Github user markap14 commented on a diff in the pull request: https://github.com/apache/nifi/pull/2130#discussion_r137844007 --- Diff: nifi-nar-bundles/nifi-standard-services/nifi-lookup-services-bundle/nifi-lookup-services/src/main/java/org/apache/nifi/lookup/CSVRecordLookupService.java --- @@ -0,0 +1,232 @@ +/* + * 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.nifi.lookup; + +import org.apache.commons.csv.CSVFormat; +import org.apache.commons.csv.CSVParser; +import org.apache.commons.csv.CSVRecord; +import org.apache.commons.lang3.StringUtils; +import org.apache.nifi.annotation.documentation.CapabilityDescription; +import org.apache.nifi.annotation.documentation.Tags; +import org.apache.nifi.annotation.lifecycle.OnEnabled; +import org.apache.nifi.components.PropertyDescriptor; +import org.apache.nifi.controller.AbstractControllerService; +import org.apache.nifi.controller.ConfigurationContext; +import org.apache.nifi.controller.ControllerServiceInitializationContext; +import org.apache.nifi.logging.ComponentLog; +import org.apache.nifi.processor.util.StandardValidators; +import org.apache.nifi.reporting.InitializationException; +import org.apache.nifi.serialization.SimpleRecordSchema; +import org.apache.nifi.serialization.record.MapRecord; +import org.apache.nifi.serialization.record.Record; +import org.apache.nifi.serialization.record.RecordField; +import org.apache.nifi.serialization.record.RecordFieldType; +import org.apache.nifi.serialization.record.RecordSchema; +import org.apache.nifi.util.file.monitor.LastModifiedMonitor; +import org.apache.nifi.util.file.monitor.SynchronousFileWatcher; + +import java.io.FileNotFoundException; +import java.io.FileReader; +import java.io.IOException; +import java.nio.file.Paths; +import java.util.ArrayList; +import java.util.Arrays; +import java.util.Collections; +import java.util.HashMap; +import java.util.List; +import java.util.Map; +import java.util.Optional; +import java.util.Set; +import java.util.concurrent.ConcurrentHashMap; +import java.util.concurrent.ConcurrentMap; +import java.util.concurrent.locks.ReentrantLock; +import java.util.stream.Collectors; +import java.util.stream.Stream; + +@Tags({"lookup", "cache", "enrich", "join", "csv", "reloadable", "key", "value", "record"}) +@CapabilityDescription("A reloadable CSV file-based lookup service. When the lookup key is found in the CSV file, the remaining columns are returned as a Record.") +public class CSVRecordLookupService extends AbstractControllerService implements RecordLookupService { + + private static final String KEY = "key"; + + private static final Set<String> REQUIRED_KEYS = Collections.unmodifiableSet(Stream.of(KEY).collect(Collectors.toSet())); + + public static final PropertyDescriptor CSV_FILE = + new PropertyDescriptor.Builder() + .name("csv-file") + .displayName("CSV File") + .description("A CSV file.") + .required(true) + .addValidator(StandardValidators.FILE_EXISTS_VALIDATOR) + .expressionLanguageSupported(true) + .build(); + + static final PropertyDescriptor CSV_FORMAT = new PropertyDescriptor.Builder() + .name("CSV Format") + .description("Specifies which \"format\" the CSV data is in, or specifies if custom formatting should be used.") + .expressionLanguageSupported(false) + .allowableValues(Arrays.asList(CSVFormat.Predefined.values()).stream().map(e -> e.toString()).collect(Collectors.toSet())) + .defaultValue(CSVFormat.Predefined.Default.toString()) + .required(true) + .build(); + + public static final PropertyDescriptor LOOKUP_KEY_COLUMN = + new PropertyDescriptor.Builder() + .name("lookup-key-column") + .displayName("Lookup Key Column") + .description("Lookup key column.") + .required(true) + .addValidator(StandardValidators.NON_EMPTY_VALIDATOR) + .expressionLanguageSupported(true) + .build(); + + public static final PropertyDescriptor IGNORE_DUPLICATES = + new PropertyDescriptor.Builder() + .name("ignore-duplicates") + .displayName("Ignore Duplicates") + .description("Ignore duplicate keys for records in the CSV file.") + .addValidator(StandardValidators.BOOLEAN_VALIDATOR) + .allowableValues("true", "false") + .defaultValue("true") + .required(true) + .build(); + + private List<PropertyDescriptor> properties; + + private volatile ConcurrentMap<String, Map<String, Object>> cache; + + private volatile String csvFile; + + private volatile CSVFormat csvFormat; + + private volatile String lookupKeyColumn; + + private volatile boolean ignoreDuplicates; + + private volatile SynchronousFileWatcher watcher; + + private final ReentrantLock lock = new ReentrantLock(); + + private void loadCache() throws IllegalStateException, IOException { + if (lock.tryLock()) { + try { + final ComponentLog logger = getLogger(); + if (logger.isDebugEnabled()) { + logger.debug("Loading lookup table from file: " + csvFile); + } + + final FileReader reader = new FileReader(csvFile); + final CSVParser records = csvFormat.withFirstRecordAsHeader().parse(reader); + this.cache = new ConcurrentHashMap<>(); + for (final CSVRecord record : records) { + final String key = record.get(lookupKeyColumn); + + if (StringUtils.isBlank(key)) { --- End diff -- Not sure that this is necessary -- for many use cases, an empty string may well be a valid value.
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