refs: eclipse#8 eclipse#9 introduce a way to handle dynamic config ch…

…anges

This is just the basic approach for now

api/src/main/java/javax/config/Config.java

@@ -32,6 +32,8 @@
 package javax.config;
 
 import java.util.Optional;
+import java.util.Set;
+import java.util.function.Consumer;
 
 import javax.config.spi.ConfigSource;
 
@@ -127,4 +129,12 @@ public interface Config {
      * @return all currently registered {@link ConfigSource configsources} sorted with descending ordinal and ConfigSource name
      */
     Iterable<ConfigSource> getConfigSources();
+
+    /**
+     * A user can register a lambda which gets notified when any configured value
+     * got changed. The parameter are the config key names which did change.
+     *
+     * @param configChangedListener
+     */
+    void registerConfigChangedListener(Consumer<Set<String>> configChangedListener);
 }

api/src/main/java/javax/config/spi/ConfigSource.java

@@ -32,6 +32,7 @@
 
 import java.util.Map;
 import java.util.Set;
+import java.util.function.Consumer;
 
 /**
  * <p>Implement this interfaces to provide a ConfigSource.
@@ -64,6 +65,8 @@
  */
 public interface ConfigSource {
     String CONFIG_ORDINAL = "config_ordinal";
+    int DEFAULT_ORDINAL = 100;
+
     /**
      * Return the properties in this config source
      * @return the map containing the properties in this config source
@@ -114,7 +117,7 @@ default int getOrdinal() {
 
             }
         }
-        return 100;
+        return DEFAULT_ORDINAL;
     }
 
     /**
@@ -131,4 +134,14 @@ default int getOrdinal() {
      */
     String getName();
 
+    /**
+     * This callback should get invoked if an attribute change got detected.
+     *
+     * @param reportAttributeChange will be set by the {@link ConfigSourceProvider} after this
+     *                              {@code ConfigSource} got created and before any configured values
+     *                              get served.
+     */
+    default void setOnAttributeChange(Consumer<Set<String>> reportAttributeChange) {
+        // do nothing by default. Just for compat with older ConfigSources.
+    }
 }

tck/src/main/java/org/eclipse/configjsr/DynamicConfigSourceTest.java

@@ -0,0 +1,94 @@
+/*
+ * Copyright (c) 2016-2017 Contributors to the Eclipse Foundation
+ *
+ * See the NOTICE file(s) distributed with this work for additional
+ * information regarding copyright ownership.
+ *
+ * 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.eclipse.configjsr;
+
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+
+import javax.config.Config;
+import javax.config.spi.ConfigSource;
+import javax.inject.Inject;
+
+import org.eclipse.configjsr.dynamic.DynamicChangeConfigSource;
+import org.jboss.arquillian.container.test.api.Deployment;
+import org.jboss.arquillian.testng.Arquillian;
+import org.jboss.shrinkwrap.api.ShrinkWrap;
+import org.jboss.shrinkwrap.api.asset.EmptyAsset;
+import org.jboss.shrinkwrap.api.spec.JavaArchive;
+import org.jboss.shrinkwrap.api.spec.WebArchive;
+import org.testng.annotations.Test;
+
+import static org.testng.Assert.assertEquals;
+import static org.testng.Assert.assertTrue;
+
+/**
+ * @author <a href="mailto:[email protected]">Mark Struberg</a>
+ */
+public class DynamicConfigSourceTest extends Arquillian {
+
+    private @Inject Config config;
+
+    @Deployment
+    public static WebArchive deploy() {
+        JavaArchive testJar = ShrinkWrap
+                .create(JavaArchive.class, "dynamicValuesTest.jar")
+                .addClass(DynamicConfigSourceTest.class)
+                .addAsManifestResource(EmptyAsset.INSTANCE, "beans.xml")
+                .addAsServiceProvider(ConfigSource.class, DynamicChangeConfigSource.class)
+                .as(JavaArchive.class);
+
+
+        WebArchive war = ShrinkWrap
+                .create(WebArchive.class, "dynamicValuesTest.war")
+                .addAsLibrary(testJar);
+        return war;
+    }
+
+
+    @Test
+    public void testBgCount() throws Exception {
+        Integer value = config.getValue(DynamicChangeConfigSource.TEST_ATTRIBUTE, Integer.class);
+        Thread.sleep(20L);
+        Integer value2 = config.getValue(DynamicChangeConfigSource.TEST_ATTRIBUTE, Integer.class);
+        assertTrue(value2 > value);
+    }
+
+    @Test
+    public void testBgCallback() throws Exception {
+        Integer value = config.getValue(DynamicChangeConfigSource.TEST_ATTRIBUTE, Integer.class);
+        Map<String, Integer> vals = new ConcurrentHashMap<>();
+
+
+        config.registerConfigChangedListener(s -> s.forEach(k -> vals.put(k, config.getValue(k, Integer.class))));
+        vals.clear();
+
+        Thread.sleep(12L);
+        assertEquals(1, vals.size());
+
+        int i1 = vals.get(DynamicChangeConfigSource.TEST_ATTRIBUTE);
+
+        Thread.sleep(15L);
+        assertEquals(1, vals.size());
+
+        int i2 = vals.get(DynamicChangeConfigSource.TEST_ATTRIBUTE);
+        assertTrue(i2 > i1);
+    }
+
+}

tck/src/main/java/org/eclipse/configjsr/dynamic/DynamicChangeConfigSource.java

@@ -0,0 +1,86 @@
+/*
+ * 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.eclipse.configjsr.dynamic;
+
+import java.io.Closeable;
+import java.io.IOException;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.function.Consumer;
+
+import javax.config.spi.ConfigSource;
+
+/**
+ * @author <a href="mailto:[email protected]">Mark Struberg</a>
+ */
+public class DynamicChangeConfigSource implements ConfigSource, Closeable {
+    public static final String TEST_ATTRIBUTE = "tck.config.test.javaconfig.dynymic.testattrib";
+
+    private Consumer<Set<String>> reportAttributeChange;
+    private AtomicInteger i = new AtomicInteger(0);
+    private Map<String, String> properties = new HashMap<>();
+    private Thread worker;
+
+    public DynamicChangeConfigSource() {
+        // start a new backgroundthread.
+        worker = new Thread() {
+            @Override
+            public void run() {
+                while (i.incrementAndGet() < 10_000) {
+                    reportAttributeChange.accept(Collections.singleton(TEST_ATTRIBUTE));
+                    try {
+                        Thread.sleep(10L);
+                    }
+                    catch (InterruptedException e) {
+                        return;
+                    }
+                }
+            }
+        };
+        worker.start();
+    }
+
+    @Override
+    public void close() throws IOException {
+        i.set(10_001);
+    }
+
+    @Override
+    public Map<String, String> getProperties() {
+        properties.put(TEST_ATTRIBUTE, Integer.toString(i.get()));
+        return properties;
+    }
+
+    @Override
+    public String getValue(String propertyName) {
+        return getProperties().get(propertyName);
+    }
+
+    @Override
+    public String getName() {
+        return this.getClass().getSimpleName();
+    }
+
+    @Override
+    public void setOnAttributeChange(Consumer<Set<String>> reportAttributeChange) {
+        this.reportAttributeChange = reportAttributeChange;
+    }
+
+}