app_ruby: print backtrace when ruby exception occurs

[fatihorhan]

Description

Hello,

When there is an error in my ruby script, app_ruby prints exception message without a stack trace, like this:

Dec 14 16:25:17 servername /usr/sbin/kamailio[24313]: ERROR: app_ruby [app_ruby_api.c:105]: app_ruby_print_last_exception(): exception: wrong number of arguments (1 for 2..3)
Dec 14 16:25:17 servername /usr/sbin/kamailio[24313]: ERROR: app_ruby [app_ruby_api.c:1078]: app_ruby_run_ex(): ruby exception (6) on callback for: ksr_request_route (res type: 17)

Altough this message tells what is the error, it doesn't tell where the error happened, so it's hard to find the source of the problem.

In ruby, exceptions have backtrace() method returning stack trace as an array of strings. It would be really helpful if app_ruby also call this method and append its result to error message.

Reproduction

in kamailio.cfg

loadmodule "app_ruby.so"
modparam("app_ruby", "load", "/etc/kamailio/ruby/routes.rb")
cfgengine "ruby"

in /etc/kamailio/ruby/routes.rb

def some_method(param1, param2)
end

def ksr_request_route
  some_method(1)
end

Expected behavior

Dec 14 16:46:24 servername /usr/sbin/kamailio[24314]: ERROR: <core> [core/kemi.c:87]: sr_kemi_core_err(): wrong number of arguments (1 for 2): /etc/kamailio/ruby/routes.rb:1:in `some_method'
                                                                     /etc/kamailio/ruby/routes.rb:4:in `ksr_request_route'

Actual observed behavior

Dec 14 16:45:42 servername /usr/sbin/kamailio[24311]: ERROR: app_ruby [app_ruby_api.c:105]: app_ruby_print_last_exception(): exception: wrong number of arguments (1 for 2)

Possible Solutions

Relevant code seem to be here: https://github.com/kamailio/kamailio/blob/master/src/modules/app_ruby/app_ruby_api.c#L98

I found example C code to print stack trace here but couldn't figure out how to integrate to app_ruby: http://zoo-project.org/svn/trunk/zoo-project/zoo-kernel/service_internal_ruby.c

Equivalent ruby code would be (this code is not idiomatic, my aim is to provide C-like ruby code):

def some_error_generating_method
  method_taking_two_params(1)
rescue => exception
  message = exception.to_s() + "\n"
  stack_trace = exception.backtrace()
  for line in stack_trace
    message = message + line + "\n"
  end
  print(message)
end

Additional Information

• Kamailio Version - output of kamailio -v

version: kamailio 5.2.0 (x86_64/linux) 535e13
flags: STATS: Off, USE_TCP, USE_TLS, USE_SCTP, TLS_HOOKS, USE_RAW_SOCKS, DISABLE_NAGLE, USE_MCAST, DNS_IP_HACK, SHM_MEM, SHM_MMAP, PKG_MALLOC, Q_MALLOC, F_MALLOC, TLSF_MALLOC, DBG_SR_MEMORY, USE_FUTEX, FAST_LOCK-ADAPTIVE_WAIT, USE_DNS_CACHE, USE_DNS_FAILOVER, USE_NAPTR, USE_DST_BLACKLIST, HAVE_RESOLV_RES
ADAPTIVE_WAIT_LOOPS=1024, MAX_RECV_BUFFER_SIZE 262144 MAX_URI_SIZE 1024, BUF_SIZE 65535, DEFAULT PKG_SIZE 8MB
poll method support: poll, epoll_lt, epoll_et, sigio_rt, select.
id: 535e13
compiled on 10:26:34 Nov 28 2018 with gcc 4.8.5

• Operating System:

Centos 7.2 64bit

Linux servername 3.10.0-327.28.2.el7.x86_64 #1 SMP Wed Aug 3 11:11:39 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux

[miconda]

If someone can propose a pull request for this feature, I will happily merge it. Right now, I am not sure when I will get some time to look deeper at it.

[github-actions]

This issue is stale because it has been open 6 weeks with no activity. Remove stale label or comment or this will be closed in 2 weeks.