DistributedQueue (Atomix API Reference (1.0.8))

java.lang.Object
- io.atomix.resource.AbstractResource<DistributedQueue<T>>
- - io.atomix.collections.DistributedQueue<T>

Type Parameters:

T - The queue value type.

All Implemented Interfaces:

Managed<DistributedQueue<T>>, io.atomix.resource.Resource<DistributedQueue<T>>
```
public class DistributedQueue<T>
extends io.atomix.resource.AbstractResource<DistributedQueue<T>>
```
Distributed collection designed for holding ordered items for processing.
The distributed queue is closely modeled on Java's queues. All methods present in the Queue interface are present in this interface. Queued items are held in memory on each stateful node and backed by replicated logs on disk, thus the size of a queue is limited by the memory available to the smallest node in the cluster.
Internally, DistributedQueue uses an ArrayDeque to enqueue items in memory in the replicated state machine. Operations submitted through this interface are replicated and result in calling the associated method on the replicated ArrayDeque on each stateful node.
To create a distributed queue, use the getQueue factory method:
```
   
   DistributedQueue<String> queue = atomix.getQueue("foo").get();
   
 
```
All queue modification operations are linearizable, so items added to or removed from the queue will be immediately reflected from the perspective of all clients operating on the queue. The queue is shared by processes based on the queue name.
Queues support relaxed consistency levels for some read operations line size(ReadConsistency) and contains(Object, ReadConsistency). By default, read operations on a queue are linearizable but require some level of communication between nodes.
Author:

Jordan Halterman

Nested Class Summary

Nested Classes
Modifier and Type	Class and Description
`static class`	`DistributedQueue.Events` Distributed queue event types.
`static class`	`DistributedQueue.ValueEvent<T>` Generic queue value event.

Nested classes/interfaces inherited from interface io.atomix.resource.Resource
io.atomix.resource.Resource.Config, io.atomix.resource.Resource.Event, io.atomix.resource.Resource.EventType, io.atomix.resource.Resource.Options, io.atomix.resource.Resource.State

Constructor Summary

Constructors
Constructor and Description

DistributedQueue(CopycatClient client, Properties options)

Constructors
Constructor and Description
`DistributedQueue(CopycatClient client, Properties options)`

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`CompletableFuture<Boolean>`	`add(T value)` Adds a value to the set.
`CompletableFuture<Void>`	`clear()` Removes all values from the set.
`CompletableFuture<Boolean>`	`contains(Object value)` Checks whether the set contains a value.
`CompletableFuture<Boolean>`	`contains(Object value, io.atomix.resource.ReadConsistency consistency)` Checks whether the set contains a value.
`CompletableFuture<T>`	`element()` Removes a value from the queue.
`CompletableFuture<Boolean>`	`isEmpty()` Checks whether the set is empty.
`CompletableFuture<Boolean>`	`isEmpty(io.atomix.resource.ReadConsistency consistency)` Checks whether the set is empty.
`CompletableFuture<Boolean>`	`offer(T value)` Adds a value to the queue.
`CompletableFuture<Listener<DistributedQueue.ValueEvent<T>>>`	`onAdd(Consumer<DistributedQueue.ValueEvent<T>> callback)` Registers a queue item add event listener.
`CompletableFuture<Listener<DistributedQueue.ValueEvent<T>>>`	`onRemove(Consumer<DistributedQueue.ValueEvent<T>> callback)` Registers a queue item remove event listener.
`CompletableFuture<T>`	`peek()` Removes a value from the queue.
`CompletableFuture<T>`	`poll()` Removes a value from the queue.
`CompletableFuture<T>`	`remove()` Removes a value from the queue.
`CompletableFuture<Boolean>`	`remove(T value)` Removes a value from the set.
`CompletableFuture<Integer>`	`size()` Gets the set count.
`CompletableFuture<Integer>`	`size(io.atomix.resource.ReadConsistency consistency)` Gets the set count.

Methods inherited from class io.atomix.resource.AbstractResource
close, config, context, delete, equals, hashCode, isClosed, isOpen, onRecovery, onStateChange, open, options, serializer, state, toString, type

Methods inherited from class java.lang.Object
getClass, notify, notifyAll, wait, wait, wait

- Constructor Detail
  - DistributedQueue
```
public DistributedQueue(CopycatClient client,
                        Properties options)
```
- Method Detail
  - add
```
public CompletableFuture<Boolean> add(T value)
```
    Adds a value to the set.
    
