io.questdb.mp.MCSequence Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of core Show documentation
QuestDB is High Performance Time Series Database
The newest version!
/*******************************************************************************
 *     ___                  _   ____  ____
 *    / _ \ _   _  ___  ___| |_|  _ \| __ )
 *   | | | | | | |/ _ \/ __| __| | | |  _ \
 *   | |_| | |_| |  __/\__ \ |_| |_| | |_) |
 *    \__\_\\__,_|\___||___/\__|____/|____/
 *
 *  Copyright (c) 2014-2019 Appsicle
 *  Copyright (c) 2019-2020 QuestDB
 *
 *  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 io.questdb.mp;

public class MCSequence extends AbstractMSequence {

    public MCSequence(int cycle) {
        this(cycle, null);
    }

    public MCSequence(int cycle, WaitStrategy waitStrategy) {
        super(cycle, waitStrategy);
    }

    public  void consumeAll(RingQueue queue, QueueConsumer consumer) {
        long cursor;
        do {
            cursor = next();
            if (cursor > -1) {
                consumer.consume(queue.get(cursor));
                done(cursor);
            }
        } while (cursor != -1);

    }

    @Override
    public long next() {
        long cached = cache;
        // this is a volatile read, we should have correct order for "cache" too
        long current = value;
        long next = current + 1;

        if (next > cached) {
            long avail = barrier.availableIndex(next);
            if (avail > cached) {
                setCacheFenced(avail);
                if (next > avail) {
                    return -1;
                }
            } else {
                return -1;
            }
        }
        return casValue(current, next) ? next : -2;
    }
}