| /* |
| * 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.ignite.examples.datagrid; |
| |
| import javax.cache.Cache; |
| import javax.cache.configuration.Factory; |
| import javax.cache.event.CacheEntryEvent; |
| import javax.cache.event.CacheEntryEventFilter; |
| import javax.cache.event.CacheEntryUpdatedListener; |
| import org.apache.ignite.Ignite; |
| import org.apache.ignite.IgniteCache; |
| import org.apache.ignite.Ignition; |
| import org.apache.ignite.cache.query.ContinuousQuery; |
| import org.apache.ignite.cache.query.QueryCursor; |
| import org.apache.ignite.cache.query.ScanQuery; |
| import org.apache.ignite.examples.ExampleNodeStartup; |
| import org.apache.ignite.lang.IgniteBiPredicate; |
| |
| /** |
| * This examples demonstrates continuous query API. |
| * <p> |
| * Remote nodes should always be started with special configuration file which |
| * enables P2P class loading: {@code 'ignite.{sh|bat} examples/config/example-ignite.xml'}. |
| * <p> |
| * Alternatively you can run {@link ExampleNodeStartup} in another JVM which will |
| * start node with {@code examples/config/example-ignite.xml} configuration. |
| */ |
| public class CacheContinuousQueryExample { |
| /** Cache name. */ |
| private static final String CACHE_NAME = CacheContinuousQueryExample.class.getSimpleName(); |
| |
| /** |
| * Executes example. |
| * |
| * @param args Command line arguments, none required. |
| * @throws Exception If example execution failed. |
| */ |
| public static void main(String[] args) throws Exception { |
| try (Ignite ignite = Ignition.start("examples/config/example-ignite.xml")) { |
| System.out.println(); |
| System.out.println(">>> Cache continuous query example started."); |
| |
| // Auto-close cache at the end of the example. |
| try (IgniteCache<Integer, String> cache = ignite.getOrCreateCache(CACHE_NAME)) { |
| int keyCnt = 20; |
| |
| // These entries will be queried by initial predicate. |
| for (int i = 0; i < keyCnt; i++) |
| cache.put(i, Integer.toString(i)); |
| |
| // Create new continuous query. |
| ContinuousQuery<Integer, String> qry = new ContinuousQuery<>(); |
| |
| qry.setInitialQuery(new ScanQuery<>(new IgniteBiPredicate<Integer, String>() { |
| @Override public boolean apply(Integer key, String val) { |
| return key > 10; |
| } |
| })); |
| |
| // Callback that is called locally when update notifications are received. |
| qry.setLocalListener(new CacheEntryUpdatedListener<Integer, String>() { |
| @Override public void onUpdated(Iterable<CacheEntryEvent<? extends Integer, ? extends String>> evts) { |
| for (CacheEntryEvent<? extends Integer, ? extends String> e : evts) |
| System.out.println("Updated entry [key=" + e.getKey() + ", val=" + e.getValue() + ']'); |
| } |
| }); |
| |
| // This filter will be evaluated remotely on all nodes. |
| // Entry that pass this filter will be sent to the caller. |
| qry.setRemoteFilterFactory(new Factory<CacheEntryEventFilter<Integer, String>>() { |
| @Override public CacheEntryEventFilter<Integer, String> create() { |
| return new CacheEntryEventFilter<Integer, String>() { |
| @Override public boolean evaluate(CacheEntryEvent<? extends Integer, ? extends String> e) { |
| return e.getKey() > 10; |
| } |
| }; |
| } |
| }); |
| |
| // Execute query. |
| try (QueryCursor<Cache.Entry<Integer, String>> cur = cache.query(qry)) { |
| // Iterate through existing data. |
| for (Cache.Entry<Integer, String> e : cur) |
| System.out.println("Queried existing entry [key=" + e.getKey() + ", val=" + e.getValue() + ']'); |
| |
| // Add a few more keys and watch more query notifications. |
| for (int i = keyCnt; i < keyCnt + 10; i++) |
| cache.put(i, Integer.toString(i)); |
| |
| // Wait for a while while callback is notified about remaining puts. |
| Thread.sleep(2000); |
| } |
| } |
| finally { |
| // Distributed cache could be removed from cluster only by #destroyCache() call. |
| ignite.destroyCache(CACHE_NAME); |
| } |
| } |
| } |
| } |