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Java library for cluster communications and computing.
/*
* Copyright 2020 The Hekate Project
*
* The Hekate Project licenses this file to you 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.hekate.cluster;
import io.hekate.cluster.internal.DefaultClusterTopology;
import io.hekate.core.internal.util.ArgAssert;
import java.util.List;
import java.util.NavigableSet;
import java.util.Set;
import java.util.function.Consumer;
import java.util.stream.Stream;
/**
* Immutable snapshot of the cluster topology.
*
*
* Nodes within the cluster topology are sorted based on the comparison rule of {@link ClusterNode#compareTo(ClusterNode)} method.
* This rule applies to the following methods:
*
*
* - {@link #nodes()}
* - {@link #stream()}
* - {@link #forEach(Consumer)}
* - {@link #iterator()}
* - {@link #spliterator()}
* - {@link #remoteNodes()}
* - {@link #first()}
* - {@link #last()}
*
*
* @see ClusterService#topology()
*/
public interface ClusterTopology extends Iterable, ClusterTopologySupport {
/**
* Returns the version of this topology.
*
*
* This method provides support for tacking changes of the cluster topology. The value of this property is
* monotonically incremented each time when the cluster topology changes.
*
*
*
* Note: Version is local to each node and can differ from node to node.
*
*
* @return Version this topology.
*/
long version();
/**
* Returns the SHA-256 hash of all {@link ClusterNode#id() cluster node identifiers} of this topology.
*
*
* If this topology is {@link #filter(ClusterNodeFilter) filtered} then only those nodes that match the filter criteria will be used to
* compute the hash.
*
*
* @return SHA-256 hash of this topology.
*/
ClusterHash hash();
/**
* Returns local node or {@code null} if local node is not within this topology.
*
* @return Local node or {@code null} if local node is not within this topology.
*
* @see ClusterNode#isLocal()
*/
ClusterNode localNode();
/**
* Returns an immutable list of all nodes with consistent ordering based on {@link ClusterNode#compareTo(ClusterNode)} method.
* Returns an empty list if there are no nodes within this topology.
*
* @return Immutable list of all nodes with consistent ordering or an empty list if there are no nodes within this topology.
*/
List nodes();
/**
* Returns the first node of the {@link #nodes()} list or {@code null} if this topology is empty.
*
* @return The first node of the {@link #nodes()} list or {@code null} if this topology is empty.
*/
ClusterNode first();
/**
* Returns the last node of the {@link #nodes()} list or {@code null} if this topology is empty.
*
* @return The last node of the {@link #nodes()} list or {@code null} if this topology is empty.
*/
ClusterNode last();
/**
* Returns an immutable set of all nodes within this topology. Returns an empty set if there are no nodes within this topology.
*
* @return Immutable set of all nodes within this topology or an empty list if there are no nodes within this topology.
*/
Set nodeSet();
/**
* Returns an immutable list of remote nodes within this topology ordered by their {@link ClusterNode#id() identifiers}. Returns an
* empty list if there are no remote nodes within this topology.
*
* @return Immutable list of remotes node within this topology ordered by their {@link ClusterNode#id() identifiers} or an empty list
* if there are no remote nodes within this topology..
*
* @see ClusterNode#isLocal()
*/
List remoteNodes();
/**
* Returns an immutable set of all nodes ordered by their {@link ClusterNode#joinOrder() join order}. The first element in this set
* is the oldest node. Returns an empty set if there are no nodes within this topology.
*
* @return Immutable set of all nodes ordered by their {@link ClusterNode#joinOrder() join order} or an empty set if there are no
* nodes within this topology.
*/
NavigableSet joinOrder();
/**
* Returns {@link Stream} of all nodes from this topology.
*
* @return {@link Stream} of all nodes from this topology.
*/
Stream stream();
/**
* Returns {@code true} if this topology contains the specified node.
*
* @param node Node to check.
*
* @return {@code true} if this topology contains the specified node.
*/
boolean contains(ClusterNode node);
/**
* Returns {@code true} if this topology contains a node with the specified identifier.
*
* @param id Node identifier to check.
*
* @return {@code true} if this topology contains a node with the specified identifier.
*/
boolean contains(ClusterNodeId id);
/**
* Returns the node for the specified identifier or {@code null} if there is no such node within this topology.
*
* @param id Node identifier.
*
* @return Node for the specified identifier or {@code null} if there is no such node within this topology.
*/
ClusterNode get(ClusterNodeId id);
/**
* Returns the number of nodes in this topology.
*
* @return Number of nodes in this topology.
*/
int size();
/**
* Returns {@code true} if this topology doesn't have any nodes.
*
* @return {@code true} if this topology doesn't have any nodes.
*/
boolean isEmpty();
/**
* Returns the oldest node of this topology. Returns {@code null} if this topology is empty.
*
*
* The oldest node is the node with the lowest {@link ClusterNode#joinOrder() join order}.
*
*
* @return Oldest node of this topology or {@code null} if this topology is empty.
*/
ClusterNode oldest();
/**
* Returns the youngest node of this topology. Returns {@code null} if this topology is empty.
*
*
* The youngest node is the node with the highest {@link ClusterNode#joinOrder() join order}.
*
*
* @return Youngest node within of this topology or {@code null} if this topology is empty.
*/
ClusterNode youngest();
/**
* Returns a random node of this topology. Returns {@code null} if this topology is empty.
*
* @return Random node or {@code null} if this topology is empty.
*/
ClusterNode random();
/**
* Returns a copy of this topology that contains only those nodes that match the specified filter. The {@link #version() topology
* version} will be preserved in the returned copy.
*
* @param filter Filter.
*
* @return Copy of this topology that contains only those nodes that match the specified filter.
*/
ClusterTopology filterAll(ClusterFilter filter);
/**
* Returns a copy of this topology containing only those nodes that match the specified filter. The {@link #version() topology
* version} will be preserved in the returned copy.
*
* @param filter Filter.
*
* @return Copy of this topology that contains only those nodes that match the specified filter.
*/
ClusterTopology filter(ClusterNodeFilter filter);
/**
* Constructs a new cluster topology.
*
* @param version See {@link #version()}.
* @param nodes See {@link #nodes()}.
*
* @return New topology.
*/
static ClusterTopology of(long version, Set nodes) {
ArgAssert.notNull(nodes, "Nodes");
return DefaultClusterTopology.of(version, nodes);
}
/**
* Return an empty cluster topology.
*
* @return Empty topology that has its {@link #version()} equals to {@code 0} and having an empty list of {@link #nodes()}.
*/
static ClusterTopology empty() {
return DefaultClusterTopology.empty();
}
}