INGEST: Implement Drop Processor (#32278)

* INGEST: Implement Drop Processor
* Adjust Processor API
* Implement Drop Processor
* Closes #23726

Author: original-brownbear

modules/ingest-common/src/main/java/org/elasticsearch/ingest/common/AbstractStringProcessor.java

@@ -57,16 +57,17 @@ String getTargetField() {
     }
 
     @Override
-    public final void execute(IngestDocument document) {
+    public final IngestDocument execute(IngestDocument document) {
         String val = document.getFieldValue(field, String.class, ignoreMissing);
 
         if (val == null && ignoreMissing) {
-            return;
+            return document;
         } else if (val == null) {
             throw new IllegalArgumentException("field [" + field + "] is null, cannot process it.");
         }
 
         document.setFieldValue(targetField, process(val));
+        return document;
     }
 
     protected abstract T process(String value);

modules/ingest-common/src/main/java/org/elasticsearch/ingest/common/AppendProcessor.java

@@ -56,8 +56,9 @@ public ValueSource getValue() {
     }
 
     @Override
-    public void execute(IngestDocument ingestDocument) throws Exception {
+    public IngestDocument execute(IngestDocument ingestDocument) throws Exception {
         ingestDocument.appendFieldValue(field, value);
+        return ingestDocument;
     }
 
     @Override

modules/ingest-common/src/main/java/org/elasticsearch/ingest/common/ConvertProcessor.java

@@ -173,12 +173,12 @@ boolean isIgnoreMissing() {
     }
 
     @Override
-    public void execute(IngestDocument document) {
+    public IngestDocument execute(IngestDocument document) {
         Object oldValue = document.getFieldValue(field, Object.class, ignoreMissing);
         Object newValue;
 
         if (oldValue == null && ignoreMissing) {
-            return;
+            return document;
         } else if (oldValue == null) {
             throw new IllegalArgumentException("Field [" + field + "] is null, cannot be converted to type [" + convertType + "]");
         }
@@ -194,6 +194,7 @@ public void execute(IngestDocument document) {
             newValue = convertType.convert(oldValue);
         }
         document.setFieldValue(targetField, newValue);
+        return document;
     }
 
     @Override

modules/ingest-common/src/main/java/org/elasticsearch/ingest/common/DateIndexNameProcessor.java

@@ -63,7 +63,7 @@ public final class DateIndexNameProcessor extends AbstractProcessor {
     }
 
     @Override
-    public void execute(IngestDocument ingestDocument) throws Exception {
+    public IngestDocument execute(IngestDocument ingestDocument) throws Exception {
         // Date can be specified as a string or long:
         Object obj = ingestDocument.getFieldValue(field, Object.class);
         String date = null;
@@ -101,6 +101,7 @@ public void execute(IngestDocument ingestDocument) throws Exception {
                 .append('>');
         String dynamicIndexName  = builder.toString();
         ingestDocument.setFieldValue(IngestDocument.MetaData.INDEX.getFieldName(), dynamicIndexName);
+        return ingestDocument;
     }
 
     @Override

modules/ingest-common/src/main/java/org/elasticsearch/ingest/common/DateProcessor.java

@@ -74,7 +74,7 @@ private Locale newLocale(Map<String, Object> params) {
     }
 
     @Override
-    public void execute(IngestDocument ingestDocument) {
+    public IngestDocument execute(IngestDocument ingestDocument) {
         Object obj = ingestDocument.getFieldValue(field, Object.class);
         String value = null;
         if (obj != null) {
@@ -98,6 +98,7 @@ public void execute(IngestDocument ingestDocument) {
         }
 
         ingestDocument.setFieldValue(targetField, ISODateTimeFormat.dateTime().print(dateTime));
+        return ingestDocument;
     }
 
     @Override

modules/ingest-common/src/main/java/org/elasticsearch/ingest/common/DissectProcessor.java

@@ -47,14 +47,15 @@ public final class DissectProcessor extends AbstractProcessor {
     }
 
