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 com.twitter.distributedlog; import com.google.common.base.Optional; import com.twitter.distributedlog.metadata.BKDLConfig; import com.twitter.distributedlog.metadata.DLMetadata; import org.apache.bookkeeper.conf.ServerConfiguration; import org.apache.bookkeeper.proto.BookieServer; import org.apache.bookkeeper.shims.zk.ZooKeeperServerShim; import org.apache.bookkeeper.util.IOUtils; import org.apache.bookkeeper.util.LocalBookKeeper; import org.apache.commons.io.FileUtils; import org.apache.commons.lang3.tuple.Pair; import org.apache.zookeeper.KeeperException; import org.apache.zookeeper.WatchedEvent; import org.apache.zookeeper.Watcher; import org.apache.zookeeper.ZooKeeper; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import java.io.File; import java.io.IOException; import java.net.BindException; import java.net.URI; import java.util.ArrayList; import java.util.List; import java.util.UUID; import java.util.concurrent.CountDownLatch; import java.util.concurrent.TimeUnit; /** * Utility class for setting up bookkeeper ensembles * and bringing individual bookies up and down */ public class LocalDLMEmulator { private static final Logger LOG = LoggerFactory.getLogger(LocalDLMEmulator.class); public static final String DLOG_NAMESPACE = "/messaging/distributedlog"; private static final int DEFAULT_BOOKIE_INITIAL_PORT = 0; // Use ephemeral ports private static final int DEFAULT_ZK_TIMEOUT_SEC = 10; private static final int DEFAULT_ZK_PORT = 2181; private static final String DEFAULT_ZK_HOST = "127.0.0.1"; private static final String DEFAULT_ZK_ENSEMBLE = DEFAULT_ZK_HOST + ":" + DEFAULT_ZK_PORT; private static final int DEFAULT_NUM_BOOKIES = 3; private static final ServerConfiguration DEFAULT_SERVER_CONFIGURATION = new ServerConfiguration(); private final String zkEnsemble; private final URI uri; private final List<File> tmpDirs = new ArrayList<File>(); private final int zkTimeoutSec; private final Thread bkStartupThread; private final String zkHost; private final int zkPort; private final int numBookies; public static class Builder { private int zkTimeoutSec = DEFAULT_ZK_TIMEOUT_SEC; private int numBookies = DEFAULT_NUM_BOOKIES; private String zkHost = DEFAULT_ZK_HOST; private int zkPort = DEFAULT_ZK_PORT; private int initialBookiePort = DEFAULT_BOOKIE_INITIAL_PORT; private boolean shouldStartZK = true; private Optional<ServerConfiguration> serverConf = Optional.absent(); public Builder numBookies(int numBookies) { this.numBookies = numBookies; return this; } public Builder zkHost(String zkHost) { this.zkHost = zkHost; return this; } public Builder zkPort(int zkPort) { this.zkPort = zkPort; return this; } public Builder zkTimeoutSec(int zkTimeoutSec) { this.zkTimeoutSec = zkTimeoutSec; return this; } public Builder initialBookiePort(int initialBookiePort) { this.initialBookiePort = initialBookiePort; return this; } public Builder shouldStartZK(boolean shouldStartZK) { this.shouldStartZK = shouldStartZK; return this; } public Builder serverConf(ServerConfiguration serverConf) { this.serverConf = Optional.of(serverConf); return this; } public LocalDLMEmulator build() throws Exception { ServerConfiguration conf = null; if (serverConf.isPresent()) { conf = serverConf.get(); } else { conf = (ServerConfiguration) DEFAULT_SERVER_CONFIGURATION.clone(); conf.setZkTimeout(zkTimeoutSec * 1000); } ServerConfiguration newConf = new ServerConfiguration(); newConf.loadConf(conf); newConf.setAllowLoopback(true); return new LocalDLMEmulator(numBookies, shouldStartZK, zkHost, zkPort, initialBookiePort, zkTimeoutSec, newConf); } } public static Builder newBuilder() { return new Builder(); } private LocalDLMEmulator(final int numBookies, final boolean shouldStartZK, final String zkHost, final int zkPort, final int initialBookiePort, final int zkTimeoutSec, final ServerConfiguration serverConf) throws Exception { this.numBookies = numBookies; this.zkHost = zkHost; this.zkPort = zkPort; this.zkEnsemble = zkHost + ":" + zkPort; this.uri = URI.create("distributedlog://" + zkEnsemble + DLOG_NAMESPACE); this.zkTimeoutSec = zkTimeoutSec; this.bkStartupThread = new Thread() { public void run() { try { LOG.info("Starting {} bookies : allowLoopback = {}", numBookies, serverConf.getAllowLoopback()); LocalBookKeeper.startLocalBookies(zkHost, zkPort, numBookies, shouldStartZK, initialBookiePort, serverConf); LOG.info("{} bookies are started."); } catch (InterruptedException e) { // go away quietly } catch (Exception e) { LOG.error("Error starting local bk", e); } } }; } public void start() throws Exception { bkStartupThread.start(); if (!LocalBookKeeper.waitForServerUp(zkEnsemble, zkTimeoutSec * 1000)) { throw new Exception("Error starting zookeeper/bookkeeper"); } int bookiesUp = checkBookiesUp(numBookies, zkTimeoutSec); assert (numBookies == bookiesUp); // Provision "/messaging/distributedlog" namespace DLMetadata.create(new BKDLConfig(zkEnsemble, "/ledgers")).create(uri); } public void teardown() throws