MessagePassingQueue (Java Concurrency Tools Core Library 2.1.2 API)

Type Parameters:

T - the event/message type

All Known Implementing Classes:

BaseMpscLinkedArrayQueue, BaseMpscLinkedAtomicArrayQueue, ConcurrentCircularArrayQueue, ConcurrentSequencedCircularArrayQueue, MpmcArrayQueue, MpmcAtomicArrayQueue, MpscArrayQueue, MpscAtomicArrayQueue, MpscChunkedArrayQueue, MpscChunkedAtomicArrayQueue, MpscCompoundQueue, MpscGrowableArrayQueue, MpscGrowableAtomicArrayQueue, MpscLinkedAtomicQueue, MpscLinkedQueue, MpscLinkedQueue7, MpscLinkedQueue8, MpscUnboundedArrayQueue, MpscUnboundedAtomicArrayQueue, SpmcArrayQueue, SpmcAtomicArrayQueue, SpscArrayQueue, SpscAtomicArrayQueue, SpscChunkedArrayQueue, SpscChunkedAtomicArrayQueue, SpscGrowableArrayQueue, SpscGrowableAtomicArrayQueue, SpscLinkedAtomicQueue, SpscLinkedQueue, SpscUnboundedArrayQueue, SpscUnboundedAtomicArrayQueue
```
public interface MessagePassingQueue<T>
```
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 provide 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.

Author:

nitsanw

Nested Class Summary

Nested Classes
Modifier and Type	Interface and Description
`static interface`	`MessagePassingQueue.Consumer<T>`
`static interface`	`MessagePassingQueue.ExitCondition`
`static interface`	`MessagePassingQueue.Supplier<T>`
`static interface`	`MessagePassingQueue.WaitStrategy`

Field Summary

Fields
Modifier and Type Field and Description

static int UNBOUNDED_CAPACITY

Fields
Modifier and Type	Field and Description
`static int`	`UNBOUNDED_CAPACITY`

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method and Description
`int`	`capacity()`
`void`	`clear()` Removes all items from the queue.
`int`	`drain(MessagePassingQueue.Consumer<T> c)` Remove all available item from the queue and hand to consume.
`int`	`drain(MessagePassingQueue.Consumer<T> c, int limit)` Remove up to limit elements from the queue and hand to consume.
`void`	`drain(MessagePassingQueue.Consumer<T> c, MessagePassingQueue.WaitStrategy wait, MessagePassingQueue.ExitCondition exit)` Remove elements from the queue and hand to consume forever.
`int`	`fill(MessagePassingQueue.Supplier<T> s)` Stuff the queue with elements from the supplier.
`int`	`fill(MessagePassingQueue.Supplier<T> s, int limit)` Stuff the queue with up to limit elements from the supplier.
`void`	`fill(MessagePassingQueue.Supplier<T> s, MessagePassingQueue.WaitStrategy wait, MessagePassingQueue.ExitCondition exit)` Stuff the queue with elements from the supplier forever.
`boolean`	`isEmpty()` This method's accuracy is subject to concurrent modifications happening as the observation is carried out.
`boolean`	`offer(T e)` Called from a producer thread subject to the restrictions appropriate to the implementation and according to the `Queue.offer(Object)` interface.
`T`	`peek()` Called from the consumer thread subject to the restrictions appropriate to the implementation and according to the `Queue.peek()` interface.
`T`	`poll()` Called from the consumer thread subject to the restrictions appropriate to the implementation and according to the `Queue.poll()` interface.
`boolean`	`relaxedOffer(T e)` Called from a producer thread subject to the restrictions appropriate to the implementation.
`T`	`relaxedPeek()` Called from the consumer thread subject to the restrictions appropriate to the implementation.
`T`	`relaxedPoll()` Called from the consumer thread subject to the restrictions appropriate to the implementation.
`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.

- Field Detail
  - UNBOUNDED_CAPACITY
```
static final int UNBOUNDED_CAPACITY
```
    See Also:
    
    Constant Field Values
- Method Detail
  - offer
```
boolean offer(T e)
```
    Called from a producer thread subject to the restrictions appropriate to the implementation and according to the Queue.offer(Object) interface.
    
