org.mapdb
Class StoreWAL

java.lang.Object
  org.mapdb.Store
      org.mapdb.StoreDirect
          org.mapdb.StoreWAL

All Implemented Interfaces:

Engine

public class StoreWAL
extends StoreDirect

Write-Ahead-Log

Field Summary

protected long[]	indexVals
protected boolean[]	indexValsModified
protected Volume	log
protected static long	LOG_MASK_OFFSET
protected static long	LOG_SEAL added to offset 8 into log file, indicates that log was synced and closed
protected AtomicInteger	logChecksum
protected long	logSize
protected LongMap<byte[]>	longStackPages
protected LongConcurrentHashMap<long[]>	modified
protected static long[]	PREALLOC
protected boolean	replayPending
protected static long[]	TOMBSTONE
static String	TRANS_LOG_FILE_EXT
protected Volume.Factory	volFac
protected static byte	WAL_INDEX_LONG
protected static byte	WAL_LONGSTACK_PAGE
protected static byte	WAL_PHYS_ARRAY
protected static byte	WAL_PHYS_ARRAY_ONE_LONG
protected static byte	WAL_SEAL last instruction in log file
protected static byte	WAL_SKIP_REST_OF_BLOCK

Fields inherited from class org.mapdb.StoreDirect

DATA_FILE_EXT, deleteFilesAfterClose, freeSize, HEADER, index, indexSize, IO_FREE_RECID, IO_FREE_SIZE, IO_INDEX_SIZE, IO_INDEX_SUM, IO_PHYS_SIZE, IO_USER_START, LONG_STACK_PREF_COUNT, LONG_STACK_PREF_COUNT_ALTER, LONG_STACK_PREF_SIZE, LONG_STACK_PREF_SIZE_ALTER, MASK_ARCHIVE, MASK_DISCARD, MASK_LINKED, MASK_OFFSET, MAX_REC_SIZE, maxUsedIoList, phys, PHYS_FREE_SLOTS_COUNT, physSize, readOnly, sizeLimit, spaceReclaimReuse, spaceReclaimSplit, spaceReclaimTrack, STORE_VERSION, syncOnCommitDisabled

Fields inherited from class org.mapdb.Store

checksum, CHECKSUM_FLAG_MASK, CHUNK_SIZE, CHUNK_SIZE_MOD_MASK, compress, COMPRESS_FLAG_MASK, encrypt, ENCRYPT_FLAG_MASK, encryptionXTEA, locks, LOG, LZF, newRecidLock, password, recycledDataOuts, serializerPojo, serializerPojoInitLock, structuralLock

Fields inherited from interface org.mapdb.Engine

CATALOG_RECID, CHECK_RECORD, CLASS_INFO_RECID, LAST_RESERVED_RECID

Constructor Summary

StoreWAL(Volume.Factory volFac)

StoreWAL(Volume.Factory volFac, boolean readOnly, boolean deleteFilesAfterClose, int spaceReclaimMode, boolean syncOnCommitDisabled, long sizeLimit, boolean checksum, boolean compress, byte[] password, boolean disableLocks, int sizeIncrement)

Method Summary

boolean	canRollback()
protected void	checkHeaders()
protected void	checkLogRounding()
void	close() Close store/cache.
void	commit() Makes all changes made since the previous commit/rollback permanent.
protected void	compactPostUnderLock() subclasses put additional cleanup after compaction finishes here
protected void	compactPreUnderLock() subclasses put additional checks before compaction starts here
<A> boolean	compareAndSwap(long recid, A expectedOldValue, A newValue, Serializer<A> serializer) Updates existing record in atomic (Compare And Swap) manner.
<A> void	delete(long recid, Serializer<A> serializer) Remove existing record from store/cache Recid must be a number returned by 'put' method.
<A> A	get(long recid, Serializer<A> serializer) Get existing record.
protected <A> A	get2(long ioRecid, Serializer<A> serializer)
protected long[]	getLinkedRecordsFromLog(long ioRecid)
protected long	indexHeaderChecksumUncommited()
protected long[]	logAllocate(long[] physPos)
protected void	logChecksumAdd(int cs)
protected boolean	logDirty()
protected void	logReset()
protected byte[]	longStackGetPage(long offset)
protected static long	longStackGetSixLong(byte[] page, int pos)
protected void	longStackPut(long ioList, long offset, boolean recursive)
protected static void	longStackPutSixLong(byte[] page, int pos, long value)
protected long	longStackTake(long ioList, boolean recursive)
long	preallocate() Preallocates recid for not yet created record.
void	preallocate(long[] recids) Preallocates recids for not yet created record.
<A> long	put(A value, Serializer<A> serializer) Insert new record.
protected void	reloadIndexFile()
protected void	replayLogFile()
void	rollback() Undoes all changes made in the current transaction.
<A> void	update(long recid, A value, Serializer<A> serializer) Update existing record with new value.
protected boolean	verifyLogFile()
protected void	walIndexVal(long logPos, long ioRecid, long indexVal)
protected void	walPhysArray(DataOutput2 out, long[] physPos, long[] logPos)