Exception { if (bkStartupThread != null) { bkStartupThread.interrupt(); bkStartupThread.join(); } for (File dir : tmpDirs) { FileUtils.deleteDirectory(dir); } } public String getZkServers() { return zkEnsemble; } public URI getUri() { return uri; } public BookieServer newBookie() throws Exception { ServerConfiguration bookieConf = new ServerConfiguration(); bookieConf.setZkTimeout(zkTimeoutSec * 1000); bookieConf.setBookiePort(0); bookieConf.setAllowLoopback(true); File tmpdir = File.createTempFile("bookie" + UUID.randomUUID() + "_", "test"); if (!tmpdir.delete()) { LOG.debug("Fail to delete tmpdir " + tmpdir); } if (!tmpdir.mkdir()) { throw new IOException("Fail to create tmpdir " + tmpdir); } tmpDirs.add(tmpdir); bookieConf.setZkServers(zkEnsemble); bookieConf.setJournalDirName(tmpdir.getPath()); bookieConf.setLedgerDirNames(new String[] { tmpdir.getPath() }); BookieServer b = new BookieServer(bookieConf); b.start(); for (int i = 0; i < 10 && !b.isRunning(); i++) { Thread.sleep(10000); } if (!b.isRunning()) { throw new IOException("Bookie would not start"); } return b; } /** * Check that a number of bookies are available * * @param count number of bookies required * @param timeout number of seconds to wait for bookies to start * @throws java.io.IOException if bookies are not started by the time the timeout hits */ public int checkBookiesUp(int count, int timeout) throws Exception { ZooKeeper zkc = connectZooKeeper(zkHost, zkPort, zkTimeoutSec); try { int mostRecentSize = 0; for (int i = 0; i < timeout; i++) { try { List<String> children = zkc.getChildren("/ledgers/available", false); children.remove("readonly"); mostRecentSize = children.size(); if ((mostRecentSize > count) || LOG.isDebugEnabled()) { LOG.info("Found " + mostRecentSize + " bookies up, " + "waiting for " + count); if ((mostRecentSize > count) || LOG.isTraceEnabled()) { for (String child : children) { LOG.info(" server: " + child); } } } if (mostRecentSize == count) { break; } } catch (KeeperException e) { // ignore } Thread.sleep(1000); } return mostRecentSize; } finally { zkc.close(); } } public static String getBkLedgerPath() { return "/ledgers"; } public static ZooKeeper connectZooKeeper(String zkHost, int zkPort) throws IOException, KeeperException, InterruptedException { return connectZooKeeper(zkHost, zkPort, DEFAULT_ZK_TIMEOUT_SEC); } public static ZooKeeper connectZooKeeper(String zkHost, int zkPort, int zkTimeoutSec) throws IOException, KeeperException, InterruptedException { final CountDownLatch latch = new CountDownLatch(1); final String zkHostPort = zkHost + ":" + zkPort; ZooKeeper zkc = new ZooKeeper(zkHostPort, zkTimeoutSec * 1000, new Watcher() { public void process(WatchedEvent event) { if (event.getState() == Event.KeeperState.SyncConnected) { latch.countDown(); } } }); if (!latch.await(zkTimeoutSec, TimeUnit.SECONDS)) { throw new IOException("Zookeeper took too long to connect"); } return zkc; } public static URI createDLMURI(String path) throws Exception { return createDLMURI(DEFAULT_ZK_ENSEMBLE, path); } public static URI createDLMURI(String zkServers, String path) throws Exception { return URI.create("distributedlog://" + zkServers + DLOG_NAMESPACE + path); } /** * Try to start zookkeeper locally on any port. */ public static Pair<ZooKeeperServerShim, Integer> runZookeeperOnAnyPort(File zkDir) throws Exception { return runZookeeperOnAnyPort((int) (Math.random() * 10000 + 7000), zkDir); } /** * Try to start zookkeeper locally on any port beginning with some base port. * Dump some socket info when bind fails. */ public static Pair<ZooKeeperServerShim, Integer> runZookeeperOnAnyPort(int basePort, File zkDir) throws Exception { final int MAX_RETRIES = 20; final int MIN_PORT = 1025; final int MAX_PORT = 65535; ZooKeeperServerShim zks = null; int zkPort = basePort; boolean success = false; int retries = 0; while (!success) { try { LOG.info("zk trying to bind to port " + zkPort); zks = LocalBookKeeper.runZookeeper(1000, zkPort, zkDir); success = true; } catch (BindException be) { retries++; if (retries > MAX_RETRIES) { throw be; } zkPort++; if (zkPort > MAX_PORT) { zkPort = MIN_PORT; } } } return Pair.of(zks, zkPort); } public static void main(String[] args) throws Exception { try { if (args.length < 1) { System.out.println("Usage: LocalDLEmulator <zk_port>"); System.exit(-1); } final int zkPort = Integer.parseInt(args[0]); final File zkDir = IOUtils.createTempDir("distrlog", "zookeeper"); final LocalDLMEmulator localDlm = LocalDLMEmulator.newBuilder().zkPort(zkPort).build(); Runtime.getRuntime().addShutdownHook(new Thread() { @Override public void run() { try { localDlm.teardown(); FileUtils.deleteDirectory(zkDir); System.out.println("ByeBye!"); } catch (Exception e) { // do nothing } } }); localDlm.start(); System.out.println( String.format("DistributedLog Sandbox is running now. You could access distributedlog://%s:%s", DEFAULT_ZK_HOST, zkPort)); } catch (Exception ex) { System.out.println("Exception occurred running emulator " + ex); } } }