Simplify ActionListener helpers and add dedicated unittests

core/src/main/java/org/elasticsearch/action/ActionListener.java

@@ -19,8 +19,11 @@
 
 package org.elasticsearch.action;
 
+import org.elasticsearch.ExceptionsHelper;
 import org.elasticsearch.common.CheckedConsumer;
 
+import java.util.ArrayList;
+import java.util.List;
 import java.util.function.Consumer;
 
 /**
@@ -72,7 +75,7 @@ public interface ActionListener<Response> {
      * listeners will be processed and the caught exception will be re-thrown.
      */
     static <Response> void onResponse(Iterable<ActionListener<Response>> listeners, Response response) {
-        RuntimeException exception = null;
+        List<Exception> exceptionList = new ArrayList<>();
         for (ActionListener<Response> listener : listeners) {
             try {
                 listener.onResponse(response);
@@ -80,17 +83,11 @@ public interface ActionListener<Response> {
                 try {
                     listener.onFailure(ex);
                 } catch (Exception ex1) {
-                    if (exception != null) {
-                        exception = new RuntimeException(ex1);
-                    } else {
-                        exception.addSuppressed(ex1);
-                    }
+                    exceptionList.add(ex1);
                 }
             }
         }
-        if (exception != null) {
-            throw exception;
-        }
+        ExceptionsHelper.maybeThrowRuntimeAndSuppress(exceptionList);
     }
 
     /**
@@ -98,20 +95,14 @@ public interface ActionListener<Response> {
      * all remaining listeners will be processed and the caught exception will be re-thrown.
      */
     static <Response> void onFailure(Iterable<ActionListener<Response>> listeners, Exception failure) {
-        RuntimeException exception = null;
+        List<Exception> exceptionList = new ArrayList<>();
         for (ActionListener<Response> listener : listeners) {
             try {
                 listener.onFailure(failure);
             } catch (Exception ex) {
-                if (exception != null) {
-                    exception = new RuntimeException(ex);
-                } else {
-                    exception.addSuppressed(ex);
-                }
+                exceptionList.add(ex);
             }
         }
-        if (exception != null) {
-            throw exception;
-        }
+        ExceptionsHelper.maybeThrowRuntimeAndSuppress(exceptionList);
     }
 }

core/src/test/java/org/elasticsearch/action/ActionListenerTests.java

@@ -0,0 +1,151 @@
+/*
+ * 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.action;
+
+import org.elasticsearch.common.CheckedConsumer;
+import org.elasticsearch.test.ESTestCase;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.atomic.AtomicReference;
+
+public class ActionListenerTests extends ESTestCase {
+
+    public void testWrap() {
+        AtomicReference<Boolean> reference = new AtomicReference<>();
+        AtomicReference<Exception> exReference = new AtomicReference<>();
+
+        CheckedConsumer<Boolean, ? extends Exception> handler = (o) -> {
+            if (Boolean.FALSE.equals(o)) {
+                throw new IllegalArgumentException("must not be false");
+            }
+            reference.set(o);
+        };
+        ActionListener<Boolean> wrap = ActionListener.wrap(handler, exReference::set);
+        wrap.onResponse(Boolean.FALSE);
+        assertNull(reference.get());
+        assertNotNull(exReference.get());
+        assertEquals("must not be false", exReference.get().getMessage());
+        exReference.set(null);
+
+        wrap.onResponse(Boolean.TRUE);
+        assertTrue(reference.get());
+        assertNull(exReference.get());
+    }
+
+    public void testOnResponse() {
+        final int numListeners = randomIntBetween(1, 20);
+        List<AtomicReference<Boolean>> refList = new ArrayList<>();
+        List<AtomicReference<Exception>> excList = new ArrayList<>();
+        List<ActionListener<Boolean>> listeners = new ArrayList<>();
+        List<Boolean> failOnTrue = new ArrayList<>();
+        AtomicInteger exceptionCounter = new AtomicInteger(0);
+        for (int i = 0; i < numListeners; i++) {
+            boolean doFailOnTrue = rarely();
+            failOnTrue.add(doFailOnTrue);
+            AtomicReference<Boolean> reference = new AtomicReference<>();
+            AtomicReference<Exception> exReference = new AtomicReference<>();
+            refList.add(reference);
+            excList.add(exReference);
+            CheckedConsumer<Boolean, ? extends Exception> handler = (o) -> {
+                if (Boolean.FALSE.equals(o)) {
+                    throw new IllegalArgumentException("must not be false " + exceptionCounter.getAndIncrement());
+                }
+                if (doFailOnTrue) {
+                    throw new IllegalStateException("must not be true");
+                }
+                reference.set(o);
+            };
+            listeners.add(ActionListener.wrap(handler, exReference::set));
+        }
+
+        ActionListener.onResponse(listeners, Boolean.TRUE);
+        for (int i = 0; i < numListeners; i++) {
+            if (failOnTrue.get(i) == false) {
+                assertTrue("listener index " + i, refList.get(i).get());
+                refList.get(i).set(null);
+            } else {
+                assertNull("listener index " + i, refList.get(i).get());
+            }
+
+        }
+
+        for (int i = 0; i < numListeners; i++) {
+            if (failOnTrue.get(i) == false) {
+                assertNull("listener index " + i, excList.get(i).get());
+            } else {
+                assertEquals("listener index " + i, "must not be true", excList.get(i).get().getMessage());
+            }
+        }
+
+        ActionListener.onResponse(listeners, Boolean.FALSE);
+        for (int i = 0; i < numListeners; i++) {
+            assertNull("listener index " + i, refList.get(i).get());
+        }
+
+        assertEquals(numListeners, exceptionCounter.get());
+        for (int i = 0; i < numListeners; i++) {
+            assertNotNull(excList.get(i).get());
+            assertEquals("listener index " + i, "must not be false " + i, excList.get(i).get().getMessage());
+        }
+    }
+
+    public void testOnFailure() {
+        final int numListeners = randomIntBetween(1, 20);
+        List<AtomicReference<Boolean>> refList = new ArrayList<>();
+        List<AtomicReference<Exception>> excList = new ArrayList<>();
+        List<ActionListener<Boolean>> listeners = new ArrayList<>();
+
+        final int listenerToFail = randomBoolean() ? -1 : randomIntBetween(0, numListeners-1);
+        for (int i = 0; i < numListeners; i++) {
+            AtomicReference<Boolean> reference = new AtomicReference<>();
+            AtomicReference<Exception> exReference = new AtomicReference<>();
+            refList.add(reference);
+            excList.add(exReference);
+            boolean fail = i == listenerToFail;
+            CheckedConsumer<Boolean, ? extends Exception> handler = (o) -> {
+                reference.set(o);
+            };
+            listeners.add(ActionListener.wrap(handler, (e) -> {
+                exReference.set(e);
+                if (fail) {
+                    throw new RuntimeException("double boom");
+                }
+            }));
+        }
+
+        try {
+            ActionListener.onFailure(listeners, new Exception("booom"));
+            assertTrue("unexpected succces listener to fail: " + listenerToFail, listenerToFail == -1);
+        } catch (RuntimeException ex) {
+            assertTrue("listener to fail: " + listenerToFail, listenerToFail >= 0);
+            assertNotNull(ex.getCause());
+            assertEquals("double boom", ex.getCause().getMessage());
+        }
+
+        for (int i = 0; i < numListeners; i++) {
+            assertNull("listener index " + i, refList.get(i).get());
+        }
+
+        for (int i = 0; i < numListeners; i++) {
+            assertEquals("listener index " + i, "booom", excList.get(i).get().getMessage());
+        }
+    }
+}