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* Licensed to the Apache Software Foundation (ASF) under one
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* 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.wal;
import java.io.IOException;
import java.io.InterruptedIOException;
import java.util.List;
import java.util.concurrent.atomic.AtomicReference;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hbase.Abortable;
import org.apache.hadoop.hbase.client.RegionInfo;
import org.apache.hadoop.hbase.regionserver.wal.MetricsWAL;
import org.apache.hadoop.hbase.regionserver.wal.ProtobufLogReader;
import org.apache.hadoop.hbase.util.CancelableProgressable;
import org.apache.hadoop.hbase.util.EnvironmentEdgeManager;
import org.apache.hadoop.hbase.util.LeaseNotRecoveredException;
import org.apache.hadoop.hbase.wal.WAL.Reader;
import org.apache.hadoop.hbase.wal.WALProvider.Writer;
import org.apache.yetus.audience.InterfaceAudience;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Entry point for users of the Write Ahead Log. Acts as the shim between internal use and the
* particular WALProvider we use to handle wal requests. Configure which provider gets used with the
* configuration setting "hbase.wal.provider". Available implementations:
*
* - defaultProvider : whatever provider is standard for the hbase version. Currently
* "asyncfs"
* - asyncfs : a provider that will run on top of an implementation of the Hadoop
* FileSystem interface via an asynchronous client.
* - filesystem : a provider that will run on top of an implementation of the Hadoop
* FileSystem interface via HDFS's synchronous DFSClient.
* - multiwal : a provider that will use multiple "filesystem" wal instances per region
* server.
*
* Alternatively, you may provide a custom implementation of {@link WALProvider} by class name.
*/
@InterfaceAudience.Private
public class WALFactory {
private static final Logger LOG = LoggerFactory.getLogger(WALFactory.class);
/**
* Maps between configuration names for providers and implementation classes.
*/
enum Providers {
defaultProvider(AsyncFSWALProvider.class),
filesystem(FSHLogProvider.class),
multiwal(RegionGroupingProvider.class),
asyncfs(AsyncFSWALProvider.class);
final Class clazz;
Providers(Class clazz) {
this.clazz = clazz;
}
}
public static final String WAL_PROVIDER = "hbase.wal.provider";
static final String DEFAULT_WAL_PROVIDER = Providers.defaultProvider.name();
public static final String META_WAL_PROVIDER = "hbase.wal.meta_provider";
public static final String WAL_ENABLED = "hbase.regionserver.hlog.enabled";
final String factoryId;
final Abortable abortable;
private final WALProvider provider;
// The meta updates are written to a different wal. If this
// regionserver holds meta regions, then this ref will be non-null.
// lazily intialized; most RegionServers don't deal with META
private final AtomicReference metaProvider = new AtomicReference<>();
/**
* Configuration-specified WAL Reader used when a custom reader is requested
*/
private final Class logReaderClass;
/**
* How long to attempt opening in-recovery wals
*/
private final int timeoutMillis;
private final Configuration conf;
// Used for the singleton WALFactory, see below.
private WALFactory(Configuration conf) {
// this code is duplicated here so we can keep our members final.
// until we've moved reader/writer construction down into providers, this initialization must
// happen prior to provider initialization, in case they need to instantiate a reader/writer.
timeoutMillis = conf.getInt("hbase.hlog.open.timeout", 300000);
/* TODO Both of these are probably specific to the fs wal provider */
logReaderClass = conf.getClass("hbase.regionserver.hlog.reader.impl", ProtobufLogReader.class,
AbstractFSWALProvider.Reader.class);
this.conf = conf;
// end required early initialization
// this instance can't create wals, just reader/writers.
provider = null;
factoryId = SINGLETON_ID;
this.abortable = null;
}
Providers getDefaultProvider() {
return Providers.defaultProvider;
}
public Class getProviderClass(String key, String defaultValue) {
try {
Providers provider = Providers.valueOf(conf.get(key, defaultValue));
// AsyncFSWALProvider is not guaranteed to work on all Hadoop versions, when it's chosen as
// the default and we can't use it, we want to fall back to FSHLog which we know works on
// all versions.
if (
provider == getDefaultProvider() && provider.clazz == AsyncFSWALProvider.class
&& !AsyncFSWALProvider.load()
) {
// AsyncFSWAL has better performance in most cases, and also uses less resources, we will
// try to use it if possible. It deeply hacks into the internal of DFSClient so will be
// easily broken when upgrading hadoop.
