| /* |
| * 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 java.io.IOException; |
| import java.util.List; |
| |
| import org.eclipse.jgit.lib.AnyObjectId; |
| import org.eclipse.jgit.transport.ReceiveCommand; |
| |
| /** |
| * One round-trip to all replicas proposing a log entry. |
| * <p> |
| * In Raft a log entry represents a state transition at a specific index in the |
| * replicated log. The leader can only append log entries to the log. |
| * <p> |
| * In Ketch a log entry is recorded under the {@code refs/txn} namespace. This |
| * occurs when: |
| * <ul> |
| * <li>a replica wants to establish itself as a new leader by proposing a new |
| * term (see {@link ElectionRound}) |
| * <li>an established leader wants to gain consensus on new {@link Proposal}s |
| * (see {@link ProposalRound}) |
| * </ul> |
| */ |
| abstract class Round { |
| final KetchLeader leader; |
| final LogIndex acceptedOldIndex; |
| LogIndex acceptedNewIndex; |
| List<ReceiveCommand> stageCommands; |
| |
| Round(KetchLeader leader, LogIndex head) { |
| this.leader = leader; |
| this.acceptedOldIndex = head; |
| } |
| |
| KetchSystem getSystem() { |
| return leader.getSystem(); |
| } |
| |
| /** |
| * Creates a commit for {@code refs/txn/accepted} and calls |
| * {@link #runAsync(AnyObjectId)} to begin execution of the round across |
| * the system. |
| * <p> |
| * If references are being updated (such as in a {@link ProposalRound}) the |
| * RefTree may be modified. |
| * <p> |
| * Invoked without {@link KetchLeader#lock} to build objects. |
| * |
| * @throws IOException |
| * the round cannot build new objects within the leader's |
| * repository. The leader may be unable to execute. |
| */ |
| abstract void start() throws IOException; |
| |
| /** |
| * Asynchronously distribute the round's new value for |
| * {@code refs/txn/accepted} to all replicas. |
| * <p> |
| * Invoked by {@link #start()} after new commits have been created for the |
| * log. The method passes {@code newId} to {@link KetchLeader} to be |
| * distributed to all known replicas. |
| * |
| * @param newId |
| * new value for {@code refs/txn/accepted}. |
| */ |
| void runAsync(AnyObjectId newId) { |
| acceptedNewIndex = acceptedOldIndex.nextIndex(newId); |
| leader.runAsync(this); |
| } |
| |
| /** |
| * Notify the round it was accepted by a majority of the system. |
| * <p> |
| * Invoked by the leader with {@link KetchLeader#lock} held by the caller. |
| */ |
| abstract void success(); |
| } |