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Main functionality for HBase
/**
*
* 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.wal;
import java.io.IOException;
import java.util.Arrays;
import java.io.InterruptedIOException;
import java.util.Collections;
import java.util.List;
import java.util.concurrent.atomic.AtomicReference;
import com.google.common.annotations.VisibleForTesting;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.hbase.classification.InterfaceAudience;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FSDataInputStream;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hbase.HConstants;
import org.apache.hadoop.hbase.wal.WAL.Reader;
import org.apache.hadoop.hbase.wal.WALProvider.Writer;
import org.apache.hadoop.hbase.util.CancelableProgressable;
import org.apache.hadoop.hbase.util.EnvironmentEdgeManager;
// imports for things that haven't moved from regionserver.wal yet.
import org.apache.hadoop.hbase.regionserver.wal.MetricsWAL;
import org.apache.hadoop.hbase.regionserver.wal.ProtobufLogReader;
import org.apache.hadoop.hbase.regionserver.wal.SequenceFileLogReader;
import org.apache.hadoop.hbase.regionserver.wal.WALActionsListener;
/**
* 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.
*
*
* Alternatively, you may provide a custome implementation of {@link WALProvider} by class name.
*/
@InterfaceAudience.Private
public class WALFactory {
private static final Log LOG = LogFactory.getLog(WALFactory.class);
/**
* Maps between configuration names for providers and implementation classes.
*/
static enum Providers {
defaultProvider(DefaultWALProvider.class);
Class clazz;
Providers(Class clazz) {
this.clazz = clazz;
}
}
static final String WAL_PROVIDER = "hbase.wal.provider";
static final String DEFAULT_WAL_PROVIDER = Providers.defaultProvider.name();
static final String META_WAL_PROVIDER = "hbase.wal.meta_provider";
static final String DEFAULT_META_WAL_PROVIDER = Providers.defaultProvider.name();
final String factoryId;
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
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,
DefaultWALProvider.Reader.class);
this.conf = conf;
// end required early initialization
// this instance can't create wals, just reader/writers.
provider = null;
factoryId = SINGLETON_ID;
}
/**
* 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(final String key, final String defaultValue,
final List listeners, final String providerId) throws IOException {
Class clazz;
try {
clazz = Providers.valueOf(conf.get(key, defaultValue)).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.
clazz = conf.getClass(key, DefaultWALProvider.class, WALProvider.class);
}
try {
final WALProvider result = clazz.newInstance();
result.init(this, conf, listeners, providerId);
return result;
} catch (InstantiationException exception) {
LOG.error("couldn't set up WALProvider, check config key " + key);
LOG.debug("Exception details for failure to load WALProvider.", exception);
throw new IOException("couldn't set up WALProvider", exception);
} catch (IllegalAccessException exception) {
LOG.error("couldn't set up WALProvider, check config key " + key);
LOG.debug("Exception details for failure to load WALProvider.", exception);
throw new IOException("couldn't set up WALProvider", exception);
}
}
/**
* @param conf must not be null, will keep a reference to read params in later reader/writer
* instances.
* @param listeners may be null. will be given to all created wals (and not meta-wals)
* @param factoryId a unique identifier for this factory. used i.e. by filesystem implementations
* to make a directory
*/
public WALFactory(final Configuration conf, final List listeners,
final String factoryId) 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,
DefaultWALProvider.Reader.class);
this.conf = conf;
this.factoryId = factoryId;
// end required early initialization
if (conf.getBoolean("hbase.regionserver.hlog.enabled", true)) {
provider = getProvider(WAL_PROVIDER, DEFAULT_WAL_PROVIDER, listeners, null);
} else {
// special handling of existing configuration behavior.
LOG.warn("Running with WAL disabled.");
provider = new DisabledWALProvider();
provider.init(this, conf, null, factoryId);
}
}
/**
* 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;
}
}
/**
* @param identifier may not be null, contents will not be altered
*/
public WAL getWAL(final byte[] identifier) throws IOException {
return provider.getWAL(identifier);
}
/**
* @param identifier may not be null, contents will not be altered
*/
public WAL getMetaWAL(final byte[] identifier) throws IOException {
WALProvider metaProvider = this.metaProvider.get();
if (null == metaProvider) {
final WALProvider temp = getProvider(META_WAL_PROVIDER, DEFAULT_META_WAL_PROVIDER,
Collections.singletonList(new MetricsWAL()),
DefaultWALProvider.META_WAL_PROVIDER_ID);
if (this.metaProvider.compareAndSet(null, temp)) {
metaProvider = temp;
} else {
// reference must now be to a provider created in another thread.
temp.close();
metaProvider = this.metaProvider.get();
}
}
return metaProvider.getWAL(identifier);
}
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.
* @throws IOException
*/
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;
while (true) {
try {
if (lrClass != ProtobufLogReader.class) {
// User is overriding the WAL reader, let them.
DefaultWALProvider.Reader reader = lrClass.newInstance();
reader.init(fs, path, conf, null);
return reader;
} else {
FSDataInputStream stream = fs.open(path);
// Note that zero-length file will fail to read PB magic, and attempt to create
// a non-PB reader and fail the same way existing code expects it to. If we get
// rid of the old reader entirely, we need to handle 0-size files differently from
// merely non-PB files.
byte[] magic = new byte[ProtobufLogReader.PB_WAL_MAGIC.length];
boolean isPbWal = (stream.read(magic) == magic.length)
&& Arrays.equals(magic, ProtobufLogReader.PB_WAL_MAGIC);
DefaultWALProvider.Reader reader =
isPbWal ? new ProtobufLogReader() : new SequenceFileLogReader();
reader.init(fs, path, conf, stream);
return reader;
}
} catch (IOException e) {
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 e;
}
}
} catch (IOException ie) {
throw ie;
} catch (Exception e) {
throw new IOException("Cannot get log reader", e);
}
}
/**
* Create a writer for the WAL.
* 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.
* @throws IOException
*/
public Writer createWALWriter(final FileSystem fs, final Path path) throws IOException {
return DefaultWALProvider.createWriter(conf, fs, path, false);
}
/**
* should be package-private, visible for recovery testing.
* @return an overwritable writer for recovered edits. caller should close.
*/
@VisibleForTesting
public Writer createRecoveredEditsWriter(final FileSystem fs, final Path path)
throws IOException {
return DefaultWALProvider.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 and UpgradeTo96
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.
* @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 DefaultWALProvider.createWriter(configuration, fs, path, true);
}
/**
* If you already have a WALFactory, you should favor the instance method.
* @return a writer that won't overwrite files. Caller must close.
*/
@VisibleForTesting
public static Writer createWALWriter(final FileSystem fs, final Path path,
final Configuration configuration)
throws IOException {
return DefaultWALProvider.createWriter(configuration, fs, path, false);
}
}