com.palantir.atlasdb.jepsen.timestamp.NonOverlappingReadsMonotonicChecker Maven / Gradle / Ivy

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/*
 * (c) Copyright 2018 Palantir Technologies Inc. All rights reserved.
 *
 * 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.
 */
package com.palantir.atlasdb.jepsen.timestamp;

import com.google.common.collect.ImmutableList;
import com.palantir.atlasdb.jepsen.CheckerResult;
import com.palantir.atlasdb.jepsen.ImmutableCheckerResult;
import com.palantir.atlasdb.jepsen.events.Checker;
import com.palantir.atlasdb.jepsen.events.Event;
import com.palantir.atlasdb.jepsen.events.EventVisitor;
import com.palantir.atlasdb.jepsen.events.FailEvent;
import com.palantir.atlasdb.jepsen.events.ImmutableOkEvent;
import com.palantir.atlasdb.jepsen.events.InvokeEvent;
import com.palantir.atlasdb.jepsen.events.OkEvent;
import com.palantir.atlasdb.jepsen.events.RequestType;
import java.util.ArrayList;
import java.util.Comparator;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.NavigableSet;
import java.util.TreeSet;

public class NonOverlappingReadsMonotonicChecker implements Checker {
    @Override
    public CheckerResult check(List events) {
        Visitor visitor = new Visitor();
        events.forEach(event -> event.accept(visitor));
        return ImmutableCheckerResult.builder()
                .valid(visitor.valid())
                .errors(visitor.errors())
                .build();
    }

    private static final class Visitor implements EventVisitor {
        private static final String DUMMY_VALUE = "-1";
        private static final int DUMMY_PROCESS = -1;

        private final Map pendingReadForProcess = new HashMap<>();
        private final NavigableSet acknowledgedReadsOverTime =
                new TreeSet<>(Comparator.comparingLong(OkEvent::time));

        private final List errors = new ArrayList<>();

        @Override
        public Void visit(InvokeEvent event) {
            Integer process = event.process();
            pendingReadForProcess.put(process, event);
            return null;
        }

        @Override
        public Void visit(OkEvent event) {
            int process = event.process();

            InvokeEvent invoke = pendingReadForProcess.get(process);
            if (invoke != null) {
                validateTimestampHigherThanReadsCompletedBeforeInvoke(invoke, event);
            }

            pendingReadForProcess.remove(process);
            acknowledgedReadsOverTime.add(event);
            return null;
        }

        @Override
        public Void visit(FailEvent event) {
            Integer process = event.process();
            pendingReadForProcess.remove(process);
            return null;
        }

        public boolean valid() {
            return errors.isEmpty();
        }

        public List errors() {
            return ImmutableList.copyOf(errors);
        }

        private void validateTimestampHigherThanReadsCompletedBeforeInvoke(InvokeEvent invoke, OkEvent event) {
            OkEvent lastAcknowledgedRead = lastAcknowledgedReadBefore(invoke.time());
            if (lastAcknowledgedRead != null) {
                long timestamp = Long.parseLong(event.value());
                long lastAcknowledgedTimestamp = Long.parseLong(lastAcknowledgedRead.value());
                if (lastAcknowledgedTimestamp >= timestamp) {
                    errors.add(lastAcknowledgedRead);
                    errors.add(invoke);
                    errors.add(event);
                }
            }
        }

        private OkEvent lastAcknowledgedReadBefore(long time) {
            OkEvent dummyOkEvent = ImmutableOkEvent.builder()
                    .time(time)
                    .process(DUMMY_PROCESS)
                    .value(DUMMY_VALUE)
                    .function(RequestType.TIMESTAMP)
                    .build();
            return acknowledgedReadsOverTime.floor(dummyOkEvent);
        }
    }
}