SammyVimes commented on a change in pull request #203: URL: https://github.com/apache/ignite-3/pull/203#discussion_r670752600
########## File path: modules/metastorage-server/src/main/java/org/apache/ignite/internal/metastorage/server/persistence/RangeCursor.java ########## @@ -0,0 +1,182 @@ +/* + * 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.ignite.internal.metastorage.server.persistence; + +import java.util.Iterator; +import java.util.List; +import java.util.Map; +import java.util.NoSuchElementException; +import org.apache.ignite.internal.metastorage.server.Entry; +import org.apache.ignite.internal.util.Cursor; +import org.jetbrains.annotations.NotNull; +import org.jetbrains.annotations.Nullable; + +/** + * Cursor by entries which correspond to the given keys range. + */ +class RangeCursor implements Cursor<Entry> { + /** Storage. */ + private final RocksDBKeyValueStorage storage; + + /** Lower iteration bound (included). */ + private final byte[] keyFrom; + + /** Upper iteration bound (excluded). */ + private final byte @Nullable [] keyTo; + + /** Revision upper bound (included). */ + private final long rev; + + /** Iterator. */ + private final Iterator<Entry> it; + + /** Next entry. */ + @Nullable + private Entry nextRetEntry; + + /** Key of the last returned entry. */ + private byte[] lastRetKey; + + /** + * {@code true} if the iteration was finished. + */ + private boolean finished; + + /** + * Constructor. + * + * @param storage Storage. + * @param keyFrom {@link #keyFrom}. + * @param keyTo {@link #keyTo}. + * @param rev {@link #rev}. + */ + RangeCursor(RocksDBKeyValueStorage storage, byte[] keyFrom, byte @Nullable [] keyTo, long rev) { + this.storage = storage; + this.keyFrom = keyFrom; + this.keyTo = keyTo; + this.rev = rev; + this.it = createIterator(); + } + + /** {@inheritDoc} */ + @Override public boolean hasNext() { + return it.hasNext(); + } + + /** {@inheritDoc} */ + @Override public Entry next() { + return it.next(); + } + + /** {@inheritDoc} */ + @Override public void close() throws Exception { + // No-op. + } + + /** {@inheritDoc} */ + @NotNull + @Override public Iterator<Entry> iterator() { + return it; + } + + /** + * Creates an iterator for this cursor. + * + * @return Iterator. + */ + @NotNull + private Iterator<Entry> createIterator() { + return new Iterator<>() { + /** {@inheritDoc} */ + @Override public boolean hasNext() { + storage.lock().readLock().lock(); + + try { + while (true) { + if (finished) + return false; + + if (nextRetEntry != null) + return true; + + byte[] key = lastRetKey; + + while (nextRetEntry == null) { + Map.Entry<byte[], List<Long>> e = + key == null ? storage.revisionCeilingEntry(keyFrom) : storage.revisionHigherEntry(key); + + if (e == null) { + finished = true; + + break; + } + + key = e.getKey(); + + if (keyTo != null && RocksDBKeyValueStorage.CMP.compare(key, keyTo) >= 0) { + finished = true; + + break; + } + + List<Long> revs = e.getValue(); + + assert revs != null && !revs.isEmpty() : + "Revisions should not be empty or null: [revs=" + revs + ']'; + + long lastRev = RocksDBKeyValueStorage.maxRevision(revs, rev); + + if (lastRev == -1) + continue; + + Entry entry = storage.doGetValue(key, lastRev); + + assert !entry.empty() : "Iterator should not return empty entry."; + + nextRetEntry = entry; + } + } + } + finally { + storage.lock().readLock().unlock(); + } + } + + /** {@inheritDoc} */ + @Override public Entry next() { + storage.lock().readLock().lock(); + + try { + if (!hasNext()) + throw new NoSuchElementException(); + + Entry e = nextRetEntry; + + nextRetEntry = null; + + lastRetKey = e.key(); Review comment: Mine does not for some reason. One assertion won't hurt, of course, but I wonder how it can possibly be null if the `hasNext` method only returns `true` if it is not. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
