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/*
* 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.cluster.impl;
import static com.google.common.base.MoreObjects.toStringHelper;
import static com.google.common.base.Preconditions.checkNotNull;
import com.google.common.hash.Hashing;
import io.atomix.cluster.MemberId;
import io.atomix.raft.RaftError;
import io.atomix.raft.cluster.RaftMember;
import io.atomix.raft.protocol.RaftResponse;
import io.atomix.raft.protocol.ReconfigureRequest;
import io.atomix.raft.storage.system.Configuration;
import io.atomix.utils.concurrent.Scheduled;
import java.time.Instant;
import java.util.Objects;
import java.util.Set;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.CopyOnWriteArraySet;
import java.util.function.Consumer;
/** Cluster member. */
public final class DefaultRaftMember implements RaftMember, AutoCloseable {
private final MemberId id;
private final int hash;
private final transient Set> typeChangeListeners = new CopyOnWriteArraySet<>();
private Type type;
private Instant updated;
private transient Scheduled configureTimeout;
private transient RaftClusterContext cluster;
public DefaultRaftMember(final MemberId id, final Type type, final Instant updated) {
this.id = checkNotNull(id, "id cannot be null");
hash = Hashing.murmur3_32_fixed().hashUnencodedChars(id.id()).asInt();
setType(checkNotNull(type, "type cannot be null"));
this.updated = checkNotNull(updated, "updated cannot be null");
}
@Override
public MemberId memberId() {
return id;
}
@Override
public int hash() {
return hash;
}
@Override
public void addTypeChangeListener(final Consumer listener) {
typeChangeListeners.add(listener);
}
@Override
public CompletableFuture promote() {
if (Type.values().length > type.ordinal() + 1) {
return configure(Type.values()[type.ordinal() + 1]);
}
return CompletableFuture.completedFuture(null);
}
@Override
public CompletableFuture promote(final Type type) {
return configure(type);
}
@Override
public CompletableFuture demote() {
if (type.ordinal() > 0) {
return configure(Type.values()[type.ordinal() - 1]);
}
return CompletableFuture.completedFuture(null);
}
@Override
public CompletableFuture demote(final Type type) {
return configure(type);
}
@Override
public CompletableFuture remove() {
return configure(Type.INACTIVE);
}
@Override
public Instant getLastUpdated() {
return updated;
}
@Override
public RaftMember.Type getType() {
return type;
}
/**
* Sets the member type.
*
* @param type the member type
*/
void setType(final Type type) {
this.type = type;
}
/**
* Updates the member type.
*
* @param type The member type.
* @return The member.
*/
public DefaultRaftMember update(final RaftMember.Type type, final Instant time) {
if (this.type != type) {
setType(checkNotNull(type, "type cannot be null"));
if (time.isAfter(updated)) {
updated = checkNotNull(time, "time cannot be null");
}
typeChangeListeners.forEach(l -> l.accept(type));
}
return this;
}
/** Demotes the server to the given type. */
private CompletableFuture configure(final RaftMember.Type type) {
if (type == this.type) {
return CompletableFuture.completedFuture(null);
}
final CompletableFuture future = new CompletableFuture<>();
cluster.getContext().getThreadContext().execute(() -> configure(type, future));
return future;
}
/** Recursively reconfigures the cluster. */
private void configure(final RaftMember.Type type, final CompletableFuture future) {
// Set a timer to retry the attempt to leave the cluster.
configureTimeout =
cluster
.getContext()
.getThreadContext()
.schedule(cluster.getContext().getElectionTimeout(), () -> configure(type, future));
// Attempt to leave the cluster by submitting a LeaveRequest directly to the server state.
// Non-leader states should forward the request to the leader if there is one. Leader states
// will log, replicate, and commit the reconfiguration.
final var currentConfiguration = cluster.getConfiguration();
cluster
.getContext()
.getRaftRole()
.onReconfigure(
ReconfigureRequest.builder()
.withIndex(currentConfiguration.index())
.withTerm(currentConfiguration.term())
.withMembers(currentConfiguration.newMembers())
// Override local member with the new type.
.withMember(new DefaultRaftMember(id, type, updated))
.from(cluster.getLocalMember().memberId().id())
.build())
.whenComplete(
(response, error) -> {
if (error == null) {
if (response.status() == RaftResponse.Status.OK) {
cancelConfigureTimer();
cluster.configure(
new Configuration(
response.index(),
response.term(),
response.timestamp(),
response.members()));
future.complete(null);
} else if (response.error() == null
|| response.error().type() == RaftError.Type.UNAVAILABLE
|| response.error().type() == RaftError.Type.PROTOCOL_ERROR
|| response.error().type() == RaftError.Type.NO_LEADER) {
cancelConfigureTimer();
configureTimeout =
cluster
.getContext()
.getThreadContext()
.schedule(
cluster.getContext().getElectionTimeout().multipliedBy(2),
() -> configure(type, future));
} else {
cancelConfigureTimer();
future.completeExceptionally(response.error().createException());
}
} else {
future.completeExceptionally(error);
}
});
}
@Override
public void close() {
cancelConfigureTimer();
}
/** Cancels the configure timeout. */
private void cancelConfigureTimer() {
if (configureTimeout != null) {
configureTimeout.cancel();
configureTimeout = null;
}
}
@Override
public int hashCode() {
return Objects.hash(getClass(), id);
}
@Override
public boolean equals(final Object object) {
return object instanceof DefaultRaftMember && ((DefaultRaftMember) object).id.equals(id);
}
@Override
public String toString() {
return toStringHelper(this).add("id", id).add("type", type).add("updated", updated).toString();
}
/** Sets the member's parent cluster. */
DefaultRaftMember setCluster(final RaftClusterContext cluster) {
this.cluster = cluster;
return this;
}
}