     @Override
-    public void execute(IngestDocument ingestDocument) {
+    public IngestDocument execute(IngestDocument ingestDocument) {
         String input = ingestDocument.getFieldValue(field, String.class, ignoreMissing);
         if (input == null && ignoreMissing) {
-            return;
+            return ingestDocument;
         } else if (input == null) {
             throw new IllegalArgumentException("field [" + field + "] is null, cannot process it.");
         }
         dissectParser.parse(input).forEach(ingestDocument::setFieldValue);
+        return ingestDocument;
     }
 
     @Override

modules/ingest-common/src/main/java/org/elasticsearch/ingest/common/DotExpanderProcessor.java

@@ -41,7 +41,7 @@ public final class DotExpanderProcessor extends AbstractProcessor {
 
     @Override
     @SuppressWarnings("unchecked")
-    public void execute(IngestDocument ingestDocument) throws Exception {
+    public IngestDocument execute(IngestDocument ingestDocument) throws Exception {
         String path;
         Map<String, Object> map;
         if (this.path != null) {
@@ -75,6 +75,7 @@ public void execute(IngestDocument ingestDocument) throws Exception {
             Object value = map.remove(field);
             ingestDocument.setFieldValue(path, value);
         }
+        return ingestDocument;
     }
 
     @Override

modules/ingest-common/src/main/java/org/elasticsearch/ingest/common/DropProcessor.java

@@ -0,0 +1,57 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch 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.elasticsearch.ingest.common;
+
+import java.util.Map;
+import org.elasticsearch.ingest.AbstractProcessor;
+import org.elasticsearch.ingest.IngestDocument;
+import org.elasticsearch.ingest.Processor;
+
+/**
+ * Drop processor only returns {@code null} for the execution result to indicate that any document
+ * executed by it should not be indexed.
+ */
+public final class DropProcessor extends AbstractProcessor {
+
+    public static final String TYPE = "drop";
+
+    private DropProcessor(final String tag) {
+        super(tag);
+    }
+
+    @Override
+    public IngestDocument execute(final IngestDocument ingestDocument) throws Exception {
+        return null;
+    }
+
+    @Override
+    public String getType() {
+        return TYPE;
+    }
+
+    public static final class Factory implements Processor.Factory {
+
+        @Override
+        public Processor create(final Map<String, Processor.Factory> processorFactories, final String tag,
+            final Map<String, Object> config) {
+            return new DropProcessor(tag);
+        }
+    }
+}

modules/ingest-common/src/main/java/org/elasticsearch/ingest/common/FailProcessor.java

@@ -48,7 +48,7 @@ public TemplateScript.Factory getMessage() {
     }
 
     @Override
-    public void execute(IngestDocument document) {
+    public IngestDocument execute(IngestDocument document) {
         throw new FailProcessorException(document.renderTemplate(message));
     }
 

modules/ingest-common/src/main/java/org/elasticsearch/ingest/common/ForEachProcessor.java

@@ -63,24 +63,29 @@ boolean isIgnoreMissing() {
     }
 
     @Override
-    public void execute(IngestDocument ingestDocument) throws Exception {
+    public IngestDocument execute(IngestDocument ingestDocument) throws Exception {
         List<?> values = ingestDocument.getFieldValue(field, List.class, ignoreMissing);
         if (values == null) {
             if (ignoreMissing) {
-                return;
+                return ingestDocument;
             }
             throw new IllegalArgumentException("field [" + field + "] is null, cannot loop over its elements.");
         }
         List<Object> newValues = new ArrayList<>(values.size());
+        IngestDocument document = ingestDocument;
         for (Object value : values) {
             Object previousValue = ingestDocument.getIngestMetadata().put("_value", value);
             try {
-                processor.execute(ingestDocument);
+                document = processor.execute(document);
+                if (document == null) {
+                    return null;
+                }
             } finally {
                 newValues.add(ingestDocument.getIngestMetadata().put("_value", previousValue));
             }
         }
-        ingestDocument.setFieldValue(field, newValues);
+        document.setFieldValue(field, newValues);
+        return document;
     }
 
     @Override