer metadataBuffer) Get whether the log is considered connected or not by the driver.
static void	isConnected(org.agrona.concurrent.UnsafeBuffer metadataBuffer, boolean isConnected) Set whether the log is considered connected or not by the driver.
static int	mtuLength(org.agrona.concurrent.UnsafeBuffer metadataBuffer) Get the value of the MTU length used for this log.
static void	mtuLength(org.agrona.concurrent.UnsafeBuffer metadataBuffer, 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	packTail(int termId, int termOffset) Pack a termId and termOffset into a raw tail value.
static int	pageSize(org.agrona.concurrent.UnsafeBuffer metadataBuffer) Get the value of the page size used for this log.
static void	pageSize(org.agrona.concurrent.UnsafeBuffer metadataBuffer, int pageSize) Set the page size used for this log.
static int	positionBitsToShift(int termBufferLength) Get the number of bits to shift when dividing or multiplying by the term buffer length.
static long	rawTail(org.agrona.concurrent.UnsafeBuffer metadataBuffer, int partitionIndex) Get the raw value of the tail for the given partition.
static void	rawTail(org.agrona.concurrent.UnsafeBuffer metadataBuffer, int partitionIndex, long rawTail) Set the raw value of the tail for the given partition.
static long	rawTailVolatile(org.agrona.concurrent.UnsafeBuffer metadataBuffer) Get the raw value of the tail for the current active partition.
static long	rawTailVolatile(org.agrona.concurrent.UnsafeBuffer metadataBuffer, int partitionIndex) Get the raw value of the tail for the given partition.
static void	rawTailVolatile(org.agrona.concurrent.UnsafeBuffer metadataBuffer, int partitionIndex, long rawTail) Set the raw value of the tail for the given partition.
static boolean	rotateLog(org.agrona.concurrent.UnsafeBuffer metadataBuffer, int termCount, int termId) Rotate the log and update the tail counter for the new term.
static void	storeDefaultFrameHeader(org.agrona.concurrent.UnsafeBuffer metadataBuffer, 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	termLength(org.agrona.concurrent.UnsafeBuffer metadataBuffer) Get the value of the Term Length used for this log.
static void	termLength(org.agrona.concurrent.UnsafeBuffer metadataBuffer, int termLength) Set the term length used for this log.
static int	termOffset(long result) The termOffset as a result of the append
static int	termOffset(long rawTail, long termLength) Read the termOffset from a packed raw tail value.

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_MAX_LENGTH

public static final int TERM_MAX_LENGTH

Maximum buffer length for a log term

See Also:

Constant Field Values

PAGE_MIN_SIZE

public static final int PAGE_MIN_SIZE

Minimum page size

See Also:

Constant Field Values

PAGE_MAX_SIZE

public static final int PAGE_MAX_SIZE

Maximum page size

See Also:

Constant Field Values

TERM_TAIL_COUNTERS_OFFSET

public static final int TERM_TAIL_COUNTERS_OFFSET

Offset within the metadata where the tail values are stored.

LOG_ACTIVE_TERM_COUNT_OFFSET

public static final int LOG_ACTIVE_TERM_COUNT_OFFSET

Offset within the log metadata where the active partition index is stored.

LOG_END_OF_STREAM_POSITION_OFFSET

public static final int LOG_END_OF_STREAM_POSITION_OFFSET

Offset within the log metadata where the position of the End of Stream is stored.

LOG_IS_CONNECTED_OFFSET

public static final int LOG_IS_CONNECTED_OFFSET

Offset within the log metadata where whether the log is connected or not is stored.

LOG_INITIAL_TERM_ID_OFFSET

public static final int LOG_INITIAL_TERM_ID_OFFSET

Offset within the log metadata 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 metadata 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 metadata which the MTU length is stored.

LOG_CORRELATION_ID_OFFSET

public static final int LOG_CORRELATION_ID_OFFSET

Offset within the log metadata which the correlation id is stored.

LOG_TERM_LENGTH_OFFSET

public static final int LOG_TERM_LENGTH_OFFSET

Offset within the log metadata which the term length is stored.

LOG_PAGE_SIZE_OFFSET

public static final int LOG_PAGE_SIZE_OFFSET

Offset within the log metadata which the page size is stored.

