| /* |
| * Copyright (C) 2016, Google Inc. and others |
| * |
| * This program and the accompanying materials are made available under the |
| * terms of the Eclipse Distribution License v. 1.0 which is available at |
| * https://www.eclipse.org/org/documents/edl-v10.php. |
| * |
| * SPDX-License-Identifier: BSD-3-Clause |
| */ |
| |
| package org.eclipse.jgit.internal.ketch; |
| |
| import static java.util.concurrent.TimeUnit.SECONDS; |
| import static org.eclipse.jgit.internal.ketch.KetchConstants.TERM; |
| |
| import java.io.IOException; |
| import java.util.List; |
| import java.util.concurrent.TimeoutException; |
| |
| import org.eclipse.jgit.lib.CommitBuilder; |
| import org.eclipse.jgit.lib.ObjectId; |
| import org.eclipse.jgit.lib.ObjectInserter; |
| import org.eclipse.jgit.lib.Repository; |
| import org.eclipse.jgit.lib.TreeFormatter; |
| import org.eclipse.jgit.revwalk.RevCommit; |
| import org.eclipse.jgit.revwalk.RevWalk; |
| import org.eclipse.jgit.util.time.ProposedTimestamp; |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| /** |
| * The initial {@link Round} for a leaderless repository, used to establish a |
| * leader. |
| */ |
| class ElectionRound extends Round { |
| private static final Logger log = LoggerFactory.getLogger(ElectionRound.class); |
| |
| private long term; |
| |
| ElectionRound(KetchLeader leader, LogIndex head) { |
| super(leader, head); |
| } |
| |
| @Override |
| void start() throws IOException { |
| ObjectId id; |
| try (Repository git = leader.openRepository(); |
| ProposedTimestamp ts = getSystem().getClock().propose(); |
| ObjectInserter inserter = git.newObjectInserter()) { |
| id = bumpTerm(git, ts, inserter); |
| inserter.flush(); |
| blockUntil(ts); |
| } |
| runAsync(id); |
| } |
| |
| @Override |
| void success() { |
| // Do nothing upon election, KetchLeader will copy the term. |
| } |
| |
| long getTerm() { |
| return term; |
| } |
| |
| private ObjectId bumpTerm(Repository git, ProposedTimestamp ts, |
| ObjectInserter inserter) throws IOException { |
| CommitBuilder b = new CommitBuilder(); |
| if (!ObjectId.zeroId().equals(acceptedOldIndex)) { |
| try (RevWalk rw = new RevWalk(git)) { |
| RevCommit c = rw.parseCommit(acceptedOldIndex); |
| if (getSystem().requireMonotonicLeaderElections()) { |
| if (ts.read(SECONDS) < c.getCommitTime()) { |
| throw new TimeIsUncertainException(); |
| } |
| } |
| b.setTreeId(c.getTree()); |
| b.setParentId(acceptedOldIndex); |
| term = parseTerm(c.getFooterLines(TERM)) + 1; |
| } |
| } else { |
| term = 1; |
| b.setTreeId(inserter.insert(new TreeFormatter())); |
| } |
| |
| StringBuilder msg = new StringBuilder(); |
| msg.append(KetchConstants.TERM.getName()) |
| .append(": ") //$NON-NLS-1$ |
| .append(term); |
| |
| String tag = leader.getSystem().newLeaderTag(); |
| if (tag != null && !tag.isEmpty()) { |
| msg.append(' ').append(tag); |
| } |
| |
| b.setAuthor(leader.getSystem().newCommitter(ts)); |
| b.setCommitter(b.getAuthor()); |
| b.setMessage(msg.toString()); |
| |
| if (log.isDebugEnabled()) { |
| log.debug("Trying to elect myself " + b.getMessage()); //$NON-NLS-1$ |
| } |
| return inserter.insert(b); |
| } |
| |
| private static long parseTerm(List<String> footer) { |
| if (footer.isEmpty()) { |
| return 0; |
| } |
| |
| String s = footer.get(0); |
| int p = s.indexOf(' '); |
| if (p > 0) { |
| s = s.substring(0, p); |
| } |
| return Long.parseLong(s, 10); |
| } |
| |
| private void blockUntil(ProposedTimestamp ts) throws IOException { |
| try { |
| ts.blockUntil(getSystem().getMaxWaitForMonotonicClock()); |
| } catch (InterruptedException | TimeoutException e) { |
| throw new TimeIsUncertainException(e); |
| } |
| } |
| } |