org.treetank.access

Class BucketReadTrx

java.lang.Object

org.treetank.access.BucketReadTrx

All Implemented Interfaces:

IBucketReadTrx

public class BucketReadTrx
extends Object
implements IBucketReadTrx

BucketReadTrx

State of a reading transaction. The only thing shared amongst transactions is the bucket cache. Everything else is exclusive to this transaction. It is required that only a single thread has access to this transaction.

A path-like cache boosts sequential operations.

Field Summary

Fields

Modifier and Type	Field and Description
protected com.google.common.cache.Cache<Long,DataBucket>	mCache Cache for reading data.
protected MetaBucket	mMetaBucket Cached name bucket of this revision.
protected RevisionRootBucket	mRootBucket Cached root bucket of this revision.
protected ISession	mSession Configuration of the session

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	BucketReadTrx(ISession pSession, UberBucket pUberBucket, RevisionRootBucket pRevBucket, MetaBucket pMetaBucket, IBackendReader pReader) Standard constructor.

Method Summary

Methods

Modifier and Type	Method and Description
protected IData	checkItemIfDeleted(IData pToCheck) Method to check if an IData is a deleted one.
boolean	close() Closing this Readtransaction.
protected static int	dataBucketOffset(long pDataKey) Calculate data bucket offset for a given data key.
protected static long[]	dereferenceLeafOfTree(IBackendReader pReader, long pStartKey, long pSeqBucketKey) Find reference pointing to leaf bucket of an indirect tree.
IData	getData(long pDataKey) Getting the data related to the given data key.
MetaBucket	getMetaBucket() Getting the map with the entire mapping for retrieving meta-information related to the bundle.
long	getRevision() Getting the revision number of this transaction
protected List<DataBucket>	getSnapshotBuckets(long pSeqDataBucketKey) Dereference data bucket reference.
boolean	isClosed() Check if transaction is closed.
String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

mRootBucket

protected final RevisionRootBucket mRootBucket

Cached root bucket of this revision.

mMetaBucket

protected final MetaBucket mMetaBucket

Cached name bucket of this revision.

mSession

protected final ISession mSession

Configuration of the session

mCache

protected final com.google.common.cache.Cache<Long,DataBucket> mCache

Cache for reading data.

Constructor Detail

BucketReadTrx

protected BucketReadTrx(ISession pSession,
             UberBucket pUberBucket,
             RevisionRootBucket pRevBucket,
             MetaBucket pMetaBucket,
             IBackendReader pReader)
                 throws TTException

Standard constructor.

Parameters:

pSession - State of state.

pUberBucket - Uber bucket to start reading with.

pRevBucket - RevisionBucket with reference from either log to commit or persistent memory.

pMetaBucket - MetaBucket with reference from either log to commit or persistent memory.

pReader - for this transaction

Throws:

TTIOException - if the read of the persistent storage fails

TTException

Method Detail

getData

public IData getData(long pDataKey)
              throws TTIOException

Getting the data related to the given data key.

Specified by:

getData in interface IBucketReadTrx

Parameters:

pDataKey - searched for

Returns:

the related data

Throws:

TTIOException - if the read to the persistent storage fails

close

public boolean close()
              throws TTIOException

Closing this Readtransaction.

Specified by:

close in interface IBucketReadTrx

Returns:

true if successful, false otherwise

Throws:

TTIOException - if the closing to the persistent storage fails.

getRevision

public long getRevision()
                 throws TTIOException

Getting the revision number of this transaction

Specified by:

getRevision in interface IBucketReadTrx

Returns:

the revision number of this transaction

Throws:

TTIOException - if deserialization fails.

isClosed

public boolean isClosed()

Check if transaction is closed.

Specified by:

isClosed in interface IBucketReadTrx

Returns:

true if closed, false otherwise

getMetaBucket

public MetaBucket getMetaBucket()

Getting the map with the entire mapping for retrieving meta-information related to the bundle.

Specified by:

getMetaBucket in interface IBucketReadTrx

Returns:

the meta bucket

checkItemIfDeleted

protected final IData checkItemIfDeleted(IData pToCheck)

Method to check if an IData is a deleted one.

Parameters:

pToCheck - of the IItem

Returns:

the item if it is valid, null otherwise

getSnapshotBuckets

protected final List<DataBucket> getSnapshotBuckets(long pSeqDataBucketKey)
                                             throws TTIOException

Dereference data bucket reference.

Parameters:

pSeqDataBucketKey - Key of data bucket.

Returns:

Dereferenced bucket.

Throws:

TTIOException - if something odd happens within the creation process.

dataBucketOffset

protected static final int dataBucketOffset(long pDataKey)

Calculate data bucket offset for a given data key.

Parameters:

pDataKey - data key to find offset for.

Returns:

Offset into data bucket.

dereferenceLeafOfTree

protected static final long[] dereferenceLeafOfTree(IBackendReader pReader,
                           long pStartKey,
                           long pSeqBucketKey)
                                             throws TTIOException

Find reference pointing to leaf bucket of an indirect tree.

Parameters:

pStartKey - Start reference pointing to the indirect tree.

pSeqBucketKey - Key to look up in the indirect tree.

Returns:

Reference denoted by key pointing to the leaf bucket.

Throws:

TTIOException - if something odd happens within the creation process.

toString

public String toString()

Overrides:

toString in class Object