LOG.warn("Failed to load AsyncFSWALProvider, falling back to FSHLogProvider");
return FSHLogProvider.class;
}
// N.b. If the user specifically requested AsyncFSWALProvider but their environment doesn't
// support using it (e.g. AsyncFSWALProvider.load() == false), we should let this fail and
// not fall back to FSHLogProvider.
return provider.clazz;
} catch (IllegalArgumentException exception) {
// Fall back to them specifying a class name
// Note that the passed default class shouldn't actually be used, since the above only fails
// when there is a config value present.
return conf.getClass(key, Providers.defaultProvider.clazz, WALProvider.class);
}
}
WALProvider createProvider(Class clazz, String providerId)
throws IOException {
LOG.info("Instantiating WALProvider of type " + clazz);
try {
final WALProvider result = clazz.getDeclaredConstructor().newInstance();
result.init(this, conf, providerId, this.abortable);
return result;
} catch (Exception e) {
LOG.error("couldn't set up WALProvider, the configured class is " + clazz);
LOG.debug("Exception details for failure to load WALProvider.", e);
throw new IOException("couldn't set up WALProvider", e);
}
}
/**
* instantiate a provider from a config property. requires conf to have already been set (as well
* as anything the provider might need to read).
*/
WALProvider getProvider(String key, String defaultValue, String providerId) throws IOException {
Class clazz = getProviderClass(key, defaultValue);
WALProvider provider = createProvider(clazz, providerId);
provider.addWALActionsListener(new MetricsWAL());
return provider;
}
public WALFactory(Configuration conf, String factoryId) throws IOException {
this(conf, factoryId, null);
}
/**
* @param conf must not be null, will keep a reference to read params in later reader/writer
* instances.
* @param abortable the server to abort
*/
public WALFactory(Configuration conf, String factoryId, Abortable abortable) throws IOException {
// until we've moved reader/writer construction down into providers, this initialization must
// happen prior to provider initialization, in case they need to instantiate a reader/writer.
timeoutMillis = conf.getInt("hbase.hlog.open.timeout", 300000);
/* TODO Both of these are probably specific to the fs wal provider */
logReaderClass = conf.getClass("hbase.regionserver.hlog.reader.impl", ProtobufLogReader.class,
AbstractFSWALProvider.Reader.class);
this.conf = conf;
this.factoryId = factoryId;
this.abortable = abortable;
// end required early initialization
if (conf.getBoolean(WAL_ENABLED, true)) {
provider = getProvider(WAL_PROVIDER, DEFAULT_WAL_PROVIDER, null);
} else {
// special handling of existing configuration behavior.
LOG.warn("Running with WAL disabled.");
provider = new DisabledWALProvider();
provider.init(this, conf, factoryId, null);
}
}
/**
* Shutdown all WALs and clean up any underlying storage. Use only when you will not need to
* replay and edits that have gone to any wals from this factory.
*/
public void close() throws IOException {
final WALProvider metaProvider = this.metaProvider.get();
if (null != metaProvider) {
metaProvider.close();
}
// close is called on a WALFactory with null provider in the case of contention handling
// within the getInstance method.
if (null != provider) {
provider.close();
}
}
/**
* Tell the underlying WAL providers to shut down, but do not clean up underlying storage. If you
* are not ending cleanly and will need to replay edits from this factory's wals, use this method
* if you can as it will try to leave things as tidy as possible.
*/
public void shutdown() throws IOException {
IOException exception = null;
final WALProvider metaProvider = this.metaProvider.get();
if (null != metaProvider) {
try {
metaProvider.shutdown();
} catch (IOException ioe) {
exception = ioe;
}
}
provider.shutdown();
if (null != exception) {
throw exception;
}
}
public List getWALs() {
return provider.getWALs();
}
/**
* Called when we lazily create a hbase:meta WAL OR from ReplicationSourceManager ahead of
* creating the first hbase:meta WAL so we can register a listener.
