org.apache.hadoop.hbase.util.CoprocessorClassLoader 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
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* 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.util;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.net.URL;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.Collection;
import java.util.Enumeration;
import java.util.HashSet;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.locks.Lock;
import java.util.jar.JarEntry;
import java.util.jar.JarFile;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileStatus;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.FileUtil;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IOUtils;
import org.apache.yetus.audience.InterfaceAudience;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.hbase.thirdparty.com.google.common.base.Preconditions;
import org.apache.hbase.thirdparty.com.google.common.collect.MapMaker;
/**
* ClassLoader used to load classes for Coprocessor instances.
*
* This ClassLoader always tries to load classes from the specified coprocessor jar first actually
* using URLClassLoader logic before delegating to the parent ClassLoader, thus avoiding dependency
* conflicts between HBase's classpath and classes in the coprocessor jar.
*
* Certain classes are exempt from being loaded by this ClassLoader because it would prevent them
* from being cast to the equivalent classes in the region server. For example, the Coprocessor
* interface needs to be loaded by the region server's ClassLoader to prevent a ClassCastException
* when casting the coprocessor implementation.
*
* A HDFS path can be used to specify the coprocessor jar. In this case, the jar will be copied to
* local at first under some folder under ${hbase.local.dir}/jars/tmp/. The local copy will be
* removed automatically when the HBase server instance is stopped.
*
* This ClassLoader also handles resource loading. In most cases this ClassLoader will attempt to
* load resources from the coprocessor jar first before delegating to the parent. However, like in
* class loading, some resources need to be handled differently. For all of the Hadoop default
* configurations (e.g. hbase-default.xml) we will check the parent ClassLoader first to prevent
* issues such as failing the HBase default configuration version check.
*/
@InterfaceAudience.Private
public class CoprocessorClassLoader extends ClassLoaderBase {
private static final Logger LOG = LoggerFactory.getLogger(CoprocessorClassLoader.class);
// A temporary place ${hbase.local.dir}/jars/tmp/ to store the local
// copy of the jar file and the libraries contained in the jar.
private static final String TMP_JARS_DIR =
File.separator + "jars" + File.separator + "tmp" + File.separator;
/**
* External class loaders cache keyed by external jar path. ClassLoader instance is stored as a
* weak-reference to allow GC'ing when it is not used (@see HBASE-7205)
*/
private static final ConcurrentMap classLoadersCache =
new MapMaker().concurrencyLevel(3).weakValues().makeMap();
/**
* If the class being loaded starts with any of these strings, we will skip trying to load it from
* the coprocessor jar and instead delegate directly to the parent ClassLoader.
*/
private static final String[] CLASS_PREFIX_EXEMPTIONS = new String[] {
// Java standard library:
"com.sun.", "java.", "javax.", "org.ietf", "org.omg", "org.w3c", "org.xml", "sunw.",
// logging
"org.slf4j", "org.apache.log4j", "com.hadoop",
// HBase:
"org.apache.hadoop.hbase", };
/**
* If the resource being loaded matches any of these patterns, we will first attempt to load the
* resource with the parent ClassLoader. Only if the resource is not found by the parent do we
* attempt to load it from the coprocessor jar.
*/
private static final Pattern[] RESOURCE_LOAD_PARENT_FIRST_PATTERNS =
new Pattern[] { Pattern.compile("^[^-]+-default\\.xml$") };
private static final Pattern libJarPattern = Pattern.compile("[/]?lib/([^/]+\\.jar)");
/**
* A locker used to synchronize class loader initialization per coprocessor jar file
*/
private static final KeyLocker locker = new KeyLocker<>();
/**
* A set used to synchronized parent path clean up. Generally, there should be only one parent
* path, but using a set so that we can support more.
*/
static final HashSet parentDirLockSet = new HashSet<>();
/**
* Creates a JarClassLoader that loads classes from the given paths.
