INT-3519 Add Poll Skip Advice

JIRA: https://jira.spring.io/browse/INT-3519

Add a mechanism to allow skipping polls, perhaps
because of some downstream condition.

INT-3519: Polishing

spring-integration-core/src/test/java/org/springframework/integration/endpoint/PollerAdviceTests.java

@@ -0,0 +1,124 @@
+/*
+ * Copyright 2014 the original author or authors.
+ *
+ * Licensed 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.springframework.integration.endpoint;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+import static org.mockito.Mockito.mock;
+
+import java.util.ArrayList;
+import java.util.Date;
+import java.util.List;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.TimeUnit;
+
+import org.aopalliance.aop.Advice;
+import org.junit.Test;
+
+import org.springframework.beans.factory.BeanFactory;
+import org.springframework.integration.channel.NullChannel;
+import org.springframework.integration.core.MessageSource;
+import org.springframework.integration.scheduling.PollSkipAdvice;
+import org.springframework.integration.scheduling.PollSkipStrategy;
+import org.springframework.messaging.Message;
+import org.springframework.scheduling.Trigger;
+import org.springframework.scheduling.TriggerContext;
+import org.springframework.scheduling.concurrent.ThreadPoolTaskScheduler;
+
+/**
+ * @author Gary Russell
+ * @since 4.1
+ *
+ */
+public class PollerAdviceTests {
+
+	@Test
+	public void testDefaultDontSkip() throws Exception {
+		SourcePollingChannelAdapter adapter = new SourcePollingChannelAdapter();
+		final CountDownLatch latch = new CountDownLatch(1);
+		adapter.setSource(new MessageSource<Object>() {
+
+			@Override
+			public Message<Object> receive() {
+				latch.countDown();
+				return null;
+			}
+		});
+		adapter.setTrigger(new Trigger() {
+
+			@Override
+			public Date nextExecutionTime(TriggerContext triggerContext) {
+				return new Date(System.currentTimeMillis() + 10);
+			}
+		});
+		configure(adapter);
+		List<Advice> adviceChain = new ArrayList<Advice>();
+		PollSkipAdvice advice = new PollSkipAdvice();
+		adviceChain.add(advice);
+		adapter.setAdviceChain(adviceChain);
+		adapter.afterPropertiesSet();
+		adapter.start();
+		assertTrue(latch.await(10, TimeUnit.SECONDS));
+		adapter.stop();
+	}
+
+	@Test
+	public void testSkipAll() throws Exception {
+		SourcePollingChannelAdapter adapter = new SourcePollingChannelAdapter();
+		final CountDownLatch latch = new CountDownLatch(1);
+		adapter.setSource(new MessageSource<Object>() {
+
+			@Override
+			public Message<Object> receive() {
+				latch.countDown();
+				return null;
+			}
+		});
+		adapter.setTrigger(new Trigger() {
+
+			@Override
+			public Date nextExecutionTime(TriggerContext triggerContext) {
+				return new Date(System.currentTimeMillis() + 10);
+			}
+		});
+		configure(adapter);
+		List<Advice> adviceChain = new ArrayList<Advice>();
+		PollSkipAdvice advice = new PollSkipAdvice(new PollSkipStrategy() {
+
+			@Override
+			public boolean skipPoll() {
+				return true;
+			}
+
+		});
+		adviceChain.add(advice);
+		adapter.setAdviceChain(adviceChain);
+		adapter.afterPropertiesSet();
+		adapter.start();
+		assertFalse(latch.await(1, TimeUnit.SECONDS));
+		adapter.stop();
+	}
+
+	private void configure(SourcePollingChannelAdapter adapter) {
+		adapter.setOutputChannel(new NullChannel());
+		adapter.setBeanFactory(mock(BeanFactory.class));
+		ThreadPoolTaskScheduler scheduler = new ThreadPoolTaskScheduler();
+		scheduler.afterPropertiesSet();
+		adapter.setTaskScheduler(scheduler);
+	}
+
+}