FLUSH(5) File Formats Manual FLUSH(5)
flush - abort a message
Tflush tag oldtag
When the response to a request is no longer needed, such as when a user
interrupts a process doing a read(2), a Tflush request is sent to the
server to purge the pending response. The message being flushed is
identified by oldtag. The semantics of flush depends on messages
arriving in order.
The server must answer the flush message immediately. If it recognizes
oldtag as the tag of a pending transaction, it should abort any pending
response and discard that tag. In either case, it should respond with
an Rflush echoing the tag (not oldtag) of the Tflush message. A Tflush
can never be responded to by an Rerror message.
When the client sends the Tflush, it should disregard all messages
received with tag oldtag until the corresponding Rflush is received, at
which point oldtag may be recycled for subsequent messages.
Several exceptional conditions are handled correctly by the above spec-
ification: sending multiple flushes for a single tag, flushing a
Tflush, and flushing an invalid tag.