LuciferYang commented on a change in pull request #34913: URL: https://github.com/apache/spark/pull/34913#discussion_r770303774
########## File path: common/kvstore/src/main/java/org/apache/spark/util/kvstore/RocksDBIterator.java ########## @@ -0,0 +1,277 @@ +/* + * 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 com.google.common.annotations.VisibleForTesting; +import com.google.common.base.Preconditions; +import com.google.common.base.Throwables; +import org.rocksdb.RocksIterator; + +import java.io.IOException; +import java.util.*; + +class RocksDBIterator<T> implements KVStoreIterator<T> { + + private final RocksDB db; + private final boolean ascending; + private final RocksIterator it; + private final Class<T> type; + private final RocksDBTypeInfo ti; + private final RocksDBTypeInfo.Index index; + private final byte[] indexKeyPrefix; + private final byte[] end; + private final long max; + + private boolean checkedNext; + private byte[] next; + private boolean closed; + private long count; + + RocksDBIterator(Class<T> type, RocksDB db, KVStoreView<T> params) throws Exception { + this.db = db; + this.ascending = params.ascending; + this.it = db.db().newIterator(); + this.type = type; + this.ti = db.getTypeInfo(type); + this.index = ti.index(params.index); + this.max = params.max; + + Preconditions.checkArgument(!index.isChild() || params.parent != null, + "Cannot iterate over child index %s without parent value.", params.index); + byte[] parent = index.isChild() ? index.parent().childPrefix(params.parent) : null; + + this.indexKeyPrefix = index.keyPrefix(parent); + + byte[] firstKey; + if (params.first != null) { + if (ascending) { + firstKey = index.start(parent, params.first); + } else { + firstKey = index.end(parent, params.first); + } + } else if (ascending) { + firstKey = index.keyPrefix(parent); + } else { + firstKey = index.end(parent); + } + it.seek(firstKey); + + byte[] end = null; + if (ascending) { + if (params.last != null) { + end = index.end(parent, params.last); + } else { + end = index.end(parent); + } + } else { + if (params.last != null) { + end = index.start(parent, params.last); + } + if (it.isValid() && compare(it.key(), indexKeyPrefix) <= 0) { + // continue + } else { + it.prev(); + } + } + this.end = end; + + if (params.skip > 0) { + skip(params.skip); + } + } + + @Override + public boolean hasNext() { + if (!checkedNext && !closed) { + next = loadNext(); + checkedNext = true; + } + if (!closed && next == null) { + try { + close(); + } catch (IOException ioe) { + throw Throwables.propagate(ioe); + } + } + return next != null; + } + + @Override + public T next() { + if (!hasNext()) { + throw new NoSuchElementException(); + } + checkedNext = false; + + try { + T ret; + if (index == null || index.isCopy()) { + ret = db.serializer.deserialize(next, type); + } else { + byte[] key = ti.buildKey(false, ti.naturalIndex().keyPrefix(null), next); + ret = db.get(key, type); + } + next = null; + return ret; + } catch (Exception e) { + throw Throwables.propagate(e); + } + } + + @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 (next != null) { + checkedNext = false; + next = null; + skipped++; + continue; + } + + if (!it.isValid()) { + checkedNext = true; + return false; + } + + if (!isEndMarker(it.key())) { + skipped++; + } + if (ascending) { + it.next(); + } else { + it.prev(); + } + } + + return hasNext(); + } + + @Override + public synchronized void close() throws IOException { + db.notifyIteratorClosed(this); + if (!closed) { + it.close(); + closed = true; + } + } + + /** + * Because it's tricky to expose closeable iterators through many internal APIs, especially + * when Scala wrappers are used, this makes sure that, hopefully, the JNI resources held by + * the iterator will eventually be released. + */ + @SuppressWarnings("deprecation") Review comment: nit: we can remove this redundant suppression -- This is an automated message from the Apache Git Service. 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