com.atomikos.persistence.LogStream Maven / Gradle / Ivy
/**
* Copyright (C) 2000-2010 Atomikos
*
* This code ("Atomikos TransactionsEssentials"), by itself,
* is being distributed under the
* Apache License, Version 2.0 ("License"), a copy of which may be found at
* http://www.atomikos.com/licenses/apache-license-2.0.txt .
* You may not use this file except in compliance with the License.
*
* While the License grants certain patent license rights,
* those patent license rights only extend to the use of
* Atomikos TransactionsEssentials by itself.
*
* This code (Atomikos TransactionsEssentials) contains certain interfaces
* in package (namespace) com.atomikos.icatch
* (including com.atomikos.icatch.Participant) which, if implemented, may
* infringe one or more patents held by Atomikos.
* It should be appreciated that you may NOT implement such interfaces;
* licensing to implement these interfaces must be obtained separately from Atomikos.
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
*/
package com.atomikos.persistence;
import java.util.Enumeration;
import java.util.Vector;
/**
* The LogStream interface is an abstract definition of a stream that
* encapsulates a physical log. In contrast to a regular input or output stream,
* a log stream has both input and output facilities to the same underlying log.
* It also allows for checkpointing, but the client is responsible for
* determining the checkpoint contents. Checkpointing allows the log stream to
* decrease in size.
*/
public interface LogStream
{
/**
* Get the size of the stream.
*
* @return long The size of the stream.
* @exception LogException
* On error.
*/
public long getSize () throws LogException;
/**
* Reads the log contents, and initializes the data structure. Should be
* called first.
*
* @return Vector The read objects from the log.
* @exception LogException
* On failure.
*/
public Vector recover () throws LogException;
/**
* After intial recovery, it is good practice to write a checkpoint with
* only the most recent data. This method does that, and can also be called
* at random intervals during normal operation.
*
* @param elements
* The elements to keep in the log.
*
*
* @exception LogException
* On failure.
*/
public void writeCheckpoint ( Enumeration elements ) throws LogException;
/**
* Flush (force) an object to the stream. If this method returns then the
* object is guaranteed to be persisted.
*
*
* @throws LogException
* On failure.
*/
public void flushObject ( Object objectToFlush , boolean shouldSync ) throws LogException;
/**
* For proper termination: a close method.
*
* @exception LogException
* On failure.
*/
public void close () throws LogException;
}