spark RocksDB 源码
spark RocksDB 代码
文件路径：/common/kvstore/src/main/java/org/apache/spark/util/kvstore/RocksDB.java
/*
* 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.spark.util.kvstore;
import java.io.File;
import java.io.IOException;
import java.lang.ref.Reference;
import java.lang.ref.WeakReference;
import java.util.*;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.atomic.AtomicReference;
import java.util.stream.Collectors;
import static java.nio.charset.StandardCharsets.UTF_8;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Preconditions;
import com.google.common.base.Throwables;
import org.rocksdb.*;
import org.apache.spark.annotation.Private;
/**
* Implementation of KVStore that uses RocksDB as the underlying data store.
*/
@Private
public class RocksDB implements KVStore {
static {
org.rocksdb.RocksDB.loadLibrary();
}
@VisibleForTesting
static final long STORE_VERSION = 1L;
@VisibleForTesting
static final byte[] STORE_VERSION_KEY = "__version__".getBytes(UTF_8);
/** DB key where app metadata is stored. */
private static final byte[] METADATA_KEY = "__meta__".getBytes(UTF_8);
/** DB key where type aliases are stored. */
private static final byte[] TYPE_ALIASES_KEY = "__types__".getBytes(UTF_8);
/**
* Use full filter.
*
* https://github.com/facebook/rocksdb/wiki/RocksDB-Bloom-Filter#full-filters-new-format
*/
private static final BloomFilter fullFilter =
new BloomFilter(10.0D /* BloomFilter.DEFAULT_BITS_PER_KEY */, false);
/** Disable compression in index data. */
private static final BlockBasedTableConfig tableFormatConfig = new BlockBasedTableConfig()
.setFilterPolicy(fullFilter)
.setEnableIndexCompression(false)
.setIndexBlockRestartInterval(8)
.setFormatVersion(5);
/**
* - Use ZSTD at the bottom most level to reduce the disk space
* - Use LZ4 at the other levels because it's better than Snappy in general.
*
* https://github.com/facebook/rocksdb/wiki/Compression#configuration
*/
private static final Options dbOptions = new Options()
.setCreateIfMissing(true)
.setBottommostCompressionType(CompressionType.ZSTD_COMPRESSION)
.setCompressionType(CompressionType.LZ4_COMPRESSION)
.setTableFormatConfig(tableFormatConfig);
/**
* - Use explicitly 'sync = false' like LevelDB KVStore implementation.
*
* https://github.com/google/leveldb/blob/1.23/include/leveldb/options.h#L182
*/
private static final WriteOptions writeOptions = new WriteOptions().setSync(false);
private final AtomicReference<org.rocksdb.RocksDB> _db;
final KVStoreSerializer serializer;
/**
* Keep a mapping of class names to a shorter, unique ID managed by the store. This serves two
* purposes: make the keys stored on disk shorter, and spread out the keys, since class names
* will often have a long, redundant prefix (think "org.apache.spark.").
*/
private final ConcurrentMap<String, byte[]> typeAliases;
private final ConcurrentMap<Class<?>, RocksDBTypeInfo> types;
/**
* Trying to close a JNI RocksDB handle with a closed DB causes JVM crashes. This is used to
* ensure that all iterators are correctly closed before RocksDB is closed. Use weak references
* to ensure that the iterator can be GCed, when it is only referenced here.
