io.atomix.raft.protocol.PollRequest Maven / Gradle / Ivy
/*
* Copyright 2015-present Open Networking Foundation
* Copyright © 2020 camunda services GmbH ([email protected])
*
* Licensed 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 io.atomix.raft.protocol;
import static com.google.common.base.MoreObjects.toStringHelper;
import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkNotNull;
import io.atomix.cluster.MemberId;
import java.util.Objects;
/**
* Server poll request.
*
* Poll requests aid in the implementation of the so-called "pre-vote" protocol. They are sent by
* followers to all other servers prior to transitioning to the candidate state. This helps ensure
* that servers that can't win elections do not disrupt existing leaders when e.g. rejoining the
* cluster after a partition.
*/
public class PollRequest extends AbstractRaftRequest {
private final long term;
private final String candidate;
private final long lastLogIndex;
private final long lastLogTerm;
public PollRequest(
final long term, final String candidate, final long lastLogIndex, final long lastLogTerm) {
this.term = term;
this.candidate = candidate;
this.lastLogIndex = lastLogIndex;
this.lastLogTerm = lastLogTerm;
}
/**
* Returns a new poll request builder.
*
* @return A new poll request builder.
*/
public static Builder builder() {
return new Builder();
}
/**
* Returns the requesting node's current term.
*
* @return The requesting node's current term.
*/
public long term() {
return term;
}
/**
* Returns the candidate's address.
*
* @return The candidate's address.
*/
public MemberId candidate() {
return MemberId.from(candidate);
}
/**
* Returns the candidate's last log index.
*
* @return The candidate's last log index.
*/
public long lastLogIndex() {
return lastLogIndex;
}
/**
* Returns the candidate's last log term.
*
* @return The candidate's last log term.
*/
public long lastLogTerm() {
return lastLogTerm;
}
@Override
public int hashCode() {
return Objects.hash(getClass(), term, candidate, lastLogIndex, lastLogTerm);
}
@Override
public boolean equals(final Object object) {
if (object instanceof PollRequest) {
final PollRequest request = (PollRequest) object;
return request.term == term
&& request.candidate == candidate
&& request.lastLogIndex == lastLogIndex
&& request.lastLogTerm == lastLogTerm;
}
return false;
}
@Override
public String toString() {
return toStringHelper(this)
.add("term", term)
.add("candidate", candidate)
.add("lastLogIndex", lastLogIndex)
.add("lastLogTerm", lastLogTerm)
.toString();
}
/** Poll request builder. */
public static class Builder extends AbstractRaftRequest.Builder {
private long term = -1;
private String candidate;
private long lastLogIndex = -1;
private long lastLogTerm = -1;
/**
* Sets the request term.
*
* @param term The request term.
* @return The poll request builder.
* @throws IllegalArgumentException if {@code term} is negative
*/
public Builder withTerm(final long term) {
checkArgument(term >= 0, "term must be positive");
this.term = term;
return this;
}
/**
* Sets the request leader.
*
* @param candidate The request candidate.
* @return The poll request builder.
* @throws IllegalArgumentException if {@code candidate} is not positive
*/
public Builder withCandidate(final MemberId candidate) {
this.candidate = checkNotNull(candidate, "candidate cannot be null").id();
return this;
}
/**
* Sets the request last log index.
*
* @param logIndex The request last log index.
* @return The poll request builder.
* @throws IllegalArgumentException if {@code index} is negative
*/
public Builder withLastLogIndex(final long logIndex) {
checkArgument(logIndex >= 0, "lastLogIndex must be positive");
lastLogIndex = logIndex;
return this;
}
/**
* Sets the request last log term.
*
* @param logTerm The request last log term.
* @return The poll request builder.
* @throws IllegalArgumentException if {@code term} is negative
*/
public Builder withLastLogTerm(final long logTerm) {
checkArgument(logTerm >= 0, "lastLogTerm must be positive");
lastLogTerm = logTerm;
return this;
}
/**
* @throws IllegalStateException if candidate is not positive or if term, lastLogIndex or
* lastLogTerm are negative
*/
@Override
public PollRequest build() {
validate();
return new PollRequest(term, candidate, lastLogIndex, lastLogTerm);
}
@Override
protected void validate() {
super.validate();
checkArgument(term >= 0, "term must be positive");
checkNotNull(candidate, "candidate cannot be null");
checkArgument(lastLogIndex >= 0, "lastLogIndex must be positive");
checkArgument(lastLogTerm >= 0, "lastLogTerm must be positive");
}
}
}