| /* |
| * 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.join; |
| |
| import org.apache.drill.exec.record.RecordBatch; |
| |
| /** |
| * This class predicts the sizes of batches given an input batch. |
| * |
| * <h4>Invariants</h4> |
| * <ul> |
| * <li>The {@link BatchSizePredictor} assumes that a {@link RecordBatch} is in a state where it can return a valid record count.</li> |
| * </ul> |
| */ |
| public interface BatchSizePredictor { |
| /** |
| * Gets the batchSize computed in the call to {@link #updateStats()}. Returns 0 if {@link #hadDataLastTime()} is false. |
| * @return Gets the batchSize computed in the call to {@link #updateStats()}. Returns 0 if {@link #hadDataLastTime()} is false. |
| * @throws IllegalStateException if {@link #updateStats()} was never called. |
| */ |
| long getBatchSize(); |
| |
| /** |
| * Gets the number of records computed in the call to {@link #updateStats()}. Returns 0 if {@link #hadDataLastTime()} is false. |
| * @return Gets the number of records computed in the call to {@link #updateStats()}. Returns 0 if {@link #hadDataLastTime()} is false. |
| * @throws IllegalStateException if {@link #updateStats()} was never called. |
| */ |
| int getNumRecords(); |
| |
| /** |
| * True if the input batch had records in the last call to {@link #updateStats()}. False otherwise. |
| * @return True if the input batch had records in the last call to {@link #updateStats()}. False otherwise. |
| */ |
| boolean hadDataLastTime(); |
| |
| /** |
| * This method can be called multiple times to collect stats about the latest data in the provided record batch. These |
| * stats are used to predict batch sizes. If the batch currently has no data, this method is a noop. This method must be |
| * called at least once before {@link #predictBatchSize(int, boolean)}. |
| */ |
| void updateStats(); |
| |
| /** |
| * Predicts the size of a batch using the current collected stats. |
| * @param desiredNumRecords The number of records contained in the batch whose size we want to predict. |
| * @param reserveHash Whether or not to include a column containing hash values. |
| * @return The size of the predicted batch. |
| * @throws IllegalStateException if {@link #hadDataLastTime()} is false or {@link #updateStats()} was not called. |
| */ |
| long predictBatchSize(int desiredNumRecords, boolean reserveHash); |
| |
| /** |
| * A factory for creating {@link BatchSizePredictor}s. |
| */ |
| interface Factory { |
| /** |
| * Creates a predictor with a batch whose data needs to be used to predict other batch sizes. |
| * @param batch The batch whose size needs to be predicted. |
| * @param fragmentationFactor A constant used to predict value vector doubling. |
| * @param safetyFactor A constant used to leave padding for unpredictable incoming batches. |
| */ |
| BatchSizePredictor create(RecordBatch batch, double fragmentationFactor, double safetyFactor); |
| } |
| } |