com.faunos.skwish
Class SegmentStore

java.lang.Object
  com.faunos.skwish.SegmentStore

All Implemented Interfaces:

Closeable, Channel

Direct Known Subclasses:

Store

public abstract class SegmentStore
extends Object
implements Channel

A managed union of segments on the file system exposed as a logical whole. This class provides transaction semantics and supports concurrent access to the logical whole segment.

Author:

Babak Farhang

Field Summary

protected static Validator<SegmentStoreException>

validator

Constructor Summary

SegmentStore()

Method Summary

abstract void	close() Closes the instance.
static Provider	getProvider() Returns the current service provider.
abstract Segment	getReadOnlySegment() Returns the live read-only view of the committed segments.
abstract long	getTxnCommitIdGap(long txnId) Returns the transaction commit id gap recorded on commit for the specified transaction, or -1, if the transaction is pending or discarded.
abstract String	getUri() Returns the URI used to load this instance.
static SegmentStore	loadInstance(String uri) Loads and returns an existing segment store from the specified URI.
abstract TxnSegment	newTransaction() Returns a new transaction [segment].
static void	setProvider(Provider provider) Sets the service provider.
static SegmentStore	writeNewInstance(String uri) Writes a new segment store to the specified URI and returns the instance.

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.nio.channels.Channel

isOpen

Field Detail

validator

protected static final Validator<SegmentStoreException> validator

Constructor Detail

SegmentStore

public SegmentStore()

Method Detail

setProvider

public static void setProvider(Provider provider)

Sets the service provider. Invoked to change the backing implementation.

getProvider

public static Provider getProvider()

Returns the current service provider.

loadInstance

public static SegmentStore loadInstance(String uri)
                                 throws IOException

Loads and returns an existing segment store from the specified URI. Presently, this just takes the form of a file path.

Throws:

IOException

writeNewInstance

public static SegmentStore writeNewInstance(String uri)
                                     throws IOException

Writes a new segment store to the specified URI and returns the instance.

Throws:

IOException

getUri

public abstract String getUri()

Returns the URI used to load this instance.

getReadOnlySegment

public abstract Segment getReadOnlySegment()
                                    throws IOException

Returns the live read-only view of the committed segments. Transactions are immediately visible on commit.

Throws:

IOException

newTransaction

public abstract TxnSegment newTransaction()
                                   throws IOException

Returns a new transaction [segment]. Transactions allow changes to be committed in all-or-nothing fashion. There is no architectural limit on the number of transactions that can be concurrently open (pending). Also, while transactions (TxnSegments) are not individually thread-safe, each transaction may be run concurrently in its own thread.

Throws:

IOException

getTxnCommitIdGap

public abstract long getTxnCommitIdGap(long txnId)
                                throws IOException,
                                       NotFoundException

Returns the transaction commit id gap recorded on commit for the specified transaction, or -1, if the transaction is pending or discarded.

Parameters:

txnId - the transaction id (from TxnSegment.getTxnId())

Throws:

NotFoundException - If txnId does not specify a known transaction

IOException

close

public abstract void close()
                    throws IOException

Closes the instance. All Segments opened by this instance are implicitly closed, and any uncommitted TxnSegments are discarded.

Specified by:

close in interface Closeable

Specified by:

close in interface Channel

Throws:

IOException