Package org.apache.flink.streaming.runtime.tasks.mailbox

Class TaskMailboxImpl

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.

  • Constructor Details

    • TaskMailboxImpl

      public TaskMailboxImpl(@Nonnull Thread taskMailboxThread)

    • TaskMailboxImpl

      @VisibleForTesting public TaskMailboxImpl()

  • Method Details

    • 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