spark InMemoryStore 源码

  • 2022-10-20
  • 浏览 (608)

spark InMemoryStore 代码

文件路径:/common/kvstore/src/main/java/org/apache/spark/util/kvstore/InMemoryStore.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.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;
import java.util.HashSet;
import java.util.List;
import java.util.NoSuchElementException;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.function.BiConsumer;
import java.util.function.Predicate;
import java.util.stream.Collectors;
import java.util.stream.Stream;

import com.google.common.base.Objects;
import com.google.common.base.Preconditions;

import org.apache.spark.annotation.Private;

/**
 * Implementation of KVStore that keeps data deserialized in memory. This store does not index
 * data; instead, whenever iterating over an indexed field, the stored data is copied and sorted
 * according to the index. This saves memory but makes iteration more expensive.
 */
@Private
public class InMemoryStore implements KVStore {

  private Object metadata;
  private InMemoryLists inMemoryLists = new InMemoryLists();

  @Override
  public <T> T getMetadata(Class<T> klass) {
    return klass.cast(metadata);
  }

  @Override
  public void setMetadata(Object value) {
    this.metadata = value;
  }

  @Override
  public long count(Class<?> type) {
    InstanceList<?> list = inMemoryLists.get(type);
    return list != null ? list.size() : 0;
  }

  @Override
  public long count(Class<?> type, String index, Object indexedValue) throws Exception {
    InstanceList<?> list = inMemoryLists.get(type);
    int count = 0;
    Object comparable = asKey(indexedValue);
    KVTypeInfo.Accessor accessor = list.getIndexAccessor(index);
    for (Object o : view(type)) {
      if (Objects.equal(comparable, asKey(accessor.get(o)))) {
        count++;
      }
    }
    return count;
  }

  @Override
  public <T> T read(Class<T> klass, Object naturalKey) {
    InstanceList<T> list = inMemoryLists.get(klass);
    T value = list != null ? list.get(naturalKey) : null;
    if (value == null) {
      throw new NoSuchElementException();
    }
    return value;
  }

  @Override
  public void write(Object value) throws Exception {
    inMemoryLists.write(value);
  }

  @Override
  public void delete(Class<?> type, Object naturalKey) {
    InstanceList<?> list = inMemoryLists.get(type);
    if (list != null) {
      list.delete(naturalKey);
    }
  }

  @Override
  public <T> KVStoreView<T> view(Class<T> type){
    InstanceList<T> list = inMemoryLists.get(type);
    return list != null ? list.view() : emptyView();
  }

  @Override
  public void close() {
    metadata = null;
    inMemoryLists.clear();
  }

  @Override
  public <T> boolean removeAllByIndexValues(
      Class<T> klass,
      String index,
      Collection<?> indexValues) {
    InstanceList<T> list = inMemoryLists.get(klass);

    if (list != null) {
      return list.countingRemoveAllByIndexValues(index, indexValues) > 0;
    } else {
      return false;
    }
  }

  @SuppressWarnings("unchecked")
  private static Comparable<Object> asKey(Object in) {
    if (in.getClass().isArray()) {
      in = ArrayWrappers.forArray(in);
    }
    return (Comparable<Object>) in;
  }

  @SuppressWarnings("unchecked")
  private static <T> KVStoreView<T> emptyView() {
    return (InMemoryView<T>) InMemoryView.EMPTY_VIEW;
  }

  /**
   * Encapsulates ConcurrentHashMap so that the typing in and out of the map strictly maps a
   * class of type T to an InstanceList of type T.
   */
  private static class InMemoryLists {
    private final ConcurrentMap<Class<?>, InstanceList<?>> data = new ConcurrentHashMap<>();

    @SuppressWarnings("unchecked")
    public <T> InstanceList<T> get(Class<T> type) {
      return (InstanceList<T>) data.get(type);
    }

