TaskMailboxImpl (Flink : Streaming Java 1.19.1 API)

java.lang.Object
- org.apache.flink.streaming.runtime.tasks.mailbox.TaskMailboxImpl

All Implemented Interfaces:

TaskMailbox
```
@ThreadSafe
public class TaskMailboxImpl
extends Object
implements TaskMailbox
```
Implementation of TaskMailbox in a BlockingQueue fashion and tailored towards our use case with multiple writers and single reader.

Nested Class Summary
- Nested classes/interfaces inherited from interface org.apache.flink.streaming.runtime.tasks.mailbox.TaskMailbox
  TaskMailbox.MailboxClosedException, TaskMailbox.State

Field Summary
- Fields inherited from interface org.apache.flink.streaming.runtime.tasks.mailbox.TaskMailbox
  MAX_PRIORITY, MIN_PRIORITY

Constructor Summary

Constructors
Constructor and Description

TaskMailboxImpl()

TaskMailboxImpl(Thread taskMailboxThread)

Constructors
Constructor and Description
`TaskMailboxImpl()`
`TaskMailboxImpl(Thread taskMailboxThread)`

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`List<Mail>`	`close()` Close the mailbox.
`boolean`	`createBatch()` Creates a batch of mails that can be taken with `TaskMailbox.tryTakeFromBatch()`.
`List<Mail>`	`drain()` Drains the mailbox and returns all mails that were still enqueued.
`TaskMailbox.State`	`getState()` Returns the current state of the mailbox as defined by the lifecycle enum `TaskMailbox.State`.
`boolean`	`hasMail()` Returns `true` if the mailbox contains mail.
`boolean`	`isMailboxThread()` Check if the current thread is the mailbox thread.
`void`	`put(Mail mail)` Enqueues the given mail to the mailbox and blocks until there is capacity for a successful put.
`void`	`putFirst(Mail mail)` Adds the given action to the head of the mailbox.
`void`	`quiesce()` Quiesce the mailbox.
`void`	`runExclusively(Runnable runnable)` Runs the given code exclusively on this mailbox.
`int`	`size()` Returns the current number of mails in this mailbox.
`Mail`	`take(int priority)` This method returns the oldest mail from the mailbox (head of queue) or blocks until a mail is available.
`Optional<Mail>`	`tryTake(int priority)` Returns an optional with either the oldest mail from the mailbox (head of queue) if the mailbox is not empty or an empty optional otherwise.
`Optional<Mail>`	`tryTakeFromBatch()` Returns an optional with either the oldest mail from the batch (head of queue) if the batch is not empty or an empty optional otherwise.

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

- Constructor Detail
  - TaskMailboxImpl
```
public TaskMailboxImpl(@Nonnull
                       Thread taskMailboxThread)
```
  - TaskMailboxImpl
```
@VisibleForTesting
public TaskMailboxImpl()
```
- Method Detail
  - isMailboxThread
```
public boolean isMailboxThread()
```
    Description copied from interface: TaskMailbox
    
    Check if the current thread is the mailbox thread.
    Read operations will fail if they are called from another thread.
    
    Specified by:
    
    isMailboxThread in interface TaskMailbox
    
    Returns:
    
    only true if called from the mailbox thread.
  - hasMail
```
public boolean hasMail()
```
    Description copied from interface: TaskMailbox
    
    Returns true if the mailbox contains mail.
    Must be called from the mailbox thread (TaskMailbox.isMailboxThread().
    
    Specified by:
    
    hasMail in interface TaskMailbox
  - size
```
public int size()
```
    Description copied from interface: TaskMailbox
    
    Returns the current number of mails in this mailbox. (This includes mails in the batch not processed yet.)
    
    Specified by:
    
    size in interface TaskMailbox
    
    Returns:
    
    number of mails in the mailbox.
  - tryTake
```
public Optional<Mail> tryTake(int priority)
```
    Description copied from interface: TaskMailbox
    
    Returns an optional with either the oldest mail from the mailbox (head of queue) if the mailbox is not empty or an empty optional otherwise.
    Must be called from the mailbox thread (TaskMailbox.isMailboxThread().
    
    Specified by:
    
    tryTake in interface TaskMailbox
    
    Returns:
    
    an optional with either the oldest mail from the mailbox (head of queue) if the mailbox is not empty or an empty optional otherwise.
  - take
```
@Nonnull
public Mail take(int priority)
                   throws InterruptedException,
                          IllegalStateException
```
    Description copied from interface: TaskMailbox
    
    This method returns the oldest mail from the mailbox (head of queue) or blocks until a mail is available.
    Must be called from the mailbox thread (TaskMailbox.isMailboxThread().
    
