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- /*
- * 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 org.eclipse.jgit.lib.AnyObjectId;
- import org.eclipse.jgit.lib.ObjectId;
-
- /**
- * An ObjectId for a commit extended with incrementing log index.
- * <p>
- * For any two LogIndex instances, {@code A} is an ancestor of {@code C}
- * reachable through parent edges in the graph if {@code A.index < C.index}.
- * LogIndex provides a performance optimization for Ketch, the same information
- * can be obtained from {@link org.eclipse.jgit.revwalk.RevWalk}.
- * <p>
- * Index values are only valid within a single {@link KetchLeader} instance
- * after it has won an election. By restricting scope to a single leader new
- * leaders do not need to traverse the entire history to determine the next
- * {@code index} for new proposals. This differs from Raft, where leader
- * election uses the log index and the term number to determine which replica
- * holds a sufficiently up-to-date log. Since Ketch uses Git objects for storage
- * of its replicated log, it keeps the term number as Raft does but uses
- * standard Git operations to imply the log index.
- * <p>
- * {@link Round#runAsync(AnyObjectId)} bumps the index as each new round is
- * constructed.
- */
- public class LogIndex extends ObjectId {
- static LogIndex unknown(AnyObjectId id) {
- return new LogIndex(id, 0);
- }
-
- private final long index;
-
- private LogIndex(AnyObjectId id, long index) {
- super(id);
- this.index = index;
- }
-
- LogIndex nextIndex(AnyObjectId id) {
- return new LogIndex(id, index + 1);
- }
-
- /** @return index provided by the current leader instance. */
- public long getIndex() {
- return index;
- }
-
- /**
- * Check if this log position committed before another log position.
- * <p>
- * Only valid for log positions in memory for the current leader.
- *
- * @param c
- * other (more recent) log position.
- * @return true if this log position was before {@code c} or equal to c and
- * therefore any agreement of {@code c} implies agreement on this
- * log position.
- */
- boolean isBefore(LogIndex c) {
- return index <= c.index;
- }
-
- /**
- * @return string suitable for debug logging containing the log index and
- * abbreviated ObjectId.
- */
- @SuppressWarnings("boxing")
- public String describeForLog() {
- return String.format("%5d/%s", index, abbreviate(6).name()); //$NON-NLS-1$
- }
-
- @SuppressWarnings("boxing")
- @Override
- public String toString() {
- return String.format("LogId[%5d/%s]", index, name()); //$NON-NLS-1$
- }
- }
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