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AsynchronousSocketChannel.write ensures TCP ACK?

Question regarding AsynchronousSocketChannel.write method

public final <A> void write(ByteBuffer src,
             A attachment,
             CompletionHandler<Integer,? super A> handler)

Does this method guarantee ACK is received before the handler is fired?

Or it just ensures the ByteBuffer is delivered to network driver of local machine?

Solution

  • Neither. It ensures that the data has been transferred into the socket send buffer. From there it goes asynchronously to the NIC and from there to the network.