-s takes the directions to splice: -s1 what the server sends (downloads),
-s2 what the client sends (uploads), -s3 both. -s alone (-s7) splices both
only where it pays, as -s5 and -s6 do for one direction:
- a body of known length is spliced if at least 16K of it is left to read
once what is already buffered is counted, so an answer read whole with
its headers is just copied;
- a stream of unknown length starts copied, is spliced after 2 reads in a
row of at least 16K, and goes back to copying after 3 splices in a row
of less than 4K, once its pipe is empty.
Pipes are made when a direction first splices and kept with the
connection for its next mappings, so a kept-alive connection no longer
makes and closes two pipes per request; one left holding data by an
error or a timeout is closed. The direction not spliced keeps its buffer.
Before, -s spliced both directions and every mapping made both pipes,
which made small answers slower than without splice: with kept-alive
50K answers 2 pipe2() and 4 close() per request, now none.
Also corrects the default buffer size in the -b help (65536 for TCP).
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
`proxy -g8000,3,10`
First parameter is average read size we want to keep, second parameter is
minimal number of packets in the same direction to apply algorythm,
last value is delay added after polling and prior to reading data.
An example above adds 10 millisecond delay before reading data if average
polling size is below 8000 bytes and 3 read operations are made in the same
direction. It's specially usefule with splice. `logdump 1 1` is useful
to see how grace delays work, choose delay value to avoid filling the read
pipe/buffer (typically 64K) but keep the request sizes close to chosen average
on large file upload/download.
