Package org.apache.jackrabbit.oak.segment.file.preloader

Class SegmentPreloader

java.lang.Object

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

org.apache.jackrabbit.oak.segment.file.preloader.SegmentPreloader

All Implemented Interfaces:

Closeable, AutoCloseable, PersistentCache

public class SegmentPreloader
extends DelegatingPersistentCache
implements Closeable

A PersistentCache decorator that preloads segments into the cache by asynchronously preloading segments referenced by a segment that is being read from the cache.

See Also:

PersistentCachePreloadingConfiguration

Method Summary

Modifier and Type	Method	Description
void	close()
static @NotNull PersistentCache	decorate(@NotNull PersistentCache delegate, @NotNull PersistentCachePreloadingConfiguration config, @NotNull Supplier<TarFiles> tarFiles)	Factory method that decorates the given PersistentCache with a SegmentPreloader if the given configuration requires preloading.
protected PersistentCache	delegate()
@Nullable Buffer	readSegment(long msb, long lsb, @NotNull Callable<Buffer> loader)	Reads the segment from cache.

Methods inherited from class org.apache.jackrabbit.oak.segment.spi.persistence.persistentcache.DelegatingPersistentCache

cleanUp, containsSegment, writeSegment

Methods inherited from class java.lang.Object

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

Method Detail

decorate

@NotNull
public static @NotNull PersistentCache decorate(@NotNull
                                                @NotNull PersistentCache delegate,
                                                @NotNull
                                                @NotNull PersistentCachePreloadingConfiguration config,
                                                @NotNull
                                                @NotNull Supplier<TarFiles> tarFiles)

Factory method that decorates the given PersistentCache with a SegmentPreloader if the given configuration requires preloading. Otherwise, the given delegate is returned as-is.

Parameters:

delegate - the cache to decorate

config - the preloading configuration

tarFiles - a supplier of the TarFiles instance used to read segments and segment graphs

Returns:

the decorated cache or the given delegate if no preloading is configured

delegate

protected PersistentCache delegate()

Specified by:

delegate in class DelegatingPersistentCache

readSegment

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

Description copied from interface: PersistentCache

Reads the segment from cache.

Specified by:

readSegment in interface PersistentCache

Overrides:

readSegment in class DelegatingPersistentCache

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

close

public void close()

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable