Java tutorial
/* * 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.solr.cloud; import java.io.ByteArrayInputStream; import java.io.File; import java.io.IOException; import java.io.InputStream; import java.lang.invoke.MethodHandles; import java.nio.file.Path; import java.util.List; import java.util.Properties; import org.apache.solr.common.SolrException; import org.apache.solr.common.SolrException.ErrorCode; import org.apache.solr.common.cloud.ZkConfigManager; import org.apache.solr.common.cloud.ZooKeeperException; import org.apache.solr.core.SolrResourceLoader; import org.apache.solr.core.SolrResourceNotFoundException; import org.apache.solr.schema.ZkIndexSchemaReader; import org.apache.zookeeper.KeeperException; import org.apache.zookeeper.data.Stat; import org.slf4j.Logger; import org.slf4j.LoggerFactory; /** * ResourceLoader that works with ZooKeeper. * */ public class ZkSolrResourceLoader extends SolrResourceLoader { private final String configSetZkPath; private ZkController zkController; private ZkIndexSchemaReader zkIndexSchemaReader; private static final Logger log = LoggerFactory.getLogger(MethodHandles.lookup().lookupClass()); public ZkSolrResourceLoader(Path instanceDir, String configSet, ZkController zooKeeperController) { super(instanceDir); this.zkController = zooKeeperController; configSetZkPath = ZkConfigManager.CONFIGS_ZKNODE + "/" + configSet; } /** * <p> * This loader will first attempt to load resources from ZooKeeper, but if not found * will delegate to the context classloader when possible, * otherwise it will attempt to resolve resources using any jar files found in * the "lib/" directory in the specified instance directory. */ public ZkSolrResourceLoader(Path instanceDir, String configSet, ClassLoader parent, Properties coreProperties, ZkController zooKeeperController) { super(instanceDir, parent, coreProperties); this.zkController = zooKeeperController; configSetZkPath = ZkConfigManager.CONFIGS_ZKNODE + "/" + configSet; } /** * Opens any resource by its name. By default, this will look in multiple * locations to load the resource: $configDir/$resource from ZooKeeper. * It will look for it in any jar * accessible through the class loader if it cannot be found in ZooKeeper. * Override this method to customize loading resources. * * @return the stream for the named resource */ @Override public InputStream openResource(String resource) throws IOException { InputStream is; String file = (".".equals(resource)) ? configSetZkPath : configSetZkPath + "/" + resource; int maxTries = 10; Exception exception = null; while (maxTries-- > 0) { try { if (zkController.pathExists(file)) { Stat stat = new Stat(); byte[] bytes = zkController.getZkClient().getData(file, null, stat, true); return new ZkByteArrayInputStream(bytes, stat); } else { //Path does not exists. We only retry for session expired exceptions. break; } } catch (KeeperException.SessionExpiredException e) { exception = e; if (!zkController.getCoreContainer().isShutDown()) { // Retry in case of session expiry try { Thread.sleep(1000); log.debug("Sleeping for 1s before retrying fetching resource=" + resource); } catch (InterruptedException ie) { Thread.currentThread().interrupt(); throw new IOException("Could not load resource=" + resource, ie); } } } catch (InterruptedException e) { Thread.currentThread().interrupt(); throw new IOException("Error opening " + file, e); } catch (Exception e) { throw new IOException("Error opening " + file, e); } } if (exception != null) { throw new IOException( "We re-tried 10 times but was still unable to fetch resource=" + resource + " from ZK", exception); } try { // delegate to the class loader (looking into $INSTANCE_DIR/lib jars) is = classLoader.getResourceAsStream(resource.replace(File.separatorChar, '/')); } catch (Exception e) { throw new IOException("Error opening " + resource, e); } if (is == null) { throw new SolrResourceNotFoundException("Can't find resource '" + resource + "' in classpath or '" + configSetZkPath + "', cwd=" + System.getProperty("user.dir")); } return is; } public static class ZkByteArrayInputStream extends ByteArrayInputStream { private final Stat stat; public ZkByteArrayInputStream(byte[] buf, Stat stat) { super(buf); this.stat = stat; } public Stat getStat() { return stat; } } @Override public String getConfigDir() { throw new ZooKeeperException(ErrorCode.SERVER_ERROR, "ZkSolrResourceLoader does not support getConfigDir() - likely, what you are trying to do is not supported in ZooKeeper mode"); } @Override public String[] listConfigDir() { List<String> list; try { list = zkController.getZkClient().getChildren(configSetZkPath, null, true); } catch (InterruptedException e) { // Restore the interrupted status Thread.currentThread().interrupt(); log.error("", e); throw new ZooKeeperException(SolrException.ErrorCode.SERVER_ERROR, "", e); } catch (KeeperException e) { log.error("", e); throw new ZooKeeperException(SolrException.ErrorCode.SERVER_ERROR, "", e); } return list.toArray(new String[0]); } public String getConfigSetZkPath() { return configSetZkPath; } public ZkController getZkController() { return zkController; } public void setZkIndexSchemaReader(ZkIndexSchemaReader zkIndexSchemaReader) { this.zkIndexSchemaReader = zkIndexSchemaReader; } public ZkIndexSchemaReader getZkIndexSchemaReader() { return zkIndexSchemaReader; } }