| /* |
| * 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.systems; |
| |
| import java.util.concurrent.atomic.AtomicLong; |
| import java.util.function.LongSupplier; |
| import java.util.function.Supplier; |
| |
| import org.apache.cassandra.service.paxos.Ballot; |
| import org.apache.cassandra.service.paxos.BallotGenerator; |
| import org.apache.cassandra.simulator.RandomSource; |
| import org.apache.cassandra.simulator.RandomSource.Choices; |
| |
| import static org.apache.cassandra.service.paxos.Ballot.atUnixMicrosWithLsb; |
| |
| // TODO (feature): link with SimulateTime, and otherwise improve |
| public class SimulatedBallots |
| { |
| enum Next { ONE, JUMP, TO_LATEST } |
| |
| final LongSupplier uniqueSupplier; // must be unique for all ballots |
| final RandomSource random; |
| final Choices<Next> nextChoice; |
| final LongSupplier nextJump; |
| final AtomicLong latest = new AtomicLong(1L); |
| |
| public SimulatedBallots(RandomSource random, Supplier<LongSupplier> jumpsSupplier) |
| { |
| this.uniqueSupplier = random.uniqueUniformSupplier(Long.MIN_VALUE, Long.MAX_VALUE); |
| this.random = random; |
| this.nextChoice = Choices.random(random, Next.values()); |
| this.nextJump = jumpsSupplier.get(); |
| } |
| |
| class Generator extends AtomicLong implements BallotGenerator |
| { |
| public Generator() |
| { |
| super(1L); |
| } |
| |
| public Ballot atUnixMicros(long unixMicros, Ballot.Flag flag) |
| { |
| return atUnixMicrosWithLsb(unixMicros, uniqueSupplier.getAsLong(), flag); |
| } |
| |
| public Ballot next(long minUnixMicros, Ballot.Flag flag) |
| { |
| return Ballot.atUnixMicrosWithLsb(nextBallotTimestampMicros(minUnixMicros), uniqueSupplier.getAsLong(), flag); |
| } |
| |
| public Ballot stale(long from, long to, Ballot.Flag flag) |
| { |
| return Ballot.atUnixMicrosWithLsb(random.uniform(from, to), uniqueSupplier.getAsLong(), flag); |
| } |
| |
| private long nextBallotTimestampMicros(long minUnixMicros) |
| { |
| long next; |
| switch (nextChoice.choose(random)) |
| { |
| default: throw new IllegalStateException(); |
| case TO_LATEST: |
| minUnixMicros = Math.max(latest.get(), minUnixMicros); |
| case ONE: |
| next = accumulateAndGet(minUnixMicros, (a, b) -> Math.max(a, b) + 1); |
| break; |
| case JUMP: |
| long jump = Math.max(1, nextJump.getAsLong()); |
| next = addAndGet(jump); |
| if (next < minUnixMicros) |
| next = accumulateAndGet(minUnixMicros, (a, b) -> Math.max(a, b) + 1); |
| } |
| latest.accumulateAndGet(next, Math::max); |
| return next; |
| } |
| |
| public long prevUnixMicros() |
| { |
| return get(); |
| } |
| } |
| |
| public BallotGenerator get() |
| { |
| return new Generator(); |
| } |
| } |