[GitHub] [nifi] alopresto commented on a change in pull request #3984: NIFI-6970 add DistributeRecord processor

[GitBox <gi...@apache.org>]

alopresto commented on a change in pull request #3984:
URL: https://github.com/apache/nifi/pull/3984#discussion_r433348987



##########
File path: nifi-nar-bundles/nifi-standard-bundle/nifi-standard-processors/src/main/java/org/apache/nifi/processors/standard/DistributeHashRecord.java
##########
@@ -0,0 +1,401 @@
+/*
+ * 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.processors.standard;
+
+import com.sangupta.murmur.Murmur2;
+
+import org.apache.nifi.annotation.behavior.DynamicProperty;
+import org.apache.nifi.annotation.behavior.InputRequirement;
+import org.apache.nifi.annotation.behavior.SideEffectFree;
+import org.apache.nifi.annotation.behavior.WritesAttributes;
+import org.apache.nifi.annotation.behavior.WritesAttribute;
+import org.apache.nifi.annotation.documentation.CapabilityDescription;
+import org.apache.nifi.annotation.documentation.Tags;
+import org.apache.nifi.annotation.lifecycle.OnScheduled;
+
+import org.apache.nifi.components.PropertyDescriptor;
+import org.apache.nifi.components.Validator;
+import org.apache.nifi.expression.ExpressionLanguageScope;
+import org.apache.nifi.flowfile.FlowFile;
+
+import org.apache.nifi.processor.AbstractProcessor;
+import org.apache.nifi.processor.ProcessContext;
+import org.apache.nifi.processor.ProcessorInitializationContext;
+import org.apache.nifi.processor.Relationship;
+import org.apache.nifi.processor.exception.ProcessException;
+import org.apache.nifi.processor.util.StandardValidators;
+import org.apache.nifi.processor.ProcessSession;
+
+import org.apache.nifi.schema.access.SchemaNotFoundException;
+import org.apache.nifi.serialization.RecordReader;
+import org.apache.nifi.serialization.RecordReaderFactory;
+import org.apache.nifi.serialization.RecordSetWriter;
+import org.apache.nifi.serialization.RecordSetWriterFactory;
+import org.apache.nifi.serialization.record.Record;
+import org.apache.nifi.serialization.record.RecordSchema;
+
+import java.io.Closeable;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Objects;
+import java.util.Optional;
+import java.util.Set;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+import java.util.LinkedList;
+import java.util.Map;
+import java.util.HashMap;
+import java.util.Comparator;
+
+
+@SideEffectFree
+@Tags({"route", "distribute", "weighted", "record"})
+@InputRequirement(InputRequirement.Requirement.INPUT_REQUIRED)
+@CapabilityDescription("Processor that distribute data over user specified relationships by distribution key/keys." +
+        " Data is distributed across relationships in the amount proportional to the relationship weight. For example, if there are " +
+        "two relationships and the first has a weight of 9 while the second has a weight of 10, the first will be sent 9 / 19 parts" +
+        " of the rows, and the second will be sent 10 / 19. " +
+        "To select the relationship that a row of data is sent to, specified keys extracted from record as string," +
+        " join with `-` delimiter and hash evaluate from this string, its remainder is taken from dividing it " +
+        "by the total weight of the relationships. If there is specified single integer key, hash value will not be calculated " +
+        "and processor just take remainder of division by the sum of the relationship weights from this value." +
+        " The row is sent to the relationship" +
+        " that corresponds to the half-interval of the remainders from 'prev_weight' to 'prev_weights + weight', where" +
+        " 'prev_weights' is the total weight of the relationships with the smallest number, and 'weight' is the weight of this relationship." +
+        " For example, if there are two relationships, and the first has a weight of 9 while the second has a weight of 10," +
+        " the row will be sent to the first relationship for the remainders from the range [0, 9), and to the second for the remainders from the range [9, 19).")
+@DynamicProperty(name = "The name of the relationship to route data to",
+        value = "Weight for this relationship.",
+        expressionLanguageScope = ExpressionLanguageScope.FLOWFILE_ATTRIBUTES,
+        description = "Each user-defined property specifies a relationship and weight for this.")
+@WritesAttributes({
+        @WritesAttribute(attribute = "mime.type", description = "Sets the mime.type attribute to the MIME Type specified by the Record Writer"),
+        @WritesAttribute(attribute = "record.count", description = "The number of records selected by the query")
+})
+public class DistributeHashRecord extends AbstractProcessor {
+
+    public static final String MURMURHASH_32 = "murmurhash_32";
+
+    public static PropertyDescriptor RECORD_READER = new PropertyDescriptor.Builder()
+            .name("reader")
+            .displayName("Record Reader")
+            .identifiesControllerService(RecordReaderFactory.class)
+            .required(true)
+            .description("Specifies the Controller Service to use for parsing incoming data and determining the data's schema")
+            .build();
+
+    public static PropertyDescriptor RECORD_WRITER = new PropertyDescriptor.Builder()
+            .name("writer")
+            .displayName("Record Writer")
+            .identifiesControllerService(RecordSetWriterFactory.class)
+            .required(true)
+            .description("Specifies the Controller Service to use for writing out the records")
+            .build();
+
+    private static final String KEY_DELIMITER = ",";
+
+    public static PropertyDescriptor KEYS = new PropertyDescriptor.Builder()
+            .name("keys")
+            .displayName("Keys")
+            .required(true)
+            .expressionLanguageSupported(ExpressionLanguageScope.FLOWFILE_ATTRIBUTES)
+            .description("Field names in a record separated by commas." +
+                    " If record has one key and this key is integer or long then hash function " +
+                    "will not be evaluated and processor will distribute record by this numerical value. " +
+                    "If this record has several keys for distribution or one key with not 'int' or 'long' type then processor will " +
+                    "obtain keys from record, trim them and join with `-` delimiter like <firstKey>-<secondKey>-<...> " +
+                    "then evaluate hash function which return numerical value for distribution")
+            .addValidator(StandardValidators.NON_EMPTY_VALIDATOR)
+            .build();
+
+    public static PropertyDescriptor HASH_FUNCTION = new PropertyDescriptor.Builder()
+            .name("hash function")
+            .displayName("Hash Function")
+            .required(true)
+            .description("Hash algorithm for keys hashing")
+            .allowableValues(MURMURHASH_32)

Review comment:
       I'm curious what this hash function is, and why there is a configurable property for it if there is only one allowable value. 




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