Github user Ben-Zvi commented on a diff in the pull request: https://github.com/apache/drill/pull/717#discussion_r98593747 --- Diff: exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/xsort/managed/CopierHolder.java --- @@ -0,0 +1,294 @@ +/* + * 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.impl.xsort.managed; + +import java.util.List; +import java.util.concurrent.TimeUnit; + +import org.apache.drill.common.exceptions.UserException; +import org.apache.drill.common.expression.SchemaPath; +import org.apache.drill.exec.exception.SchemaChangeException; +import org.apache.drill.exec.expr.TypeHelper; +import org.apache.drill.exec.memory.BufferAllocator; +import org.apache.drill.exec.ops.FragmentContext; +import org.apache.drill.exec.physical.impl.xsort.managed.ExternalSortBatch.SortResults; +import org.apache.drill.exec.record.BatchSchema; +import org.apache.drill.exec.record.MaterializedField; +import org.apache.drill.exec.record.VectorAccessible; +import org.apache.drill.exec.record.VectorContainer; +import org.apache.drill.exec.record.VectorWrapper; +import org.apache.drill.exec.vector.ValueVector; + +import com.google.common.base.Stopwatch; + +/** + * Manages a {@link PriorityQueueCopier} instance produced from code generation. + * Provides a wrapper around a copier "session" to simplify reading batches + * from the copier. + */ + +public class CopierHolder { + private static final org.slf4j.Logger logger = org.slf4j.LoggerFactory.getLogger(CopierHolder.class); + + private PriorityQueueCopier copier; + + private final FragmentContext context; + private final BufferAllocator allocator; + private OperatorCodeGenerator opCodeGen; + + public CopierHolder(FragmentContext context, BufferAllocator allocator, OperatorCodeGenerator opCodeGen) { + this.context = context; + this.allocator = allocator; + this.opCodeGen = opCodeGen; + } + + /** + * Start a merge operation using a temporary vector container. Used for + * intermediate merges. + * + * @param schema + * @param batchGroupList + * @param targetRecordCount + * @return + */ + + public CopierHolder.BatchMerger startMerge(BatchSchema schema, List<? extends BatchGroup> batchGroupList, int targetRecordCount) { + return new BatchMerger(this, schema, batchGroupList, targetRecordCount); + } + + /** + * Start a merge operation using the specified vector container. Used for + * the final merge operation. + * + * @param schema + * @param batchGroupList + * @param outputContainer + * @param targetRecordCount + * @return + */ + public CopierHolder.BatchMerger startFinalMerge(BatchSchema schema, List<? extends BatchGroup> batchGroupList, VectorContainer outputContainer, int targetRecordCount) { + return new BatchMerger(this, schema, batchGroupList, outputContainer, targetRecordCount); + } + + /** + * Prepare a copier which will write a collection of vectors to disk. The copier + * uses generated code to to the actual writes. If the copier has not yet been + * created, generated code and create it. If it has been created, close it and + * prepare it for a new collection of batches. + * + * @param batch the (hyper) batch of vectors to be copied + * @param batchGroupList same batches as above, but represented as a list + * of individual batches + * @param outputContainer the container into which to copy the batches + * @param allocator allocator to use to allocate memory in the operation + */ + + @SuppressWarnings("unchecked") + private void createCopier(VectorAccessible batch, List<? extends BatchGroup> batchGroupList, VectorContainer outputContainer) { + if (copier != null) { + opCodeGen.closeCopier(); + } else { + copier = opCodeGen.getCopier(batch); + } + + // Initialize the value vectors for the output container using the + // allocator provided + + for (VectorWrapper<?> i : batch) { + @SuppressWarnings("resource") + ValueVector v = TypeHelper.getNewVector(i.getField(), allocator); + outputContainer.add(v); + } + try { + copier.setup(context, allocator, batch, (List<BatchGroup>) batchGroupList, outputContainer); + } catch (SchemaChangeException e) { + throw UserException.unsupportedError(e) + .message("Unexpected schema change - likely code error.") + .build(logger); + } + } + + public BufferAllocator getAllocator() { return allocator; } + + public void close() { + opCodeGen.closeCopier(); + copier = null; + } + + /** + * We've gathered a set of batches, each of which has been sorted. The batches + * may have passed through a filter and thus may have "holes" where rows have + * been filtered out. We will spill records in blocks of targetRecordCount. + * To prepare, copy that many records into an outputContainer as a set of + * contiguous values in new vectors. The result is a single batch with + * vectors that combine a collection of input batches up to the + * given threshold. + * <p> + * Input (selection vector, data vector):<pre> + * [3 7 4 8 0 6 1] [5 3 6 8 2 0] + * [eh_ad_ibf] [r_qm_kn_p]</pre> + * <p> + * Output (assuming blocks of 5 records, data vectors only):<pre> + * [abcde] [fhikm] [npqr]</pre> + * <p> + * The copying operation does a merge as well: copying + * values from the sources in ordered fashion. + * <pre> + * Input: [aceg] [bdfh] + * Output: [abcdefgh]</pre> + * <p> + * Here we bind the copier to the batchGroupList of sorted, buffered batches + * to be merged. We bind the copier output to outputContainer: the copier will write its + * merged "batches" of records to that container. + * <p> + * Calls to the {@link #next()} method sequentially return merged batches + * of the desired row count. + */ + + public static class BatchMerger implements SortResults, AutoCloseable { + + private CopierHolder holder; + private VectorContainer hyperBatch; + private VectorContainer outputContainer; + private int targetRecordCount; + private int copyCount; + private int batchCount; + + /** + * Creates a merger with an temporary output container. + * + * @param holder --- End diff -- missing param: "schema"
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