InmemQueue (ddth-queue-core 0.4.2 API)

java.lang.Object
- com.github.ddth.queue.impl.InmemQueue

All Implemented Interfaces:

IQueue, Closeable, AutoCloseable

Direct Known Subclasses:

BaseUniversalInmemQueue
```
public class InmemQueue
extends Object
implements IQueue, Closeable, AutoCloseable
```
In-Memory implementation of IQueue.
Implementation:
- A Queue as queue storage.
- A ConcurrentMap as ephemeral storage.
Since:

0.4.0

Author:

Thanh Ba Nguyen

Constructor Summary

Constructors
Constructor and Description

InmemQueue()

InmemQueue(int boundary)

Constructors
Constructor and Description
`InmemQueue()`
`InmemQueue(int boundary)`

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`close()`
`protected Queue<IQueueMessage>`	`createQueue(int boundary)` This method will create a `Queue` instance with the following rules: If `boundary` is set and larger than `1024`, a `LinkedBlockingQueue` is created; if `boundary` is less than or equals to `1024`, an `ArrayBlockingQueue` is created instead. Otherwise, a `ConcurrentLinkedQueue` is created.
`void`	`destroy()` Destroy method.
`int`	`ephemeralSize()` Gets ephemeral-storage's number of items.
`void`	`finish(IQueueMessage msg)` Called when finish processing the message to cleanup ephemeral storage.
`int`	`getBoundary()` Gets queue's boundary (max number of elements).
`boolean`	`getEphemeralDisabled()` Is ephemeral storage disabled?
`Collection<IQueueMessage>`	`getOrphanMessages(long thresholdTimestampMs)` Gets all orphan messages (messages that were left in ephemeral storage for a long time).
`InmemQueue`	`init()` Init method.
`boolean`	`isEphemeralDisabled()` Is ephemeral storage disabled?
`boolean`	`moveFromEphemeralToQueueStorage(IQueueMessage _msg)` Moves a message from ephemeral back to queue storage.
`protected boolean`	`putToQueue(IQueueMessage msg)` Puts a message to the internal queue.
`boolean`	`queue(IQueueMessage _msg)` Queues a message.
`int`	`queueSize()` Gets queue's number of items.
`boolean`	`requeue(IQueueMessage _msg)` Re-queues a message.
`boolean`	`requeueSilent(IQueueMessage msg)` Silently re-queues a message.
`InmemQueue`	`setBoundary(int boundary)` Sets queue's boundary (max number of elements).
`InmemQueue`	`setEphemeralDisabled(boolean ephemeralDisabled)` Disables/Enables ephemeral storage.
`IQueueMessage`	`take()` Takes a message out of queue.
`protected IQueueMessage`	`takeFromQueue()` Takes a message from the internal queue.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - InmemQueue
```
public InmemQueue()
```
  - InmemQueue
```
public InmemQueue(int boundary)
```
- Method Detail
  - getEphemeralDisabled
```
public boolean getEphemeralDisabled()
```
    Is ephemeral storage disabled?
    
    Returns:
  - isEphemeralDisabled
```
public boolean isEphemeralDisabled()
```
    Is ephemeral storage disabled?
    
    Returns:
  - setEphemeralDisabled
```
public InmemQueue setEphemeralDisabled(boolean ephemeralDisabled)
```
    Disables/Enables ephemeral storage.
    
    Parameters:
    
    ephemeralDisabled - true to disable ephemeral storage, false otherwise.
    
    Returns:
  - getBoundary
```
public int getBoundary()
```
    Gets queue's boundary (max number of elements).
    
    Returns:
  - setBoundary
```
public InmemQueue setBoundary(int boundary)
```
    Sets queue's boundary (max number of elements).
    
    Parameters:
    
    boundary - queue's max number of elements, a value less than 1 mean "no boundary".
    
    Returns:
  - createQueue
```
protected Queue<IQueueMessage> createQueue(int boundary)
```
    This method will create a Queue instance with the following rules:
    - If boundary is set and larger than 1024, a LinkedBlockingQueue is created; if boundary is less than or equals to 1024, an ArrayBlockingQueue is created instead.
    - Otherwise, a ConcurrentLinkedQueue is created.
    Parameters:
    
    boundary -
    
    Returns:
  - init
```
public InmemQueue init()
```
    Init method.
    
