# Mailboxes are objects that enable synchronous IPC via short message-passing
# of tagged handles.

object mailbox : object {
    uid 99934ad04ece1e07

    capabilities [
        send
        receive
        close
    ]

    method create [constructor]
    method close [destructor cap:close]

    # Send a message to the reciever, and block until a
    # response is sent. Note that getting this response
    # does not require the receive capability.
    method call [cap:send] {
        param tag uint64 [inout]
        param subtag uint64 [inout]
        param handles ref object [inout list zero_ok]
    }

    # Respond to a message sent using call, and wait for another
    # message to arrive. Note that this does not require the send
    # capability. A reply tag of 0 skips the reply and goes directly
    # to waiting for a new message.
    method respond [cap:receive] {
        param tag uint64 [inout]
        param subtag uint64 [inout]
        param handles ref object [inout list zero_ok]
        param handles_in size
        param reply_tag uint16 [inout]
        param flags uint64
    }
}
