paul-rogers commented on a change in pull request #1618: DRILL-6950: Row set-based scan framework URL: https://github.com/apache/drill/pull/1618#discussion_r251218664
########## File path: exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/scan/file/BaseFileScanFramework.java ########## @@ -0,0 +1,177 @@ +/* + * 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.scan.file; + +import java.io.IOException; +import java.util.ArrayList; +import java.util.Iterator; +import java.util.List; + +import org.apache.drill.common.exceptions.ExecutionSetupException; +import org.apache.drill.common.exceptions.UserException; +import org.apache.drill.common.expression.SchemaPath; +import org.apache.drill.exec.physical.impl.scan.RowBatchReader; +import org.apache.drill.exec.physical.impl.scan.framework.AbstractScanFramework; +import org.apache.drill.exec.physical.impl.scan.framework.ManagedReader; +import org.apache.drill.exec.physical.impl.scan.framework.SchemaNegotiator; +import org.apache.drill.exec.physical.impl.scan.framework.ShimBatchReader; +import org.apache.drill.exec.store.dfs.DrillFileSystem; +import org.apache.drill.exec.store.dfs.easy.FileWork; +import org.apache.hadoop.conf.Configuration; +import org.apache.hadoop.fs.Path; +import org.apache.hadoop.mapred.FileSplit; + +/** + * Scan framework for a file that implements metadata columns (AKA "implicit" + * columns and partition columns.) + * <p> + * Framework iterators over file descriptions, creating readers at the + * moment they are needed. This allows simpler logic because, at the point of + * reader creation, we have a file system, context and so on. + */ + +public abstract class BaseFileScanFramework<T extends BaseFileScanFramework.FileSchemaNegotiator> + extends AbstractScanFramework<T> { + + static final org.slf4j.Logger logger = org.slf4j.LoggerFactory.getLogger(BaseFileScanFramework.class); + + /** + * The file schema negotiator adds no behavior at present, but is + * created as a placeholder anticipating the need for file-specific + * behavior later. Review comment: Done. This is more about ensuring that reader code need not change if we later decide we need a file-specific negotiator class. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org With regards, Apache Git Services
