ihuzenko commented on a change in pull request #1899: DRILL-7445: Create batch copier based on result set framework URL: https://github.com/apache/drill/pull/1899#discussion_r347362163
########## File path: exec/java-exec/src/main/java/org/apache/drill/exec/physical/resultSet/impl/ResultSetCopierImpl.java ########## @@ -0,0 +1,321 @@ +/* + * 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.drill.exec.physical.resultSet.impl; + +import org.apache.drill.exec.memory.BufferAllocator; +import org.apache.drill.exec.physical.impl.protocol.BatchAccessor; +import org.apache.drill.exec.physical.resultSet.ResultSetCopier; +import org.apache.drill.exec.physical.resultSet.ResultSetLoader; +import org.apache.drill.exec.physical.resultSet.ResultSetReader; +import org.apache.drill.exec.physical.resultSet.RowSetLoader; +import org.apache.drill.exec.physical.rowSet.RowSetReader; +import org.apache.drill.exec.record.VectorContainer; +import org.apache.drill.exec.record.metadata.MetadataUtils; +import org.apache.drill.exec.record.metadata.TupleMetadata; +import org.apache.drill.exec.vector.accessor.ColumnReader; +import org.apache.drill.exec.vector.accessor.ColumnWriter; +import org.apache.drill.shaded.guava.com.google.common.base.Preconditions; + +public class ResultSetCopierImpl implements ResultSetCopier { + + private enum State { + START, + NO_SCHEMA, + BETWEEN_BATCHES, + BATCH_ACTIVE, + NEW_SCHEMA, + SCHEMA_PENDING, + CLOSED + } + + private interface BlockCopy { + void copy(); + boolean hasMore(); + } + + private class CopyAll implements BlockCopy { + + @Override + public void copy() { + while (!rowWriter.isFull() && rowReader.next()) { + project(); + } + } + + @Override + public boolean hasMore() { + return rowReader.hasNext(); + } + } + + private static class CopyPair { + protected final ColumnWriter writer; + protected final ColumnReader reader; + + protected CopyPair(ColumnWriter writer, ColumnReader reader) { + this.writer = writer; + this.reader = reader; + } + } + + // Input state + + private int currentSchemaVersion = -1; + private final ResultSetReader resultSetReader; + protected RowSetReader rowReader; + + // Output state + + private final BufferAllocator allocator; + private final OptionBuilder writerOptions; + private ResultSetLoader resultSetWriter; + private RowSetLoader rowWriter; + + // Copy state + + private State state; + private CopyPair[] projection; + private BlockCopy activeCopy; + + public ResultSetCopierImpl(BufferAllocator allocator, BatchAccessor inputBatch) { + this(allocator, inputBatch, new OptionBuilder()); + } + + public ResultSetCopierImpl(BufferAllocator allocator, BatchAccessor inputBatch, + OptionBuilder outputOptions) { + this.allocator = allocator; + resultSetReader = new ResultSetReaderImpl(inputBatch); + writerOptions = outputOptions; + writerOptions.setVectorCache(new ResultVectorCacheImpl(allocator)); + state = State.START; + } + + @Override + public void startBatch() { + if (state == State.START) { + + // No schema yet. Defer real batch start until we see an input + // batch. + + state = State.NO_SCHEMA; + return; + } + Preconditions.checkState(state == State.BETWEEN_BATCHES || state == State.SCHEMA_PENDING); + if (state == State.SCHEMA_PENDING) { + + // We have a pending new schema. Create new writers to match. + + createMapping(); + } + resultSetWriter.startBatch(); + state = State.BATCH_ACTIVE; + if (isCopyPending()) { + + // Resume copying if a copy is active. + + copyBlock(); + } + } + + @Override + public void startInput() { + Preconditions.checkState(state == State.NO_SCHEMA || state == State.NEW_SCHEMA || + state == State.BATCH_ACTIVE, + "Can only start input while in an output batch"); + Preconditions.checkState(!isCopyPending(), + "Finish the pending copy before changing input"); + + bindInput(); + + if (state == State.BATCH_ACTIVE) { + + // If no schema change, we are ready to copy. + + if (currentSchemaVersion == resultSetReader.inputBatch().schemaVersion()) { + return; + } + + // The schema has changed. Handle it now or later. + + if (hasRows()) { + + // Output batch has rows. Can't switch and bind inputs + // until current batch is sent downstream. + + state = State.NEW_SCHEMA; + return; + } + } + + // The schema changed: first schema, or a change while a bath + // is active, but is empty. + + if (state == State.NO_SCHEMA) { + state = State.BATCH_ACTIVE; + } else { + + // Discard the unused empty batch + + harvest().zeroVectors(); + } + createMapping(); + resultSetWriter.startBatch(); + + // Stay in the current state. + } + + protected void bindInput() { + resultSetReader.start(); + rowReader = resultSetReader.reader(); + } + + @Override + public void freeInput() { + Preconditions.checkState(state != State.CLOSED); + resultSetReader.release(); + } + + private void createMapping() { Review comment: ```suggestion private void createProjection() { ``` ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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