net.openhft.chronicle.queue

Interface Excerpt

All Superinterfaces:

ExcerptCommon, ExcerptTailer

public interface Excerpt
extends ExcerptTailer

The main data container of a ChronicleQueue, an extended version of ExcerptTailer which also facilitates random access.

Author:

peter.lawrey

Method Summary

Modifier and Type	Method and Description
long	findMatch(ExcerptComparator comparator) Find any entry which return a match i.e.
void	findRange(long[] startEnd, ExcerptComparator comparator) Find entries which return a match.
boolean	moveToIndex(long index) Randomly select an Excerpt.
Excerpt	toEnd() Wind to the upper.
Excerpt	toStart() Replay from the lower.

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

index, readBytes, readBytes, readDocument

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

prefetch, queue

Method Detail

findMatch

long findMatch(@NotNull
               ExcerptComparator comparator)

Find any entry which return a match i.e. 0, or a negative value which is the boundary between -1 and +1

Parameters:

comparator - to use for comparison.

Returns:

0 to size()-1 for a match, -1 to -size()-1 for index of closest match

findRange

void findRange(@NotNull
               long[] startEnd,
               @NotNull
               ExcerptComparator comparator)

Find entries which return a match. This is a combined search which is usually faster than two binary search. This doesn't access the same index two. The best case is one additional comparison and the worst case is the same.

Parameters:

startEnd - lower (inclusive) to upper (exclusive). Will be equal if no exact match is found.

comparator - to use for comparison.

moveToIndex

boolean moveToIndex(long index)
             throws IOException

Randomly select an Excerpt.

Specified by:

moveToIndex in interface ExcerptTailer

Parameters:

index - index to look up

Returns:

true if this is a valid entries and not padding.

Throws:

IOException - if not able to read the chronicle file

toStart

@NotNull
Excerpt toStart()

Replay from the lower.

Specified by:

toStart in interface ExcerptTailer

Returns:

this Excerpt

toEnd

@NotNull
Excerpt toEnd()

Wind to the upper.

Specified by:

toEnd in interface ExcerptTailer

Returns:

this Excerpt