Class ValueStoreWAL

java.lang.Object

org.eclipse.rdf4j.sail.nativerdf.wal.ValueStoreWAL

All Implemented Interfaces:

AutoCloseable

public final class ValueStoreWAL
extends Object
implements AutoCloseable

Write-ahead log (WAL) for the ValueStore. The WAL records minted values in append-only segments so they can be recovered or searched independently from the on-disk ValueStore files. This class is thread-safe for concurrent producers and uses a background writer thread to serialize and fsync according to the configured ValueStoreWalConfig.SyncPolicy.

Field Summary

Fields

Modifier and Type	Field	Description
static final int	MAX_FRAME_BYTES
static final long	NO_LSN

Method Summary

Modifier and Type	Method	Description
void	awaitDurable(long lsn)	Block until the given LSN is durably forced to disk according to the configured sync policy.
void	close()
ValueStoreWalConfig	config()
BlockingQueue<ValueStoreWalRecord>	getQueue()
boolean	hasInitialSegments()	Returns true if WAL segments were already present in the directory when this WAL was opened.
boolean	isClosed()	Returns true once close() has been invoked and the writer thread has terminated.
long	logMint(int id, ValueStoreWalValueKind kind, String lexical, String datatype, String language, int hash)	Append a minted value record to the WAL.
static ValueStoreWAL	open(ValueStoreWalConfig config)	Open a ValueStore WAL for the provided configuration.
void	purgeAllSegments()	Purge all WAL segments from the WAL directory.

Methods inherited from class Object

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

Field Details

NO_LSN

public static final long NO_LSN

See Also:

• Constant Field Values

MAX_FRAME_BYTES

public static final int MAX_FRAME_BYTES

See Also:

• Constant Field Values

Method Details

getQueue

public BlockingQueue<ValueStoreWalRecord> getQueue()

open

public static ValueStoreWAL open(ValueStoreWalConfig config)
                          throws IOException

Open a ValueStore WAL for the provided configuration. The WAL directory is created if it does not already exist. If existing segments are detected, the next LSN is seeded from the last valid record to ensure monotonicity across restarts.

Throws:

IOException

config

public ValueStoreWalConfig config()

logMint

public long logMint(int id,
 ValueStoreWalValueKind kind,
 String lexical,
 String datatype,
 String language,
 int hash)
             throws IOException

Append a minted value record to the WAL.

Parameters:

id - the ValueStore internal id

kind - the kind of value (IRI, BNODE, LITERAL, NAMESPACE)

lexical - the lexical form (may be empty but never null)

datatype - the datatype IRI string for literals, otherwise empty

language - the language tag for literals, otherwise empty

hash - a hash of the underlying serialized value

Returns:

the log sequence number (LSN) assigned to the record

Throws:

IOException

awaitDurable

public void awaitDurable(long lsn)
                  throws InterruptedException,
IOException

Block until the given LSN is durably forced to disk according to the configured sync policy. This is a no-op when lsn <= NO_LSN or after the WAL is closed.

Throws:

InterruptedException

IOException

hasInitialSegments

public boolean hasInitialSegments()

Returns true if WAL segments were already present in the directory when this WAL was opened.

isClosed

public boolean isClosed()

Returns true once close() has been invoked and the writer thread has terminated.

purgeAllSegments

public void purgeAllSegments()
                      throws IOException

Purge all WAL segments from the WAL directory. Coordinated with the writer thread to close the current segment before deletion and reset to a fresh segment after purge completes.

Throws:

IOException

close

public void close()
           throws IOException

Specified by:

close in interface AutoCloseable

Throws:

IOException