com.hazelcast.internal.monitors.PerformanceMonitorPlugin Maven / Gradle / Ivy
/*
* Copyright (c) 2008-2016, Hazelcast, Inc. All Rights Reserved.
*
* 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 com.hazelcast.internal.monitors;
/**
* A Plugin for the {@link PerformanceMonitor}.
*
* The plugin will not be called concurrently, unless threads are introduced outside of the PerformanceMonitor.
*
* There is a happens before relation between {@link #onStart()} and {@link #run(PerformanceLogWriter)}, and therefor
* there is no need to make variables volatile. The source of the happens-before relation is the scheduler.queue inside
* of the PerformanceMonitor or the AtomicReference in case of static plugins.
*/
public abstract class PerformanceMonitorPlugin {
/**
* Indicates that a plugin should be run once per performance log file.
*/
protected static final long STATIC = -1;
/**
* Indicates that the plugin is disabled.
*/
protected static final long DISABLED = 0;
/**
* Returns the period of executing the monitor in millis.
*
* If a monitor is disabled, 0 is returned.
*
* If a monitor should run only once, a negative value is returned. This is useful for 'static' monitors like the
* {@link SystemPropertiesPlugin} that run at the beginning of a log file but their contents will not change.
*
* @return the period in millis.
*/
public abstract long getPeriodMillis();
public abstract void onStart();
public abstract void run(PerformanceLogWriter writer);
}