KAFKA-3209: KIP-66: more single message transforms

build.gradle

@@ -508,7 +508,7 @@ project(':core') {
 
   task siteDocsTar(dependsOn: ['genProtocolErrorDocs', 'genProtocolApiKeyDocs', 'genProtocolMessageDocs',
                                'genProducerConfigDocs', 'genConsumerConfigDocs', 'genKafkaConfigDocs',
-                               'genTopicConfigDocs', ':connect:runtime:genConnectConfigDocs',
+                               'genTopicConfigDocs', ':connect:runtime:genConnectConfigDocs', ':connect:runtime:genConnectTransformationDocs',
                                ':streams:genStreamsConfigDocs'], type: Tar) {
     classifier = 'site-docs'
     compression = Compression.GZIP
@@ -948,6 +948,13 @@ project(':connect:runtime') {
     if( !generatedDocsDir.exists() ) { generatedDocsDir.mkdirs() }
     standardOutput = new File(generatedDocsDir, "connect_config.html").newOutputStream()
   }
+
+  task genConnectTransformationDocs(type: JavaExec) {
+    classpath = sourceSets.main.runtimeClasspath
+    main = 'org.apache.kafka.connect.tools.TransformationDoc'
+    if( !generatedDocsDir.exists() ) { generatedDocsDir.mkdirs() }
+    standardOutput = new File(generatedDocsDir, "connect_transforms.html").newOutputStream()
+  }
 }
 
 project(':connect:file') {

connect/runtime/src/main/java/org/apache/kafka/connect/tools/TransformationDoc.java

@@ -0,0 +1,85 @@
+/**
+ * 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
+ * <p/>
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * <p/>
+ * 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.kafka.connect.tools;
+
+import org.apache.kafka.common.config.ConfigDef;
+import org.apache.kafka.connect.transforms.ExtractField;
+import org.apache.kafka.connect.transforms.HoistField;
+import org.apache.kafka.connect.transforms.InsertField;
+import org.apache.kafka.connect.transforms.MaskField;
+import org.apache.kafka.connect.transforms.RegexRouter;
+import org.apache.kafka.connect.transforms.SetSchemaMetadata;
+import org.apache.kafka.connect.transforms.TimestampRouter;
+import org.apache.kafka.connect.transforms.ValueToKey;
+
+import java.io.PrintStream;
+import java.util.Arrays;
+import java.util.List;
+
+public class TransformationDoc {
+
+    private static final class DocInfo {
+        final String transformationName;
+        final String overview;
+        final ConfigDef configDef;
+
+        private DocInfo(String transformationName, String overview, ConfigDef configDef) {
+            this.transformationName = transformationName;
+            this.overview = overview;
+            this.configDef = configDef;
+        }
+    }
+
+    private static final List<DocInfo> TRANSFORMATIONS = Arrays.asList(
+            new DocInfo(InsertField.class.getName(), InsertField.OVERVIEW_DOC, InsertField.CONFIG_DEF),
+            new DocInfo(MaskField.class.getName(), MaskField.OVERVIEW_DOC, MaskField.CONFIG_DEF),
+            new DocInfo(ValueToKey.class.getName(), ValueToKey.OVERVIEW_DOC, ValueToKey.CONFIG_DEF),
+            new DocInfo(HoistField.class.getName(), HoistField.OVERVIEW_DOC, HoistField.CONFIG_DEF),
+            new DocInfo(ExtractField.class.getName(), ExtractField.OVERVIEW_DOC, ExtractField.CONFIG_DEF),
+            new DocInfo(SetSchemaMetadata.class.getName(), SetSchemaMetadata.OVERVIEW_DOC, SetSchemaMetadata.CONFIG_DEF),
+            new DocInfo(TimestampRouter.class.getName(), TimestampRouter.OVERVIEW_DOC, TimestampRouter.CONFIG_DEF),
+            new DocInfo(RegexRouter.class.getName(), RegexRouter.OVERVIEW_DOC, RegexRouter.CONFIG_DEF)
+    );
+
+    private static void printTransformationHtml(PrintStream out, DocInfo docInfo) {
+        out.println("<div id=\"" + docInfo.transformationName + "\">");
+
+        out.print("<h5>");
+        out.print(docInfo.transformationName);
+        out.println("</h5>");
+
+        out.println(docInfo.overview);
+
+        out.println("<p/>");
+
+        out.println(docInfo.configDef.toHtmlTable());
+
+        out.println("</div>");
+    }
+
+    private static void printHtml(PrintStream out) throws NoSuchFieldException, IllegalAccessException, InstantiationException {
+        for (final DocInfo docInfo : TRANSFORMATIONS) {
+            printTransformationHtml(out, docInfo);
+        }
+    }
+
+    public static void main(String... args) throws Exception {
+        printHtml(System.out);
+    }
+
+}

connect/transforms/src/main/java/org/apache/kafka/connect/transforms/ExtractField.java

