| /* |
| * Copyright 2014-2015 Open Networking Laboratory |
| * |
| * 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 org.onosproject.cluster; |
| |
| import java.util.Objects; |
| import java.util.List; |
| import java.util.Optional; |
| |
| import org.joda.time.DateTime; |
| |
| import com.google.common.base.MoreObjects; |
| import com.google.common.collect.ImmutableList; |
| |
| /** |
| * Abstract leadership concept. The information carried by this construct |
| * include the topic of contention, the {@link NodeId}s of Nodes that could |
| * become leader for the topic, the epoch when the term for a given leader |
| * began, and the system time when the term began. Note: |
| * <ul> |
| * <li>The list of NodeIds may include the current leader at index 0, and the |
| * rest in decreasing preference order.</li> |
| * <li>The epoch is the logical age of a Leadership construct, and should be |
| * used for comparing two Leaderships, but only of the same topic.</li> |
| * <li>The leader may be null if its accuracy can't be guaranteed. This applies |
| * to CANDIDATES_CHANGED events and candidate board contents.</li> |
| * </ul> |
| */ |
| public class Leadership { |
| |
| private final String topic; |
| private final Optional<NodeId> leader; |
| private final List<NodeId> candidates; |
| private final long epoch; |
| private final long electedTime; |
| |
| public Leadership(String topic, NodeId leader, long epoch, long electedTime) { |
| this.topic = topic; |
| this.leader = Optional.of(leader); |
| this.candidates = ImmutableList.of(leader); |
| this.epoch = epoch; |
| this.electedTime = electedTime; |
| } |
| |
| public Leadership(String topic, NodeId leader, List<NodeId> candidates, |
| long epoch, long electedTime) { |
| this.topic = topic; |
| this.leader = Optional.of(leader); |
| this.candidates = ImmutableList.copyOf(candidates); |
| this.epoch = epoch; |
| this.electedTime = electedTime; |
| } |
| |
| public Leadership(String topic, List<NodeId> candidates, |
| long epoch, long electedTime) { |
| this.topic = topic; |
| this.leader = Optional.empty(); |
| this.candidates = ImmutableList.copyOf(candidates); |
| this.epoch = epoch; |
| this.electedTime = electedTime; |
| } |
| |
| /** |
| * The topic for which this leadership applies. |
| * |
| * @return leadership topic. |
| */ |
| public String topic() { |
| return topic; |
| } |
| |
| /** |
| * The nodeId of leader for this topic. |
| * |
| * @return leader node. |
| */ |
| // This will return Optional<NodeId> in the future. |
| public NodeId leader() { |
| return leader.orElse(null); |
| } |
| |
| /** |
| * Returns an preference-ordered list of nodes that are in the leadership |
| * race for this topic. |
| * |
| * @return a list of NodeIds in priority-order, or an empty list. |
| */ |
| public List<NodeId> candidates() { |
| return candidates; |
| } |
| |
| /** |
| * The epoch when the leadership was assumed. |
| * <p> |
| * Comparing epochs is only appropriate for leadership events for the same |
| * topic. The system guarantees that for any given topic the epoch for a new |
| * term is higher (not necessarily by 1) than the epoch for any previous |
| * term. |
| * |
| * @return leadership epoch |
| */ |
| public long epoch() { |
| return epoch; |
| } |
| |
| /** |
| * The system time when the term started. |
| * <p> |
| * The elected time is initially set on the node coordinating |
| * the leader election using its local system time. Due to possible |
| * clock skew, relying on this value for determining event ordering |
| * is discouraged. Epoch is more appropriate for determining |
| * event ordering. |
| * |
| * @return elected time. |
| */ |
| public long electedTime() { |
| return electedTime; |
| } |
| |
| @Override |
| public int hashCode() { |
| return Objects.hash(topic, leader, candidates, epoch, electedTime); |
| } |
| |
| @Override |
| public boolean equals(Object obj) { |
| if (this == obj) { |
| return true; |
| } |
| if (obj instanceof Leadership) { |
| final Leadership other = (Leadership) obj; |
| return Objects.equals(this.topic, other.topic) && |
| Objects.equals(this.leader, other.leader) && |
| Objects.equals(this.candidates, other.candidates) && |
| Objects.equals(this.epoch, other.epoch) && |
| Objects.equals(this.electedTime, other.electedTime); |
| } |
| return false; |
| } |
| |
| @Override |
| public String toString() { |
| return MoreObjects.toStringHelper(this.getClass()) |
| .add("topic", topic) |
| .add("leader", leader) |
| .add("candidates", candidates) |
| .add("epoch", epoch) |
| .add("electedTime", new DateTime(electedTime)) |
| .toString(); |
| } |
| } |