Package org.apache.jackrabbit.oak.segment.remote

Class AbstractRemoteSegmentArchiveReader

java.lang.Object

org.apache.jackrabbit.oak.segment.remote.AbstractRemoteSegmentArchiveReader

All Implemented Interfaces:

Closeable, AutoCloseable, SegmentArchiveReader

Direct Known Subclasses:

AwsSegmentArchiveReader, AzureSegmentArchiveReader

public abstract class AbstractRemoteSegmentArchiveReader
extends Object
implements SegmentArchiveReader

Field Summary

Fields

Modifier and Type	Field	Description
protected Boolean	hasGraph
protected Map<UUID,RemoteSegmentArchiveEntry>	index
protected IOMonitor	ioMonitor

Constructor Summary

Constructors

Constructor	Description
AbstractRemoteSegmentArchiveReader(IOMonitor ioMonitor)

Method Summary

Modifier and Type	Method	Description
protected abstract File	archivePathAsFile()	Returns the decoded file component of this archive.
void	close()	Close the archive.
protected abstract long	computeArchiveIndexAndLength()	Populates the archive index, summing up each entry's length.
boolean	containsSegment(long msb, long lsb)	Check if the segment exists.
protected abstract Buffer	doReadDataFile(String extension)	Reads a data file inside the archive.
protected abstract void	doReadSegmentToBuffer(String segmentFileName, Buffer buffer)	Reads the segment from the remote storage.
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.
Buffer	getGraph()	Load the segment graph.
boolean	hasGraph()	Check if the segment graph has been persisted for this 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.
List<SegmentArchiveEntry>	listSegments()	List all the segments, in the order as they have been written to the archive.
Buffer	readSegment(long msb, long lsb)	Read the segment.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.jackrabbit.oak.segment.spi.persistence.SegmentArchiveReader

getName, length

Field Detail

ioMonitor

protected final IOMonitor ioMonitor

index

protected final Map<UUID,RemoteSegmentArchiveEntry> index

hasGraph

protected Boolean hasGraph

Constructor Detail

AbstractRemoteSegmentArchiveReader

public AbstractRemoteSegmentArchiveReader(IOMonitor ioMonitor)
                                   throws IOException

Throws:

IOException

Method Detail

readSegment

public Buffer readSegment(long msb,
                          long lsb)
                   throws IOException

Description copied from interface: SegmentArchiveReader

Read the segment.

Specified by:

readSegment in interface SegmentArchiveReader

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

public boolean containsSegment(long msb,
                               long lsb)

Description copied from interface: SegmentArchiveReader

Check if the segment exists.

Specified by:

containsSegment in interface SegmentArchiveReader

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

public List<SegmentArchiveEntry> listSegments()

Description copied from interface: SegmentArchiveReader

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

Specified by:

listSegments in interface SegmentArchiveReader

Returns:

segment list, ordered by their position in the archive

getGraph

public Buffer getGraph()
                throws IOException

Description copied from interface: SegmentArchiveReader

Load the segment graph.

Specified by:

getGraph in interface SegmentArchiveReader

Returns:

byte buffer representing the graph or null if the graph hasn't been persisted.

Throws:

IOException

hasGraph

public boolean hasGraph()

Description copied from interface: SegmentArchiveReader

Check if the segment graph has been persisted for this archive.

Specified by:

hasGraph in interface SegmentArchiveReader

Returns:

true if the graph exists, false otherwise

getBinaryReferences

public Buffer getBinaryReferences()
                           throws IOException

Description copied from interface: SegmentArchiveReader

Load binary references.

Specified by:

getBinaryReferences in interface SegmentArchiveReader

Returns:

byte buffer representing the binary references structure.

Throws:

IOException

close

public void close()

Description copied from interface: SegmentArchiveReader

Close the archive.

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable

Specified by:

close in interface SegmentArchiveReader

getEntrySize

public int getEntrySize(int size)

Description copied from interface: SegmentArchiveReader

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.)

Specified by:

getEntrySize in interface SegmentArchiveReader

Parameters:

size - the segment size in bytes

Returns:

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

computeArchiveIndexAndLength

protected abstract long computeArchiveIndexAndLength()
                                              throws IOException

Populates the archive index, summing up each entry's length.

Returns:

length, the total length of the archive

Throws:

IOException

doReadSegmentToBuffer

protected abstract void doReadSegmentToBuffer(String segmentFileName,
                                              Buffer buffer)
                                       throws IOException

Reads the segment from the remote storage.

Parameters:

segmentFileName - , the name of the segment (msb + lsb) prefixed by its position in the archive

buffer - , the buffer to which to read

Throws:

IOException

doReadDataFile

protected abstract Buffer doReadDataFile(String extension)
                                  throws IOException

Reads a data file inside the archive. This entry is not a segment. Its full name is given by archive name + extension.

Parameters:

extension - , extension of the file

Returns:

the buffer containing the data file bytes

Throws:

IOException

archivePathAsFile

protected abstract File archivePathAsFile()

Returns the decoded file component of this archive.

Returns:

the decoded file component of this archive.

isRemote

public boolean isRemote()

Description copied from interface: SegmentArchiveReader

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.

Specified by:

isRemote in interface SegmentArchiveReader

Returns: