carp84 commented on a change in pull request #9501: [FLINK-12697] [State Backends] Support on-disk state storage for spill-able heap backend URL: https://github.com/apache/flink/pull/9501#discussion_r325986596
########## File path: flink-state-backends/flink-statebackend-heap-spillable/src/main/java/org/apache/flink/runtime/state/heap/CopyOnWriteSkipListStateMap.java ########## @@ -0,0 +1,1527 @@ +/* + * 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.flink.runtime.state.heap; + +import org.apache.flink.annotation.VisibleForTesting; +import org.apache.flink.api.common.typeutils.TypeSerializer; +import org.apache.flink.api.java.tuple.Tuple2; +import org.apache.flink.core.memory.ByteBufferUtils; +import org.apache.flink.runtime.state.StateEntry; +import org.apache.flink.runtime.state.StateTransformationFunction; +import org.apache.flink.runtime.state.heap.space.Allocator; +import org.apache.flink.runtime.state.heap.space.Chunk; +import org.apache.flink.runtime.state.heap.space.SpaceUtils; +import org.apache.flink.runtime.state.internal.InternalKvState; +import org.apache.flink.util.Preconditions; +import org.apache.flink.util.ResourceGuard; + +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import javax.annotation.Nonnull; + +import java.nio.ByteBuffer; +import java.util.ArrayList; +import java.util.Collection; +import java.util.Collections; +import java.util.HashSet; +import java.util.Iterator; +import java.util.NoSuchElementException; +import java.util.Set; +import java.util.Spliterators; +import java.util.TreeSet; +import java.util.concurrent.ConcurrentHashMap; +import java.util.concurrent.ThreadLocalRandom; +import java.util.concurrent.atomic.AtomicBoolean; +import java.util.stream.Stream; +import java.util.stream.StreamSupport; + +import static org.apache.flink.runtime.state.heap.SkipListUtils.HEAD_NODE; +import static org.apache.flink.runtime.state.heap.SkipListUtils.NIL_NODE; +import static org.apache.flink.runtime.state.heap.SkipListUtils.NIL_VALUE_POINTER; + +/** + * Implementation of state map which is based on skip list with copy-on-write support. states will + * be serialized to bytes and stored in the space allocated with the given allocator. + * + * @param <K> type of key + * @param <N> type of namespace + * @param <S> type of state + */ +public class CopyOnWriteSkipListStateMap<K, N, S> extends StateMap<K, N, S> implements AutoCloseable { + + private static final Logger LOG = LoggerFactory.getLogger(CopyOnWriteSkipListStateMap.class); + + /** + * Default max number of logically-removed keys to delete one time. + */ + private static final int DEFAULT_MAX_KEYS_TO_DELETE_ONE_TIME = 3; + + /** + * Default ratio of the logically-removed keys to trigger deletion when snapshot. + */ + private static final float DEFAULT_LOGICAL_REMOVED_KEYS_RATIO = 0.2f; + + /** + * The serializer used to serialize the key and namespace to bytes stored in skip list. + */ + private final SkipListKeySerializer<K, N> skipListKeySerializer; + + /** + * The serializer used to serialize the state to bytes stored in skip list. + */ + private final SkipListValueSerializer<S> skipListValueSerializer; + + /** + * Space allocator. + */ + private final Allocator spaceAllocator; + + /** + * The level index header. + */ + private final LevelIndexHeader levelIndexHeader; + + /** + * Seed to generate random index level. + */ + private int randomSeed; + + /** + * The current version of this map. Used for copy-on-write mechanics. + */ + private int stateMapVersion; + + /** + * The highest version of this map that is still required by any unreleased snapshot. + */ + private int highestRequiredSnapshotVersion; + + /** + * Snapshots no more than this version must have been finished, but there may be some + * snapshots more than this version are still running. + */ + private volatile int highestFinishedSnapshotVersion; + + /** + * Maintains an ordered set of version ids that are still used by unreleased snapshots. + */ + private final TreeSet<Integer> snapshotVersions; + + /** + * The size of skip list which includes the logical removed keys. + */ + private int totalSize; + + /** + * Number of requests for this skip list. + */ + private int requestCount; + + /** + * Set of logical removed nodes. + */ + private final Set<Long> logicallyRemovedNodes; + + /** + * Number of keys to remove physically one time. + */ + private int numKeysToDeleteOneTime; + + /** + * Ratio of the logically-removed keys to trigger deletion when snapshot. + */ + private float logicalRemovedKeysRatio; + + /** + * Set of nodes whose values are being pruned by snapshots. + */ + private final Set<Long> pruningValueNodes; + + /** + * Whether this map has been closed. + */ + private final AtomicBoolean closed; + + /** + * Guards for the free of space when state map is closed. This is mainly + * used to synchronize with snapshots. + */ + private final ResourceGuard resourceGuard; + + public CopyOnWriteSkipListStateMap( + @Nonnull TypeSerializer<K> keySerializer, + @Nonnull TypeSerializer<N> namespaceSerializer, + @Nonnull TypeSerializer<S> stateSerializer, + @Nonnull Allocator spaceAllocator) { + this(keySerializer, namespaceSerializer, stateSerializer, spaceAllocator, + DEFAULT_MAX_KEYS_TO_DELETE_ONE_TIME, DEFAULT_LOGICAL_REMOVED_KEYS_RATIO); + } + + public CopyOnWriteSkipListStateMap( + @Nonnull TypeSerializer<K> keySerializer, + @Nonnull TypeSerializer<N> namespaceSerializer, + @Nonnull TypeSerializer<S> stateSerializer, + @Nonnull Allocator spaceAllocator, + int numKeysToDeleteOneTime, + float logicalRemovedKeysRatio) { + this.skipListKeySerializer = new SkipListKeySerializer<>(keySerializer, namespaceSerializer); + this.skipListValueSerializer = new SkipListValueSerializer<>(stateSerializer); + this.spaceAllocator = spaceAllocator; + Preconditions.checkArgument(numKeysToDeleteOneTime >= 0, + "numKeysToDeleteOneTime should be non-negative, but is " + numKeysToDeleteOneTime); + this.numKeysToDeleteOneTime = numKeysToDeleteOneTime; + Preconditions.checkArgument(logicalRemovedKeysRatio >= 0 && logicalRemovedKeysRatio <= 1, + "logicalRemovedKeysRatio should be in [0, 1], but is " + logicalRemovedKeysRatio); + this.logicalRemovedKeysRatio = logicalRemovedKeysRatio; + + this.levelIndexHeader = new OnHeapLevelIndexHeader(); + this.randomSeed = ThreadLocalRandom.current().nextInt() | 0x0100; + + this.stateMapVersion = 0; + this.highestRequiredSnapshotVersion = 0; + this.highestFinishedSnapshotVersion = 0; + this.snapshotVersions = new TreeSet<>(); + + this.totalSize = 0; + this.requestCount = 0; + + this.logicallyRemovedNodes = new HashSet<>(); + this.pruningValueNodes = ConcurrentHashMap.newKeySet(); + + this.closed = new AtomicBoolean(false); + this.resourceGuard = new ResourceGuard(); + } + + @Override + public int size() { + return totalSize - logicallyRemovedNodes.size(); + } + + /** + * Returns total size of this map, including logically removed state. + */ + public int totalSize() { + return totalSize; + } + + public int getRequestCount() { + return requestCount; + } + + @Override + public S get(K key, N namespace) { + updateStat(); + + long node = getNodeInternal(key, namespace); + + if (node == NIL_NODE) { + return null; + } + + return helpGetNodeState(node); + } + + @Override + public boolean containsKey(K key, N namespace) { + updateStat(); + + long node = getNodeInternal(key, namespace); + + return node != NIL_NODE; + } + + @Override + public void put(K key, N namespace, S state) { + updateStat(); + ByteBuffer keyByteBuffer = getKeyByteBuffer(key, namespace); + int keyLen = keyByteBuffer.limit(); + byte[] value = skipListValueSerializer.serialize(state); + + putNode(keyByteBuffer, 0, keyLen, value, false); + } + + @Override + public S putAndGetOld(K key, N namespace, S state) { + updateStat(); + ByteBuffer keyByteBuffer = getKeyByteBuffer(key, namespace); + int keyLen = keyByteBuffer.limit(); + byte[] value = skipListValueSerializer.serialize(state); + + return