rx.internal.util.unsafe.QueueProgressIndicators Maven / Gradle / Ivy
/*
* 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.
*
* Original License: https://github.com/JCTools/JCTools/blob/master/LICENSE
* Original location: https://github.com/JCTools/JCTools/blob/master/jctools-core/src/main/java/org/jctools/queues/QueueProgressIndicators.java
*/
package rx.internal.util.unsafe;
/**
* This interface is provided for monitoring purposes only and is only available on queues where it is easy to
* provide it. The producer/consumer progress indicators usually correspond with the number of elements
* offered/polled, but they are not guaranteed to maintain that semantic.
*
* @author nitsanw
*
*/
public interface QueueProgressIndicators {
/**
* This method has no concurrent visibility semantics. The value returned may be negative. Under normal
* circumstances 2 consecutive calls to this method can offer an idea of progress made by producer threads
* by subtracting the 2 results though in extreme cases (if producers have progressed by more than 2^64)
* this may also fail.
* This value will normally indicate number of elements passed into the queue, but may under some
* circumstances be a derivative of that figure. This method should not be used to derive size or
* emptiness.
*
* @return the current value of the producer progress index
*/
long currentProducerIndex();
/**
* This method has no concurrent visibility semantics. The value returned may be negative. Under normal
* circumstances 2 consecutive calls to this method can offer an idea of progress made by consumer threads
* by subtracting the 2 results though in extreme cases (if consumers have progressed by more than 2^64)
* this may also fail.
* This value will normally indicate number of elements taken out of the queue, but may under some
* circumstances be a derivative of that figure. This method should not be used to derive size or
* emptiness.
*
* @return the current value of the consumer progress index
*/
long currentConsumerIndex();
}
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