*/
private CoprocessorClassLoader(ClassLoader parent) {
super(parent);
}
private void init(Path pathPattern, String pathPrefix, Configuration conf) throws IOException {
// Copy the jar to the local filesystem
String parentDirStr = conf.get(LOCAL_DIR_KEY, DEFAULT_LOCAL_DIR) + TMP_JARS_DIR;
synchronized (parentDirLockSet) {
if (!parentDirLockSet.contains(parentDirStr)) {
Path parentDir = new Path(parentDirStr);
FileSystem fs = FileSystem.getLocal(conf);
fs.delete(parentDir, true); // it's ok if the dir doesn't exist now
parentDirLockSet.add(parentDirStr);
if (!fs.mkdirs(parentDir) && !fs.getFileStatus(parentDir).isDirectory()) {
throw new RuntimeException("Failed to create local dir " + parentDirStr
+ ", CoprocessorClassLoader failed to init");
}
}
}
FileSystem fs = pathPattern.getFileSystem(conf);
// append "*.jar" if a directory is specified
Path pathPattern1 = fs.isDirectory(pathPattern) ? new Path(pathPattern, "*.jar") : pathPattern;
// return all files that match the pattern
FileStatus[] fileStatuses = fs.globStatus(pathPattern1);
if (fileStatuses == null || fileStatuses.length == 0) {
// if no one matches
throw new FileNotFoundException(pathPattern1.toString());
} else {
boolean validFileEncountered = false;
// for each file that match the pattern
for (Path path : FileUtil.stat2Paths(fileStatuses)) {
if (fs.isFile(path)) {
// only process files, skip for directories
File dst = new File(parentDirStr,
"." + pathPrefix + "." + path.getName() + "." + System.currentTimeMillis() + ".jar");
fs.copyToLocalFile(path, new Path(dst.toString()));
dst.deleteOnExit();
addURL(dst.getCanonicalFile().toURI().toURL());
JarFile jarFile = new JarFile(dst.toString());
try {
// get entries inside a jar file
Enumeration entries = jarFile.entries();
while (entries.hasMoreElements()) {
JarEntry entry = entries.nextElement();
Matcher m = libJarPattern.matcher(entry.getName());
if (m.matches()) {
File file = new File(parentDirStr, "." + pathPrefix + "." + path.getName() + "."
+ System.currentTimeMillis() + "." + m.group(1));
try (FileOutputStream outStream = new FileOutputStream(file)) {
IOUtils.copyBytes(jarFile.getInputStream(entry), outStream, conf, true);
}
file.deleteOnExit();
addURL(file.toURI().toURL());
}
}
} finally {
jarFile.close();
}
// Set to true when encountering a file
validFileEncountered = true;
}
}
if (validFileEncountered == false) {
// all items returned by globStatus() are directories
throw new FileNotFoundException("No file found matching " + pathPattern1.toString());
}
}
}
// This method is used in unit test
public static CoprocessorClassLoader getIfCached(final Path path) {
Preconditions.checkNotNull(path, "The jar path is null!");
return classLoadersCache.get(path);
}
// This method is used in unit test
public static Collection getAllCached() {
return classLoadersCache.values();
}
// This method is used in unit test
public static void clearCache() {
classLoadersCache.clear();
}
/**
* Get a CoprocessorClassLoader for a coprocessor jar path from cache. If not in cache, create
* one.
* @param path the path to the coprocessor jar file to load classes from
* @param parent the parent class loader for exempted classes
* @param pathPrefix a prefix used in temp path name to store the jar file locally
* @param conf the configuration used to create the class loader, if needed
* @return a CoprocessorClassLoader for the coprocessor jar path n
*/
public static CoprocessorClassLoader getClassLoader(final Path path, final ClassLoader parent,
final String pathPrefix, final Configuration conf) throws IOException {
CoprocessorClassLoader cl = getIfCached(path);
String pathStr = path.toString();
if (cl != null) {
LOG.debug("Found classloader " + cl + " for " + pathStr);
return cl;
}
if (path.getFileSystem(conf).isFile(path) && !pathStr.endsWith(".jar")) {
throw new IOException(pathStr + ": not a jar file?");
}
Lock lock = locker.acquireLock(pathStr);
try {
cl = getIfCached(path);
if (cl != null) {
LOG.debug("Found classloader " + cl + " for " + pathStr);
return cl;
}
cl = AccessController.doPrivileged(new PrivilegedAction() {
@Override
public CoprocessorClassLoader run() {
return new CoprocessorClassLoader(parent);
}
});
cl.init(path, pathPrefix, conf);
// Cache class loader as a weak value, will be GC'ed when no reference left
CoprocessorClassLoader prev = classLoadersCache.putIfAbsent(path, cl);
if (prev != null) {
// Lost update race, use already added class loader
LOG.warn("THIS SHOULD NOT HAPPEN, a class loader" + " is already cached for " + pathStr);
cl = prev;
}
return cl;
} finally {
lock.unlock();
}
}
@Override
public Class loadClass(String name) throws ClassNotFoundException {
return loadClass(name, null);
}
public Class loadClass(String name, String[] includedClassPrefixes)
throws ClassNotFoundException {
// Delegate to the parent immediately if this class is exempt
if (isClassExempt(name, includedClassPrefixes)) {
if (LOG.isDebugEnabled()) {
LOG.debug("Skipping exempt class " + name + " - delegating directly to parent");
}
return parent.loadClass(name);
}
synchronized (getClassLoadingLock(name)) {
// Check whether the class has already been loaded:
Class clasz = findLoadedClass(name);
if (clasz != null) {
if (LOG.isDebugEnabled()) {
LOG.debug("Class " + name + " already loaded");
}
} else {
try {
// Try to find this class using the URLs passed to this ClassLoader
if (LOG.isDebugEnabled()) {
LOG.debug("Finding class: " + name);
}
clasz = findClass(name);
} catch (ClassNotFoundException e) {
// Class not found using this ClassLoader, so delegate to parent
if (LOG.isDebugEnabled()) {
LOG.debug("Class " + name + " not found - delegating to parent");
}
try {
clasz = parent.loadClass(name);
} catch (ClassNotFoundException e2) {
// Class not found in this ClassLoader or in the parent ClassLoader
// Log some debug output before re-throwing ClassNotFoundException
if (LOG.isDebugEnabled()) {
LOG.debug("Class " + name + " not found in parent loader");
}
throw e2;
}
}
}
return clasz;
}
}
@Override
public URL getResource(String name) {
URL resource = null;
boolean parentLoaded = false;
// Delegate to the parent first if necessary
if (loadResourceUsingParentFirst(name)) {
if (LOG.isDebugEnabled()) {
LOG.debug("Checking parent first for resource " + name);
}
resource = super.getResource(name);
parentLoaded = true;
}
if (resource == null) {
synchronized (getClassLoadingLock(name)) {
// Try to find the resource in this jar
resource = findResource(name);
if ((resource == null) && !parentLoaded) {
// Not found in this jar and we haven't attempted to load
// the resource in the parent yet; fall back to the parent
resource = super.getResource(name);
}
}
}
return resource;
}
/**
* Determines whether the given class should be exempt from being loaded by this ClassLoader.
* @param name the name of the class to test.
* @return true if the class should *not* be loaded by this ClassLoader; false otherwise.
*/
protected boolean isClassExempt(String name, String[] includedClassPrefixes) {
if (includedClassPrefixes != null) {
for (String clsName : includedClassPrefixes) {
if (name.startsWith(clsName)) {
return false;
}
}
}
for (String exemptPrefix : CLASS_PREFIX_EXEMPTIONS) {
if (name.startsWith(exemptPrefix)) {
return true;
}
}
return false;
}
/**
* Determines whether we should attempt to load the given resource using the parent first before
* attempting to load the resource using this ClassLoader.
* @param name the name of the resource to test.
* @return true if we should attempt to load the resource using the parent first; false if we
* should attempt to load the resource using this ClassLoader first.
*/
protected boolean loadResourceUsingParentFirst(String name) {
for (Pattern resourcePattern : RESOURCE_LOAD_PARENT_FIRST_PATTERNS) {
if (resourcePattern.matcher(name).matches()) {
return true;
}
}
return false;
}
}