[isis] 03/04: ISIS-1871 ISIS-1755 let CDI ignore beans as specified

[ah...@apache.org]

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commit 7e409ca00e07c632f645035bc1e160d2fb79cd07
Author: Andi Huber <ah...@apache.org>
AuthorDate: Fri Feb 23 10:47:39 2018 +0100

    ISIS-1871 ISIS-1755 let CDI ignore beans as specified
---
 .../webapp/jee/IsisCDIBeanScanInterceptor.java     | 102 +++++++++++++++++++++
 .../services/javax.enterprise.inject.spi.Extension |   1 +
 2 files changed, 103 insertions(+)

diff --git a/core/runtime/src/main/java/org/apache/isis/core/webapp/jee/IsisCDIBeanScanInterceptor.java b/core/runtime/src/main/java/org/apache/isis/core/webapp/jee/IsisCDIBeanScanInterceptor.java
new file mode 100644
index 0000000..06fe4bf
--- /dev/null
+++ b/core/runtime/src/main/java/org/apache/isis/core/webapp/jee/IsisCDIBeanScanInterceptor.java
@@ -0,0 +1,102 @@
+/*
+ * 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
+ *
+ *       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.apache.isis.core.webapp.jee;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.function.Predicate;
+
+import javax.enterprise.event.Observes;
+import javax.enterprise.inject.spi.AfterBeanDiscovery;
+import javax.enterprise.inject.spi.BeforeBeanDiscovery;
+import javax.enterprise.inject.spi.Extension;
+import javax.enterprise.inject.spi.ProcessAnnotatedType;
+
+import org.apache.isis.applib.annotation.DomainService;
+import org.apache.isis.applib.services.exceprecog.ExceptionRecognizer;
+import org.apache.isis.applib.services.metrics.MetricsService;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * 
+ * A CDI inject extension @see <a href="https://docs.jboss.org/weld/reference/latest/en-US/html/extend.html">weld</a>,
+ * that lets CDI ignore certain Beans we declare tabu. 
+ * <p>
+ * This extension is registered as a service provider by creating a file named 
+ * {@code META-INF/services/javax.enterprise.inject.spi.Extension}, 
+ * which contains the name of this extension class.
+ * </p>
+ * 
+ * <p>
+ * Beans declared tabu are managed (meaning instantiation and dependency injection) 
+ * by Isis itself. All other Beans are allowed to be managed by CDI.
+ * </p>
+ * 
+ * @author ahuber@apache.org
+ *
+ */
+public final class IsisCDIBeanScanInterceptor implements Extension {
+	
+	private static final Logger log = LoggerFactory.getLogger(IsisCDIBeanScanInterceptor.class);
+
+	/**
+	 * Declaration of Beans that are managed by Isis and should be ignored by CDI. 
+	 * (in addition to those that have the @DomainService annotation)
+	 */
+	private static final List<Predicate<Class<?>>> tabu = new ArrayList<>();
+	{
+		tabu.add(MetricsService.class::equals);
+		tabu.add(ExceptionRecognizer.class::isAssignableFrom);
+	}
+	
+	void beforeBeanDiscovery(@Observes BeforeBeanDiscovery event) {
+		log.info("beginning the scanning process");
+	}
+
+	<T> void processAnnotatedType(@Observes ProcessAnnotatedType<T> event) {
+
+		final Class<?> clazz = event.getAnnotatedType().getJavaClass();
+		final String className = clazz.getName();
+		
+		if(isTabu(clazz, event)) {
+			log.debug("veto type: " + className);
+			event.veto();
+		} else {
+			log.debug("allowing type: " + className);
+		}
+	}
+
+	void afterBeanDiscovery(@Observes AfterBeanDiscovery event) {
+		log.info("finished the scanning process");
+	}
+	
+	// -- HELPER
+	
+	private boolean isTabu(Class<?> clazz, ProcessAnnotatedType<?> event) {
+		if(event.getAnnotatedType().isAnnotationPresent(DomainService.class))
+			return true;
+		for(Predicate<Class<?>> isTabu : tabu) {
+			if(isTabu.test(clazz))
+				return true;
+		}
+		return false;
+	}
+
+}
diff --git a/core/runtime/src/main/resources/META-INF/services/javax.enterprise.inject.spi.Extension b/core/runtime/src/main/resources/META-INF/services/javax.enterprise.inject.spi.Extension
new file mode 100644
index 0000000..1be69b2
--- /dev/null
+++ b/core/runtime/src/main/resources/META-INF/services/javax.enterprise.inject.spi.Extension
@@ -0,0 +1 @@
+org.apache.isis.core.webapp.jee.IsisCDIBeanScanInterceptor
\ No newline at end of file

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