com.bigdata.service.AbstractService 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
*/
/*
* Created on Apr 28, 2008
*/
package com.bigdata.service;
import java.util.UUID;
import org.apache.log4j.Logger;
import org.apache.log4j.MDC;
import com.bigdata.Banner;
import com.bigdata.counters.AbstractStatisticsCollector;
import com.bigdata.counters.CounterSet;
/**
* Abstract base class defines protocols for setting the service {@link UUID},
* etc.
*
* @author Bryan Thompson
* @version $Id$
*/
abstract public class AbstractService implements IService {
private static final Logger log = Logger.getLogger(AbstractService.class);
private String serviceName;
private UUID serviceUUID;
/**
*
*/
protected AbstractService() {
// show the copyright banner during statup.
Banner.banner();
/*
* Note: This is more or less the same pattern use by AbstractServer (in
* the bigdata-jini module) to assign a default service name, but the
* latter will report the server's class name. That class also makes
* sure to reports the name which it assigns to the service.
*/
serviceName = getServiceIface().getName() + "@" + getHostname() + "#"
+ hashCode();
}
/**
* This method must be invoked to set the service {@link UUID}.
*
* Note: This method gets invoked at different times depending on whether
* the service is embedded (generally invoked from the service constructor)
* or written against a service discovery framework (invoked once the
* service has been assigned a UUID by a registrar or during re-start since
* the service UUID is read from a local file).
*
* Several things depend on when this method is invoked, including the setup
* of the per-service {@link CounterSet} reported by the service to the
* {@link ILoadBalancerService}.
*
* @param serviceUUID
* The {@link UUID} assigned to the service.
*
* @throws IllegalArgumentException
* if the parameter is null.
* @throws IllegalStateException
* if the service {@link UUID} has already been set to a
* different value.
*/
synchronized public void setServiceUUID(final UUID serviceUUID)
throws IllegalStateException {
if (serviceUUID == null)
throw new IllegalArgumentException();
if (this.serviceUUID != null && !this.serviceUUID.equals(serviceUUID)) {
throw new IllegalStateException();
}
if (log.isInfoEnabled())
log.info("uuid=" + serviceUUID);
this.serviceUUID = serviceUUID;
}
final public UUID getServiceUUID() {
return serviceUUID;
}
/**
* Return the most interesting interface for the service.
*/
abstract public Class getServiceIface();
/**
* Starts the {@link AbstractService}.
*
* Note: A {@link #start()} is required in order to give subclasses an
* opportunity to be fully initialized before they are required to begin
* operations. It is impossible to encapsulate the startup logic cleanly
* without this ctor() + start() pattern. Those familiar with Objective-C
* will recognized this.
*
* @return this (the return type should be strengthened by the
* concrete implementation to return the actual type).
*/
abstract public AbstractService start();
/**
* Return the proxy used to access other services in the federation.
*/
abstract public AbstractFederation getFederation();
public final String getHostname() {
return AbstractStatisticsCollector.fullyQualifiedHostName;
}
// /**
// * Shuts down the {@link #getFederation()} used by this service.
// */
public synchronized void shutdown() {
// if(!isOpen()) return;
// getFederation().shutdown();
// open = false;
}
// /**
// * Shuts down the {@link #getFederation()} used by this service.
// */
public synchronized void shutdownNow() {
// if(!isOpen()) return;
// getFederation().shutdownNow();
// open = false;
}
// final public boolean isOpen() {
//
// return open;
//
// }
// private boolean open = true;
public void destroy() {
shutdownNow();
}
/**
* Note: This is overridden in the jini integration to return a configured
* name for the service.
*/
public String getServiceName() {
return serviceName;
}
/**
* Sets up the {@link MDC} logging context. You should do this on every
* client facing point of entry and then call {@link #clearLoggingContext()}
* in a finally clause. You can extend this method to add
* additional context.
*
* This implementation adds the following parameters to the {@link MDC}.
*
* - serviceName
* - The serviceName is typically a configuration property for the
* service. This datum can be injected into log messages using
* %X{serviceName} in your log4j pattern layout.
* - serviceUUID
* - The serviceUUID is, in general, assigned asynchronously by the
* service registrar. Once the serviceUUID becomes available it will be
* added to the {@link MDC}. This datum can be injected into log messages
* using %X{serviceUUID} in your log4j pattern layout.
* - hostname
* - The hostname statically determined. This datum can be injected into
* log messages using %X{hostname} in your log4j pattern layout.
*
*/
protected void setupLoggingContext() {
try {
// Note: This _is_ a local method call.
UUID serviceUUID = getServiceUUID();
// Will be null until assigned by the service registrar.
if (serviceUUID != null) {
MDC.put("serviceUUID", serviceUUID);
}
MDC.put("serviceName", getServiceName());
MDC.put("hostname", getHostname());
} catch(Throwable t) {
/*
* Ignore.
*/
}
}
/**
* Clear the logging context.
*/
protected void clearLoggingContext() {
MDC.remove("serviceName");
MDC.remove("serviceUUID");
MDC.remove("hostname");
}
}