Methods inherited from class org.mapdb.StoreDirect

calculateStatistics, clearCache, compact, countLongStackItems, createStructure, freeIoRecidPut, freeIoRecidTake, freePhysPut, freePhysTake, getCurrSize, getFreeRecids, getFreeSize, getLinkedRecordsIndexVals, getMaxRecid, getRaw, getSizeLimit, indexHeaderChecksum, isClosed, isReadOnly, physAllocate, put2, roundTo16, size2ListIoRecid, update2, updateRaw

Methods inherited from class org.mapdb.Store

canSnapshot, closeListenerRegister, closeListenerUnregister, deserialize, expectedMasks, forDB, forEngine, getSerializerPojo, lockAllWrite, lockPos, newDataOut2, printStatistics, serialize, snapshot, unlockAllWrite

Methods inherited from class java.lang.Object

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

Field Detail

LOG_MASK_OFFSET

protected static final long LOG_MASK_OFFSET

See Also:

Constant Field Values

WAL_INDEX_LONG

protected static final byte WAL_INDEX_LONG

See Also:

Constant Field Values

WAL_LONGSTACK_PAGE

protected static final byte WAL_LONGSTACK_PAGE

See Also:

Constant Field Values

WAL_PHYS_ARRAY_ONE_LONG

protected static final byte WAL_PHYS_ARRAY_ONE_LONG

See Also:

Constant Field Values

WAL_PHYS_ARRAY

protected static final byte WAL_PHYS_ARRAY

See Also:

Constant Field Values

WAL_SKIP_REST_OF_BLOCK

protected static final byte WAL_SKIP_REST_OF_BLOCK

See Also:

Constant Field Values

WAL_SEAL

protected static final byte WAL_SEAL

last instruction in log file

See Also:

Constant Field Values

LOG_SEAL

protected static final long LOG_SEAL

added to offset 8 into log file, indicates that log was synced and closed

See Also:

Constant Field Values

TRANS_LOG_FILE_EXT

public static final String TRANS_LOG_FILE_EXT

See Also:

Constant Field Values

TOMBSTONE

protected static final long[] TOMBSTONE

PREALLOC

protected static final long[] PREALLOC

volFac

protected final Volume.Factory volFac

log

protected Volume log

logSize

protected volatile long logSize

modified

protected final LongConcurrentHashMap<long[]> modified

longStackPages

protected final LongMap<byte[]> longStackPages

indexVals

protected final long[] indexVals

indexValsModified

protected final boolean[] indexValsModified

replayPending

protected boolean replayPending

logChecksum

protected final AtomicInteger logChecksum

Constructor Detail

StoreWAL

public StoreWAL(Volume.Factory volFac)

StoreWAL

public StoreWAL(Volume.Factory volFac,
                boolean readOnly,
                boolean deleteFilesAfterClose,
                int spaceReclaimMode,
                boolean syncOnCommitDisabled,
                long sizeLimit,
                boolean checksum,
                boolean compress,
                byte[] password,
                boolean disableLocks,
                int sizeIncrement)

Method Detail

checkHeaders

protected void checkHeaders()

Overrides:

checkHeaders in class StoreDirect

reloadIndexFile

protected void reloadIndexFile()

logReset

protected void logReset()

preallocate

public long preallocate()

Description copied from interface: Engine

Preallocates recid for not yet created record. It does not insert any data into it.

Specified by:

preallocate in interface Engine

Overrides:

preallocate in class StoreDirect

Returns:

new recid

preallocate

public void preallocate(long[] recids)

Description copied from interface: Engine

Preallocates recids for not yet created record. It does not insert any data into it. This is done in batch of given size (determied by size of array in argument)

Specified by:

preallocate in interface Engine

Overrides:

preallocate in class StoreDirect

Parameters:

recids - array to put result into

put

public <A> long put(A value,
                    Serializer<A> serializer)

Description copied from interface: Engine

Insert new record.

Specified by:

put in interface Engine

Overrides:

put in class StoreDirect

Parameters:

value - records to be added

serializer - used to convert record into/from binary form

Returns:

recid (record identifier) under which record is stored.

walPhysArray

protected void walPhysArray(DataOutput2 out,
                            long[] physPos,
                            long[] logPos)

walIndexVal

protected void walIndexVal(long logPos,
                           long ioRecid,
                           long indexVal)

logAllocate

protected long[] logAllocate(long[] physPos)

checkLogRounding

protected void checkLogRounding()

get

public <A> A get(long recid,
                 Serializer<A> serializer)

Description copied from interface: Engine

Get existing record.

