org.apache.cassandra.distributed.api.TokenSupplier Maven / Gradle / Ivy

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/*
 * 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
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 */

package org.apache.cassandra.distributed.api;

public interface TokenSupplier
{
    long token(int nodeId);

    static TokenSupplier evenlyDistributedTokens(int numNodes)
    {
        long increment = (Long.MAX_VALUE / numNodes) * 2;
        return (int nodeId) -> {
            assert nodeId <= numNodes : String.format("Can not allocate a token for a node %s, since only %s nodes are allowed by the token allocation strategy",
                                                      nodeId, numNodes);
            return Long.MIN_VALUE + 1 + nodeId * increment;
        };
    }
}