    Parameters:
    
    value - The value to add.
    
    Returns:
    
    A completable future to be completed with the result once complete.
  - offer
```
public CompletableFuture<Boolean> offer(T value)
```
    Adds a value to the queue.
    
    Parameters:
    
    value - The value to add.
    
    Returns:
    
    A completable future to be completed with the result once complete.
  - peek
```
public CompletableFuture<T> peek()
```
    Removes a value from the queue.
    
    Returns:
    
    A completable future to be completed with the result once complete.
  - poll
```
public CompletableFuture<T> poll()
```
    Removes a value from the queue.
    
    Returns:
    
    A completable future to be completed with the result once complete.
  - element
```
public CompletableFuture<T> element()
```
    Removes a value from the queue.
    
    Returns:
    
    A completable future to be completed with the result once complete.
  - remove
```
public CompletableFuture<T> remove()
```
    Removes a value from the queue.
    
    Returns:
    
    A completable future to be completed with the result once complete.
  - remove
```
public CompletableFuture<Boolean> remove(T value)
```
    Removes a value from the set.
    
    Parameters:
    
    value - The value to remove.
    
    Returns:
    
    A completable future to be completed with the result once complete.
  - contains
```
public CompletableFuture<Boolean> contains(Object value)
```
    Checks whether the set contains a value.
    
    Parameters:
    
    value - The value to check.
    
    Returns:
    
    A completable future to be completed with the result once complete.
  - contains
```
public CompletableFuture<Boolean> contains(Object value,
                                           io.atomix.resource.ReadConsistency consistency)
```
    Checks whether the set contains a value.
    
    Parameters:
    
    value - The value to check.
    
    consistency - The read consistency level.
    
    Returns:
    
    A completable future to be completed with the result once complete.
  - size
```
public CompletableFuture<Integer> size()
```
    Gets the set count.
    
    Returns:
    
    A completable future to be completed with the set count.
  - size
```
public CompletableFuture<Integer> size(io.atomix.resource.ReadConsistency consistency)
```
    Gets the set count.
    
    Parameters:
    
    consistency - The read consistency level.
    
    Returns:
    
    A completable future to be completed with the set count.
  - isEmpty
```
public CompletableFuture<Boolean> isEmpty()
```
    Checks whether the set is empty.
    
    Returns:
    
    A completable future to be completed with a boolean value indicating whether the set is empty.
  - isEmpty
```
public CompletableFuture<Boolean> isEmpty(io.atomix.resource.ReadConsistency consistency)
```
    Checks whether the set is empty.
    
    Parameters:
    
    consistency - The read consistency level.
    
    Returns:
    
    A completable future to be completed with a boolean value indicating whether the set is empty.
  - clear
```
public CompletableFuture<Void> clear()
```
    Removes all values from the set.
    
    Returns:
    
    A completable future to be completed once the operation is complete.
  - onAdd
```
public CompletableFuture<Listener<DistributedQueue.ValueEvent<T>>> onAdd(Consumer<DistributedQueue.ValueEvent<T>> callback)
```
    Registers a queue item add event listener.
    
    Parameters:
    
    callback - The event listener callback to be called when an item is added to the queue.
    
    Returns:
    
    A completable future to be completed once the listener has been registered with the cluster.
  - onRemove
```
public CompletableFuture<Listener<DistributedQueue.ValueEvent<T>>> onRemove(Consumer<DistributedQueue.ValueEvent<T>> callback)
```
    Registers a queue item remove event listener.
    
    Parameters:
    
    callback - The event listener callback to be called when an item is removed from the queue.
    
    Returns:
    
    A completable future to be completed once the listener has been registered with the cluster.

Class DistributedQueue<T>

Nested Class Summary

Nested classes/interfaces inherited from interface io.atomix.resource.Resource

Constructor Summary

Method Summary

Methods inherited from class io.atomix.resource.AbstractResource

Methods inherited from class java.lang.Object

Constructor Detail

DistributedQueue

Method Detail

add

offer

peek

poll

element

remove

remove

contains

contains

size

size

isEmpty

isEmpty

clear

onAdd

onRemove