* @see #getMetaWALProvider()
*/
public WALProvider getMetaProvider() throws IOException {
for (;;) {
WALProvider provider = this.metaProvider.get();
if (provider != null) {
return provider;
}
Class clz = null;
if (conf.get(META_WAL_PROVIDER) == null) {
try {
clz = conf.getClass(WAL_PROVIDER, Providers.defaultProvider.clazz, WALProvider.class);
} catch (Throwable t) {
// the WAL provider should be an enum. Proceed
}
}
if (clz == null) {
clz = getProviderClass(META_WAL_PROVIDER, conf.get(WAL_PROVIDER, DEFAULT_WAL_PROVIDER));
}
provider = createProvider(clz, AbstractFSWALProvider.META_WAL_PROVIDER_ID);
if (metaProvider.compareAndSet(null, provider)) {
return provider;
} else {
// someone is ahead of us, close and try again.
provider.close();
}
}
}
/**
* @param region the region which we want to get a WAL for. Could be null.
*/
public WAL getWAL(RegionInfo region) throws IOException {
// Use different WAL for hbase:meta. Instantiates the meta WALProvider if not already up.
if (
region != null && region.isMetaRegion()
&& region.getReplicaId() == RegionInfo.DEFAULT_REPLICA_ID
) {
return getMetaProvider().getWAL(region);
} else {
return provider.getWAL(region);
}
}
public Reader createReader(final FileSystem fs, final Path path) throws IOException {
return createReader(fs, path, (CancelableProgressable) null);
}
/**
* Create a reader for the WAL. If you are reading from a file that's being written to and need to
* reopen it multiple times, use {@link WAL.Reader#reset()} instead of this method then just seek
* back to the last known good position.
* @return A WAL reader. Close when done with it.
*/
public Reader createReader(final FileSystem fs, final Path path, CancelableProgressable reporter)
throws IOException {
return createReader(fs, path, reporter, true);
}
public Reader createReader(final FileSystem fs, final Path path, CancelableProgressable reporter,
boolean allowCustom) throws IOException {
Class lrClass =
allowCustom ? logReaderClass : ProtobufLogReader.class;
try {
// A wal file could be under recovery, so it may take several
// tries to get it open. Instead of claiming it is corrupted, retry
// to open it up to 5 minutes by default.
long startWaiting = EnvironmentEdgeManager.currentTime();
long openTimeout = timeoutMillis + startWaiting;
int nbAttempt = 0;
AbstractFSWALProvider.Reader reader = null;
while (true) {
try {
reader = lrClass.getDeclaredConstructor().newInstance();
reader.init(fs, path, conf, null);
return reader;
} catch (Exception e) {
// catch Exception so that we close reader for all exceptions. If we don't
// close the reader, we leak a socket.
if (reader != null) {
try {
reader.close();
} catch (IOException exception) {
LOG.warn("Could not close FSDataInputStream" + exception.getMessage());
LOG.debug("exception details", exception);
}
}
// Only inspect the Exception to consider retry when it's an IOException
if (e instanceof IOException) {
String msg = e.getMessage();
if (
msg != null && (msg.contains("Cannot obtain block length")
|| msg.contains("Could not obtain the last block")
|| msg.matches("Blocklist for [^ ]* has changed.*"))
) {
if (++nbAttempt == 1) {
LOG.warn("Lease should have recovered. This is not expected. Will retry", e);
}
if (reporter != null && !reporter.progress()) {
throw new InterruptedIOException("Operation is cancelled");
}
if (nbAttempt > 2 && openTimeout < EnvironmentEdgeManager.currentTime()) {
LOG.error("Can't open after " + nbAttempt + " attempts and "
+ (EnvironmentEdgeManager.currentTime() - startWaiting) + "ms " + " for " + path);
} else {
try {
Thread.sleep(nbAttempt < 3 ? 500 : 1000);
continue; // retry
} catch (InterruptedException ie) {
InterruptedIOException iioe = new InterruptedIOException();
iioe.initCause(ie);
throw iioe;
}
}
throw new LeaseNotRecoveredException(e);
}
}
// Rethrow the original exception if we are not retrying due to HDFS-isms.
throw e;
}
}
} catch (IOException ie) {
throw ie;
} catch (Exception e) {
throw new IOException("Cannot get log reader", e);
}
}
/**
* Create a writer for the WAL. Uses defaults.
