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mctrace

mctrace is an Erlang tool that makes it easy to trace process messages and produce some meaningful output like dot sequence diagrams (planned). Project Page

Building

You need rebar (http://github.com/basho/rebar) for building mctrace.

Just add following lines in rebar.config:

{deps, [
        {mctrace, ".*", {git, "git://github.com/metachord/mctrace.git", "master"}}
       ]}.

Planned

• Generating dot-file for Graphviz
• Use state of process in events handling

Description

mctrace uses parse_transform to inject own hooks in some functions (now only init/1 and terminate/2,3).

Traced process sends message to mctrace on startup which contains its pid() and some options, like list of hooks functions and traced events. mctrace call erlang:trace/3 function to trace specified events on process and print it on stdout using specified hooks functions.

Usage

1. Add section in head of your erl-file:

   -ifdef(MCTRACE).
    ...
   -endif.

2. Put here following attributes:

• Header file of mctrace with record definition:

  -include_lib("mctrace/include/mctrace.hrl").

• Compile option:

  -compile({parse_transform, mctrace}).

• Export hooks functions (for gen_server here) if they defined in this module:

  -export([
       hook_send_cast/5,
       hook_send_call/5,
       hook_send_info/5,
       hook_receive_cast/4,
       hook_receive_call/5,
       hook_receive_info/4,
       hook_exit/4
      ]).

• Say to mctrace what you want to trace and which functions use to handle specified trace events:

  -mct_opts([
       {tracing, [send, procs, 'receive', timestamp]},
       {hook_send_cast,       hook_send_cast},
       {hook_send_call,       hook_send_call},
       {hook_send_info,       hook_send_info},
       {hook_receive_cast,    hook_receive_cast},
       {hook_receive_call,    hook_receive_call},
       {hook_receive_info,    hook_receive_info},
       {hook_exit,            hook_exit}
      ]).

• If your hooks defined in other module, write following:

  ...
  {hook_send_info,       {my_hooks_mod, hook_send_info}},
  ...

3. Implement hook functions (see examples in examples/ttm/src/ttm_hooks.erl)

4. Compile source code with -D MCTRACE, or put analog to rebar.config

5. Run mctrace application before yours

6. Start your application with traced processes