putNode(keyByteBuffer, 0, keyLen, value, true); + } + + @Override + public void remove(K key, N namespace) { + updateStat(); + ByteBuffer keyByteBuffer = getKeyByteBuffer(key, namespace); + int keyLen = keyByteBuffer.limit(); + + removeNode(keyByteBuffer, 0, keyLen, false); + } + + @Override + public S removeAndGetOld(K key, N namespace) { + updateStat(); + ByteBuffer keyByteBuffer = getKeyByteBuffer(key, namespace); + int keyLen = keyByteBuffer.limit(); + + return removeNode(keyByteBuffer, 0, keyLen, true); + } + + @Override + public <T> void transform( + K key, + N namespace, + T value, + StateTransformationFunction<S, T> transformation) throws Exception { + updateStat(); + ByteBuffer keyByteBuffer = getKeyByteBuffer(key, namespace); + int keyLen = keyByteBuffer.limit(); + + long node = getNode(keyByteBuffer, 0, keyLen); + S oldState = node == NIL_NODE ? null : helpGetNodeState(node); + S newState = transformation.apply(oldState, value); + byte[] stateBytes = skipListValueSerializer.serialize(newState); + putNode(keyByteBuffer, 0, keyLen, stateBytes, false); + } + + // Detail implementation methods --------------------------------------------------------------- + + /** + * Find the node containing the given key. + * + * @param keyByteBuffer byte buffer storing the key. + * @param keyOffset offset of the key. + * @param keyLen length of the key. + * @return id of the node. NIL_NODE will be returned if key does no exist. + */ + @VisibleForTesting + long getNode(ByteBuffer keyByteBuffer, int keyOffset, int keyLen) { + int deleteCount = 0; + long prevNode = findPredecessor(keyByteBuffer, keyOffset, 1); + long currentNode = helpGetNextNode(prevNode, 0); + long nextNode; + + int c; + while (currentNode != NIL_NODE) { + nextNode = helpGetNextNode(currentNode, 0); + + boolean isRemoved = isNodeRemoved(currentNode); + if (isRemoved) { + // remove the node physically when there is no snapshot running + if (highestRequiredSnapshotVersion == 0 && deleteCount < numKeysToDeleteOneTime) { + doPhysicalRemove(currentNode, prevNode, nextNode); + logicallyRemovedNodes.remove(currentNode); + totalSize--; + deleteCount++; + } else { + prevNode = currentNode; + } + currentNode = nextNode; + continue; + } + + c = compareByteBufferAndNode(keyByteBuffer, keyOffset, keyLen, currentNode); + + // find the key + if (c == 0) { + return currentNode; + } + + // the key is less than the current node, and nodes after current + // node can not be equal to the key. + if (c < 0) { + break; + } + + prevNode = currentNode; + currentNode = helpGetNextNode(currentNode, 0); + } + + return NIL_NODE; + } + + /** + * Put the key into the skip list. If the key does not exist before, a new node + * will be created. If the key exists before, the old state will be returned. + * + * @param keyByteBuffer byte buffer storing the key. + * @param keyOffset offset of the key. + * @param keyLen length of the key. + * @param value the value. + * @param returnOldState whether to return old state. + * @return the old state. Null will be returned if key does not exist or returnOldState is false. + */ + @VisibleForTesting + S putNode(ByteBuffer keyByteBuffer, int keyOffset, int keyLen, byte[] value, boolean returnOldState) { + int deleteCount = 0; + long prevNode = findPredecessor(keyByteBuffer, keyOffset, 1); + long currentNode = helpGetNextNode(prevNode, 0); + long nextNode; + + int c; + for ( ; ; ) { + if (currentNode != NIL_NODE) { + nextNode = helpGetNextNode(currentNode, 0); + + boolean isRemoved = isNodeRemoved(currentNode); + + // note that the key may be put again before the node is physically removed, + // so the node still need to compare with the key although they can not be + // physically removed here Review comment: Nice catch! This is something we plan to improve but forget to do, will make it in next commit. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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