org.apache.directory.mavibot.btree

Class ReadTransaction<K,V>

java.lang.Object

org.apache.directory.mavibot.btree.ReadTransaction<K,V>

Type Parameters:

K - The type for the Key

V - The type for the stored value

public class ReadTransaction<K,V>
extends java.lang.Object

The Transaction is used to protect the BTree against concurrent modification, and insure that a read is always done against one single revision. It's also used to gather many modifications under one single revision, if needed.

A Transaction should be closed when the user is done with it, otherwise the pages associated with the given revision, and all the referenced pages, will remain on the storage.

A Transaction can be hold for quite a long time, for instance while doing a browse against a big BTree. At some point, transactions which are pending for too long will be closed by the transaction manager.

Field Summary

Fields

Modifier and Type	Field and Description
private BTreeHeader<K,V>	btreeHeader The associated B-tree header
private boolean	closed A flag used to tell if a transaction is closed or not
private long	creationDate The date of creation
private java.util.concurrent.ConcurrentLinkedQueue<ReadTransaction<K,V>>	readTransactions The list of read transactions being executed
private RecordManager	recordManager The reference to the recordManager, if any
private long	revision The associated revision

Constructor Summary

Constructors

Constructor and Description
ReadTransaction(BTreeHeader<K,V> btreeHeader, java.util.concurrent.ConcurrentLinkedQueue<ReadTransaction<K,V>> readTransactions) Creates a new transaction instance
ReadTransaction(RecordManager recordManager, BTreeHeader<K,V> btreeHeader, java.util.concurrent.ConcurrentLinkedQueue<ReadTransaction<K,V>> readTransactions) Creates a new transaction instance

Method Summary

Modifier and Type	Method and Description
void	close() Close the transaction, releasing the revision it was using.
BTreeHeader<K,V>	getBtreeHeader()
long	getCreationDate()
long	getRevision()
boolean	isClosed()
java.lang.String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

revision

private long revision

The associated revision

creationDate

private long creationDate

The date of creation

btreeHeader

private BTreeHeader<K,V> btreeHeader

The associated B-tree header

closed

private volatile boolean closed

A flag used to tell if a transaction is closed or not

readTransactions

private java.util.concurrent.ConcurrentLinkedQueue<ReadTransaction<K,V>> readTransactions

The list of read transactions being executed

recordManager

private RecordManager recordManager

The reference to the recordManager, if any

Constructor Detail

ReadTransaction

public ReadTransaction(RecordManager recordManager,
                       BTreeHeader<K,V> btreeHeader,
                       java.util.concurrent.ConcurrentLinkedQueue<ReadTransaction<K,V>> readTransactions)

Creates a new transaction instance

Parameters:

btreeHeader - The BtreeHeader we will use for this read transaction

ReadTransaction

public ReadTransaction(BTreeHeader<K,V> btreeHeader,
                       java.util.concurrent.ConcurrentLinkedQueue<ReadTransaction<K,V>> readTransactions)

Creates a new transaction instance

Parameters:

btreeHeader - The BtreeHeader we will use for this read transaction

Method Detail

getRevision

public long getRevision()

Returns:

the associated revision

getCreationDate

public long getCreationDate()

Returns:

the creationDate

getBtreeHeader

public BTreeHeader<K,V> getBtreeHeader()

Returns:

the btreeHeader

close

public void close()

Close the transaction, releasing the revision it was using.

isClosed

public boolean isClosed()

Returns:

true if this transaction has been closed

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

See Also:

Object.toString()