    Returns:
  - destroy
```
public void destroy()
```
    Destroy method.
  - close
```
public void close()
```
    Specified by:
    
    close in interface Closeable
    
    Specified by:
    
    close in interface AutoCloseable
  - putToQueue
```
protected boolean putToQueue(IQueueMessage msg)
```
    Puts a message to the internal queue.
    
    Parameters:
    
    msg -
    
    Returns:
  - queue
```
public boolean queue(IQueueMessage _msg)
```
    Queues a message.
    Implementation flow:
    - Put message to tail of queue storage.
    Specified by:
    
    queue in interface IQueue
    
    Returns:
  - requeue
```
public boolean requeue(IQueueMessage _msg)
```
    Re-queues a message.
    Implementation flow:
    - Put message to tail of queue storage; and increase message's re-queue count & update message's queue timestamp.
    - Remove message from ephemeral storage.
    Note: ephemeral storage implementation is optional, depends on implementation.
    Specified by:
    
    requeue in interface IQueue
    
    Returns:
  - requeueSilent
```
public boolean requeueSilent(IQueueMessage msg)
```
    Silently re-queues a message.
    Implementation flow:
    - Put message to tail of queue storage; do NOT increase message's re-queue count and do NOT update message's queue timestamp.
    - Remove message from ephemeral storage.
    Note: ephemeral storage implementation is optional, depends on implementation.
    Specified by:
    
    requeueSilent in interface IQueue
    
    Returns:
  - finish
```
public void finish(IQueueMessage msg)
```
    Called when finish processing the message to cleanup ephemeral storage.
    Implementation flow:
    - Remove message from ephemeral storage.
    Note: ephemeral storage implementation is optional, depends on implementation.
    Specified by:
    
    finish in interface IQueue
  - takeFromQueue
```
protected IQueueMessage takeFromQueue()
```
    Takes a message from the internal queue.
    
    Returns:
  - take
```
public IQueueMessage take()
```
    Takes a message out of queue.
    Implementation flow:
    - Read message from head of queue storage.
    - Write message to ephemeral storage.
    - Remove message from queue storage.
    Note: ephemeral storage implementation is optional, depends on implementation.
    Specified by:
    
    take in interface IQueue
    
    Returns:
  - getOrphanMessages
```
public Collection<IQueueMessage> getOrphanMessages(long thresholdTimestampMs)
```
    Gets all orphan messages (messages that were left in ephemeral storage for a long time).
    
    Specified by:
    
    getOrphanMessages in interface IQueue
    
    Parameters:
    
    thresholdTimestampMs -
    
    Returns:
  - moveFromEphemeralToQueueStorage
```
public boolean moveFromEphemeralToQueueStorage(IQueueMessage _msg)
```
    Moves a message from ephemeral back to queue storage. Useful when dealing with orphan messages.
    Implementation flow:
    - Read message from the ephemeral storage.
    - Put the message back to queue.
    - Remove the message from the ephemeral storage.
    Specified by:
    
    moveFromEphemeralToQueueStorage in interface IQueue
    
    Returns:
    
    true if a move has been made, false otherwise (e.g. the message didn't exist in ephemeral storage)
  - queueSize
```
public int queueSize()
```
    Gets queue's number of items.
    
    Specified by:
    
    queueSize in interface IQueue
    
    Returns:
  - ephemeralSize
```
public int ephemeralSize()
```
    Gets ephemeral-storage's number of items.
    Note: ephemeral storage implementation is optional, depends on implementation.
    
    Specified by:
    
    ephemeralSize in interface IQueue
    
    Returns:

Class InmemQueue

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

InmemQueue

InmemQueue

Method Detail

getEphemeralDisabled

isEphemeralDisabled

setEphemeralDisabled

getBoundary

setBoundary

createQueue

init

destroy

close

putToQueue

queue

requeue

requeueSilent

finish

takeFromQueue

take

getOrphanMessages

moveFromEphemeralToQueueStorage

queueSize

ephemeralSize