/*
* ModeShape (http://www.modeshape.org)
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* 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.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.modeshape.jcr.api.monitor;
import java.util.concurrent.TimeUnit;
import org.modeshape.jcr.api.value.DateTime;
/**
* An immutable history of a metric for a given window in time.
*
* @since 3.0
*/
public interface History {
/**
* A history with no statistics, no window, no start or end time, and no duration.
*/
public History NO_HISTORY = new History() {
/**
* {@inheritDoc}
* <p>
* <strong>Always returns <code>null</code>.</strong>
*
* @see org.modeshape.jcr.api.monitor.History#getWindow()
*/
@Override
public Window getWindow() {
return null;
}
/**
* {@inheritDoc}
* <p>
* <strong>Always returns <code>0</code> (zero).</strong>
*
* @see org.modeshape.jcr.api.monitor.History#getTotalDuration(java.util.concurrent.TimeUnit)
*/
@Override
public long getTotalDuration( final TimeUnit unit ) {
return 0;
}
/**
* {@inheritDoc}
* <p>
* <strong>Always returns <code>null</code>.</strong>
*
* @see org.modeshape.jcr.api.monitor.History#getStartTime()
*/
@Override
public DateTime getStartTime() {
return null;
}
/**
* {@inheritDoc}
* <p>
* <strong>Always returns <code>null</code>.</strong>
*
* @see org.modeshape.jcr.api.monitor.History#getEndTime()
*/
@Override
public DateTime getEndTime() {
return null;
}
/**
* {@inheritDoc}
* <p>
* <strong>Always returns an empty statistics array.</strong>
*
* @see org.modeshape.jcr.api.monitor.History#getStats()
*/
@Override
public Statistics[] getStats() {
return Statistics.NO_STATISTICS;
}
};
/**
* Get the kind of window.
*
* @return the window type; never null
*/
public Window getWindow();
/**
* Get the total duration of this history window.
*
* @param unit the desired time unit; if null, then {@link TimeUnit#SECONDS} is used
* @return the duration
*/
public long getTotalDuration( TimeUnit unit );
/**
* Get the timestamp (including time zone information) at which this history window starts.
*
* @return the time at which this window starts
*/
public DateTime getStartTime();
/**
* Get the timestamp (including time zone information) at which this history window ends.
*
* @return the time at which this window ends
*/
public DateTime getEndTime();
/**
* Get the statistics for that make up the history.
*
* @return the statistics; never null, but the array may contain null if the window is longer than the lifetime of the
* repository
*/
Statistics[] getStats();
}