    Specified by:
    
    take in interface TaskMailbox
    
    Returns:
    
    the oldest mail from the mailbox (head of queue).
    
    Throws:
    
    InterruptedException - on interruption.
    
    IllegalStateException - if mailbox is already closed.
  - createBatch
```
public boolean createBatch()
```
    Description copied from interface: TaskMailbox
    
    Creates a batch of mails that can be taken with TaskMailbox.tryTakeFromBatch(). The batch does not affect TaskMailbox.tryTake(int) and TaskMailbox.take(int); that is, they return the same mails even if no batch had been created.
    The default batch is empty. Thus, this method must be invoked once before TaskMailbox.tryTakeFromBatch().
    If a batch is not completely consumed by TaskMailbox.tryTakeFromBatch(), its elements are carried over to the new batch.
    Must be called from the mailbox thread (TaskMailbox.isMailboxThread().
    
    Specified by:
    
    createBatch in interface TaskMailbox
    
    Returns:
    
    true if there is at least one element in the batch; that is, if there is any mail at all at the time of the invocation.
  - tryTakeFromBatch
```
public Optional<Mail> tryTakeFromBatch()
```
    Description copied from interface: TaskMailbox
    
    Returns an optional with either the oldest mail from the batch (head of queue) if the batch is not empty or an empty optional otherwise.
    Must be called from the mailbox thread (TaskMailbox.isMailboxThread().
    Note that there is no blocking takeFromBatch as batches can only be created and consumed from the mailbox thread.
    
    Specified by:
    
    tryTakeFromBatch in interface TaskMailbox
    
    Returns:
    
    an optional with either the oldest mail from the batch (head of queue) if the batch is not empty or an empty optional otherwise.
  - put
```
public void put(@Nonnull
                Mail mail)
```
    Description copied from interface: TaskMailbox
    
    Enqueues the given mail to the mailbox and blocks until there is capacity for a successful put.
    Mails can be added from any thread.
    
    Specified by:
    
    put in interface TaskMailbox
    
    Parameters:
    
    mail - the mail to enqueue.
  - putFirst
```
public void putFirst(@Nonnull
                     Mail mail)
```
    Description copied from interface: TaskMailbox
    
    Adds the given action to the head of the mailbox.
    Mails can be added from any thread.
    
    Specified by:
    
    putFirst in interface TaskMailbox
    
    Parameters:
    
    mail - the mail to enqueue.
  - drain
```
public List<Mail> drain()
```
    Description copied from interface: TaskMailbox
    
    Drains the mailbox and returns all mails that were still enqueued.
    
    Specified by:
    
    drain in interface TaskMailbox
    
    Returns:
    
    list with all mails that where enqueued in the mailbox.
  - quiesce
```
public void quiesce()
```
    Description copied from interface: TaskMailbox
    
    Quiesce the mailbox. In this state, the mailbox supports only take operations and all pending and future put operations will throw TaskMailbox.MailboxClosedException.
    
    Specified by:
    
    quiesce in interface TaskMailbox
  - close
```
@Nonnull
public List<Mail> close()
```
    Description copied from interface: TaskMailbox
    
    Close the mailbox. In this state, all pending and future put operations and all pending and future take operations will throw TaskMailbox.MailboxClosedException. Returns all mails that were still enqueued.
    
    Specified by:
    
    close in interface TaskMailbox
    
    Returns:
    
    list with all mails that where enqueued in the mailbox at the time of closing.
  - getState
```
@Nonnull
public TaskMailbox.State getState()
```
    Description copied from interface: TaskMailbox
    
    Returns the current state of the mailbox as defined by the lifecycle enum TaskMailbox.State.
    
    Specified by:
    
    getState in interface TaskMailbox
    
    Returns:
    
    the current state of the mailbox.
  - runExclusively
```
public void runExclusively(Runnable runnable)
```
    Description copied from interface: TaskMailbox
    
    Runs the given code exclusively on this mailbox. No synchronized operations can be run concurrently to the given runnable (e.g., TaskMailbox.put(Mail) or modifying lifecycle methods).
    Use this methods when you want to atomically execute code that uses different methods (e.g., check for state and then put message if open).
    
    Specified by:
    
    runExclusively in interface TaskMailbox
    
    Parameters:
    
    runnable - the runnable to execute

Class TaskMailboxImpl

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.flink.streaming.runtime.tasks.mailbox.TaskMailbox

Field Summary

Fields inherited from interface org.apache.flink.streaming.runtime.tasks.mailbox.TaskMailbox

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

TaskMailboxImpl

TaskMailboxImpl

Method Detail

isMailboxThread

hasMail

size

tryTake

take

createBatch

tryTakeFromBatch

put

putFirst

drain

quiesce

close

getState

runExclusively