org.apache.hadoop.util.ReflectionUtils Maven / Gradle / Ivy
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/**
* 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.util;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.PrintWriter;
import java.lang.management.ManagementFactory;
import java.lang.management.ThreadInfo;
import java.lang.management.ThreadMXBean;
import java.lang.reflect.Constructor;
import java.lang.reflect.Method;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import org.apache.commons.logging.Log;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.conf.Configurable;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.io.DataInputBuffer;
import org.apache.hadoop.io.DataOutputBuffer;
import org.apache.hadoop.io.Writable;
import org.apache.hadoop.io.serializer.Deserializer;
import org.apache.hadoop.io.serializer.SerializationFactory;
import org.apache.hadoop.io.serializer.Serializer;
/**
* General reflection utils
*/
@InterfaceAudience.Public
@InterfaceStability.Evolving
public class ReflectionUtils {
private static final Class[] EMPTY_ARRAY = new Class[]{};
volatile private static SerializationFactory serialFactory = null;
/**
* Cache of constructors for each class. Pins the classes so they
* can't be garbage collected until ReflectionUtils can be collected.
*/
private static final Map, Constructor> CONSTRUCTOR_CACHE =
new ConcurrentHashMap, Constructor>();
/**
* Check and set 'configuration' if necessary.
*
* @param theObject object for which to set configuration
* @param conf Configuration
*/
public static void setConf(Object theObject, Configuration conf) {
if (conf != null) {
if (theObject instanceof Configurable) {
((Configurable) theObject).setConf(conf);
}
setJobConf(theObject, conf);
}
}
/**
* This code is to support backward compatibility and break the compile
* time dependency of core on mapred.
* This should be made deprecated along with the mapred package HADOOP-1230.
* Should be removed when mapred package is removed.
*/
private static void setJobConf(Object theObject, Configuration conf) {
//If JobConf and JobConfigurable are in classpath, AND
//theObject is of type JobConfigurable AND
//conf is of type JobConf then
//invoke configure on theObject
try {
Class jobConfClass =
conf.getClassByName("org.apache.hadoop.mapred.JobConf");
Class jobConfigurableClass =
conf.getClassByName("org.apache.hadoop.mapred.JobConfigurable");
if (jobConfClass.isAssignableFrom(conf.getClass()) &&
jobConfigurableClass.isAssignableFrom(theObject.getClass())) {
Method configureMethod =
jobConfigurableClass.getMethod("configure", jobConfClass);
configureMethod.invoke(theObject, conf);
}
} catch (ClassNotFoundException e) {
//JobConf/JobConfigurable not in classpath. no need to configure
} catch (Exception e) {
throw new RuntimeException("Error in configuring object", e);
}
}
/** Create an object for the given class and initialize it from conf
*
* @param theClass class of which an object is created
* @param conf Configuration
* @return a new object
*/
@SuppressWarnings("unchecked")
public static T newInstance(Class theClass, Configuration conf) {
T result;
try {
Constructor meth = (Constructor) CONSTRUCTOR_CACHE.get(theClass);
if (meth == null) {
meth = theClass.getDeclaredConstructor(EMPTY_ARRAY);
meth.setAccessible(true);
CONSTRUCTOR_CACHE.put(theClass, meth);
}
result = meth.newInstance();
} catch (Exception e) {
throw new RuntimeException(e);
}
setConf(result, conf);
return result;
}
static private ThreadMXBean threadBean =
ManagementFactory.getThreadMXBean();
public static void setContentionTracing(boolean val) {
threadBean.setThreadContentionMonitoringEnabled(val);
}
private static String getTaskName(long id, String name) {
if (name == null) {
return Long.toString(id);
}
return id + " (" + name + ")";
}
/**
* Print all of the thread's information and stack traces.