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 metadata 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 Term Count                        |
  +---------------------------------------------------------------+
  |                     Cache Line Padding                       ...
 ...                                                              |
  +---------------------------------------------------------------+
  |                    End of Stream Position                     |
  |                                                               |
  +---------------------------------------------------------------+
  |                        Is Connected                           |
  +---------------------------------------------------------------+
  |                      Cache Line Padding                      ...
 ...                                                              |
  +---------------------------------------------------------------+
  |                 Registration / Correlation ID                 |
  |                                                               |
  +---------------------------------------------------------------+
  |                        Initial Term Id                        |
  +---------------------------------------------------------------+
  |                  Default Frame Header Length                  |
  +---------------------------------------------------------------+
  |                          MTU Length                           |
  +---------------------------------------------------------------+
  |                         Term Length                           |
  +---------------------------------------------------------------+
  |                          Page Size                            |
  +---------------------------------------------------------------+
  |                      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.

checkPageSize

public static void checkPageSize(int pageSize)

Check that page size is valid and alignment is valid.

Parameters:

pageSize - to be checked.

Throws:

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

initialTermId

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

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

Parameters:

metadataBuffer - 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 metadataBuffer,
                                 int initialTermId)

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

Parameters:

metadataBuffer - containing the meta data.

initialTermId - value to be set.

mtuLength

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

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

Parameters:

metadataBuffer - containing the meta data.

Returns:

the value of the MTU length used for this log.

mtuLength

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

Set the MTU length used for this log.

Parameters:

metadataBuffer - containing the meta data.

mtuLength - value to be set.

termLength

public static int termLength(org.agrona.concurrent.UnsafeBuffer metadataBuffer)

Get the value of the Term Length used for this log.

Parameters:

metadataBuffer - containing the meta data.

Returns:

the value of the term length used for this log.

termLength

public static void termLength(org.agrona.concurrent.UnsafeBuffer metadataBuffer,
                              int termLength)

Set the term length used for this log.

Parameters:

metadataBuffer - containing the meta data.

termLength - value to be set.

pageSize

public static int pageSize(org.agrona.concurrent.UnsafeBuffer metadataBuffer)

Get the value of the page size used for this log.

Parameters:

metadataBuffer - containing the meta data.

Returns:

the value of the page size used for this log.

pageSize

public static void pageSize(org.agrona.concurrent.UnsafeBuffer metadataBuffer,
                            int pageSize)

Set the page size used for this log.

Parameters:

metadataBuffer - containing the meta data.

pageSize - value to be set.

correlationId

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

Get the value of the correlation ID for this log relating to the command which created it.

Parameters:

metadataBuffer - containing the meta data.

Returns:

the value of the correlation ID used for this log.

correlationId

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

Set the correlation ID used for this log relating to the command which created it.

Parameters:

metadataBuffer - containing the meta data.

id - value to be set.

isConnected

public static boolean isConnected(org.agrona.concurrent.UnsafeBuffer metadataBuffer)

Get whether the log is considered connected or not by the driver.

Parameters:

metadataBuffer - containing the meta data.

Returns:

whether the log is considered connected or not by the driver.

isConnected

public static void isConnected(org.agrona.concurrent.UnsafeBuffer metadataBuffer,
                               boolean isConnected)

Set whether the log is considered connected or not by the driver.

Parameters:

metadataBuffer - containing the meta data.

isConnected - or not

endOfStreamPosition

public static long endOfStreamPosition(org.agrona.concurrent.UnsafeBuffer metadataBuffer)

Get the value of the end of stream position.

Parameters:

metadataBuffer - containing the meta data.

Returns:

the value of end of stream position

endOfStreamPosition

public static void endOfStreamPosition(org.agrona.concurrent.UnsafeBuffer metadataBuffer,
                                       long position)

Set the value of the end of stream position.

Parameters:

metadataBuffer - containing the meta data.

position - value of the end of stream position

activeTermCount

public static int activeTermCount(org.agrona.concurrent.UnsafeBuffer metadataBuffer)

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

Parameters:

metadataBuffer - containing the meta data.

Returns:

the value of the active term count used by the producer of this log.

activeTermCountOrdered

public static void activeTermCountOrdered(org.agrona.concurrent.UnsafeBuffer metadataBuffer,
                                          int termCount)

Set the value of the current active term count for the producer using memory ordered semantics.

