help with gen_fsm for a new erlang user

[Greg Smyth]

Hi all,

I'm learning erlang/OTP and I'm trying to write a pretty simple gen_fsm
service, but i'm having a bit of trouble and was wondering if someone could
help correct my mistakes:-

The service should have 2 states:-

1) waiting - where it will be waiting on a specified timeout.
2) running - where it will be running a function over a list of hosts
(specified in 'Hostlist' dictionary with the host as the key)

The code i have compiles ok, and returns {ok, Pid} from start_link/1 - but i
see none of my io:format messages ever appear...

Here's the code:-

%%%%%%%%%

-module(runner_fsm).
-behaviour(gen_fsm).

%% API
-export([start_link/1]).

%% gen_fsm callbacks
-export([init/1, wait/2, run/2, wait/3, run/3, handle_event/3,
         handle_sync_event/4, handle_info/3, terminate/3, code_change/4]).

%% internals
-export([pinger/1]).

-define(SERVER, ?MODULE).

start_link(Hostlist) ->
  gen_fsm:start_link({local, ?SERVER}, ?MODULE, Hostlist, []).

init(Hostlist) ->
  {ok, wait, Hostlist, 30000}.

wait(timeout, State) ->
  {next_state, run, State}.

run(_Event, State) ->
  Hosts = dict:fetch_keys(State),
  case lists:foreach(fun(Elem) -> runner_fsm:pinger(Elem) end, Hosts) of
    ok ->
      doNothingforNow;
    fail ->
      doNothingforNow
  end,
  {next_state, wait, State, 30000}.

wait(_Event, _From, State) ->
  Reply = ok,
  {reply, Reply, wait, State, 30000}.

run(_Event, _From, State) ->
  Reply = ok,
  {reply, Reply, run, State}.

handle_event(_Event, StateName, State) ->
  {next_state, StateName, State}.

handle_sync_event(Event, From, StateName, State) ->
  Reply = ok,
  {reply, Reply, StateName, State}.

handle_info(_Info, StateName, State) ->
  {next_state, StateName, State}.

terminate(_Reason, _StateName, _State) ->
  ok.

code_change(_OldVsn, StateName, State, _Extra) ->
  {ok, StateName, State}.

pinger(Host) ->
  Command = lists:concat(["ping -c 1 ", Host, "; echo $?"]),
  ExitCode = lists:last(string:tokens(os:cmd(Command), "\n")),
  case ExitCode of
    "0" -> io:format("OK: ~p~n", [Host]),
           ok;
     _  -> io:format("BAD: ~p~n", [Host]),
           fail
  end.

%%%%%%%%%%%

Any ideas/hints as to what i'm doing wrong?

Many thanks,
Greg