handle_stream_disconnection

# Demonstrate the effects of a slow stream (that's causing a build up of
# waiting requests) being disconnected. This test is similar to the one in
# handle_single_slow_stream, except the slow stream is eventually disconnected.

init
handle=h
----

# Set up a triply connected handle (to s1, s2, s3) and start issuing writes at
# 1MiB/s. For two of the streams, return tokens at exactly the rate its being
# deducted (1MiB/s). For the third stream (s3), we return flow tokens at only
# 0.5MiB/s. At t=40s, disconnect the slow stream.
timeline
t=0s        handle=h op=connect    stream=t1/s1   log-position=4/0
t=0s        handle=h op=connect    stream=t1/s2   log-position=4/0
t=0s        handle=h op=connect    stream=t1/s3   log-position=4/0
t=[0s,50s)   handle=h class=regular adjust=-1MiB/s   rate=10/s
t=[0.2s,50s) handle=h class=regular adjust=+1MiB/s   rate=10/s stream=t1/s1
t=[0.2s,50s) handle=h class=regular adjust=+1MiB/s   rate=10/s stream=t1/s2
t=[0.2s,40s) handle=h class=regular adjust=+0.5MiB/s rate=10/s stream=t1/s3
t=40s        handle=h op=disconnect stream=t1/s3
----

simulate
----

# Zoom in near the point where writes are being shaped by the slowest stream
# (s3, at 0.5MiB/s). We see the blocked stream count bouncing between 0 and 1
# as tokens get depleted and replenished (demand here is higher than the
# replenishment rate).
#
# As soon as s3 is disconnected, we see a release of 16MiB of held tokens back
# into the node-level controller (32MiB -> 48MiB). We see a burst in the number
# of stream-specific requests bypassing Admit() due to the stream
# disconnecting. 
plot t=[30s,50s)
kvadmission.flow_controller.regular_blocked_stream_count        unit=streams
kvadmission.flow_controller.regular_tokens_available            unit=MiB
kvadmission.flow_controller.regular_requests_bypassed           unit=reqs/s rate=true
----
----
 1.0 ┤         ╭╮       ╭╮
 0.9 ┤         ││       ││
 0.8 ┤       ╭╮││       ││
 0.8 ┤       ││││╭╮     ││
 0.7 ┤       ││││││   ╭╮││
 0.6 ┤       ││││││   ││││
 0.6 ┤     ╭╮││││││╭╮ ││││
 0.5 ┤    ╭╯││││││││╰╮││││
 0.5 ┤    │ ││││││││ │││││
 0.4 ┤   ╭╯ ││││││││ ╰╯│││
 0.3 ┤   │  ││││││╰╯   │││
 0.3 ┤   │  ╰╯││││     │││
 0.2 ┤   │    ││││     │││
 0.1 ┤   │    ││╰╯     ╰╯│
 0.1 ┤   │    ╰╯         │
 0.0 ┼───╯               ╰───────────────────
       regular_blocked_stream_count (streams)


 47.6 ┤                   ╭───────────────────
 46.5 ┤                   │
 45.5 ┤                   │
 44.4 ┤                   │
 43.3 ┤                   │
 42.3 ┤                   │
 41.2 ┤                   │
 40.1 ┤                   │
 39.1 ┤                   │
 38.0 ┤                   │
 36.9 ┤                   │
 35.9 ┤                   │
 34.8 ┤                   │
 33.7 ┤                   │
 32.7 ┤                   │
 31.6 ┼───────────────────╯
            regular_tokens_available (MiB)


 42.0 ┤                   ╭─╮
 39.2 ┤                   │ │
 36.4 ┤                   │ │
 33.6 ┤                   │ │
 30.8 ┤                   │ │
 28.0 ┤                   │ │
 25.2 ┤                   │ │
 22.4 ┤                   │ │
 19.6 ┤                   │ │
 16.8 ┤                   │ │
 14.0 ┤                   │ │
 11.2 ┤                   │ │
  8.4 ┤                   │ │
  5.6 ┤                   │ │
  2.8 ┤                   │ │
  0.0 ┼───────────────────╯ ╰─────────────────
       rate(regular_requests_bypassed) (reqs/s)
----
----

# vim:ft=conf