MessagePassingQueue

Type Parameters:

M - the event/message type

All Known Implementing Classes:

ConcurrentCircularArrayQueue, ConcurrentCircularArrayQueueL0Pad, ConcurrentSequencedCircularArrayQueue, MpmcArrayQueue, MpmcArrayQueueConsumerField, MpmcArrayQueueL1Pad, MpmcArrayQueueL2Pad, MpmcArrayQueueProducerField, SpmcArrayQueue, SpmcArrayQueueConsumerField, SpmcArrayQueueL1Pad, SpmcArrayQueueL2Pad, SpmcArrayQueueL3Pad, SpmcArrayQueueMidPad, SpmcArrayQueueProducerField, SpmcArrayQueueProducerIndexCacheField, SpscArrayQueue, SpscArrayQueueColdField, SpscArrayQueueConsumerField, SpscArrayQueueL1Pad, SpscArrayQueueL2Pad, SpscArrayQueueL3Pad, SpscArrayQueueProducerFields
```
public interface MessagePassingQueue<M>
```
This is a tagging interface for the queues in this library which implement a subset of the Queue interface sufficient for concurrent message passing.
Message passing queues offer happens before semantics to messages passed through, namely that writes made by the producer before offering the message are visible to the consuming thread after the message has been polled out of the queue.

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`boolean`	`isEmpty()`	This method's accuracy is subject to concurrent modifications happening as the observation is carried out.
`boolean`	`offer(M message)`	Called from a producer thread subject to the restrictions appropriate to the implementation and according to the `Queue.offer(Object)` interface.
`M`	`peek()`	Called from the consumer thread subject to the restrictions appropriate to the implementation and according to the `Queue.peek()` interface.
`M`	`poll()`	Called from the consumer thread subject to the restrictions appropriate to the implementation and according to the `Queue.poll()` interface.
`int`	`size()`	This method's accuracy is subject to concurrent modifications happening as the size is estimated and as such is a best effort rather than absolute value.

- Method Detail
  - offer
```
boolean offer(M message)
```
    Called from a producer thread subject to the restrictions appropriate to the implementation and according to the Queue.offer(Object) interface.
    
    Parameters:
    
    message -
    
    Returns:
    
    true if element was inserted into the queue, false iff full
  - poll
```
M poll()
```
    Called from the consumer thread subject to the restrictions appropriate to the implementation and according to the Queue.poll() interface.
    
    Returns:
    
    a message from the queue if one is available, null iff empty
  - peek
```
M peek()
```
    Called from the consumer thread subject to the restrictions appropriate to the implementation and according to the Queue.peek() interface.
    
    Returns:
    
    a message from the queue if one is available, null iff empty
  - size
```
int size()
```
    This method's accuracy is subject to concurrent modifications happening as the size is estimated and as such is a best effort rather than absolute value. For some implementations this method may be O(n) rather than O(1).
    
    Returns:
    
    number of messages in the queue, between 0 and queue capacity or Integer.MAX_VALUE if not bounded
  - isEmpty
```
boolean isEmpty()
```
    This method's accuracy is subject to concurrent modifications happening as the observation is carried out.
    
    Returns:
    
    true if empty, false otherwise