QueueProgressIndicators (Java Concurrency Tools Core Library 4.0.1 API)

All Known Implementing Classes:

ConcurrentSequencedCircularArrayQueue, ConcurrentSequencedCircularUnpaddedArrayQueue, MpmcArrayQueue, MpmcAtomicArrayQueue, MpmcUnboundedXaddArrayQueue, MpmcUnpaddedArrayQueue, MpscArrayQueue, MpscAtomicArrayQueue, MpscBlockingConsumerArrayQueue, MpscChunkedArrayQueue, MpscChunkedAtomicArrayQueue, MpscChunkedUnpaddedArrayQueue, MpscGrowableArrayQueue, MpscGrowableAtomicArrayQueue, MpscGrowableUnpaddedArrayQueue, MpscUnboundedArrayQueue, MpscUnboundedAtomicArrayQueue, MpscUnboundedUnpaddedArrayQueue, MpscUnboundedXaddArrayQueue, MpscUnpaddedArrayQueue, SpmcArrayQueue, SpmcAtomicArrayQueue, SpmcUnpaddedArrayQueue, SpscArrayQueue, SpscAtomicArrayQueue, SpscChunkedArrayQueue, SpscChunkedAtomicArrayQueue, SpscChunkedUnpaddedArrayQueue, SpscGrowableArrayQueue, SpscGrowableAtomicArrayQueue, SpscGrowableUnpaddedArrayQueue, SpscUnboundedArrayQueue, SpscUnboundedAtomicArrayQueue, SpscUnboundedUnpaddedArrayQueue, SpscUnpaddedArrayQueue
```
public interface QueueProgressIndicators
```
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.

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`long`	`currentConsumerIndex()`	This method has no concurrent visibility semantics.
`long`	`currentProducerIndex()`	This method has no concurrent visibility semantics.

- Method Detail
  - currentProducerIndex
```
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 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.
    
    Returns:
    
    the current value of the producer progress index
  - currentConsumerIndex
```
long currentConsumerIndex()
```
    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.
    
    Returns:
    
    the current value of the consumer progress index