org.wali

Class MinimalLockingWriteAheadLog<T>

java.lang.Object

org.wali.MinimalLockingWriteAheadLog<T>

Type Parameters:

T - type of record this WAL is for

All Implemented Interfaces:

WriteAheadRepository<T>

public final class MinimalLockingWriteAheadLog<T>
extends java.lang.Object
implements WriteAheadRepository<T>

This implementation provides as little Locking as possible in order to provide the highest throughput possible. However, this implementation is ONLY appropriate if it can be guaranteed that only a single thread will ever issue updates for a given Record at any one time.

Constructor Summary

Constructors

Constructor and Description
MinimalLockingWriteAheadLog(java.nio.file.Path path, int partitionCount, SerDe<T> serde, SyncListener syncListener)
MinimalLockingWriteAheadLog(java.nio.file.Path path, int partitionCount, SerDeFactory<T> serdeFactory, SyncListener syncListener)
MinimalLockingWriteAheadLog(java.util.SortedSet<java.nio.file.Path> paths, int partitionCount, SerDe<T> serde, SyncListener syncListener)
MinimalLockingWriteAheadLog(java.util.SortedSet<java.nio.file.Path> paths, int partitionCount, SerDeFactory<T> serdeFactory, SyncListener syncListener)

Method Summary

Modifier and Type	Method and Description
int	checkpoint() Compacts the contents of the Repository so that rather than having a Snapshot and an Edit Log indicating many Updates to the Snapshot, the Snapshot is updated to contain the current state of the Repository, and the edit log is purged.
java.util.Set<java.lang.String>	getRecoveredSwapLocations() Recovers all External Swap locations that were persisted.
int	getVersion()
java.util.Collection<T>	recoverRecords() Recovers all records from the persisted state.
void	shutdown() Causes the repository to checkpoint and then close any open resources.
int	update(java.util.Collection<T> records, boolean forceSync) Updates the repository with the specified Records.

Methods inherited from class java.lang.Object

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

Constructor Detail

MinimalLockingWriteAheadLog

public MinimalLockingWriteAheadLog(java.nio.file.Path path,
                                   int partitionCount,
                                   SerDe<T> serde,
                                   SyncListener syncListener)
                            throws java.io.IOException

Throws:

java.io.IOException

MinimalLockingWriteAheadLog

public MinimalLockingWriteAheadLog(java.nio.file.Path path,
                                   int partitionCount,
                                   SerDeFactory<T> serdeFactory,
                                   SyncListener syncListener)
                            throws java.io.IOException

Throws:

java.io.IOException

MinimalLockingWriteAheadLog

public MinimalLockingWriteAheadLog(java.util.SortedSet<java.nio.file.Path> paths,
                                   int partitionCount,
                                   SerDe<T> serde,
                                   SyncListener syncListener)
                            throws java.io.IOException

Throws:

java.io.IOException

MinimalLockingWriteAheadLog

public MinimalLockingWriteAheadLog(java.util.SortedSet<java.nio.file.Path> paths,
                                   int partitionCount,
                                   SerDeFactory<T> serdeFactory,
                                   SyncListener syncListener)
                            throws java.io.IOException

Parameters:

paths - a sorted set of Paths to use for the partitions/journals and the snapshot. The snapshot will always be written to the first path specified.

partitionCount - the number of partitions/journals to use. For best performance, this should be close to the number of threads that are expected to update the repository simultaneously

serdeFactory - the factory for the serializer/deserializer for records

syncListener - the listener

Throws:

java.io.IOException - if unable to initialize due to IO issue

Method Detail

update

public int update(java.util.Collection<T> records,
                  boolean forceSync)
           throws java.io.IOException

Description copied from interface: WriteAheadRepository

Updates the repository with the specified Records. The Collection must not contain multiple records with the same ID

Specified by:

update in interface WriteAheadRepository<T>

Parameters:

records - the records to update

forceSync - specifies whether or not the Repository forces the data to be flushed to disk. If false, the data may be stored in Operating System buffers, which improves performance but could cause loss of data if power is lost or the Operating System crashes

Returns:

the index of the Partition that performed the update

Throws:

java.io.IOException - if failure to update repo

recoverRecords

public java.util.Collection<T> recoverRecords()
                                       throws java.io.IOException

Description copied from interface: WriteAheadRepository

Recovers all records from the persisted state. This method must be called before any updates are issued to the Repository.

Specified by:

recoverRecords in interface WriteAheadRepository<T>

Returns:

recovered records

Throws:

java.io.IOException - if failure to read from repo

getRecoveredSwapLocations

public java.util.Set<java.lang.String> getRecoveredSwapLocations()
                                                          throws java.io.IOException

Description copied from interface: WriteAheadRepository

Recovers all External Swap locations that were persisted. If this method is to be called, it must be called AFTER WriteAheadRepository.recoverRecords() and BEFORE update.

Specified by:

getRecoveredSwapLocations in interface WriteAheadRepository<T>

Returns:

swap location

Throws:

java.io.IOException - if failure reading swap locations

checkpoint

public int checkpoint()
               throws java.io.IOException

Description copied from interface: WriteAheadRepository

Compacts the contents of the Repository so that rather than having a Snapshot and an Edit Log indicating many Updates to the Snapshot, the Snapshot is updated to contain the current state of the Repository, and the edit log is purged.

Specified by:

checkpoint in interface WriteAheadRepository<T>

Returns:

the number of records that were written to the new snapshot

Throws:

java.io.IOException - if failure during checkpoint

shutdown

public void shutdown()
              throws java.io.IOException

Description copied from interface: WriteAheadRepository

Causes the repository to checkpoint and then close any open resources.

Specified by:

shutdown in interface WriteAheadRepository<T>

Throws:

java.io.IOException - if failure to shutdown cleanly

getVersion

public int getVersion()