| /* |
| * Copyright (C) 2016, Google Inc. |
| * and other copyright owners as documented in the project's IP log. |
| * |
| * This program and the accompanying materials are made available |
| * under the terms of the Eclipse Distribution License v1.0 which |
| * accompanies this distribution, is reproduced below, and is |
| * available at http://www.eclipse.org/org/documents/edl-v10.php |
| * |
| * All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or |
| * without modification, are permitted provided that the following |
| * conditions are met: |
| * |
| * - Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * |
| * - Redistributions in binary form must reproduce the above |
| * copyright notice, this list of conditions and the following |
| * disclaimer in the documentation and/or other materials provided |
| * with the distribution. |
| * |
| * - Neither the name of the Eclipse Foundation, Inc. nor the |
| * names of its contributors may be used to endorse or promote |
| * products derived from this software without specific prior |
| * written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND |
| * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, |
| * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
| * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR |
| * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
| * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; |
| * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER |
| * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, |
| * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
| * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF |
| * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| package org.eclipse.jgit.internal.ketch; |
| |
| import static org.eclipse.jgit.internal.ketch.KetchConstants.ACCEPTED; |
| import static org.eclipse.jgit.internal.ketch.KetchConstants.COMMITTED; |
| import static org.eclipse.jgit.internal.ketch.KetchConstants.CONFIG_KEY_TYPE; |
| import static org.eclipse.jgit.internal.ketch.KetchConstants.CONFIG_SECTION_KETCH; |
| import static org.eclipse.jgit.internal.ketch.KetchConstants.DEFAULT_TXN_NAMESPACE; |
| import static org.eclipse.jgit.internal.ketch.KetchConstants.STAGE; |
| import static org.eclipse.jgit.lib.ConfigConstants.CONFIG_KEY_NAME; |
| import static org.eclipse.jgit.lib.ConfigConstants.CONFIG_KEY_REMOTE; |
| |
| import java.net.URISyntaxException; |
| import java.util.ArrayList; |
| import java.util.List; |
| import java.util.Random; |
| import java.util.concurrent.Executors; |
| import java.util.concurrent.ScheduledExecutorService; |
| import java.util.concurrent.ThreadFactory; |
| import java.util.concurrent.atomic.AtomicInteger; |
| |
| import org.eclipse.jgit.annotations.Nullable; |
| import org.eclipse.jgit.lib.Config; |
| import org.eclipse.jgit.lib.PersonIdent; |
| import org.eclipse.jgit.lib.Repository; |
| import org.eclipse.jgit.transport.RemoteConfig; |
| import org.eclipse.jgit.transport.URIish; |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| /** |
| * Ketch system-wide configuration. |
| * <p> |
| * This class provides useful defaults for testing and small proof of concepts. |
| * Full scale installations are expected to subclass and override methods to |
| * provide consistent configuration across all managed repositories. |
| * <p> |
| * Servers should configure their own {@link ScheduledExecutorService}. |
| */ |
| public class KetchSystem { |
| private static final Random RNG = new Random(); |
| |
| /** @return default executor, one thread per available processor. */ |
| public static ScheduledExecutorService defaultExecutor() { |
| return DefaultExecutorHolder.I; |
| } |
| |
| private final ScheduledExecutorService executor; |
| private final String txnNamespace; |
| private final String txnAccepted; |
| private final String txnCommitted; |
| private final String txnStage; |
| |
| /** Create a default system with a thread pool of 1 thread per CPU. */ |
| public KetchSystem() { |
| this(defaultExecutor(), DEFAULT_TXN_NAMESPACE); |
| } |
| |
| /** |
| * Create a Ketch system with the provided executor service. |
| * |
| * @param executor |
| * thread pool to run background operations. |
| * @param txnNamespace |
| * reference namespace for the RefTree graph and associated |
| * transaction state. Must begin with {@code "refs/"} and end |
| * with {@code '/'}, for example {@code "refs/txn/"}. |
| */ |
| public KetchSystem(ScheduledExecutorService executor, String txnNamespace) { |
| this.executor = executor; |
| this.txnNamespace = txnNamespace; |
| this.txnAccepted = txnNamespace + ACCEPTED; |
| this.txnCommitted = txnNamespace + COMMITTED; |
| this.txnStage = txnNamespace + STAGE; |
| } |
| |
| /** @return executor to perform background operations. */ |
| public ScheduledExecutorService getExecutor() { |
| return executor; |
| } |
| |
| /** |
| * Get the namespace used for the RefTree graph and transaction management. |
| * |
| * @return reference namespace such as {@code "refs/txn/"}. |
| */ |
| public String getTxnNamespace() { |
| return txnNamespace; |
| } |
| |
| /** @return name of the accepted RefTree graph. */ |
| public String getTxnAccepted() { |
| return txnAccepted; |
| } |
| |
| /** @return name of the committed RefTree graph. */ |
| public String getTxnCommitted() { |
| return txnCommitted; |
| } |
| |