Recid must be a number returned by 'put' method. Behaviour for invalid recid (random number or already deleted record) is not defined, typically it returns null or throws 'EndOfFileException'

Specified by:

get in interface Engine

Overrides:

get in class StoreDirect

Parameters:

recid - (record identifier) under which record was persisted

serializer - used to deserialize record from binary form

Returns:

record matching given recid, or null if record is not found under given recid.

get2

protected <A> A get2(long ioRecid,
                     Serializer<A> serializer)
          throws IOException

Overrides:

get2 in class StoreDirect

Throws:

IOException

update

public <A> void update(long recid,
                       A value,
                       Serializer<A> serializer)

Description copied from interface: Engine

Update existing record with new value.

Recid must be a number returned by 'put' method. Behaviour for invalid recid (random number or already deleted record) is not defined, typically it throws 'EndOfFileException', but it may also corrupt store.

Specified by:

update in interface Engine

Overrides:

update in class StoreDirect

Parameters:

recid - (record identifier) under which record was persisted.

value - new record value to be stored

serializer - used to serialize record into binary form

compareAndSwap

public <A> boolean compareAndSwap(long recid,
                                  A expectedOldValue,
                                  A newValue,
                                  Serializer<A> serializer)

Description copied from interface: Engine

Updates existing record in atomic (Compare And Swap) manner. Value is modified only if old value matches expected value. There are three ways to match values, MapDB may use any of them:

1. Equality check oldValue==expectedOldValue when old value is found in instance cache
2. Deserializing oldValue using serializer and checking oldValue.equals(expectedOldValue)
3. Serializing expectedOldValue using serializer and comparing binary array with already serialized oldValue

Recid must be a number returned by 'put' method. Behaviour for invalid recid (random number or already deleted record) is not defined, typically it throws 'EndOfFileException', but it may also corrupt store.

Specified by:

compareAndSwap in interface Engine

Overrides:

compareAndSwap in class StoreDirect

Parameters:

recid - (record identifier) under which record was persisted.

expectedOldValue - old value to be compared with existing record

newValue - to be written if values are matching

serializer - used to serialize record into binary form

Returns:

true if values matched and newValue was written

delete

public <A> void delete(long recid,
                       Serializer<A> serializer)

Description copied from interface: Engine

Remove existing record from store/cache

Recid must be a number returned by 'put' method. Behaviour for invalid recid (random number or already deleted record) is not defined, typically it throws 'EndOfFileException', but it may also corrupt store.

Specified by:

delete in interface Engine

Overrides:

delete in class StoreDirect

Parameters:

recid - (record identifier) under which was record persisted

serializer - which may be used in some circumstances to deserialize and store old object

commit

public void commit()

Description copied from interface: Engine

Makes all changes made since the previous commit/rollback permanent. In transactional mode (on by default) it means creating journal file and replaying it to storage. In other modes it may flush disk caches or do nothing at all (check your config options)

Specified by:

commit in interface Engine

Overrides:

commit in class StoreDirect

logDirty

protected boolean logDirty()

indexHeaderChecksumUncommited

protected long indexHeaderChecksumUncommited()

verifyLogFile

protected boolean verifyLogFile()

replayLogFile

protected void replayLogFile()

rollback

public void rollback()
              throws UnsupportedOperationException

Description copied from interface: Engine

Undoes all changes made in the current transaction. If transactions are disabled it throws UnsupportedOperationException.

Specified by:

rollback in interface Engine

Overrides:

rollback in class StoreDirect

Throws:

UnsupportedOperationException - if transactions are disabled

getLinkedRecordsFromLog

protected long[] getLinkedRecordsFromLog(long ioRecid)

longStackTake

protected long longStackTake(long ioList,
                             boolean recursive)

Overrides:

longStackTake in class StoreDirect

longStackPut

protected void longStackPut(long ioList,
                            long offset,
                            boolean recursive)

Overrides:

longStackPut in class StoreDirect

longStackGetSixLong

protected static long longStackGetSixLong(byte[] page,
                                          int pos)

longStackPutSixLong

protected static void longStackPutSixLong(byte[] page,
                                          int pos,
                                          long value)

longStackGetPage

protected byte[] longStackGetPage(long offset)

close

public void close()

Description copied from interface: Engine

Close store/cache. This method must be called before JVM exits to flush all caches and prevent store corruption. Also it releases resources used by MapDB (disk, memory..).

Engine can no longer be used after this method was called. If Engine is used after closing, it may throw any exception including NullPointerException

There is an configuration option DBMaker.closeOnJvmShutdown() which uses shutdown hook to automatically close Engine when JVM shutdowns.

Specified by:

close in interface Engine

Overrides:

close in class StoreDirect

compactPreUnderLock

protected void compactPreUnderLock()

Description copied from class: StoreDirect

subclasses put additional checks before compaction starts here

Overrides:

compactPreUnderLock in class StoreDirect

compactPostUnderLock

protected void compactPostUnderLock()

Description copied from class: StoreDirect

subclasses put additional cleanup after compaction finishes here

Overrides:

compactPostUnderLock in class StoreDirect

canRollback

public boolean canRollback()

Specified by:

canRollback in interface Engine

Overrides:

canRollback in class StoreDirect

Returns:

true if engine supports rollback

logChecksumAdd

protected void logChecksumAdd(int cs)