*
* Should be package-private. public only for tests and
* {@link org.apache.hadoop.hbase.regionserver.wal.Compressor}
* @return A WAL writer. Close when done with it.
*/
public Writer createWALWriter(final FileSystem fs, final Path path) throws IOException {
return FSHLogProvider.createWriter(conf, fs, path, false);
}
/**
* Should be package-private, visible for recovery testing. Uses defaults.
* @return an overwritable writer for recovered edits. caller should close.
*/
public Writer createRecoveredEditsWriter(final FileSystem fs, final Path path)
throws IOException {
return FSHLogProvider.createWriter(conf, fs, path, true);
}
// These static methods are currently used where it's impractical to
// untangle the reliance on state in the filesystem. They rely on singleton
// WALFactory that just provides Reader / Writers.
// For now, first Configuration object wins. Practically this just impacts the reader/writer class
private static final AtomicReference singleton = new AtomicReference<>();
private static final String SINGLETON_ID = WALFactory.class.getName();
// Public only for FSHLog
public static WALFactory getInstance(Configuration configuration) {
WALFactory factory = singleton.get();
if (null == factory) {
WALFactory temp = new WALFactory(configuration);
if (singleton.compareAndSet(null, temp)) {
factory = temp;
} else {
// someone else beat us to initializing
try {
temp.close();
} catch (IOException exception) {
LOG.debug("failed to close temporary singleton. ignoring.", exception);
}
factory = singleton.get();
}
}
return factory;
}
/**
* Create a reader for the given path, accept custom reader classes from conf. If you already have
* a WALFactory, you should favor the instance method.
* @return a WAL Reader, caller must close.
*/
public static Reader createReader(final FileSystem fs, final Path path,
final Configuration configuration) throws IOException {
return getInstance(configuration).createReader(fs, path);
}
/**
* Create a reader for the given path, accept custom reader classes from conf. If you already have
* a WALFactory, you should favor the instance method.
* @return a WAL Reader, caller must close.
*/
static Reader createReader(final FileSystem fs, final Path path,
final Configuration configuration, final CancelableProgressable reporter) throws IOException {
return getInstance(configuration).createReader(fs, path, reporter);
}
/**
* Create a reader for the given path, ignore custom reader classes from conf. If you already have
* a WALFactory, you should favor the instance method. only public pending move of
* {@link org.apache.hadoop.hbase.regionserver.wal.Compressor}
* @return a WAL Reader, caller must close.
*/
public static Reader createReaderIgnoreCustomClass(final FileSystem fs, final Path path,
final Configuration configuration) throws IOException {
return getInstance(configuration).createReader(fs, path, null, false);
}
/**
* If you already have a WALFactory, you should favor the instance method. Uses defaults.
* @return a Writer that will overwrite files. Caller must close.
*/
static Writer createRecoveredEditsWriter(final FileSystem fs, final Path path,
final Configuration configuration) throws IOException {
return FSHLogProvider.createWriter(configuration, fs, path, true);
}
/**
* If you already have a WALFactory, you should favor the instance method. Uses defaults.
* @return a writer that won't overwrite files. Caller must close.
*/
public static Writer createWALWriter(final FileSystem fs, final Path path,
final Configuration configuration) throws IOException {
return FSHLogProvider.createWriter(configuration, fs, path, false);
}
public String getFactoryId() {
return factoryId;
}
public final WALProvider getWALProvider() {
return this.provider;
}
/**
* @return Current metaProvider... may be null if not yet initialized.
* @see #getMetaProvider()
*/
public final WALProvider getMetaWALProvider() {
return this.metaProvider.get();
}
}