*/
private final ConcurrentLinkedQueue<Reference<RocksDBIterator<?>>> iteratorTracker;
public RocksDB(File path) throws Exception {
this(path, new KVStoreSerializer());
}
public RocksDB(File path, KVStoreSerializer serializer) throws Exception {
this.serializer = serializer;
this.types = new ConcurrentHashMap<>();
this._db = new AtomicReference<>(org.rocksdb.RocksDB.open(dbOptions, path.toString()));
byte[] versionData = db().get(STORE_VERSION_KEY);
if (versionData != null) {
long version = serializer.deserializeLong(versionData);
if (version != STORE_VERSION) {
close();
throw new UnsupportedStoreVersionException();
}
} else {
db().put(STORE_VERSION_KEY, serializer.serialize(STORE_VERSION));
}
Map<String, byte[]> aliases;
try {
aliases = get(TYPE_ALIASES_KEY, TypeAliases.class).aliases;
} catch (NoSuchElementException e) {
aliases = new HashMap<>();
}
typeAliases = new ConcurrentHashMap<>(aliases);
iteratorTracker = new ConcurrentLinkedQueue<>();
}
@Override
public <T> T getMetadata(Class<T> klass) throws Exception {
try {
return get(METADATA_KEY, klass);
} catch (NoSuchElementException nsee) {
return null;
}
}
@Override
public void setMetadata(Object value) throws Exception {
if (value != null) {
put(METADATA_KEY, value);
} else {
db().delete(METADATA_KEY);
}
}
<T> T get(byte[] key, Class<T> klass) throws Exception {
byte[] data = db().get(key);
if (data == null) {
throw new NoSuchElementException(new String(key, UTF_8));
}
return serializer.deserialize(data, klass);
}
private void put(byte[] key, Object value) throws Exception {
Preconditions.checkArgument(value != null, "Null values are not allowed.");
db().put(key, serializer.serialize(value));
}
@Override
public <T> T read(Class<T> klass, Object naturalKey) throws Exception {
Preconditions.checkArgument(naturalKey != null, "Null keys are not allowed.");
byte[] key = getTypeInfo(klass).naturalIndex().start(null, naturalKey);
return get(key, klass);
}
@Override
public void write(Object value) throws Exception {
Preconditions.checkArgument(value != null, "Null values are not allowed.");
RocksDBTypeInfo ti = getTypeInfo(value.getClass());
byte[] data = serializer.serialize(value);
synchronized (ti) {
try (WriteBatch writeBatch = new WriteBatch()) {
updateBatch(writeBatch, value, data, value.getClass(), ti.naturalIndex(), ti.indices());
db().write(writeOptions, writeBatch);
}
}
}
public void writeAll(List<?> values) throws Exception {
Preconditions.checkArgument(values != null && !values.isEmpty(),
"Non-empty values required.");
// Group by class, in case there are values from different classes in the values
// Typical usecase is for this to be a single class.
// A NullPointerException will be thrown if values contain null object.
for (Map.Entry<? extends Class<?>, ? extends List<?>> entry :
values.stream().collect(Collectors.groupingBy(Object::getClass)).entrySet()) {
final Iterator<?> valueIter = entry.getValue().iterator();
final Iterator<byte[]> serializedValueIter;
// Deserialize outside synchronized block
List<byte[]> list = new ArrayList<>(entry.getValue().size());
for (Object value : values) {
list.add(serializer.serialize(value));
}
serializedValueIter = list.iterator();
final Class<?> klass = entry.getKey();
final RocksDBTypeInfo ti = getTypeInfo(klass);
synchronized (ti) {
final RocksDBTypeInfo.Index naturalIndex = ti.naturalIndex();
final Collection<RocksDBTypeInfo.Index> indices = ti.indices();
try (WriteBatch writeBatch = new WriteBatch()) {
while (valueIter.hasNext()) {
updateBatch(writeBatch, valueIter.next(), serializedValueIter.next(), klass,
naturalIndex, indices);
}
db().write(writeOptions, writeBatch);
}
}
}
}
private void updateBatch(
WriteBatch batch,
Object value,
byte[] data,
Class<?> klass,
RocksDBTypeInfo.Index naturalIndex,
Collection<RocksDBTypeInfo.Index> indices) throws Exception {
Object existing;
try {
existing = get(naturalIndex.entityKey(null, value), klass);
} catch (NoSuchElementException e) {
existing = null;
}
PrefixCache cache = new PrefixCache(value);
byte[] naturalKey = naturalIndex.toKey(naturalIndex.getValue(value));
for (RocksDBTypeInfo.Index idx : indices) {
byte[] prefix = cache.getPrefix(idx);
idx.add(batch, value, existing, data, naturalKey, prefix);
}
}
@Override
public void delete(Class<?> type, Object naturalKey) throws Exception {
Preconditions.checkArgument(naturalKey != null, "Null keys are not allowed.");
try (WriteBatch writeBatch = new WriteBatch()) {
RocksDBTypeInfo ti = getTypeInfo(type);
byte[] key = ti.naturalIndex().start(null, naturalKey);
synchronized (ti) {
byte[] data = db().get(key);
if (data != null) {
Object existing = serializer.deserialize(data, type);
PrefixCache cache = new PrefixCache(existing);
byte[] keyBytes = ti.naturalIndex().toKey(ti.naturalIndex().getValue(existing));
for (RocksDBTypeInfo.Index idx : ti.indices()) {
idx.remove(writeBatch, existing, keyBytes, cache.getPrefix(idx));
}
db().write(writeOptions, writeBatch);
}
}
} catch (NoSuchElementException nse) {
// Ignore.
