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PageCacheCounters.java
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PageCacheCounters.java
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/*
* Copyright (c) 2002-2016 "Neo Technology,"
* Network Engine for Objects in Lund AB [http://neotechnology.com]
*
* This file is part of Neo4j.
*
* Neo4j 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, either version 3 of the License, or
* (at your option) any later version.
*
* 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, see <http://www.gnu.org/licenses/>.
*/
package org.neo4j.io.pagecache.monitoring;
/**
* The PageCacheCounters exposes internal counters from the page cache.
* The data for these counters is sourced through the PageCacheTracer API.
*/
public interface PageCacheCounters
{
/**
* @return The number of page faults observed thus far.
*/
long faults();
/**
* @return The number of page evictions observed thus far.
*/
long evictions();
/**
* @return The number of page pins observed thus far.
*/
long pins();
/**
* @return The number of page unpins observed thus far.
*/
long unpins();
/**
* @return The number of page flushes observed thus far.
*/
long flushes();
/**
* @return The sum total of bytes read in through page faults thus far.
*/
long bytesRead();
/**
* @return The sum total of bytes written through flushes thus far.
*/
long bytesWritten();
/**
* @return The number of file mappings observed thus far.
*/
long filesMapped();
/**
* @return The number of file unmappings observed thus far.
*/
long filesUnmapped();
/**
* @return The number of page evictions that have thrown exceptions thus far.
*/
long evictionExceptions();
}