@@ -0,0 +1,114 @@
+/**
+ * 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
+ * <p/>
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * <p/>
+ * 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.kafka.connect.transforms;
+
+import org.apache.kafka.common.config.ConfigDef;
+import org.apache.kafka.connect.connector.ConnectRecord;
+import org.apache.kafka.connect.data.Schema;
+import org.apache.kafka.connect.data.Struct;
+import org.apache.kafka.connect.transforms.util.SimpleConfig;
+
+import java.util.Map;
+
+import static org.apache.kafka.connect.transforms.util.Requirements.requireMap;
+import static org.apache.kafka.connect.transforms.util.Requirements.requireStruct;
+
+public abstract class ExtractField<R extends ConnectRecord<R>> implements Transformation<R> {
+
+    public static final String OVERVIEW_DOC =
+            "Extract the specified field from a Struct when schema present, or a Map in the case of schemaless data."
+                    + "<p/>Use the concrete transformation type designed for the record key (<code>" + Key.class.getCanonicalName() + "</code>) "
+                    + "or value (<code>" + Value.class.getCanonicalName() + "</code>).";
+
+    private static final String FIELD_CONFIG = "field";
+
+    public static final ConfigDef CONFIG_DEF = new ConfigDef()
+            .define(FIELD_CONFIG, ConfigDef.Type.STRING, ConfigDef.NO_DEFAULT_VALUE, ConfigDef.Importance.MEDIUM, "Field name to extract.");
+
+    private static final String PURPOSE = "field extraction";
+
+    private String fieldName;
+
+    @Override
+    public void configure(Map<String, ?> props) {
+        final SimpleConfig config = new SimpleConfig(CONFIG_DEF, props);
+        fieldName = config.getString(FIELD_CONFIG);
+    }
+
+    @Override
+    public R apply(R record) {
+        final Schema schema = operatingSchema(record);
+        if (schema == null) {
+            final Map<String, Object> value = requireMap(operatingValue(record), PURPOSE);
+            return newRecord(record, null, value.get(fieldName));
+        } else {
+            final Struct value = requireStruct(operatingValue(record), PURPOSE);
+            return newRecord(record, schema.field(fieldName).schema(), value.get(fieldName));
+        }
+    }
+
+    @Override
+    public void close() {
+    }
+
+    @Override
+    public ConfigDef config() {
+        return CONFIG_DEF;
+    }
+
+    protected abstract Schema operatingSchema(R record);
+
+    protected abstract Object operatingValue(R record);
+
+    protected abstract R newRecord(R record, Schema updatedSchema, Object updatedValue);
+
+    public static class Key<R extends ConnectRecord<R>> extends ExtractField<R> {
+        @Override
+        protected Schema operatingSchema(R record) {
+            return record.keySchema();
+        }
+
+        @Override
+        protected Object operatingValue(R record) {
+            return record.key();
+        }
+
+        @Override
+        protected R newRecord(R record, Schema updatedSchema, Object updatedValue) {
+            return record.newRecord(record.topic(), record.kafkaPartition(), updatedSchema, updatedValue, record.valueSchema(), record.value(), record.timestamp());
+        }
+    }
+
+    public static class Value<R extends ConnectRecord<R>> extends ExtractField<R> {
+        @Override
+        protected Schema operatingSchema(R record) {
+            return record.valueSchema();
+        }
+
+        @Override
+        protected Object operatingValue(R record) {
+            return record.value();
+        }
+
+        @Override
+        protected R newRecord(R record, Schema updatedSchema, Object updatedValue) {
+            return record.newRecord(record.topic(), record.kafkaPartition(), record.keySchema(), record.key(), updatedSchema, updatedValue, record.timestamp());
+        }
+    }
+
+}

connect/transforms/src/main/java/org/apache/kafka/connect/transforms/HoistToStruct.java → connect/transforms/src/main/java/org/apache/kafka/connect/transforms/HoistField.java

