All Known Implementing Classes:

GrpcSendingMailbox, InMemorySendingMailbox
```
public interface SendingMailbox
```
Mailbox that's used to send data.

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`void`	`cancel(Throwable t)`	Cancels the mailbox and notifies the receiver of the cancellation so that it can release the underlying resources.
`void`	`complete()`	Called when there is no more data to be sent by the `BlockExchange`.
`boolean`	`isTerminated()`	Returns whether the `ReceivingMailbox` is already closed.
`void`	`send(TransferableBlock block)`	Sends a block to the receiver.

- Method Detail
  - send
```
void send(TransferableBlock block)
   throws IOException,
          TimeoutException
```
    Sends a block to the receiver. Note that SendingMailbox are required to acquire resources lazily in this call, and they should not acquire any resources when they are created. This method should throw if there was an error sending the data, since that would allow BlockExchange to exit early.
    
    Throws:
    
    IOException
    
    TimeoutException
  - complete
```
void complete()
```
    Called when there is no more data to be sent by the BlockExchange. This is also a signal for the SendingMailbox that the sender is done sending data from its end. Note that this doesn't mean that the receiver has received all the data.
    Note: While this is similar to a close() method that's usually provided with objects that hold releasable resources, the key difference is that a SendingMailbox cannot completely release the resources on its end gracefully, since it would be waiting for the receiver to ack that it has received all the data. See cancel(java.lang.Throwable) which can allow callers to force release the underlying resources.
  - cancel
```
void cancel(Throwable t)
```
    Cancels the mailbox and notifies the receiver of the cancellation so that it can release the underlying resources. No more blocks can be sent after calling this method.
  - isTerminated
```
boolean isTerminated()
```
    Returns whether the ReceivingMailbox is already closed. There is no need to send more blocks after the mailbox is terminated.

Interface SendingMailbox

Method Summary

Method Detail

send

complete

cancel

isTerminated