| /** @return prefix for staged objects, e.g. {@code "refs/txn/stage/"}. */ |
| public String getTxnStage() { |
| return txnStage; |
| } |
| |
| /** @return identity line for the committer header of a RefTreeGraph. */ |
| public PersonIdent newCommitter() { |
| String name = "ketch"; //$NON-NLS-1$ |
| String email = "ketch@system"; //$NON-NLS-1$ |
| return new PersonIdent(name, email); |
| } |
| |
| /** |
| * Construct a random tag to identify a candidate during leader election. |
| * <p> |
| * Multiple processes trying to elect themselves leaders at exactly the same |
| * time (rounded to seconds) using the same {@link #newCommitter()} identity |
| * strings, for the same term, may generate the same ObjectId for the |
| * election commit and falsely assume they have both won. |
| * <p> |
| * Candidates add this tag to their election ballot commit to disambiguate |
| * the election. The tag only needs to be unique for a given triplet of |
| * {@link #newCommitter()}, system time (rounded to seconds), and term. If |
| * every replica in the system uses a unique {@code newCommitter} (such as |
| * including the host name after the {@code "@"} in the email address) the |
| * tag could be the empty string. |
| * <p> |
| * The default implementation generates a few bytes of random data. |
| * |
| * @return unique tag; null or empty string if {@code newCommitter()} is |
| * sufficiently unique to identify the leader. |
| */ |
| @Nullable |
| public String newLeaderTag() { |
| int n = RNG.nextInt(1 << (6 * 4)); |
| return String.format("%06x", Integer.valueOf(n)); //$NON-NLS-1$ |
| } |
| |
| /** |
| * Construct the KetchLeader instance of a repository. |
| * |
| * @param repo |
| * local repository stored by the leader. |
| * @return leader instance. |
| * @throws URISyntaxException |
| * a follower configuration contains an unsupported URI. |
| */ |
| public KetchLeader createLeader(final Repository repo) |
| throws URISyntaxException { |
| KetchLeader leader = new KetchLeader(this) { |
| @Override |
| protected Repository openRepository() { |
| repo.incrementOpen(); |
| return repo; |
| } |
| }; |
| leader.setReplicas(createReplicas(leader, repo)); |
| return leader; |
| } |
| |
| /** |
| * Get the collection of replicas for a repository. |
| * <p> |
| * The collection of replicas must include the local repository. |
| * |
| * @param leader |
| * the leader driving these replicas. |
| * @param repo |
| * repository to get the replicas of. |
| * @return collection of replicas for the specified repository. |
| * @throws URISyntaxException |
| * a configured URI is invalid. |
| */ |
| protected List<KetchReplica> createReplicas(KetchLeader leader, |
| Repository repo) throws URISyntaxException { |
| List<KetchReplica> replicas = new ArrayList<>(); |
| Config cfg = repo.getConfig(); |
| String localName = getLocalName(cfg); |
| for (String name : cfg.getSubsections(CONFIG_KEY_REMOTE)) { |
| if (!hasParticipation(cfg, name)) { |
| continue; |
| } |
| |
| ReplicaConfig kc = ReplicaConfig.newFromConfig(cfg, name); |
| if (name.equals(localName)) { |
| replicas.add(new LocalReplica(leader, name, kc)); |
| continue; |
| } |
| |
| RemoteConfig rc = new RemoteConfig(cfg, name); |
| List<URIish> uris = rc.getPushURIs(); |
| if (uris.isEmpty()) { |
| uris = rc.getURIs(); |
| } |
| for (URIish uri : uris) { |
| String n = uris.size() == 1 ? name : uri.getHost(); |
| replicas.add(new RemoteGitReplica(leader, n, uri, kc, rc)); |
| } |
| } |
| return replicas; |
| } |
| |
| private static boolean hasParticipation(Config cfg, String name) { |
| return cfg.getString(CONFIG_KEY_REMOTE, name, CONFIG_KEY_TYPE) != null; |
| } |
| |
| private static String getLocalName(Config cfg) { |
| return cfg.getString(CONFIG_SECTION_KETCH, null, CONFIG_KEY_NAME); |
| } |
| |
| static class DefaultExecutorHolder { |
| private static final Logger log = LoggerFactory.getLogger(KetchSystem.class); |
| static final ScheduledExecutorService I = create(); |
| |
| private static ScheduledExecutorService create() { |
| int cores = Runtime.getRuntime().availableProcessors(); |
| int threads = Math.max(5, cores); |
| log.info("Using {} threads", Integer.valueOf(threads)); //$NON-NLS-1$ |
| return Executors.newScheduledThreadPool( |
| threads, |
| new ThreadFactory() { |
| private final AtomicInteger threadCnt = new AtomicInteger(); |
| |
| @Override |
| public Thread newThread(Runnable r) { |
| int id = threadCnt.incrementAndGet(); |
| Thread thr = new Thread(r); |
| thr.setName("KetchExecutor-" + id); //$NON-NLS-1$ |
| return thr; |
| } |
| }); |
| } |
| |
| private DefaultExecutorHolder() { |
| } |
| } |
| |
| /** |
| * Compute a delay in a {@code min..max} interval with random jitter. |
| * |
| * @param last |
| * amount of delay waited before the last attempt. This is used |
| * to seed the next delay interval. Should be 0 if there was no |
| * prior delay. |
| * @param min |
| * shortest amount of allowable delay between attempts. |
| * @param max |
| * longest amount of allowable delay between attempts. |
| * @return new amount of delay to wait before the next attempt. |
| */ |
| static long delay(long last, long min, long max) { |
| long r = Math.max(0, last * 3 - min); |
| if (r > 0) { |
| int c = (int) Math.min(r + 1, Integer.MAX_VALUE); |
| r = RNG.nextInt(c); |
| } |
| return Math.max(Math.min(min + r, max), min); |
| } |
| } |