}
}
@Override
public <T> KVStoreView<T> view(Class<T> type) throws Exception {
return new KVStoreView<T>() {
@Override
public Iterator<T> iterator() {
try {
RocksDBIterator<T> it = new RocksDBIterator<>(type, RocksDB.this, this);
iteratorTracker.add(new WeakReference<>(it));
return it;
} catch (Exception e) {
throw Throwables.propagate(e);
}
}
};
}
@Override
public <T> boolean removeAllByIndexValues(
Class<T> klass,
String index,
Collection<?> indexValues) throws Exception {
RocksDBTypeInfo.Index naturalIndex = getTypeInfo(klass).naturalIndex();
boolean removed = false;
KVStoreView<T> view = view(klass).index(index);
for (Object indexValue : indexValues) {
try (KVStoreIterator<T> iterator =
view.first(indexValue).last(indexValue).closeableIterator()) {
while (iterator.hasNext()) {
T value = iterator.next();
Object itemKey = naturalIndex.getValue(value);
delete(klass, itemKey);
removed = true;
}
}
}
return removed;
}
@Override
public long count(Class<?> type) throws Exception {
RocksDBTypeInfo.Index idx = getTypeInfo(type).naturalIndex();
return idx.getCount(idx.end(null));
}
@Override
public long count(Class<?> type, String index, Object indexedValue) throws Exception {
RocksDBTypeInfo.Index idx = getTypeInfo(type).index(index);
return idx.getCount(idx.end(null, indexedValue));
}
@Override
public void close() throws IOException {
synchronized (this._db) {
org.rocksdb.RocksDB _db = this._db.getAndSet(null);
if (_db == null) {
return;
}
try {
if (iteratorTracker != null) {
for (Reference<RocksDBIterator<?>> ref: iteratorTracker) {
RocksDBIterator<?> it = ref.get();
if (it != null) {
it.close();
}
}
}
_db.close();
} catch (IOException ioe) {
throw ioe;
} catch (Exception e) {
throw new IOException(e.getMessage(), e);
}
}
}
/**
* Closes the given iterator if the DB is still open. Trying to close a JNI RocksDB handle
* with a closed DB can cause JVM crashes, so this ensures that situation does not happen.
*/
void closeIterator(RocksDBIterator<?> it) throws IOException {
notifyIteratorClosed(it);
synchronized (this._db) {
org.rocksdb.RocksDB _db = this._db.get();
if (_db != null) {
it.close();
}
}
}
/**
* Remove iterator from iterator tracker. `RocksDBIterator` calls it to notify
* iterator is closed.
*/
void notifyIteratorClosed(RocksDBIterator<?> it) {
iteratorTracker.removeIf(ref -> it.equals(ref.get()));
}
/** Returns metadata about indices for the given type. */
RocksDBTypeInfo getTypeInfo(Class<?> type) throws Exception {
RocksDBTypeInfo ti = types.get(type);
if (ti == null) {
RocksDBTypeInfo tmp = new RocksDBTypeInfo(this, type, getTypeAlias(type));
ti = types.putIfAbsent(type, tmp);
if (ti == null) {
ti = tmp;
}
}
return ti;
}
/**
* Try to avoid use-after close since that has the tendency of crashing the JVM. This doesn't
* prevent methods that retrieved the instance from using it after close, but hopefully will
* catch most cases; otherwise, we'll need some kind of locking.
*/
org.rocksdb.RocksDB db() {
org.rocksdb.RocksDB _db = this._db.get();
if (_db == null) {
throw new IllegalStateException("DB is closed.");
}
return _db;
}
private byte[] getTypeAlias(Class<?> klass) throws Exception {
byte[] alias = typeAliases.get(klass.getName());
if (alias == null) {
synchronized (typeAliases) {
byte[] tmp = String.valueOf(typeAliases.size()).getBytes(UTF_8);
alias = typeAliases.putIfAbsent(klass.getName(), tmp);
if (alias == null) {
alias = tmp;
put(TYPE_ALIASES_KEY, new TypeAliases(typeAliases));
}
}
}
return alias;
}
/** Needs to be public for Jackson. */
public static class TypeAliases {
public Map<String, byte[]> aliases;
TypeAliases(Map<String, byte[]> aliases) {
this.aliases = aliases;
}
TypeAliases() {
this(null);
}
}
private static class PrefixCache {
private final Object entity;
private final Map<RocksDBTypeInfo.Index, byte[]> prefixes;
PrefixCache(Object entity) {
this.entity = entity;
this.prefixes = new HashMap<>();
}
byte[] getPrefix(RocksDBTypeInfo.Index idx) throws Exception {
byte[] prefix = null;
if (idx.isChild()) {
prefix = prefixes.get(idx.parent());
if (prefix == null) {
prefix = idx.parent().childPrefix(idx.parent().getValue(entity));
prefixes.put(idx.parent(), prefix);
}
}
return prefix;
}
}
}
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