@@ -27,15 +27,21 @@
 import org.apache.kafka.connect.data.Struct;
 import org.apache.kafka.connect.transforms.util.SimpleConfig;
 
+import java.util.Collections;
 import java.util.Map;
 
-public abstract class HoistToStruct<R extends ConnectRecord<R>> implements Transformation<R> {
+public abstract class HoistField<R extends ConnectRecord<R>> implements Transformation<R> {
 
-    public static final String FIELD_CONFIG = "field";
+    public static final String OVERVIEW_DOC =
+            "Wrap data using the specified field name in a Struct when schema present, or a Map in the case of schemaless data."
+                    + "<p/>Use the concrete transformation type designed for the record key (<code>" + Key.class.getCanonicalName() + "</code>) "
+                    + "or value (<code>" + Value.class.getCanonicalName() + "</code>).";
 
-    private static final ConfigDef CONFIG_DEF = new ConfigDef()
+    private static final String FIELD_CONFIG = "field";
+
+    public static final ConfigDef CONFIG_DEF = new ConfigDef()
             .define(FIELD_CONFIG, ConfigDef.Type.STRING, ConfigDef.NO_DEFAULT_VALUE, ConfigDef.Importance.MEDIUM,
-                    "Field name for the single field that will be created in the resulting Struct.");
+                    "Field name for the single field that will be created in the resulting Struct or Map.");
 
     private Cache<Schema, Schema> schemaUpdateCache;
 
@@ -53,15 +59,19 @@ public R apply(R record) {
         final Schema schema = operatingSchema(record);
         final Object value = operatingValue(record);
 
-        Schema updatedSchema = schemaUpdateCache.get(schema);
-        if (updatedSchema == null) {
-            updatedSchema = SchemaBuilder.struct().field(fieldName, schema).build();
-            schemaUpdateCache.put(schema, updatedSchema);
-        }
+        if (schema == null) {
+            return newRecord(record, null, Collections.singletonMap(fieldName, value));
+        } else {
+            Schema updatedSchema = schemaUpdateCache.get(schema);
+            if (updatedSchema == null) {
+                updatedSchema = SchemaBuilder.struct().field(fieldName, schema).build();
+                schemaUpdateCache.put(schema, updatedSchema);
+            }
 
-        final Struct updatedValue = new Struct(updatedSchema).put(fieldName, value);
+            final Struct updatedValue = new Struct(updatedSchema).put(fieldName, value);
 
-        return newRecord(record, updatedSchema, updatedValue);
+            return newRecord(record, updatedSchema, updatedValue);
+        }
     }
 
     @Override
@@ -80,11 +90,7 @@ public ConfigDef config() {
 
     protected abstract R newRecord(R record, Schema updatedSchema, Object updatedValue);
 
-    /**
-     * Wraps the record key in a {@link org.apache.kafka.connect.data.Struct} with specified field name.
-     */
-    public static class Key<R extends ConnectRecord<R>> extends HoistToStruct<R> {
-
+    public static class Key<R extends ConnectRecord<R>> extends HoistField<R> {
         @Override
         protected Schema operatingSchema(R record) {
             return record.keySchema();
@@ -99,14 +105,9 @@ protected Object operatingValue(R record) {
         protected R newRecord(R record, Schema updatedSchema, Object updatedValue) {
             return record.newRecord(record.topic(), record.kafkaPartition(), updatedSchema, updatedValue, record.valueSchema(), record.value(), record.timestamp());
         }
-
     }
 
-    /**
-     * Wraps the record value in a {@link org.apache.kafka.connect.data.Struct} with specified field name.
-     */
-    public static class Value<R extends ConnectRecord<R>> extends HoistToStruct<R> {
-
+    public static class Value<R extends ConnectRecord<R>> extends HoistField<R> {
         @Override
         protected Schema operatingSchema(R record) {
             return record.valueSchema();
@@ -121,7 +122,6 @@ protected Object operatingValue(R record) {
         protected R newRecord(R record, Schema updatedSchema, Object updatedValue) {
             return record.newRecord(record.topic(), record.kafkaPartition(), record.keySchema(), record.key(), updatedSchema, updatedValue, record.timestamp());
         }
-
     }
 
 }