com.bigdata.mdi.IResourceMetadata Maven / Gradle / Ivy
/**
Copyright (C) SYSTAP, LLC DBA Blazegraph 2006-2016. All rights reserved.
Contact:
SYSTAP, LLC DBA Blazegraph
2501 Calvert ST NW #106
Washington, DC 20008
[email protected]
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
package com.bigdata.mdi;
import java.io.Serializable;
import java.util.UUID;
import com.bigdata.btree.ILocalBTreeView;
import com.bigdata.btree.IndexSegment;
import com.bigdata.journal.AbstractJournal;
import com.bigdata.journal.Journal;
import com.bigdata.resources.ResourceManager;
/**
* Interface for metadata about a {@link Journal} or {@link IndexSegment}.
*
* @author Bryan Thompson
* @version $Id$
*/
public interface IResourceMetadata extends Serializable, Cloneable {
/**
* True iff this resource is an {@link IndexSegment}. Each
* {@link IndexSegment} contains historical read-only data for exactly one
* partition of a scale-out index.
*/
public boolean isIndexSegment();
/**
* True iff this resource is a {@link Journal}. When the resource is a
* {@link Journal}, there will be a named mutable btree on the journal that
* is absorbing writes for one or more index partition of a scale-out index.
*/
public boolean isJournal();
/**
* The name of the file containing the resource (this is always relative to
* some local data directory).
*
* Note: This property is primarily used for debugging. It is NOT used by
* the {@link ResourceManager}. Instead, the {@link ResourceManager} builds
* up the mapping from resource {@link UUID} to local filename during
* startup.
*/
public String getFile();
/*
* Note: size() was removed since (a) required a new instance of the
* resource metadata object for the ManagedJournal each time we obtained an
* iterator reading on a data service; and (b) the resources are the same
* regardless of their size. it is the file and UUID that identify them.
* the file in the file system and the UUID in our code.
*/
// /**
// * The #of bytes in the store file.
// */
// public long size();
/**
* The unique identifier for the resource.
*
* @see IRootBlockView#getUUID(), the UUID for an {@link AbstractJournal}.
*
* @see IndexSegmentCheckpoint#segmentUUID, the UUID for an
* {@link IndexSegment}.
*/
public UUID getUUID();
/**
* The commit time associated with the creation of this resource. When the
* index is an {@link IndexSegment} this is the commit time of the view from
* which that {@link IndexSegment} was generated. When the resource is a
* {@link Journal}, the create time is the commit time associated with the
* journal creation, which is generally an overflow operation. Regardless,
* the create time MUST be assigned by the same time source that is used to
* assign commit timestamps.
*/
public long getCreateTime();
/**
* The commit time of the view from which the caller should read. For an
* {@link IndexSegment}, this is always the same as {@link #getCreateTime()}
* . For a {@link Journal}, this may be a specific commit time for a source
* in an {@link ILocalBTreeView}. A value of 0L indicates that
* no specific commit time is indicated. For historical journals, this
* implies a read from the lastCommitTime on the journal in order to
* constitute the view. For the current journal, this implies a read at
* whatever timestamp the caller desires.
*
* @see IndexManager
*/
public long getCommitTime();
/**
* The hash code of the {@link #getUUID() resource UUID}.
*/
public int hashCode();
/**
* Compares two resource metadata objects for consistent state.
*
* @param o
*
* @return
*/
public boolean equals(IResourceMetadata o);
}