    @SuppressWarnings("unchecked")
    public <T> void write(T value) throws Exception {
      InstanceList<T> list =
        (InstanceList<T>) data.computeIfAbsent(value.getClass(), InstanceList::new);
      list.put(value);
    }

    public void clear() {
      data.clear();
    }
  }

  /**
   * An alias class for the type "{@literal ConcurrentHashMap<Comparable<Object>, Boolean>}",
   * which is used as a concurrent hashset for storing natural keys
   * and the boolean value doesn't matter.
   */
  private static class NaturalKeys extends ConcurrentHashMap<Comparable<Object>, Boolean> {}

  private static class InstanceList<T> {

    /**
     * A BiConsumer to control multi-entity removal.  We use this in a forEach rather than an
     * iterator because there is a bug in jdk8 which affects remove() on all concurrent map
     * iterators.  https://bugs.openjdk.java.net/browse/JDK-8078645
     */
    private static class CountingRemoveIfForEach<T> implements BiConsumer<Comparable<Object>, T> {
      private final InstanceList<T> instanceList;
      private final Predicate<? super T> filter;

      /**
       * Keeps a count of the number of elements removed.  This count is not currently surfaced
       * to clients of KVStore as Java's generic removeAll() construct returns only a boolean,
       * but I found it handy to have the count of elements removed while debugging; a count being
       * no more complicated than a boolean, I've retained that behavior here, even though there
       * is no current requirement.
       */
      private int count = 0;

      CountingRemoveIfForEach(InstanceList<T> instanceList, Predicate<? super T> filter) {
        this.instanceList = instanceList;
        this.filter = filter;
      }

      @Override
      public void accept(Comparable<Object> key, T value) {
        if (filter.test(value)) {
          if (instanceList.delete(key, value)) {
            count++;
          }
        }
      }

      public int count() { return count; }
    }

    private final KVTypeInfo ti;
    private final KVTypeInfo.Accessor naturalKey;
    private final ConcurrentMap<Comparable<Object>, T> data;
    private final String naturalParentIndexName;
    private final Boolean hasNaturalParentIndex;
    // A mapping from parent to the natural keys of its children.
    // For example, a mapping from a stage ID to all the task IDs in the stage.
    private final ConcurrentMap<Comparable<Object>, NaturalKeys> parentToChildrenMap;

    private InstanceList(Class<?> klass) {
      this.ti = new KVTypeInfo(klass);
      this.naturalKey = ti.getAccessor(KVIndex.NATURAL_INDEX_NAME);
      this.data = new ConcurrentHashMap<>();
      this.naturalParentIndexName = ti.getParentIndexName(KVIndex.NATURAL_INDEX_NAME);
      this.parentToChildrenMap = new ConcurrentHashMap<>();
      this.hasNaturalParentIndex = !naturalParentIndexName.isEmpty();
    }

    KVTypeInfo.Accessor getIndexAccessor(String indexName) {
      return ti.getAccessor(indexName);
    }

    int countingRemoveAllByIndexValues(String index, Collection<?> indexValues) {
      int count = 0;
      if (KVIndex.NATURAL_INDEX_NAME.equals(index)) {
        for (Object naturalKey : indexValues) {
          count += delete(asKey(naturalKey)) ? 1 : 0;
        }
        return count;
      } else if (hasNaturalParentIndex && naturalParentIndexName.equals(index)) {
        // If there is a parent index for the natural index and `index` happens to be it,
        // Spark can use the `parentToChildrenMap` to get the related natural keys, and then
        // delete them from `data`.
        for (Object indexValue : indexValues) {
          Comparable<Object> parentKey = asKey(indexValue);
          NaturalKeys children = parentToChildrenMap.getOrDefault(parentKey, new NaturalKeys());
          for (Comparable<Object> naturalKey : children.keySet()) {
            data.remove(naturalKey);
            count ++;
          }
          parentToChildrenMap.remove(parentKey);
        }
        return count;
      } else {
        Predicate<? super T> filter = getPredicate(ti.getAccessor(index), indexValues);
        CountingRemoveIfForEach<T> callback = new CountingRemoveIfForEach<>(this, filter);

