I am trying to make sense of the following error:
4> c(sv).
{ok,sv}
5> B=sv:start().
<0.93.0>
6> =ERROR REPORT==== 14-Jul-2020::21:44:13.256000 ===
Error in process <0.93.0> with exit value:
{undef,[{common,createProcess,
[{monitor,monitor,
{monstate,undefined,undefined,undefined,true,
undefined,false}}],
[]},
{sv,server,1,[{file,"sv.erl"},{line,14}]}]}
I have a sv module that instantiates a process from monitor module which in turn instantiates a process from worker module.
Instantiantions take place via a call to the common module.
Both sv and monitor use records defined in a .hrl module.
sv.erl -> monitor.erl -> worker.erl
| |
common.erl
records.hrl
common.erl
%%% common functionality module
-module(common).
-export([createProcess/1]).
-import(worker,[worker/1]).
-import(monitor,[monitor/1]).
-include("records.hrl").
createProcess({M,F,A})->
Pid=spawn(M,F,[A]),
Ref=erlang:monitor(process,Pid),
{Pid,Ref}.
records.hrl
-record(monstate,{
queue,
qc,
wpid,
free=true,
wref,
init=false
}).
-record(sstate,{
init=false,
mpid=null,
mref=null
}).
sv.erl
-module(sv).
-import(common,[createProcess/1]).
-include("records.hrl").
-export([start/0,server/1]).
start()->
spawn(?MODULE,server,[#sstate{init=false}]).
server(State=#sstate{init=I})when I=:=false ->
{MPid,MRef}=createProcess({monitor,monitor,#monstate{init=false}}),
server(State#sstate{init=true,mpid=MPid,mref=MRef});
server(State=#sstate{mpid=MPid,mref=MRef})->
receive
{From,state}->From ! State,
server(State);
{From,Message}-> MPid ! {request,{From,Message}},
server(State);
{'DOWN',MRef,process,MPid,_}-> {NewMPid,NewMRef}=createProcess({?MODULE,monitor,#monstate{init=false}}),
server(State#sstate{mpid=NewMPid,mref=NewMRef});
_ ->exit(invalid_message)
end.
monitor.erl
%%% servers as both a gen_server that can be queried and a supervisor for its worker process
-module(monitor).
-export([monitor/1]).
-import(common,[createProcess/1]).
-include("records.hrl").
-define(QUEUE_SIZE,5).
tryEnqueue(Message,MState=#monstate{queue=Q,qc=C}) when C<?QUEUE_SIZE->
NewQueue=queue:in(Message,Q),
{queued,MState#monstate{qc=C+1,queue=NewQueue}};
tryEnqueue(_,MState)->{queue_full,MState}.
monitor(MState=#monstate{wpid=_,wref=_,init=I}) when I=:= false ->
{WorkerPid,WorkerRef}=createProcess({worker,worker,self()}),
monitor(MState#monstate{wpid=WorkerPid,wref=WorkerRef,init=true,qc=0,queue=queue:new()});
monitor(MState=#monstate{wpid=W,free=Free,wref=Ref,queue=Q,qc=C})->
receive
{request,{From ,Message}} -> case Free of
true -> W ! {From,Message},
monitor(MState#monstate{free=false});
false ->
St=case tryEnqueue({From,Message},MState) of
{queue_full,S} -> From ! {queue_full,Message},S;
{queued,S} -> S
end,
monitor(St)
end;
{worker,{finished,_}}-> case queue:out(Q) of
{{_,Element},Rest} -> W ! Element,
monitor(MState#monstate{free=false,queue=Rest,qc=C-1});
{empty,Rest} -> monitor(MState#monstate{free=true,queue=Rest})
end;
{'DOWN',Ref,process,_,_}->
{NewWorkerPid,NewWorkerRef}=createProcess({?MODULE,worker,self()}),
monitor(MState#monstate{wpid=NewWorkerPid,wref=NewWorkerRef,free=true});
_->exit(invalid_message)
end.
So i do not know how to interpret the error:
common module , that had a MFA of : [{monitor,monitor,{monstate,undefined,undefined,.....}] . The content inside the { } looks okay but i do not get the encompassing [ ].P.S My common module that spawns processes from both the sv and the monitor module has those modules imported and their associated records included too.I do not understand the problem.
The error states that the common:createProcess/1 is undefined.
Most likely this is happening because the module common was not loaded previously in the code server.
Run an c(common). too.
Keep in mind that the -import compile directive only means Calls in this module to the funcion X/Y are to be performed by the module Module as Module:X/Y , but does not create a module dependency