Package org.apache.jackrabbit.oak.segment.spi.persistence.persistentcache

Interface PersistentCache

All Known Implementing Classes:

AbstractPersistentCache, DelegatingPersistentCache, PersistentDiskCache, PersistentRedisCache, SegmentPreloader

public interface PersistentCache

This interface represents a cache which survives segment store restarts. The cache is agnostic to any archive structure. Segments are only identified by their UUIDs, specified as msb and lsb parts of the segment id.

Method Summary

Modifier and Type	Method	Description
void	cleanUp()	Purges the cache entries according to the implementation policy (e.g.
boolean	containsSegment(long msb, long lsb)	Check if the segment exists in the cache.
@Nullable Buffer	readSegment(long msb, long lsb, @NotNull Callable<Buffer> loader)	Reads the segment from cache.
void	writeSegment(long msb, long lsb, Buffer buffer)	Writes the segment to the cache.

Method Detail

readSegment

@Nullable
@Nullable Buffer readSegment(long msb,
                             long lsb,
                             @NotNull
                             @NotNull Callable<Buffer> loader)

Reads the segment from cache.

Parameters:

msb - the most significant bits of the identifier of the segment

lsb - the least significant bits of the identifier of the segment

loader - in case of cache miss, with loader.call() missing element will be retrieved

Returns:

byte buffer containing the segment data or null if the segment doesn't exist

containsSegment

boolean containsSegment(long msb,
                        long lsb)

Check if the segment exists in the cache.

Parameters:

msb - the most significant bits of the identifier of the segment

lsb - the least significant bits of the identifier of the segment

Returns:

true if the segment exists

writeSegment

void writeSegment(long msb,
                  long lsb,
                  Buffer buffer)

Writes the segment to the cache.

Parameters:

msb - the most significant bits of the identifier of the segment

lsb - the least significant bits of the identifier of the segment

buffer - the byte buffer containing the segment data

cleanUp

void cleanUp()

Purges the cache entries according to the implementation policy (e.g. maximum cache size, maximum number of entries, etc.)