net.openhft.chronicle.queue.rollcycles

Enum SparseRollCycles

java.lang.Object

java.lang.Enum<SparseRollCycles>

net.openhft.chronicle.queue.rollcycles.SparseRollCycles

All Implemented Interfaces:

Serializable, Comparable<SparseRollCycles>, RollCycle

public enum SparseRollCycles
extends Enum<SparseRollCycles>
implements RollCycle

These are largely used for testing and benchmarks to almost turn off indexing.

Enum Constant Summary

Enum Constants

Enum Constant and Description
HUGE_DAILY_XSPARSE 0xffffffffffff entries per day with super-sparse indexing (every (2^20)th entry)
LARGE_HOURLY_SPARSE 0x3ffffffff entries per hour with sparse indexing (every 1024th entry)
LARGE_HOURLY_XSPARSE 0x3ffffffffff entries per hour with super-sparse indexing (every (2^20)th entry)
SMALL_DAILY 0x20000000 entries per day, indexing every 8th entry

Field Summary

Fields inherited from interface net.openhft.chronicle.queue.RollCycle

MAX_INDEX_COUNT

Method Summary

Modifier and Type	Method and Description
int	defaultIndexCount()
int	defaultIndexSpacing() Returns the space between excerpts that are explicitly indexed.
String	format() Returns the format that is to be applied when file names are calculated for a new roll cycle.
int	lengthInMillis() Returns the length in milliseconds (i.e.
long	maxMessagesPerCycle()
int	toCycle(long index) Returns the cycle for the given index.
long	toIndex(int cycle, long sequenceNumber) Returns the index for the provided cycle and sequenceNumber.
long	toSequenceNumber(long index) Returns the sequence number for the provided index.
static SparseRollCycles	valueOf(String name) Returns the enum constant of this type with the specified name.
static SparseRollCycles[]	values() Returns an array containing the constants of this enum type, in the order they are declared.

Methods inherited from class java.lang.Enum

clone, compareTo, equals, finalize, getDeclaringClass, hashCode, name, ordinal, toString, valueOf

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface net.openhft.chronicle.queue.RollCycle

current, defaultEpoch

Enum Constant Detail

SMALL_DAILY

public static final SparseRollCycles SMALL_DAILY

0x20000000 entries per day, indexing every 8th entry

LARGE_HOURLY_SPARSE

public static final SparseRollCycles LARGE_HOURLY_SPARSE

0x3ffffffff entries per hour with sparse indexing (every 1024th entry)

LARGE_HOURLY_XSPARSE

public static final SparseRollCycles LARGE_HOURLY_XSPARSE

0x3ffffffffff entries per hour with super-sparse indexing (every (2^20)th entry)

HUGE_DAILY_XSPARSE

public static final SparseRollCycles HUGE_DAILY_XSPARSE

0xffffffffffff entries per day with super-sparse indexing (every (2^20)th entry)

Method Detail

values

public static SparseRollCycles[] values()

Returns an array containing the constants of this enum type, in the order they are declared. This method may be used to iterate over the constants as follows:

for (SparseRollCycles c : SparseRollCycles.values())
    System.out.println(c);

Returns:

an array containing the constants of this enum type, in the order they are declared

valueOf

public static SparseRollCycles valueOf(String name)

Returns the enum constant of this type with the specified name. The string must match exactly an identifier used to declare an enum constant in this type. (Extraneous whitespace characters are not permitted.)

Parameters:

name - the name of the enum constant to be returned.

Returns:

the enum constant with the specified name

Throws:

IllegalArgumentException - if this enum type has no constant with the specified name

NullPointerException - if the argument is null

maxMessagesPerCycle

public long maxMessagesPerCycle()

Specified by:

maxMessagesPerCycle in interface RollCycle

Returns:

the maximum number of messages per cycle

format

public String format()

Description copied from interface: RollCycle

Returns the format that is to be applied when file names are calculated for a new roll cycle.

For example, the following formats can be returned:

• "yyyyMMdd-HHmm" (MINUTELY)
• "yyyyMMdd" (DAILY)

Lexicographical order of formatted cycles must preserve chronological order, i.e. if cycle1 < cycle2, the same relation must be kept for their string representations.

Specified by:

format in interface RollCycle

Returns:

the format that is to be applied when file names are calculated for a new roll cycle

lengthInMillis

public int lengthInMillis()

Description copied from interface: RollCycle

Returns the length in milliseconds (i.e. the maximum duration) for a roll cycle.

For example, the following lengths can be returned:

• 60 * 1,000 = 60,000 (MINUTELY)
• 24 * 60 * 60 * 1,000 = 86,400,000 (DAILY)

Specified by:

lengthInMillis in interface RollCycle

Returns:

the length in milliseconds (i.e. the maximum duration) for a roll cycle

defaultIndexCount

public int defaultIndexCount()

Specified by:

defaultIndexCount in interface RollCycle

Returns:

this is the size of each index array, note: indexCount^2 is the maximum number of index queue entries.

defaultIndexSpacing

public int defaultIndexSpacing()

Description copied from interface: RollCycle

Returns the space between excerpts that are explicitly indexed.

A higher number means higher sequential write performance but slower random access read. The sequential read performance is not affected by this property.

For example, the following default index spacing can be returned:

• 16 (MINUTELY)
• 64 (DAILY)

Specified by:

defaultIndexSpacing in interface RollCycle

Returns:

the space between excerpts that are explicitly indexed

toIndex

public long toIndex(int cycle,
                    long sequenceNumber)

Description copied from interface: RollCycle

Returns the index for the provided cycle and sequenceNumber.

An index is made up of cycle shifted left + sequenceNumber. sequenceNumber starts at 0 for each new cycle. DAILY cycle has cycleShift=32 and sequenceMask=0xFFFFFFFF so the top 32 bits are for cycle and bottom 32 bits are for sequence. This means you can only store 2^32 entries per day. HUGE_DAILY has shift=48 and mask=0xFFFFFFFFFFFF thus allowing 2^48 entries per day.

Specified by:

toIndex in interface RollCycle

Parameters:

cycle - to be composed into an index

sequenceNumber - to be composed into an index

Returns:

the index for the given cycle and sequenceNumber

toSequenceNumber

public long toSequenceNumber(long index)

Description copied from interface: RollCycle

Returns the sequence number for the provided index.

An index comprises both a cycle and a sequence number but the way the index is composed of said properties may vary. This method decomposes the provided index and extracts the sequence number.

Specified by:

toSequenceNumber in interface RollCycle

Parameters:

index - to use to extract the sequence number

Returns:

the sequence number for the provided index

toCycle

public int toCycle(long index)

Description copied from interface: RollCycle

Returns the cycle for the given index.

An index comprises both a cycle and a sequence number but the way the index is composed of said properties may vary. This method decomposes the provided index and extracts the cycle.

Specified by:

toCycle in interface RollCycle

Parameters:

index - to use when extracting the cycle

Returns:

the sequence number for the given index