com.datastax.oss.driver.internal.core.metadata.token.CanonicalNodeSetBuilder Maven / Gradle / Ivy
The newest version!
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF 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 com.datastax.oss.driver.internal.core.metadata.token;
import com.datastax.oss.driver.api.core.metadata.Node;
import com.datastax.oss.driver.shaded.guava.common.collect.ImmutableSet;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;
import net.jcip.annotations.NotThreadSafe;
/**
* A reusable set builder that guarantees that identical sets (same elements in the same order) will
* be represented by the same instance.
*/
@NotThreadSafe
class CanonicalNodeSetBuilder {
private final Map, Set> canonicalSets = new HashMap<>();
private final List elements = new ArrayList<>();
void add(Node node) {
// This is O(n), but the cardinality is low (max possible size is the replication factor).
if (!elements.contains(node)) {
elements.add(node);
}
}
int size() {
return elements.size();
}
Set build() {
return canonicalSets.computeIfAbsent(elements, ImmutableSet::copyOf);
}
void clear() {
elements.clear();
}
}