/*
* Hibernate Search, full-text search for your domain model
*
* License: GNU Lesser General Public License (LGPL), version 2.1 or later
* See the lgpl.txt file in the root directory or <http://www.gnu.org/licenses/lgpl-2.1.html>.
*/
package org.hibernate.search.engine.spi;
/**
* Lucene delegates responsibility for efficient time tracking to an external service;
* this is needed for example by the
* {@link org.apache.lucene.search.TimeLimitingCollector#TimeLimitingCollector(org.apache.lucene.search.Collector, org.apache.lucene.util.Counter, long)}
* used by Hibernate Search when time limits are enabled on fulltext queries.
*
* @author Sanne Grinovero (C) 2012 Red Hat Inc.
* @since 4.1
*/
public interface TimingSource {
/**
* Returns an approximation of {@link java.lang.System#nanoTime()}.
* Performance should be preferred over accuracy by the implementation, but the value is monotonic
* and expresses time in milliseconds, however, subsequent invocations could return the same value.
*
* @return an increasing value related to time in milliseconds. Only meaningful to compare time intervals, with no guarantees of high precision.
*/
long getMonotonicTimeEstimate();
/**
* Invoked on SearchIntegrator shutdown. There is no start method as it's expected to be lazily initialized
*/
void stop();
/**
* Needs to be invoked at least once before {@link #getMonotonicTimeEstimate()} can be used.
* Safe to be invoked multiple times.
*/
void ensureInitialized();
}