*
* @param stream the stream to
* @param title a string title for the stack trace
*/
public static void printThreadInfo(PrintWriter stream,
String title) {
final int STACK_DEPTH = 20;
boolean contention = threadBean.isThreadContentionMonitoringEnabled();
long[] threadIds = threadBean.getAllThreadIds();
stream.println("Process Thread Dump: " + title);
stream.println(threadIds.length + " active threads");
for (long tid: threadIds) {
ThreadInfo info = threadBean.getThreadInfo(tid, STACK_DEPTH);
if (info == null) {
stream.println(" Inactive");
continue;
}
stream.println("Thread " +
getTaskName(info.getThreadId(),
info.getThreadName()) + ":");
Thread.State state = info.getThreadState();
stream.println(" State: " + state);
stream.println(" Blocked count: " + info.getBlockedCount());
stream.println(" Waited count: " + info.getWaitedCount());
if (contention) {
stream.println(" Blocked time: " + info.getBlockedTime());
stream.println(" Waited time: " + info.getWaitedTime());
}
if (state == Thread.State.WAITING) {
stream.println(" Waiting on " + info.getLockName());
} else if (state == Thread.State.BLOCKED) {
stream.println(" Blocked on " + info.getLockName());
stream.println(" Blocked by " +
getTaskName(info.getLockOwnerId(),
info.getLockOwnerName()));
}
stream.println(" Stack:");
for (StackTraceElement frame: info.getStackTrace()) {
stream.println(" " + frame.toString());
}
}
stream.flush();
}
private static long previousLogTime = 0;
/**
* Log the current thread stacks at INFO level.
* @param log the logger that logs the stack trace
* @param title a descriptive title for the call stacks
* @param minInterval the minimum time from the last
*/
public static void logThreadInfo(Log log,
String title,
long minInterval) {
boolean dumpStack = false;
if (log.isInfoEnabled()) {
synchronized (ReflectionUtils.class) {
long now = System.currentTimeMillis();
if (now - previousLogTime >= minInterval * 1000) {
previousLogTime = now;
dumpStack = true;
}
}
if (dumpStack) {
ByteArrayOutputStream buffer = new ByteArrayOutputStream();
printThreadInfo(new PrintWriter(buffer), title);
log.info(buffer.toString());
}
}
}
/**
* Return the correctly-typed {@link Class} of the given object.
*
* @param o object whose correctly-typed Class is to be obtained
* @return the correctly typed Class of the given object.
*/
@SuppressWarnings("unchecked")
public static Class getClass(T o) {
return (Class)o.getClass();
}
// methods to support testing
static void clearCache() {
CONSTRUCTOR_CACHE.clear();
}
static int getCacheSize() {
return CONSTRUCTOR_CACHE.size();
}
/**
* A pair of input/output buffers that we use to clone writables.
*/
private static class CopyInCopyOutBuffer {
DataOutputBuffer outBuffer = new DataOutputBuffer();
DataInputBuffer inBuffer = new DataInputBuffer();
/**
* Move the data from the output buffer to the input buffer.
*/
void moveData() {
inBuffer.reset(outBuffer.getData(), outBuffer.getLength());
}
}
/**
* Allocate a buffer for each thread that tries to clone objects.
*/
private static ThreadLocal cloneBuffers
= new ThreadLocal() {
protected synchronized CopyInCopyOutBuffer initialValue() {
return new CopyInCopyOutBuffer();
}
};
private static SerializationFactory getFactory(Configuration conf) {
if (serialFactory == null) {
serialFactory = new SerializationFactory(conf);
}
return serialFactory;
}
/**
* Make a copy of the writable object using serialization to a buffer
* @param dst the object to copy from
* @param src the object to copy into, which is destroyed
* @throws IOException
*/
@SuppressWarnings("unchecked")
public static T copy(Configuration conf,
T src, T dst) throws IOException {
CopyInCopyOutBuffer buffer = cloneBuffers.get();
buffer.outBuffer.reset();
SerializationFactory factory = getFactory(conf);
Class cls = (Class) src.getClass();
Serializer serializer = factory.getSerializer(cls);
serializer.open(buffer.outBuffer);
serializer.serialize(src);
buffer.moveData();
Deserializer deserializer = factory.getDeserializer(cls);
deserializer.open(buffer.inBuffer);
dst = deserializer.deserialize(dst);
return dst;
}
@Deprecated
public static void cloneWritableInto(Writable dst,
Writable src) throws IOException {
CopyInCopyOutBuffer buffer = cloneBuffers.get();
buffer.outBuffer.reset();
src.write(buffer.outBuffer);
buffer.moveData();
dst.readFields(buffer.inBuffer);
}
}