        // Go through all the values in `data` and delete objects that meets the predicate `filter`.
        // This can be slow when there is a large number of entries in `data`.
        data.forEach(callback);
        return callback.count();
      }
    }

    public T get(Object key) {
      return data.get(asKey(key));
    }

    public void put(T value) throws Exception {
      data.put(asKey(naturalKey.get(value)), value);
      if (hasNaturalParentIndex) {
        Comparable<Object> parentKey = asKey(getIndexAccessor(naturalParentIndexName).get(value));
        NaturalKeys children =
          parentToChildrenMap.computeIfAbsent(parentKey, k -> new NaturalKeys());
        children.put(asKey(naturalKey.get(value)), true);
      }
    }

    public boolean delete(Object key) {
      boolean entryExists = data.remove(asKey(key)) != null;
      if (entryExists) {
        deleteParentIndex(key);
      }
      return entryExists;
    }

    public boolean delete(Object key, T value) {
      boolean entryExists = data.remove(asKey(key), value);
      if (entryExists) {
        deleteParentIndex(key);
      }
      return entryExists;
    }

    private void deleteParentIndex(Object key) {
      if (hasNaturalParentIndex) {
        for (NaturalKeys v : parentToChildrenMap.values()) {
          if (v.remove(asKey(key)) != null) {
            // `v` can be empty after removing the natural key and we can remove it from
            // `parentToChildrenMap`. However, `parentToChildrenMap` is a ConcurrentMap and such
            // checking and deleting can be slow.
            // This method is to delete one object with certain key, let's make it simple here.
            break;
          }
        }
      }
    }

    public int size() {
      return data.size();
    }

    public InMemoryView<T> view() {
      return new InMemoryView<>(data, ti, naturalParentIndexName, parentToChildrenMap);
    }

    private static <T> Predicate<? super T> getPredicate(
        KVTypeInfo.Accessor getter,
        Collection<?> values) {
      if (Comparable.class.isAssignableFrom(getter.getType())) {
        HashSet<?> set = new HashSet<>(values);

        return (value) -> set.contains(indexValueForEntity(getter, value));
      } else {
        HashSet<Comparable<?>> set = new HashSet<>(values.size());
        for (Object key : values) {
          set.add(asKey(key));
        }
        return (value) -> set.contains(asKey(indexValueForEntity(getter, value)));
      }
    }

    private static Object indexValueForEntity(KVTypeInfo.Accessor getter, Object entity) {
      try {
        return getter.get(entity);
      } catch (ReflectiveOperationException e) {
        throw new RuntimeException(e);
      }
    }
  }

  private static class InMemoryView<T> extends KVStoreView<T> {
    private static final InMemoryView<?> EMPTY_VIEW =
      new InMemoryView<>(new ConcurrentHashMap<>(), null, "", new ConcurrentHashMap<>());

    private final ConcurrentMap<Comparable<Object>, T> data;
    private final KVTypeInfo ti;
    private final KVTypeInfo.Accessor natural;
    private final ConcurrentMap<Comparable<Object>, NaturalKeys> parentToChildrenMap;
    private final String naturalParentIndexName;
    private final Boolean hasNaturalParentIndex;

    InMemoryView(
        ConcurrentMap<Comparable<Object>, T> data,
        KVTypeInfo ti,
        String naturalParentIndexName,
        ConcurrentMap<Comparable<Object>, NaturalKeys> parentToChildrenMap) {
      this.data = data;
      this.ti = ti;
      this.natural = ti != null ? ti.getAccessor(KVIndex.NATURAL_INDEX_NAME) : null;
      this.naturalParentIndexName = naturalParentIndexName;
      this.parentToChildrenMap = parentToChildrenMap;
      this.hasNaturalParentIndex = !naturalParentIndexName.isEmpty();
    }

    @Override
    public Iterator<T> iterator() {
      if (data.isEmpty()) {
        return new InMemoryIterator<>(Collections.emptyIterator());
      }

