New effector to remove entities

core/src/main/java/org/apache/brooklyn/core/effector/RemoveEntityEffector.java

@@ -0,0 +1,105 @@
+/*
+ * 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.brooklyn.core.effector;
+
+import java.util.Map;
+
+import org.apache.brooklyn.api.effector.Effector;
+import org.apache.brooklyn.api.entity.Entity;
+import org.apache.brooklyn.config.ConfigKey;
+import org.apache.brooklyn.core.config.ConfigKeys;
+import org.apache.brooklyn.core.effector.Effectors.EffectorBuilder;
+import org.apache.brooklyn.core.entity.EntityInitializers;
+import org.apache.brooklyn.core.entity.EntityPredicates;
+import org.apache.brooklyn.util.core.config.ConfigBag;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import com.google.common.annotations.Beta;
+import com.google.common.base.Optional;
+import com.google.common.base.Predicate;
+import com.google.common.collect.Iterables;
+import com.google.common.reflect.TypeToken;
+
+/**
+ * @since 0.11.0
+ */
+@Beta
+public class RemoveEntityEffector extends AddEffector {
+
+    private static final Logger LOG = LoggerFactory.getLogger(RemoveEntityEffector.class);
+
+    public static final ConfigKey<String> ENTITY_ID = ConfigKeys.builder(String.class)
+            .name("entityId")
+            .description("The id of the entity to be removed")
+            .build();
+
+    public static final ConfigKey<Predicate<Entity>> ENTITY_PREDICATE = ConfigKeys.builder(new TypeToken<Predicate<Entity>>() { })
+            .name("predicate")
+            .description("A predicate that will match the entity to be removed")
+            .build();
+
+    public RemoveEntityEffector(ConfigBag params) {
+        super(newEffectorBuilder(params).build());
+    }
+
+    public RemoveEntityEffector(Map<String,String> params) {
+        this(ConfigBag.newInstance(params));
+    }
+
+    public static EffectorBuilder<Boolean> newEffectorBuilder(ConfigBag params) {
+        EffectorBuilder<Boolean> eff = (EffectorBuilder) AddEffector.newEffectorBuilder(Boolean.class, params);
+        eff.impl(new Body(eff.buildAbstract(), params));
+        return eff;
+    }
+
+    protected static class Body extends EffectorBody<Boolean> {
+        protected final Effector<?> effector;
+        protected final ConfigBag config;
+
+        protected Object mutex = new Object[0];
+
+        public Body(Effector<?> eff, ConfigBag config) {
+            this.effector = eff;
+            this.config = config;
+        }
+
+        @Override
+        public Boolean call(final ConfigBag params) {
+            synchronized (mutex) {
+                Predicate<Entity> predicate = EntityInitializers.resolve(params, ENTITY_PREDICATE);
+                if (predicate == null) {
+                    String entityId = EntityInitializers.resolve(params, ENTITY_ID);
+                    predicate = EntityPredicates.idEqualTo(entityId);
+                }
+                Optional<Entity> child = Iterables.tryFind(entity().getChildren(), predicate);
+                if (child.isPresent()) {
+                    boolean success = entity().removeChild(child.get());
+                    if (success) {
+                        LOG.debug("{}: Removed child {} from {}", new Object[] { this, child.get(), entity() });
+                        return true;
+                    }
+                }
+                LOG.warn("{}: Could not find child of {} using {}", new Object[] { this, entity(), predicate });
+                return false;
+            }
+        }
+    }
+
+}