cassandra-trunk/test/simulator/main/org/apache/cassandra/simulator/paxos/PaxosRepairValidator.java
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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
 * limitations under the License.
 */

package org.apache.cassandra.simulator.paxos;

import org.apache.cassandra.distributed.Cluster;
import org.apache.cassandra.simulator.cluster.ClusterActionListener.RepairValidator;
import org.apache.cassandra.simulator.cluster.Topology;

import static java.util.Arrays.stream;
import static org.apache.cassandra.simulator.systems.NonInterceptible.Permit.REQUIRED;

public class PaxosRepairValidator implements RepairValidator
{
    final Cluster cluster;
    final String keyspace;
    final String table;
    final Object id;

    boolean isPaxos;
    Topology topology;
    Ballots.LatestBallots[][] ballotsBefore;

    public PaxosRepairValidator(Cluster cluster, String keyspace, String table, Object id)
    {
        this.cluster = cluster;
        this.keyspace = keyspace;
        this.table = table;
        this.id = id;
    }

    @Override
    public void before(Topology topology, boolean repairPaxos, boolean repairOnlyPaxos)
    {
        if (repairOnlyPaxos)
            return;

        this.isPaxos = isPaxos;
        this.topology = topology;
        this.ballotsBefore = Ballots.read(REQUIRED, cluster, keyspace, table, topology.primaryKeys, topology.replicasForKeys, false);
    }

    @Override
    public void after()
    {
        if (ballotsBefore == null)
            return;

        int[] primaryKeys = topology.primaryKeys;
        int[][] replicasForKeys = topology.replicasForKeys;
        int quorumRf = topology.quorumRf;
        int quorum = quorumRf / 2 + 1;
        Ballots.LatestBallots[][] ballotsAfter  = Ballots.read(REQUIRED, cluster, keyspace, table, primaryKeys, replicasForKeys, true);
        for (int pki = 0; pki < primaryKeys.length ; ++pki)
        {
            Ballots.LatestBallots[] before = ballotsBefore[pki];
            Ballots.LatestBallots[] after  = ballotsAfter[pki];

            if (before.length != after.length || before.length != quorumRf)
                throw new AssertionError("Inconsistent ownership information");

            String kind;
            long expectPersisted;
            if (isPaxos)
            {
                long committedBefore = stream(before).mapToLong(Ballots.LatestBallots::permanent).max().orElse(0L);
                // anything accepted by a quorum should be persisted
                long acceptedBefore = stream(before).mapToLong(n -> n.accept).max().orElse(0L);
                long acceptedOfBefore = stream(before).filter(n -> n.accept == acceptedBefore).mapToLong(n -> n.acceptOf).findAny().orElse(0L);
                int countAccepted = (int) stream(before).filter(n -> n.accept == acceptedBefore).count();
                expectPersisted = countAccepted >= quorum ? acceptedOfBefore : committedBefore;
                kind = countAccepted >= quorum ? "agreed" : "committed";
            }
            else
            {
                expectPersisted = stream(before).mapToLong(n -> n.persisted).max().orElse(0L);
                kind = "persisted";
            }

            int countAfter = (int) stream(after).filter(n -> n.persisted >= expectPersisted).count();
            if (countAfter < quorum)
                throw new AssertionError(String.format("%d: %d %s before %s but only persisted on %d after (out of %d)",
                                                       primaryKeys[pki], expectPersisted, kind, id, countAfter, quorumRf));
        }

    }
}