Parameters:

metadataBuffer - containing the meta data.

termCount - value of the active term count used by the producer of this log.

casActiveTermCount

public static boolean casActiveTermCount(org.agrona.concurrent.UnsafeBuffer metadataBuffer,
                                         int expectedTermCount,
                                         int updateTermCount)

Compare and set the value of the current active term count.

Parameters:

metadataBuffer - containing the meta data.

expectedTermCount - value of the active term count expected in the log

updateTermCount - value of the active term count to be updated in the log

Returns:

true if successful otherwise false.

activeTermCount

public static void activeTermCount(org.agrona.concurrent.UnsafeBuffer metadataBuffer,
                                   int termCount)

Set the value of the current active partition index for the producer.

Parameters:

metadataBuffer - containing the meta data.

termCount - value of the active term count 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

computeLogLength

public static long computeLogLength(int termLength,
                                    int filePageSize)

Compute the total length of a log file given the term length. Assumes TERM_MAX_LENGTH is 1GB and that filePageSize is 1GB or less and a power of 2.

Parameters:

termLength - on which to base the calculation.

filePageSize - to use for log.

Returns:

the total length of the log file.

storeDefaultFrameHeader

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

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

Parameters:

metadataBuffer - into which the default headers should be stored.

defaultHeader - to be stored.

Throws:

java.lang.IllegalArgumentException - if the defaultHeader larger than LOG_DEFAULT_FRAME_HEADER_MAX_LENGTH

defaultFrameHeader

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

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

Parameters:

metadataBuffer - 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 metadataBuffer,
                                      org.agrona.concurrent.UnsafeBuffer termBuffer,
                                      int termOffset)

Apply the default header for a message in a term.

Parameters:

metadataBuffer - containing the default headers.

termBuffer - to which the default header should be applied.

termOffset - at which the default should be applied.

rotateLog

public static boolean rotateLog(org.agrona.concurrent.UnsafeBuffer metadataBuffer,
                                int termCount,
                                int termId)

Rotate the log and update the tail counter for the new term. This method is safe for concurrent use.

Parameters:

metadataBuffer - for the log.

termCount - from which to rotate.

termId - to be used in the default headers.

Returns:

true if log was rotated.

initialiseTailWithTermId

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

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

Parameters:

metadataBuffer - 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.

termOffset

public static int termOffset(long result)

The termOffset as a result of the append

Parameters:

result - into which the termOffset value has been packed.

Returns:

the termOffset after the append

packTail

public static long packTail(int termId,
                            int termOffset)

Pack a termId and termOffset into a raw tail value.

Parameters:

termId - to be packed.

termOffset - to be packed.

Returns:

the packed value.

rawTail

public static void rawTail(org.agrona.concurrent.UnsafeBuffer metadataBuffer,
                           int partitionIndex,
                           long rawTail)

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

Parameters:

metadataBuffer - containing the tail counters.

partitionIndex - for the tail counter.

rawTail - to be stored

rawTail

public static long rawTail(org.agrona.concurrent.UnsafeBuffer metadataBuffer,
                           int partitionIndex)

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

Parameters:

metadataBuffer - containing the tail counters.

partitionIndex - for the tail counter.

Returns:

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

rawTailVolatile

public static void rawTailVolatile(org.agrona.concurrent.UnsafeBuffer metadataBuffer,
                                   int partitionIndex,
                                   long rawTail)

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

Parameters:

metadataBuffer - containing the tail counters.

partitionIndex - for the tail counter.

rawTail - to be stored

rawTailVolatile

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

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

Parameters:

metadataBuffer - 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 metadataBuffer)

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

Parameters:

metadataBuffer - containing the tail counters.

Returns:

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

casRawTail

public static boolean casRawTail(org.agrona.concurrent.UnsafeBuffer metadataBuffer,
                                 int partitionIndex,
                                 long expectedRawTail,
                                 long updateRawTail)

Compare and set the raw value of the tail for the given partition.

Parameters:

metadataBuffer - containing the tail counters.

partitionIndex - for the tail counter.

expectedRawTail - expected current value.

updateRawTail - to be applied.

Returns:

true if the update was successful otherwise false.

positionBitsToShift

public static int positionBitsToShift(int termBufferLength)

Get the number of bits to shift when dividing or multiplying by the term buffer length.

Parameters:

termBufferLength - to compute the number of bits to shift for.

Returns:

the number of bits to shift to divide or multiply by the term buffer length.