    Parameters:
    
    e - not null, will throw NPE if it is
    
    Returns:
    
    true if element was inserted into the queue, false iff full
  - poll
```
T 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
```
T 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 Integer.MAX_VALUE but less or equals to capacity (if bounded).
  - clear
```
void clear()
```
    Removes all items from the queue. Called from the consumer thread subject to the restrictions appropriate to the implementation and according to the Collection.clear() interface.
  - 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
  - capacity
```
int capacity()
```
    Returns:
    
    the capacity of this queue or UNBOUNDED_CAPACITY if not bounded
  - relaxedOffer
```
boolean relaxedOffer(T e)
```
    Called from a producer thread subject to the restrictions appropriate to the implementation. As opposed to Queue.offer(Object) this method may return false without the queue being full.
    
    Parameters:
    
    e - not null, will throw NPE if it is
    
    Returns:
    
    true if element was inserted into the queue, false if unable to offer
  - relaxedPoll
```
T relaxedPoll()
```
    Called from the consumer thread subject to the restrictions appropriate to the implementation. As opposed to Queue.poll() this method may return null without the queue being empty.
    
    Returns:
    
    a message from the queue if one is available, null if unable to poll
  - relaxedPeek
```
T relaxedPeek()
```
    Called from the consumer thread subject to the restrictions appropriate to the implementation. As opposed to Queue.peek() this method may return null without the queue being empty.
    
    Returns:
    
    a message from the queue if one is available, null if unable to peek
  - drain
```
int drain(MessagePassingQueue.Consumer<T> c)
```
    Remove all available item from the queue and hand to consume. This should be semantically similar to: M m; while((m = relaxedPoll()) != null){ c.accept(m); } There's no strong commitment to the queue being empty at the end of a drain. Called from a consumer thread subject to the restrictions appropriate to the implementation.
    
    Returns:
    
    the number of polled elements
  - fill
```
int fill(MessagePassingQueue.Supplier<T> s)
```
    Stuff the queue with elements from the supplier. Semantically similar to: while(relaxedOffer(s.get()); There's no strong commitment to the queue being full at the end of a fill. Called from a producer thread subject to the restrictions appropriate to the implementation.
    
    Returns:
    
    the number of offered elements
  - drain
```
int drain(MessagePassingQueue.Consumer<T> c,
          int limit)
```
    Remove up to limit elements from the queue and hand to consume. This should be semantically similar to:
```
 
   M m;
   int i = 0;
   for(;i < limit && (m = relaxedPoll()) != null; i++){
     c.accept(m);
   }
   return i;
 
 
```
    There's no strong commitment to the queue being empty at the end of a drain. Called from a consumer thread subject to the restrictions appropriate to the implementation.
    Returns:
    
    the number of polled elements
  - fill
```
int fill(MessagePassingQueue.Supplier<T> s,
         int limit)
```
    Stuff the queue with up to limit elements from the supplier. Semantically similar to:
```
 
   for(int i=0; i < limit && relaxedOffer(s.get()); i++);

 
 
```
    There's no strong commitment to the queue being full at the end of a fill. Called from a producer thread subject to the restrictions appropriate to the implementation.
    Returns:
    
    the number of offered elements
  - drain
```
void drain(MessagePassingQueue.Consumer<T> c,
           MessagePassingQueue.WaitStrategy wait,
           MessagePassingQueue.ExitCondition exit)
```
    Remove elements from the queue and hand to consume forever. Semantically similar to:
```
 
  int idleCounter = 0;
  while (exit.keepRunning()) {
      E e = relaxedPoll();
      if(e==null){
          idleCounter = wait.idle(idleCounter);
          continue;
      }
      idleCounter = 0;
      c.accept(e);
  }
 
 
```
    Called from a consumer thread subject to the restrictions appropriate to the implementation.
  - fill
```
void fill(MessagePassingQueue.Supplier<T> s,
          MessagePassingQueue.WaitStrategy wait,
          MessagePassingQueue.ExitCondition exit)
```
    Stuff the queue with elements from the supplier forever. Semantically similar to:
```
 
  int idleCounter = 0;
  while (exit.keepRunning()) {
      E e = s.get();
      while (!relaxedOffer(e)) {
          idleCounter = wait.idle(idleCounter);
          continue;
      }
      idleCounter = 0;
  }
 
 
```
    Called from a producer thread subject to the restrictions appropriate to the implementation.

Interface MessagePassingQueue<T>

Nested Class Summary

Field Summary

Method Summary

Field Detail

UNBOUNDED_CAPACITY

Method Detail

offer

poll

peek

size

clear

isEmpty

capacity

relaxedOffer

relaxedPoll

relaxedPeek

drain

fill

drain

fill

drain

fill