      KVTypeInfo.Accessor getter = index != null ? ti.getAccessor(index) : null;
      int modifier = ascending ? 1 : -1;

      final List<T> sorted = copyElements();
      sorted.sort((e1, e2) -> modifier * compare(e1, e2, getter));
      Stream<T> stream = sorted.stream();

      if (first != null) {
        Comparable<?> firstKey = asKey(first);
        stream = stream.filter(e -> modifier * compare(e, getter, firstKey) >= 0);
      }

      if (last != null) {
        Comparable<?> lastKey = asKey(last);
        stream = stream.filter(e -> modifier * compare(e, getter, lastKey) <= 0);
      }

      if (skip > 0) {
        stream = stream.skip(skip);
      }

      if (max < sorted.size()) {
        stream = stream.limit((int) max);
      }

      return new InMemoryIterator<>(stream.iterator());
    }

    /**
     * Create a copy of the input elements, filtering the values for child indices if needed.
     */
    private List<T> copyElements() {
      if (parent != null) {
        Comparable<Object> parentKey = asKey(parent);
        if (hasNaturalParentIndex && naturalParentIndexName.equals(ti.getParentIndexName(index))) {
          // If there is a parent index for the natural index and the parent of `index` happens to
          // be it, Spark can use the `parentToChildrenMap` to get the related natural keys, and
          // then copy them from `data`.
          NaturalKeys children = parentToChildrenMap.getOrDefault(parentKey, new NaturalKeys());
          ArrayList<T> elements = new ArrayList<>();
          for (Comparable<Object> naturalKey : children.keySet()) {
            data.computeIfPresent(naturalKey, (k, v) -> {
              elements.add(v);
              return v;
            });
          }
          return elements;
        } else {
          // Go through all the values in `data` and collect all the objects has certain parent
          // value. This can be slow when there is a large number of entries in `data`.
          KVTypeInfo.Accessor parentGetter = ti.getParentAccessor(index);
          Preconditions.checkArgument(parentGetter != null, "Parent filter for non-child index.");
          return data.values().stream()
            .filter(e -> compare(e, parentGetter, parentKey) == 0)
            .collect(Collectors.toList());
        }
      } else {
        return new ArrayList<>(data.values());
      }
    }

    private int compare(T e1, T e2, KVTypeInfo.Accessor getter) {
      try {
        int diff = compare(e1, getter, asKey(getter.get(e2)));
        if (diff == 0 && getter != natural) {
          diff = compare(e1, natural, asKey(natural.get(e2)));
        }
        return diff;
      } catch (ReflectiveOperationException e) {
        throw new RuntimeException(e);
      }
    }

    private int compare(T e1, KVTypeInfo.Accessor getter, Comparable<?> v2) {
      try {
        return asKey(getter.get(e1)).compareTo(v2);
      } catch (ReflectiveOperationException e) {
        throw new RuntimeException(e);
      }
    }
  }

  private static class InMemoryIterator<T> implements KVStoreIterator<T> {

    private final Iterator<T> iter;

    InMemoryIterator(Iterator<T> iter) {
      this.iter = iter;
    }

    @Override
    public boolean hasNext() {
      return iter.hasNext();
    }

    @Override
    public T next() {
      return iter.next();
    }

    @Override
    public void remove() {
      throw new UnsupportedOperationException();
    }

    @Override
    public List<T> next(int max) {
      List<T> list = new ArrayList<>(max);
      while (hasNext() && list.size() < max) {
        list.add(next());
      }
      return list;
    }

    @Override
    public boolean skip(long n) {
      long skipped = 0;
      while (skipped < n) {
        if (hasNext()) {
          next();
          skipped++;
        } else {
          return false;
        }
      }

      return hasNext();
    }

    @Override
    public void close() {
      // no op.
    }

  }

}

相关信息

spark 源码目录

相关文章

spark ArrayWrappers 源码

spark KVIndex 源码

spark KVStore 源码

spark KVStoreIterator 源码

spark KVStoreSerializer 源码

spark KVStoreView 源码

spark KVTypeInfo 源码

spark LevelDB 源码

spark LevelDBIterator 源码

spark LevelDBTypeInfo 源码

0  赞