ibessonov commented on code in PR #787: URL: https://github.com/apache/ignite-3/pull/787#discussion_r853855813
########## modules/storage-rocksdb/src/main/java/org/apache/ignite/internal/storage/rocksdb/RocksDbMvPartitionStorage.java: ########## @@ -0,0 +1,494 @@ +/* + * 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.storage.rocksdb; + +import static java.lang.ThreadLocal.withInitial; +import static java.nio.ByteBuffer.allocateDirect; +import static java.nio.ByteOrder.BIG_ENDIAN; +import static org.apache.ignite.internal.storage.IgniteRowId.MAX_ROW_ID_SIZE; +import static org.apache.ignite.internal.util.ArrayUtils.BYTE_EMPTY_ARRAY; + +import java.nio.ByteBuffer; +import java.util.Arrays; +import java.util.NoSuchElementException; +import java.util.UUID; +import java.util.function.Predicate; +import org.apache.ignite.internal.schema.BinaryRow; +import org.apache.ignite.internal.schema.ByteBufferRow; +import org.apache.ignite.internal.storage.IgniteRowId; +import org.apache.ignite.internal.storage.MvPartitionStorage; +import org.apache.ignite.internal.storage.StorageException; +import org.apache.ignite.internal.storage.TxIdMismatchException; +import org.apache.ignite.internal.tx.Timestamp; +import org.apache.ignite.internal.util.Cursor; +import org.apache.ignite.internal.util.GridUnsafe; +import org.apache.ignite.internal.util.IgniteUtils; +import org.apache.ignite.lang.IgniteInternalException; +import org.jetbrains.annotations.Nullable; +import org.rocksdb.ColumnFamilyHandle; +import org.rocksdb.ReadOptions; +import org.rocksdb.RocksDB; +import org.rocksdb.RocksDBException; +import org.rocksdb.RocksIterator; +import org.rocksdb.Slice; +import org.rocksdb.WriteOptions; + +/** + * Mult-versioned partition storage implementation based on RocksDB. Stored data has the following format: + * <pre><code> + * | partId (2 bytes, BE) | rowId ({@link #igniteRowIdSize} bytes) |</code></pre> + * or + * <pre><code> + * | partId (2 bytes, BE) | rowId ({@link #igniteRowIdSize} bytes) | timestamp (16 bytes, DESC) |</code></pre> + * depending on transaction status. Pending transactions data doesn't have a timestamp assigned. + * + * <p/>BE means Big Endian, meaning that lexicographical bytes order matches a natural order of partitions. + * + * <p/>DESC means that timestamps are sorted from newest to oldest (N2O). Please refer to {@link #putTimestamp(ByteBuffer, Timestamp)} to + * see how it's achieved. Missing timestamp could be interpreted as a moment infinitely far away in the future. + */ +public class RocksDbMvPartitionStorage implements MvPartitionStorage { + /** Position of row id inside of the key. */ + private static final int ROW_ID_OFFSET = Short.BYTES; + + /** Timestamp size in bytes. */ + private static final int TIMESTAMP_SIZE = 2 * Long.BYTES; + + /** Maximum possible size of the key. */ + private static final int MAX_KEY_SIZE = /* partId */ ROW_ID_OFFSET + /* rowId */ MAX_ROW_ID_SIZE + /* timestamp */ TIMESTAMP_SIZE; + + /** Threadlocal direct buffer instance to read keys from RocksDB. */ + private static final ThreadLocal<ByteBuffer> MV_KEY_BUFFER = withInitial(() -> allocateDirect(MAX_KEY_SIZE).order(BIG_ENDIAN)); + + /** Threadlocal on-heap byte buffer instance to use for key manipulations. */ + private final ThreadLocal<ByteBuffer> heapKeyBuffer; + + /** Size of the {@link IgniteRowId} identifiers for this particular partition storage. */ + private final int igniteRowIdSize; + + /** + * Partition ID (should be treated as an unsigned short). + * + * <p/>Partition IDs are always stored in the big endian order, since they need to be compared lexicographically. + */ + private final int partId; + + /** RocksDb instance. */ + private final RocksDB db; + + /** Partitions column family. */ + private final ColumnFamilyHandle cf; + + /** Write options. */ + private final WriteOptions writeOpts = new WriteOptions().setDisableWAL(true); + + /** Upper bound for scans and reads. */ + private final Slice upperBound; + + /** + * Constructor. + * + * @param igniteRowIdSize Size of row id. + * @param partId Partition id. + * @param db RocksDB instance. + * @param cf Column family handle to store partition data. + */ + public RocksDbMvPartitionStorage(int igniteRowIdSize, int partId, RocksDB db, ColumnFamilyHandle cf) { + this.igniteRowIdSize = igniteRowIdSize; + this.partId = partId; + this.db = db; + this.cf = cf; + + heapKeyBuffer = withInitial(() -> + ByteBuffer.allocate(Short.BYTES + igniteRowIdSize + ROW_ID_OFFSET * Long.BYTES) + .order(BIG_ENDIAN) + .putShort((short) partId) + ); + + upperBound = new Slice(partitionEndPrefix()); + } + + /** {@inheritDoc} */ + @Override + public void addWrite(IgniteRowId rowId, @Nullable BinaryRow row, UUID txId) throws TxIdMismatchException, StorageException { + // Prepare a buffer with partition id and row id. + ByteBuffer keyBuf = prepareHeapKeyBuf(rowId); + + try { + // Check concurrent transaction data. + if (RocksDB.NOT_FOUND != db.get(cf, keyBuf.array(), 0, keyBuf.position(), BYTE_EMPTY_ARRAY, 0, 0)) { + throw new TxIdMismatchException(); + } + + if (row == null) { + // Write empty array as a tombstone. + db.put(cf, writeOpts, keyBuf.array(), 0, keyBuf.position(), BYTE_EMPTY_ARRAY, 0, 0); + } else { + byte[] valueBytes = row.bytes(); + + // Write binary row data as a value. + db.put(cf, writeOpts, keyBuf.array(), 0, keyBuf.position(), valueBytes, 0, valueBytes.length); + } + } catch (RocksDBException e) { + throw new StorageException(e); + } + } + + /** {@inheritDoc} */ + @Override + public void abortWrite(IgniteRowId rowId) throws StorageException { + // Prepare a buffer with partition id and row id. + ByteBuffer keyBuf = prepareHeapKeyBuf(rowId); + + try { + // Perform unconditional remove for the key without associated timestamp. + db.delete(cf, writeOpts, keyBuf.array(), 0, keyBuf.position()); + } catch (RocksDBException e) { + throw new StorageException(e); + } + } + + /** {@inheritDoc} */ + @Override + public void commitWrite(IgniteRowId rowId, Timestamp timestamp) throws StorageException { + // Prepare a buffer with partition id and row id. + ByteBuffer keyBuf = prepareHeapKeyBuf(rowId); + + try { + // Read a value associated with pending write. + byte[] valueBytes = db.get(cf, keyBuf.array(), 0, keyBuf.position()); + + // Delete pending write. + db.delete(cf, writeOpts, keyBuf.array(), 0, keyBuf.position()); + + // Add timestamp to the key put the value back into the storage. + putTimestamp(keyBuf, timestamp); + + db.put(cf, writeOpts, keyBuf.array(), 0, keyBuf.position(), valueBytes, 0, valueBytes.length); + } catch (RocksDBException e) { + throw new StorageException(e); + } + } + + /** {@inheritDoc} */ + @Override + public @Nullable BinaryRow read(IgniteRowId rowId, @Nullable Timestamp timestamp) { + // Prepare a buffer with partition id and row id. + ByteBuffer keyBuf = prepareHeapKeyBuf(rowId); + + try ( + // Set next partition as an upper bound. + var readOpts = new ReadOptions().setIterateUpperBound(upperBound); + RocksIterator it = db.newIterator(cf, readOpts) + ) { + if (timestamp == null) { + // Seek to the first appearance of row id if timestamp isn't set. + // Since timestamps are sorted from newest to oldest, first occurance will always be the latest version. + // Unfortunately, copy here is unavoidable with current API. + it.seek(Arrays.copyOf(keyBuf.array(), keyBuf.position())); + } else { + // Put timestamp restriction according to N2O timestamps order. + putTimestamp(keyBuf, timestamp); + + // This seek will either find a key with timestamp that's less or equal than required value, or a different key whatsoever. + // It is guaranteed by descending order of timestamps. + it.seek(keyBuf.array()); + } + + // Return null if nothing was found. + if (invalid(it)) { + return null; + } + + // There's no guarantee that required key even exists. If it doesn't, then "seek" will point to a different key, obviously. + // To avoid returning its value, we have to check that actual key matches what we need. + // Here we prepare direct buffer to read key without timestamp. Shared direct buffer is used to avoid extra memory allocations. + ByteBuffer directBuffer = MV_KEY_BUFFER.get().position(0).limit(ROW_ID_OFFSET + igniteRowIdSize); + + it.key(directBuffer); + + // Comparison starts from the position of the row id. + directBuffer.position(ROW_ID_OFFSET); + + // Return null if seek found a wrong key. + if (rowId.compareTo(directBuffer, false) != 0) { + return null; + } + + // Get binary row from the iterator. It has the exact payload that we need. Review Comment: My idea was - the more comments, the better. This adds consistency even if comment is obvious - method is split into small digestible sections -- This is an automated message from the Apache Git Service. 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