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

Interface SegmentArchiveReader

All Superinterfaces:

AutoCloseable, Closeable

All Known Implementing Classes:

AbstractRemoteSegmentArchiveReader, AwsSegmentArchiveReader, AzureSegmentArchiveReader, AzureSegmentArchiveReaderV8, CachingSegmentArchiveReader, SegmentTarReader

public interface SegmentArchiveReader
extends Closeable

This interface represents a read-only segment archive. Since the underlying data structure is immutable, the implementation should be thread safe.

Method Summary

Modifier and Type	Method	Description
void	close()	Close the archive.
boolean	containsSegment(long msb, long lsb)	Check if the segment exists.
@Nullable Buffer	getBinaryReferences()	Load binary references.
int	getEntrySize(int size)	Transforms the segment size in bytes into the effective size on disk for the given entry (eg.
@NotNull SegmentGraph	getGraph()	Load the segment graph.
@NotNull String	getName()	Get the name of the archive.
boolean	isRemote()	This method returns true if the storage is accessed via a network protocol, not tight to the traditional storage technology, for example, HTTP.
long	length()	Get the current length of the archive.
List<SegmentArchiveEntry>	listSegments()	List all the segments, in the order as they have been written to the archive.
@Nullable Buffer	readSegment(long msb, long lsb)	Read the segment.

Method Detail

readSegment

@Nullable
@Nullable Buffer readSegment(long msb,
                             long lsb)
                      throws IOException

Read the segment.

Parameters:

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

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

Returns:

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

Throws:

IOException

containsSegment

boolean containsSegment(long msb,
                        long lsb)

Check if the segment exists.

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

listSegments

List<SegmentArchiveEntry> listSegments()

List all the segments, in the order as they have been written to the archive.

Returns:

segment list, ordered by their position in the archive

getGraph

@NotNull
@NotNull SegmentGraph getGraph()
                        throws IOException

Load the segment graph.

Returns:

segment graph instance

Throws:

IOException

getBinaryReferences

@Nullable
@Nullable Buffer getBinaryReferences()
                              throws IOException

Load binary references.

Returns:

byte buffer representing the binary references structure.

Throws:

IOException

length

long length()

Get the current length of the archive.

Returns:

length of the archive, in bytes

getName

@NotNull
@NotNull String getName()

Get the name of the archive.

Returns:

archive name

close

void close()
    throws IOException

Close the archive.

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable

Throws:

IOException

getEntrySize

int getEntrySize(int size)

Transforms the segment size in bytes into the effective size on disk for the given entry (eg. by adding the number of padding bytes, header, etc.)

Parameters:

size - the segment size in bytes

Returns:

the number of bytes effectively used on the storage to save the segment

isRemote

boolean isRemote()

This method returns true if the storage is accessed via a network protocol, not tight to the traditional storage technology, for example, HTTP. Based on that info, for instance, calling classes can decide to update archive metadata (graph, binary references, index) more frequently, and not only when the archive is being closed. With that multiple Oak processes can access the storage simultaneously, with one process in read-write mode and one or more processes in read-only mode.

Returns: