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Server functionality for HBase
/*
* Copyright The Apache Software Foundation
*
* 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.fs;
import java.io.Closeable;
import java.io.IOException;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.lang.reflect.Proxy;
import java.lang.reflect.UndeclaredThrowableException;
import java.net.URI;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FSDataOutputStream;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.FilterFileSystem;
import org.apache.hadoop.fs.LocalFileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hbase.ServerName;
import org.apache.hadoop.hbase.wal.DefaultWALProvider;
import org.apache.hadoop.hdfs.DFSClient;
import org.apache.hadoop.hdfs.DistributedFileSystem;
import org.apache.hadoop.hdfs.protocol.ClientProtocol;
import org.apache.hadoop.hdfs.protocol.DatanodeInfo;
import org.apache.hadoop.hdfs.protocol.LocatedBlock;
import org.apache.hadoop.hdfs.protocol.LocatedBlocks;
import org.apache.hadoop.ipc.RPC;
import org.apache.hadoop.util.Progressable;
import org.apache.hadoop.util.ReflectionUtils;
/**
* An encapsulation for the FileSystem object that hbase uses to access
* data. This class allows the flexibility of using
* separate filesystem objects for reading and writing hfiles and wals.
* In future, if we want to make wals be in a different filesystem,
* this is the place to make it happen.
*/
public class HFileSystem extends FilterFileSystem {
public static final Log LOG = LogFactory.getLog(HFileSystem.class);
private final FileSystem noChecksumFs; // read hfile data from storage
private final boolean useHBaseChecksum;
/**
* Create a FileSystem object for HBase regionservers.
* @param conf The configuration to be used for the filesystem
* @param useHBaseChecksum if true, then use
* checksum verfication in hbase, otherwise
* delegate checksum verification to the FileSystem.
*/
public HFileSystem(Configuration conf, boolean useHBaseChecksum)
throws IOException {
// Create the default filesystem with checksum verification switched on.
// By default, any operation to this FilterFileSystem occurs on
// the underlying filesystem that has checksums switched on.
this.fs = FileSystem.get(conf);
this.useHBaseChecksum = useHBaseChecksum;
fs.initialize(getDefaultUri(conf), conf);
// disable checksum verification for local fileSystem, see HBASE-11218
if (fs instanceof LocalFileSystem) {
fs.setWriteChecksum(false);
fs.setVerifyChecksum(false);
}
addLocationsOrderInterceptor(conf);
// If hbase checksum verification is switched on, then create a new
// filesystem object that has cksum verification turned off.
// We will avoid verifying checksums in the fs client, instead do it
// inside of hbase.
// If this is the local file system hadoop has a bug where seeks
// do not go to the correct location if setVerifyChecksum(false) is called.
// This manifests itself in that incorrect data is read and HFileBlocks won't be able to read
// their header magic numbers. See HBASE-5885
if (useHBaseChecksum && !(fs instanceof LocalFileSystem)) {
conf = new Configuration(conf);
conf.setBoolean("dfs.client.read.shortcircuit.skip.checksum", true);
this.noChecksumFs = newInstanceFileSystem(conf);
this.noChecksumFs.setVerifyChecksum(false);
} else {
this.noChecksumFs = fs;
}
}
/**
* Wrap a FileSystem object within a HFileSystem. The noChecksumFs and
* writefs are both set to be the same specified fs.
* Do not verify hbase-checksums while reading data from filesystem.
* @param fs Set the noChecksumFs and writeFs to this specified filesystem.
*/
public HFileSystem(FileSystem fs) {
this.fs = fs;
this.noChecksumFs = fs;
this.useHBaseChecksum = false;
}
/**
* Returns the filesystem that is specially setup for
* doing reads from storage. This object avoids doing
* checksum verifications for reads.
* @return The FileSystem object that can be used to read data
* from files.
*/
public FileSystem getNoChecksumFs() {
return noChecksumFs;
}
/**
* Returns the underlying filesystem
* @return The underlying FileSystem for this FilterFileSystem object.
*/
public FileSystem getBackingFs() throws IOException {
return fs;
}
/**
* Are we verifying checksums in HBase?
* @return True, if hbase is configured to verify checksums,
* otherwise false.
*/
public boolean useHBaseChecksum() {
return useHBaseChecksum;
}
/**
* Close this filesystem object
*/
@Override
public void close() throws IOException {
super.close();
if (this.noChecksumFs != fs) {
this.noChecksumFs.close();
}
}
/**
* Returns a brand new instance of the FileSystem. It does not use
* the FileSystem.Cache. In newer versions of HDFS, we can directly
* invoke FileSystem.newInstance(Configuration).
*
* @param conf Configuration
* @return A new instance of the filesystem
*/
private static FileSystem newInstanceFileSystem(Configuration conf)
throws IOException {
URI uri = FileSystem.getDefaultUri(conf);
FileSystem fs = null;
Class clazz = conf.getClass("fs." + uri.getScheme() + ".impl", null);
if (clazz != null) {
// This will be true for Hadoop 1.0, or 0.20.
fs = (FileSystem)ReflectionUtils.newInstance(clazz, conf);
fs.initialize(uri, conf);
} else {
// For Hadoop 2.0, we have to go through FileSystem for the filesystem
// implementation to be loaded by the service loader in case it has not
// been loaded yet.
Configuration clone = new Configuration(conf);
clone.setBoolean("fs." + uri.getScheme() + ".impl.disable.cache", true);
fs = FileSystem.get(uri, clone);
}
if (fs == null) {
throw new IOException("No FileSystem for scheme: " + uri.getScheme());
}
return fs;
}
public static boolean addLocationsOrderInterceptor(Configuration conf) throws IOException {
return addLocationsOrderInterceptor(conf, new ReorderWALBlocks());
}
/**
* Add an interceptor on the calls to the namenode#getBlockLocations from the DFSClient
* linked to this FileSystem. See HBASE-6435 for the background.
*
* There should be no reason, except testing, to create a specific ReorderBlocks.
*
* @return true if the interceptor was added, false otherwise.
*/
static boolean addLocationsOrderInterceptor(Configuration conf, final ReorderBlocks lrb) {
if (!conf.getBoolean("hbase.filesystem.reorder.blocks", true)) { // activated by default
LOG.debug("addLocationsOrderInterceptor configured to false");
return false;
}
FileSystem fs;
try {
fs = FileSystem.get(conf);
} catch (IOException e) {
LOG.warn("Can't get the file system from the conf.", e);
return false;
}
if (!(fs instanceof DistributedFileSystem)) {
LOG.debug("The file system is not a DistributedFileSystem. " +
"Skipping on block location reordering");
return false;
}
DistributedFileSystem dfs = (DistributedFileSystem) fs;
DFSClient dfsc = dfs.getClient();
if (dfsc == null) {
LOG.warn("The DistributedFileSystem does not contain a DFSClient. Can't add the location " +
"block reordering interceptor. Continuing, but this is unexpected."
);
return false;
}
try {
Field nf = DFSClient.class.getDeclaredField("namenode");
nf.setAccessible(true);
Field modifiersField = Field.class.getDeclaredField("modifiers");
modifiersField.setAccessible(true);
modifiersField.setInt(nf, nf.getModifiers() & ~Modifier.FINAL);
ClientProtocol namenode = (ClientProtocol) nf.get(dfsc);
if (namenode == null) {
LOG.warn("The DFSClient is not linked to a namenode. Can't add the location block" +
" reordering interceptor. Continuing, but this is unexpected."
);
return false;
}
ClientProtocol cp1 = createReorderingProxy(namenode, lrb, conf);
nf.set(dfsc, cp1);
LOG.info("Added intercepting call to namenode#getBlockLocations so can do block reordering" +
" using class " + lrb.getClass().getName());
} catch (NoSuchFieldException e) {
LOG.warn("Can't modify the DFSClient#namenode field to add the location reorder.", e);
return false;
} catch (IllegalAccessException e) {
LOG.warn("Can't modify the DFSClient#namenode field to add the location reorder.", e);
return false;
}
return true;
}
private static ClientProtocol createReorderingProxy(final ClientProtocol cp,
final ReorderBlocks lrb, final Configuration conf) {
return (ClientProtocol) Proxy.newProxyInstance
(cp.getClass().getClassLoader(),
new Class[]{ClientProtocol.class, Closeable.class},
new InvocationHandler() {
public Object invoke(Object proxy, Method method,
Object[] args) throws Throwable {
try {
if ((args == null || args.length == 0)
&& "close".equals(method.getName())) {
RPC.stopProxy(cp);
return null;
} else {
Object res = method.invoke(cp, args);
if (res != null && args != null && args.length == 3
&& "getBlockLocations".equals(method.getName())
&& res instanceof LocatedBlocks
&& args[0] instanceof String
&& args[0] != null) {
lrb.reorderBlocks(conf, (LocatedBlocks) res, (String) args[0]);
}
return res;
}
} catch (InvocationTargetException ite) {
// We will have this for all the exception, checked on not, sent
// by any layer, including the functional exception
Throwable cause = ite.getCause();
if (cause == null){
throw new RuntimeException(
"Proxy invocation failed and getCause is null", ite);
}
if (cause instanceof UndeclaredThrowableException) {
Throwable causeCause = cause.getCause();
if (causeCause == null) {
throw new RuntimeException("UndeclaredThrowableException had null cause!");
}
cause = cause.getCause();
}
throw cause;
}
}
});
}
/**
* Interface to implement to add a specific reordering logic in hdfs.
*/
interface ReorderBlocks {
/**
*
* @param conf - the conf to use
* @param lbs - the LocatedBlocks to reorder
* @param src - the file name currently read
* @throws IOException - if something went wrong
*/
void reorderBlocks(Configuration conf, LocatedBlocks lbs, String src) throws IOException;
}
/**
* We're putting at lowest priority the wal files blocks that are on the same datanode
* as the original regionserver which created these files. This because we fear that the
* datanode is actually dead, so if we use it it will timeout.
*/
static class ReorderWALBlocks implements ReorderBlocks {
public void reorderBlocks(Configuration conf, LocatedBlocks lbs, String src)
throws IOException {
ServerName sn = DefaultWALProvider.getServerNameFromWALDirectoryName(conf, src);
if (sn == null) {
// It's not an WAL
return;
}
// Ok, so it's an WAL
String hostName = sn.getHostname();
if (LOG.isTraceEnabled()) {
LOG.trace(src +
" is an WAL file, so reordering blocks, last hostname will be:" + hostName);
}
// Just check for all blocks
for (LocatedBlock lb : lbs.getLocatedBlocks()) {
DatanodeInfo[] dnis = lb.getLocations();
if (dnis != null && dnis.length > 1) {
boolean found = false;
for (int i = 0; i < dnis.length - 1 && !found; i++) {
if (hostName.equals(dnis[i].getHostName())) {
// advance the other locations by one and put this one at the last place.
DatanodeInfo toLast = dnis[i];
System.arraycopy(dnis, i + 1, dnis, i, dnis.length - i - 1);
dnis[dnis.length - 1] = toLast;
found = true;
}
}
}
}
}
}
/**
* Create a new HFileSystem object, similar to FileSystem.get().
* This returns a filesystem object that avoids checksum
* verification in the filesystem for hfileblock-reads.
* For these blocks, checksum verification is done by HBase.
*/
static public FileSystem get(Configuration conf) throws IOException {
return new HFileSystem(conf, true);
}
/**
* Wrap a LocalFileSystem within a HFileSystem.
*/
static public FileSystem getLocalFs(Configuration conf) throws IOException {
return new HFileSystem(FileSystem.getLocal(conf));
}
/**
* The org.apache.hadoop.fs.FilterFileSystem does not yet support
* createNonRecursive. This is a hadoop bug and when it is fixed in Hadoop,
* this definition will go away.
*/
@SuppressWarnings("deprecation")
public FSDataOutputStream createNonRecursive(Path f,
boolean overwrite,
int bufferSize, short replication, long blockSize,
Progressable progress) throws IOException {
return fs.createNonRecursive(f, overwrite, bufferSize, replication,
blockSize, progress);
}
}