https://issues.apache.org/jira/browse/AMQ-3379 - unique property eviction strategy

git-svn-id: https://svn.apache.org/repos/asf/activemq/trunk@1140531 13f79535-47bb-0310-9956-ffa450edef68

activemq-core/src/main/java/org/apache/activemq/broker/region/policy/UniquePropertyMessageEvictionStrategy.java

@@ -0,0 +1,77 @@
+/**
+ * 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.activemq.broker.region.policy;
+
+import org.apache.activemq.broker.region.MessageReference;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.Iterator;
+import java.util.LinkedList;
+
+
+/**
+ * An eviction strategy which evicts the oldest message with the lowest priority first.
+ *
+ * @org.apache.xbean.XBean
+ *
+ * messageEvictionStrategy
+ */
+public class UniquePropertyMessageEvictionStrategy extends MessageEvictionStrategySupport {
+
+    protected String propertyName;
+
+    public String getPropertyName() {
+        return propertyName;
+    }
+
+    public void setPropertyName(String propertyName) {
+        this.propertyName = propertyName;
+    }
+
+    @Override
+    public MessageReference[] evictMessages(LinkedList messages) throws IOException {
+        HashMap<Object, MessageReference> pivots = new HashMap<Object, MessageReference>();
+        Iterator iter = messages.iterator();
+
+        for (int i = 0; iter.hasNext(); i++) {
+            MessageReference reference = (MessageReference) iter.next();
+            if (propertyName != null && reference.getMessage().getProperty(propertyName) != null) {
+                Object key = reference.getMessage().getProperty(propertyName);
+                if (pivots.containsKey(key)) {
+                    MessageReference pivot = pivots.get(key);
+                    if (reference.getMessage().getTimestamp() > pivot.getMessage().getTimestamp()) {
+                         pivots.put(key, reference);
+                    }
+                } else {
+                    pivots.put(key, reference);
+                }
+            }
+        }
+
+        if (!pivots.isEmpty()) {
+            for (MessageReference ref : pivots.values()) {
+                messages.remove(ref);
+            }
+            return (MessageReference[])messages.toArray(new MessageReference[messages.size()]);
+        } else {
+            return new MessageReference[] {(MessageReference) messages.removeFirst()};
+        }
+
+    }
+}

activemq-core/src/test/java/org/apache/activemq/broker/region/UniquePropertyMessageEvictionStrategyTest.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.activemq.broker.region;
+
+import org.apache.activemq.EmbeddedBrokerTestSupport;
+import org.apache.activemq.broker.BrokerService;
+import org.apache.activemq.broker.region.policy.ConstantPendingMessageLimitStrategy;
+import org.apache.activemq.broker.region.policy.PolicyEntry;
+import org.apache.activemq.broker.region.policy.PolicyMap;
+import org.apache.activemq.broker.region.policy.UniquePropertyMessageEvictionStrategy;
+
+import javax.jms.*;
+import java.util.ArrayList;
+import java.util.List;
+
+public class UniquePropertyMessageEvictionStrategyTest extends EmbeddedBrokerTestSupport {
+
+
+
+    @Override
+    protected BrokerService createBroker() throws Exception {
+        BrokerService broker =  super.createBroker();
+                final List<PolicyEntry> policyEntries = new ArrayList<PolicyEntry>();
+        final PolicyEntry entry = new PolicyEntry();
+        entry.setTopic(">");
+
+        entry.setAdvisoryForDiscardingMessages(true);
+        entry.setTopicPrefetch(1);
+
+        ConstantPendingMessageLimitStrategy pendingMessageLimitStrategy = new ConstantPendingMessageLimitStrategy();
+        pendingMessageLimitStrategy.setLimit(10);
+        entry.setPendingMessageLimitStrategy(pendingMessageLimitStrategy);
+
+
+        UniquePropertyMessageEvictionStrategy messageEvictionStrategy = new UniquePropertyMessageEvictionStrategy();
+        messageEvictionStrategy.setPropertyName("sequenceI");
+        entry.setMessageEvictionStrategy(messageEvictionStrategy);
+
+        // let evicted messages disappear
+        entry.setDeadLetterStrategy(null);
+        policyEntries.add(entry);
+
+        final PolicyMap policyMap = new PolicyMap();
+        policyMap.setPolicyEntries(policyEntries);
+        broker.setDestinationPolicy(policyMap);
+
+        return broker;
+    }
+
+    public void testEviction() throws Exception {
+        Connection conn = connectionFactory.createConnection();
+        conn.start();
+        Session session = conn.createSession(false, Session.AUTO_ACKNOWLEDGE);
+        javax.jms.Topic destination = session.createTopic("TEST");
+
+        MessageProducer producer = session.createProducer(destination);
+        MessageConsumer consumer = session.createConsumer(destination);
+
+        for (int i = 0; i < 10; i++) {
+            for (int j = 0; j < 10; j++) {
+                TextMessage msg = session.createTextMessage("message " + i + j);
+                msg.setIntProperty("sequenceI", i);
+                msg.setIntProperty("sequenceJ", j);
+                producer.send(msg);
+                Thread.sleep(100);
+            }
+        }
+
+
+        for (int i = 0; i < 11; i++) {
+            javax.jms.Message msg = consumer.receive(1000);
+            assertNotNull(msg);
+            int seqI = msg.getIntProperty("sequenceI");
+            int seqJ = msg.getIntProperty("sequenceJ");
+            if (i ==0 ) {
+                assertEquals(0, seqI);
+                assertEquals(0, seqJ);
+            } else {
+                    assertEquals(9, seqJ);
+                    assertEquals(i - 1, seqI);
+            }
+            //System.out.println(msg.getIntProperty("sequenceI") + " " + msg.getIntProperty("sequenceJ"));
+        }
+
+        javax.jms.Message msg = consumer.receive(1000);
+        assertNull(msg);
+
+    }
+
+}