/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.apache.hadoop.hbase.trace;
import java.io.IOException;
import java.util.Collection;
import java.util.HashSet;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.util.ReflectionUtils;
import org.cloudera.htrace.SpanReceiver;
import org.cloudera.htrace.Trace;
import org.cloudera.htrace.impl.ZipkinSpanReceiver;
/**
* This class provides functions for reading the names of SpanReceivers from
* hbase-site.xml, adding those SpanReceivers to the Tracer, and closing those
* SpanReceivers when appropriate.
*/
public class SpanReceiverHost {
public static final String SPAN_RECEIVERS_CONF_KEY = "hbase.trace.spanreceiver.classes";
private static final Log LOG = LogFactory.getLog(SpanReceiverHost.class);
private Collection<SpanReceiver> receivers;
private Configuration conf;
private boolean closed = false;
private static enum SingleTonholder {
INSTANCE;
Object lock = new Object();
SpanReceiverHost host = null;
}
public static SpanReceiverHost getInstance(Configuration conf) {
if (SingleTonholder.INSTANCE.host != null) {
return SingleTonholder.INSTANCE.host;
}
synchronized (SingleTonholder.INSTANCE.lock) {
if (SingleTonholder.INSTANCE.host != null) {
return SingleTonholder.INSTANCE.host;
}
SpanReceiverHost host = new SpanReceiverHost(conf);
host.loadSpanReceivers();
SingleTonholder.INSTANCE.host = host;
return SingleTonholder.INSTANCE.host;
}
}
SpanReceiverHost(Configuration conf) {
receivers = new HashSet<SpanReceiver>();
this.conf = conf;
}
/**
* Reads the names of classes specified in the
* "hbase.trace.spanreceiver.classes" property and instantiates and registers
* them with the Tracer as SpanReceiver's.
*
*/
public void loadSpanReceivers() {
Class<?> implClass = null;
String[] receiverNames = conf.getStrings(SPAN_RECEIVERS_CONF_KEY);
if (receiverNames == null || receiverNames.length == 0) {
return;
}
for (String className : receiverNames) {
className = className.trim();
try {
implClass = Class.forName(className);
SpanReceiver receiver = loadInstance(implClass);
if (receiver != null) {
receivers.add(receiver);
LOG.info("SpanReceiver " + className + " was loaded successfully.");
}
} catch (ClassNotFoundException e) {
LOG.warn("Class " + className + " cannot be found. " + e.getMessage());
} catch (IOException e) {
LOG.warn("Load SpanReceiver " + className + " failed. "
+ e.getMessage());
}
}
for (SpanReceiver rcvr : receivers) {
Trace.addReceiver(rcvr);
}
}
private SpanReceiver loadInstance(Class<?> implClass)
throws IOException {
SpanReceiver impl = null;
try {
Object o = implClass.newInstance();
impl = (SpanReceiver)o;
impl.configure(new HBaseHTraceConfiguration(this.conf));
} catch (SecurityException e) {
throw new IOException(e);
} catch (IllegalArgumentException e) {
throw new IOException(e);
} catch (RuntimeException e) {
throw new IOException(e);
} catch (InstantiationException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
}
return impl;
}
/**
* Calls close() on all SpanReceivers created by this SpanReceiverHost.
*/
public synchronized void closeReceivers() {
if (closed) return;
closed = true;
for (SpanReceiver rcvr : receivers) {
try {
rcvr.close();
} catch (IOException e) {
LOG.warn("Unable to close SpanReceiver correctly: " + e.getMessage(), e);
}
}
}
}