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/*
* ============LICENSE_START=======================================================
* ONAP
* ================================================================================
* Copyright (C) 2018-2021 AT&T Intellectual Property. All rights reserved.
* Modifications Copyright (C) 2024 Nordix Foundation.
* ================================================================================
* 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.
* ============LICENSE_END=========================================================
*/
package org.onap.policy.drools.pooling.message;
import java.util.Arrays;
import java.util.HashSet;
import java.util.Set;
import lombok.Getter;
import lombok.NoArgsConstructor;
import lombok.Setter;
import org.onap.policy.drools.pooling.PoolingFeatureException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Bucket assignments, which is simply an array of host names.
*/
@Getter
@Setter
@NoArgsConstructor
public class BucketAssignments {
private static final Logger logger = LoggerFactory.getLogger(BucketAssignments.class);
/**
* The number of bits in the maximum number of buckets.
*/
private static final int MAX_BUCKET_BITS = 10;
/**
* Maximum number of buckets. Must be a power of two.
*/
public static final int MAX_BUCKETS = 1 << MAX_BUCKET_BITS;
/**
* Used to ensure that a hash code is not negative.
*/
private static final int MAX_BUCKETS_MASK = MAX_BUCKETS - 1;
/**
* Identifies the host serving a particular bucket.
*/
private String[] hostArray = null;
/**
* Constructor.
*
* @param hostArray maps a bucket number (i.e., array index) to a host. All values
* must be non-null
*/
public BucketAssignments(String[] hostArray) {
this.hostArray = hostArray;
}
/**
* Gets the leader, which is the host with the minimum UUID.
*
* @return the assignment leader
*/
public String getLeader() {
if (hostArray == null) {
return null;
}
String leader = null;
for (String host : hostArray) {
if (host != null && (leader == null || host.compareTo(leader) < 0)) {
leader = host;
}
}
return leader;
}
/**
* Determines if a host has an assignment.
*
* @param host host to be checked
* @return {@code true} if the host has an assignment, {@code false} otherwise
*/
public boolean hasAssignment(String host) {
if (hostArray == null) {
return false;
}
for (String host2 : hostArray) {
if (host.equals(host2)) {
return true;
}
}
return false;
}
/**
* Gets all the hosts that have an assignment.
*
* @return all the hosts that have an assignment
*/
public Set<String> getAllHosts() {
Set<String> set = new HashSet<>();
if (hostArray == null) {
return set;
}
for (String host : hostArray) {
if (host != null) {
set.add(host);
}
}
return set;
}
/**
* Gets the host assigned to a given bucket.
*
* @param hashCode hash code of the item whose assignment is desired
* @return the assigned host, or {@code null} if the item has no assigned host
*/
public String getAssignedHost(int hashCode) {
if (hostArray == null || hostArray.length == 0) {
logger.error("no buckets have been assigned");
return null;
}
return hostArray[(Math.abs(hashCode) & MAX_BUCKETS_MASK) % hostArray.length];
}
/**
* Gets the number of buckets.
*
* @return the number of buckets
*/
public int size() {
return (hostArray != null ? hostArray.length : 0);
}
/**
* Checks the validity of the assignments, verifying that all buckets have been
* assigned to a host.
*
* @throws PoolingFeatureException if the assignments are invalid
*/
public void checkValidity() throws PoolingFeatureException {
if (hostArray == null || hostArray.length == 0) {
throw new PoolingFeatureException("missing hosts in message bucket assignments");
}
if (hostArray.length > MAX_BUCKETS) {
throw new PoolingFeatureException("too many hosts in message bucket assignments");
}
for (var x = 0; x < hostArray.length; ++x) {
if (hostArray[x] == null) {
throw new PoolingFeatureException("bucket " + x + " has no assignment");
}
}
}
@Override
public int hashCode() {
final var prime = 31;
var result = 1;
result = prime * result + Arrays.hashCode(hostArray);
return result;
}
@Override
public boolean equals(Object obj) {
if (this == obj) {
return true;
}
if (obj == null) {
return false;
}
if (getClass() != obj.getClass()) {
return false;
}
BucketAssignments other = (BucketAssignments) obj;
return Arrays.equals(hostArray, other.hostArray);
}
}
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