Retrieve processors instead of checking existence (#45354)

The previous hasProcessors method would validate if a processor was
present within a pipeline, but would not return the contents of the
processors. This does not allow a consumer to inspect the processor for
specific metadata. The method now returns the list of processors based
on the class of the processor passed in.

server/src/main/java/org/elasticsearch/ingest/IngestService.java

@@ -562,26 +562,27 @@ public class IngestService implements ClusterStateApplier {
     }
 
     /**
-     * Determine if a pipeline contains a processor class within it by introspecting all of the processors within the pipeline.
+     * Gets all the Processors of the given type from within a Pipeline.
      * @param pipelineId the pipeline to inspect
      * @param clazz the Processor class to look for
      * @return True if the pipeline contains an instance of the Processor class passed in
      */
-    public boolean hasProcessor(String pipelineId, Class<? extends Processor> clazz) {
+    public<P extends Processor> List<P> getProcessorsInPipeline(String pipelineId, Class<P> clazz) {
         Pipeline pipeline = getPipeline(pipelineId);
         if (pipeline == null) {
-            return false;
+            throw new IllegalArgumentException("pipeline with id [" + pipelineId + "] does not exist");
         }
 
+        List<P> processors = new ArrayList<>();
         for (Processor processor: pipeline.flattenAllProcessors()) {
             if (clazz.isAssignableFrom(processor.getClass())) {
-                return true;
+                processors.add(clazz.cast(processor));
             }
 
             while (processor instanceof WrappingProcessor) {
                 WrappingProcessor wrappingProcessor = (WrappingProcessor) processor;
                 if (clazz.isAssignableFrom(wrappingProcessor.getInnerProcessor().getClass())) {
-                    return true;
+                    processors.add(clazz.cast(wrappingProcessor.getInnerProcessor()));
                 }
                 processor = wrappingProcessor.getInnerProcessor();
                 // break in the case of self referencing processors in the event a processor author creates a
@@ -592,7 +593,7 @@ public class IngestService implements ClusterStateApplier {
             }
         }
 
-        return false;
+        return processors;
     }
 
     private static Pipeline substitutePipeline(String id, ElasticsearchParseException e) {

server/src/test/java/org/elasticsearch/ingest/IngestServiceTests.java

@@ -289,7 +289,7 @@ public class IngestServiceTests extends ESTestCase {
         ingestService.validatePipeline(Collections.singletonMap(discoveryNode, ingestInfo), putRequest);
     }
 
-    public void testHasProcessor() throws Exception {
+    public void testGetProcessorsInPipeline() throws Exception {
         IngestService ingestService = createWithProcessors();
         String id = "_id";
         Pipeline pipeline = ingestService.getPipeline(id);
@@ -306,15 +306,19 @@ public class IngestServiceTests extends ESTestCase {
         pipeline = ingestService.getPipeline(id);
         assertThat(pipeline, notNullValue());
 
-        assertTrue(ingestService.hasProcessor(id, Processor.class));
+        assertThat(ingestService.getProcessorsInPipeline(id, Processor.class).size(), equalTo(3));
-        assertTrue(ingestService.hasProcessor(id, WrappingProcessorImpl.class));
+        assertThat(ingestService.getProcessorsInPipeline(id, WrappingProcessorImpl.class).size(), equalTo(1));
-        assertTrue(ingestService.hasProcessor(id, WrappingProcessor.class));
+        assertThat(ingestService.getProcessorsInPipeline(id, WrappingProcessor.class).size(), equalTo(1));
-        assertTrue(ingestService.hasProcessor(id, FakeProcessor.class));
+        assertThat(ingestService.getProcessorsInPipeline(id, FakeProcessor.class).size(), equalTo(2));
 
-        assertFalse(ingestService.hasProcessor(id, ConditionalProcessor.class));
+        assertThat(ingestService.getProcessorsInPipeline(id, ConditionalProcessor.class).size(), equalTo(0));
+
+        IllegalArgumentException e = expectThrows(IllegalArgumentException.class,
+            () -> ingestService.getProcessorsInPipeline("fakeID", Processor.class));
+        assertThat("pipeline with id [fakeID] does not exist", equalTo(e.getMessage()));
     }
 
-    public void testHasProcessorComplexConditional() throws Exception {
+    public void testGetProcessorsInPipelineComplexConditional() throws Exception {
         LongSupplier relativeTimeProvider = mock(LongSupplier.class);
         String scriptName = "conditionalScript";
         ScriptService scriptService = new ScriptService(Settings.builder().build(),
@@ -364,12 +368,12 @@ public class IngestServiceTests extends ESTestCase {
         pipeline = ingestService.getPipeline(id);
         assertThat(pipeline, notNullValue());
 
-        assertTrue(ingestService.hasProcessor(id, Processor.class));
+        assertThat(ingestService.getProcessorsInPipeline(id, Processor.class).size(), equalTo(3));
-        assertTrue(ingestService.hasProcessor(id, WrappingProcessor.class));
+        assertThat(ingestService.getProcessorsInPipeline(id, WrappingProcessor.class).size(), equalTo(2));
-        assertTrue(ingestService.hasProcessor(id, FakeProcessor.class));
+        assertThat(ingestService.getProcessorsInPipeline(id, FakeProcessor.class).size(), equalTo(1));
-        assertTrue(ingestService.hasProcessor(id, ConditionalProcessor.class));
+        assertThat(ingestService.getProcessorsInPipeline(id, ConditionalProcessor.class).size(), equalTo(2));
 
-        assertFalse(ingestService.hasProcessor(id, WrappingProcessorImpl.class));
+        assertThat(ingestService.getProcessorsInPipeline(id, WrappingProcessorImpl.class).size(), equalTo(0));
     }
 
     public void testCrud() throws Exception {