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pesky unhandled exception in Async scheduler #566

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reservoirman opened this issue Jul 15, 2017 · 3 comments
Open

pesky unhandled exception in Async scheduler #566

reservoirman opened this issue Jul 15, 2017 · 3 comments

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@reservoirman
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hello so I'm basically trying to update the policy whenever certain events occur. After the event occurs, the program crashes with the following exception:

(((pid 24589) (thread_id 0))
 ((human_readable 2017-07-15T02:21:10-0400)
  (int63_ns_since_epoch 1500099670959842000))
 "unhandled exception in Async scheduler"
 ("unhandled exception"
  ((src/monitor.ml.Error_
    ((exn Not_found)
     (backtrace
      ("Raised at file \"src/core_hashtbl.ml\", line 296, characters 29-38"
       "Called from file \"lib/Frenetic_Vlr.ml\", line 181, characters 24-31"
       "Called from file \"lib/Frenetic_NetKAT_Compiler.ml\", line 356, characters 38-49"
       "Called from file \"lib/Frenetic_NetKAT_Compiler.ml\", line 363, characters 18-56"
       "Called from file \"async/Frenetic_OpenFlow0x01_Plugin.ml\", line 364, characters 16-76"
       "Called from file \"src/deferred_list.ml\", line 14, characters 22-29"
       "Called from file \"src/deferred0.ml\", line 57, characters 2-10"
       "Called from file \"src/deferred0.ml\", line 64, characters 64-69"
       "Called from file \"src/job_queue.ml\", line 160, characters 6-47" ""))
     (monitor
      (((name main) (here ()) (id 1) (has_seen_error true)
        (is_detached false))))))
   ((pid 24589) (thread_id 0)))))

any idea why this is the case?
@jnfoster
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jnfoster commented Jul 17, 2017 via email

@reservoirman
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Hi Nate, sorry for the delay. Here is the code that triggers it. I'm also running the following tree topology in mininet and attempting a pingall command:

sudo mn --controller=remote --topo=tree,2,2 --mac --arp

I've narrowed down the culprit to the call to the Controller.update (takeCareOfSentCounters srcMac); The problem goes away if I bind the return value of takeCareOfSentCounters to a variable and pass that into Controller.update, however I'd still like to know what's the difference. I'm also a beginner in OCaml so it could be something inherent in the language. Thanks for your help in advance!

`open Frenetic_NetKAT
module StdMap = Map
open Core.Std
open Async.Std
open Frenetic_OpenFlow
open Frenetic_OpenFlow0x01
module Log = Frenetic_Log

module PacketTable = StdMap.Make(Int64)

let counter = ref 0
let cs1 = ref 0
let cs2 = ref 0
let cs3 = ref 0
let cs4 = ref 0

let cr1 = ref 0
let cr2 = ref 0
let cr3 = ref 0
let cr4 = ref 0

let h1forwarded = ref 0
let h2forwarded = ref 0
let h3forwarded = ref 0
let h4forwarded = ref 0

let sendToController : policy = Mod(Location(Pipe("sendToController")))

let%nk monitor = {| if true then $sendToController else drop |}

(* this is based on the tutorial http://frenetic-lang.github.io/tutorials/NetKATRouting/ *)
let%nk routing =
{| if switch = 1 then
if port = 1 then port := 2
else if port = 2 then port := 1
else drop
else if switch = 2 then
if ethDst = 1 then port := 1
else if ethDst = 2 then port := 2
else port := 3
else if switch = 3 then
if ethDst = 3 then port := 1
else if ethDst = 4 then port := 2
else port := 3
else drop
|}

let%nk routingMonitoring = {| $routing + $monitor |}

(this is an attempt at the extra credit portion)
let sendToPacketLogger counter forwarded srcMac : policy =
if (counter > 10 && !forwarded <= 0) then
(
printf "Hey forwarding packets to the logger! From Host %Ld\n" srcMac;
forwarded := 1;
let%nk routingMonitoring = {|$routingMonitoring + (if ethSrc = $srcMac then ethDst := 4 else id)|} in routingMonitoring
)
else routingMonitoring

let takeCareOfReceivedCounters dstMac =
match dstMac with
1L -> cr1 := !cr1 + 1; printf "%d packets received on Host %Ld!\n" !cr1 dstMac;
|2L -> cr2 := !cr2 + 1; printf "%d packets received on Host %Ld!\n" !cr2 dstMac;
|3L -> cr3 := !cr3 + 1; printf "%d packets received on Host %Ld!\n" !cr3 dstMac;
|4L -> cr4 := !cr4 + 1; printf "%d packets received on Host %Ld!\n" !cr4 dstMac;
|_ -> printf "Holla unknown dest Mac %Ld\n" dstMac

let takeCareOfSentCounters srcMac: policy =
match srcMac with
1L -> cs1 := !cs1 + 1; printf "%d packets sent on Host %Ld!\n" !cs1 srcMac; sendToPacketLogger !cs1 h1forwarded srcMac;
|2L -> cs2 := !cs2 + 1; printf "%d packets sent on Host %Ld!\n" !cs2 srcMac; sendToPacketLogger !cs2 h1forwarded srcMac;
|3L -> cs3 := !cs3 + 1; printf "%d packets sent on Host %Ld!\n" !cs3 srcMac; sendToPacketLogger !cs3 h1forwarded srcMac;
|4L -> cs4 := !cs4 + 1; printf "%d packets sent on Host %Ld!\n" !cs4 srcMac; sendToPacketLogger !cs4 h1forwarded srcMac;
|_ -> printf "Holla unknown source Mac %Ld\n" srcMac; routingMonitoring

let rec handle_events (module Controller : Frenetic_NetKAT_Controller.CONTROLLER) =
let open Controller in
event () >>=
fun evt ->
match evt with
PacketIn(a,b,port,Buffered(_, cstruct),d,e)
| PacketIn(a,b,port,NotBuffered(cstruct),d,e) ->
let dstMac = (Frenetic_Packet.parse cstruct).dlDst in
let srcMac = (Frenetic_Packet.parse cstruct).dlSrc in
(* increment counters for packets sent/received per host. *)
takeCareOfReceivedCounters dstMac;
Controller.update (takeCareOfSentCounters srcMac);
handle_events (module Controller)
| _ -> handle_events (module Controller)

let _ =
let module Controller = Frenetic_NetKAT_Controller.Make (Frenetic_OpenFlow0x01_Plugin) in
Controller.start 6633;
Controller.update routingMonitoring;
Deferred.don't_wait_for(handle_events (module Controller));
(* Controller.update is equivalent to the OpenFlow Flow Mod call*)
never_returns (Scheduler.go ());`

@jnfoster
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jnfoster commented Jul 26, 2017 via email

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@jnfoster @reservoirman