io.questdb.mp.MCSequence Maven / Gradle / Ivy
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* ___ _ ____ ____
* / _ \ _ _ ___ ___| |_| _ \| __ )
* | | | | | | |/ _ \/ __| __| | | | _ \
* | |_| | |_| | __/\__ \ |_| |_| | |_) |
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*
* 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;
}
}