| /* |
| * 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.store; |
| |
| import java.util.Map; |
| |
| import com.fasterxml.jackson.annotation.JsonSubTypes; |
| import com.fasterxml.jackson.annotation.JsonTypeInfo; |
| import org.apache.drill.common.exceptions.ExecutionSetupException; |
| import org.apache.drill.exec.exception.OutOfMemoryException; |
| import org.apache.drill.exec.ops.OperatorContext; |
| import org.apache.drill.exec.physical.impl.OutputMutator; |
| import org.apache.drill.exec.planner.sql.handlers.FindLimit0Visitor; |
| import org.apache.drill.exec.store.pojo.PojoRecordReader; |
| import org.apache.drill.exec.vector.ValueVector; |
| |
| /** |
| * For new implementations please use new {@link org.apache.drill.exec.physical.impl.scan.framework.ManagedReader} |
| */ |
| @JsonTypeInfo( |
| use = JsonTypeInfo.Id.NAME, |
| include = JsonTypeInfo.As.PROPERTY, |
| property = "type") |
| @JsonSubTypes({ |
| @JsonSubTypes.Type(value = PojoRecordReader.class, name = "PojoRecordReader"), |
| @JsonSubTypes.Type(value = FindLimit0Visitor.RelDataTypeReader.class, name = "RelDataTypeRecordReader") }) |
| public interface RecordReader extends AutoCloseable { |
| long ALLOCATOR_INITIAL_RESERVATION = 1 * 1024 * 1024; |
| long ALLOCATOR_MAX_RESERVATION = 20L * 1000 * 1000 * 1000; |
| |
| /** |
| * Configure the RecordReader with the provided schema and the record batch that should be written to. |
| * |
| * @param context operator context for the reader |
| * @param output |
| * The place where output for a particular scan should be written. The record reader is responsible for |
| * mutating the set of schema values for that particular record. |
| * @throws ExecutionSetupException |
| */ |
| void setup(OperatorContext context, OutputMutator output) throws ExecutionSetupException; |
| |
| void allocate(Map<String, ValueVector> vectorMap) throws OutOfMemoryException; |
| |
| /** |
| * Check if the reader may have potentially more data to be read in subsequent iterations. Certain types of readers |
| * such as repeatable readers can be invoked multiple times, so this method will allow ScanBatch to check with |
| * the reader before closing it. |
| * @return return true if there could potentially be more reads, false otherwise |
| */ |
| boolean hasNext(); |
| |
| /** |
| * Increments this record reader forward, writing via the provided output |
| * mutator into the output batch. |
| * |
| * @return The number of additional records added to the output. |
| */ |
| int next(); |
| } |