org.mapdb

Class Store

java.lang.Object

org.mapdb.Store

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable, Engine

Direct Known Subclasses:

StoreAppend, StoreArchive, StoreDirect, StoreHeap

public abstract class Store
extends java.lang.Object
implements Engine

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	Store.Cache Cache implementation, part of Store class.
static class	Store.LongLongMap Open Hash Map which uses primitive long as values and keys.
static class	Store.LongObjectMap<V> Open Hash Map which uses primitive long as keys.
static class	Store.LongObjectObjectMap<V1,V2> Open Hash Map which uses primitive long as keys.
static class	Store.LongQueue Queue of primitive long.
static class	Store.MemoryBarrierLessLock Lock which blocks parallel execution, but does not use MemoryBarrier (and does not flush CPU cache)
static class	Store.ReadWriteSingleLock fake read/write lock which in fact locks on single write lock

Nested classes/interfaces inherited from interface org.mapdb.Engine

Engine.CloseOnJVMShutdown, Engine.ReadOnly, Engine.ReadOnlyWrapper

Field Summary

Fields

Modifier and Type	Field and Description
static int	LOCKING_STRATEGY_NOLOCK
static int	LOCKING_STRATEGY_READWRITELOCK
static int	LOCKING_STRATEGY_WRITELOCK
static java.util.concurrent.locks.Lock	NOLOCK fake lock

Fields inherited from interface org.mapdb.Engine

CLOSED_ENGINE, RECID_CLASS_CATALOG, RECID_FIRST, RECID_LAST_RESERVED, RECID_NAME_CATALOG, RECID_RECORD_CHECK

Method Summary

Modifier and Type	Method and Description
abstract void	backup(java.io.OutputStream out, boolean incremental)
abstract void	backupRestore(java.io.InputStream[] in)
boolean	canSnapshot()
void	clearCache() clears any underlying cache
<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
abstract boolean	fileLoad() If underlying storage is memory-mapped-file, this method will try to load and precache all file data into disk cache.
static Store	forDB(DB db) traverses Engine wrappers and returns underlying Store
static Store	forEngine(Engine e) traverses Engine wrappers and returns underlying Store
<A> A	get(long recid, Serializer<A> serializer) Get existing record.
abstract long	getCurrSize()
abstract long	getFreeSize()
Engine	getWrappedEngine() if this is wrapper return underlying engine, or null
void	init()
boolean	isClosed() Checks whether Engine was closed.
boolean	isReadOnly() Check if you can write into this Engine.
void	metricsCollect(java.util.Map<java.lang.String,java.lang.Long> map) puts metrics into given map
<A> void	update(long recid, A value, Serializer<A> serializer) Update existing record with new value.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.mapdb.Engine

canRollback, close, commit, compact, preallocate, put, rollback, snapshot

Field Detail

LOCKING_STRATEGY_READWRITELOCK

public static final int LOCKING_STRATEGY_READWRITELOCK

See Also:

Constant Field Values

LOCKING_STRATEGY_WRITELOCK

public static final int LOCKING_STRATEGY_WRITELOCK

See Also:

Constant Field Values

LOCKING_STRATEGY_NOLOCK

public static final int LOCKING_STRATEGY_NOLOCK

See Also:

Constant Field Values

NOLOCK

public static final java.util.concurrent.locks.Lock NOLOCK

fake lock

Method Detail

init

public void init()

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

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.

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

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

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

Parameters:

recid - (record identifier) under which was record persisted

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

isClosed

public boolean isClosed()

Description copied from interface: Engine

Checks whether Engine was closed.

Specified by:

isClosed in interface Engine

Returns:

true if engine was closed

isReadOnly

public boolean isReadOnly()

Description copied from interface: Engine

Check if you can write into this Engine. It may be readonly in some cases (snapshot, read-only files).

Specified by:

isReadOnly in interface Engine

Returns:

true if engine is read-only

forDB

public static Store forDB(DB db)

traverses Engine wrappers and returns underlying Store

forEngine

public static Store forEngine(Engine e)

traverses Engine wrappers and returns underlying Store

getCurrSize

public abstract long getCurrSize()

getFreeSize

public abstract long getFreeSize()

fileLoad

public abstract boolean fileLoad()

If underlying storage is memory-mapped-file, this method will try to load and precache all file data into disk cache. Most likely it will call MappedByteBuffer.load(), but could also read content of entire file etc This method will not pin data into memory, they might be removed at any time.

Returns:

true if this method did something, false if underlying storage does not support loading, or is already in-memory

clearCache

public void clearCache()

Description copied from interface: Engine

clears any underlying cache

Specified by:

clearCache in interface Engine

metricsCollect

public void metricsCollect(java.util.Map<java.lang.String,java.lang.Long> map)

puts metrics into given map

backup

public abstract void backup(java.io.OutputStream out,
                            boolean incremental)

backupRestore

public abstract void backupRestore(java.io.InputStream[] in)

getWrappedEngine

public Engine getWrappedEngine()

Description copied from interface: Engine

if this is wrapper return underlying engine, or null

Specified by:

getWrappedEngine in interface Engine

canSnapshot

public boolean canSnapshot()

Specified by:

canSnapshot in interface Engine

Returns:

true if engine can create read-only snapshots