Problematic dependency - hdr_histogram

[afronski]

Currently we're leveraging work done by hdr_histogram regarding statistics accumulation / storage, which brings set of problems to the table:

1. It is a NIF - and that causes a lot of troubles when building xprof on various platforms (too old GCC, too new GCC.
2. Current hex.pm package is too old and it is not in sync with upstream - that's why we're using this fork https://github.com/afronski/hdr_histogram_erl and different name on hex.pm (customized_hdr_histogram).

We need to improve that. Possible solutions:

1. Getting rid of NIFs - Erlang / Elixir only library.
2. Contributing build process fixes and enforcing updating hex.pm package regularly.

[afronski]

One of the errors that affected people on macOS during the ElixirConf US workshops:

user@hostname ~/.../elixir-fire-brigade-workshop/apps/tracing_4 $ iex -S mix
Erlang/OTP 20 [erts-9.0.4] [source] [64-bit] [smp:8:8] [ds:8:8:10] [async-threads:10] 
[hipe] [kernel-poll:false] [dtrace]
 
===> Compiling customized_hdr_histogram
cc ...
Undefined symbols for architecture x86_64:
  "_deflate", referenced from:
      _hdr_encode_compressed in hdr_histogram_log.o
  "_deflateEnd", referenced from:
      _hdr_encode_compressed in hdr_histogram_log.o
  "_deflateInit_", referenced from:
      _hdr_encode_compressed in hdr_histogram_log.o
  "_enif_alloc", referenced from:
      __hi_init in hdr_histogram_nif.o
      _on_load in hdr_histogram_nif.o
  "_enif_alloc_binary", referenced from:
      __hh_to_binary in hdr_histogram_nif.o
      __hh_to_binary_uncompressed in hdr_histogram_nif.o
  "_enif_alloc_resource", referenced from:
      __hh_open in hdr_histogram_nif.o
      __hh_from_binary in hdr_histogram_nif.o
      __hi_open in hdr_histogram_nif.o
  "_enif_free", referenced from:
      __hi_close in hdr_histogram_nif.o
      _on_unload in hdr_histogram_nif.o
      __hi_ctx_dtor in hdr_histogram_nif.o
  "_enif_get_double", referenced from:
      __hh_percentile in hdr_histogram_nif.o
      _parse_opt in hdr_histogram_nif.o
  "_enif_get_int", referenced from:
      __hh_open in hdr_histogram_nif.o
  "_enif_get_list_cell", referenced from:
      _parse_opts in hdr_histogram_nif.o
      __hi_init in hdr_histogram_nif.o
  "_enif_get_long", referenced from:
      __hh_open in hdr_histogram_nif.o
      __hh_record in hdr_histogram_nif.o
      __hh_record_corrected in hdr_histogram_nif.o
      __hh_record_many in hdr_histogram_nif.o
      __hh_same in hdr_histogram_nif.o
      __hh_lowest_at in hdr_histogram_nif.o
      __hh_count_at in hdr_histogram_nif.o
      ...
  "_enif_get_resource", referenced from:
      __hh_get_memory_size in hdr_histogram_nif.o
      __hh_get_total_count in hdr_histogram_nif.o
      __hh_record in hdr_histogram_nif.o
      __hh_record_corrected in hdr_histogram_nif.o
      __hh_record_many in hdr_histogram_nif.o
      __hh_add in hdr_histogram_nif.o
      __hh_min in hdr_histogram_nif.o
      ...
  "_enif_get_string", referenced from:
      __hh_log_classic in hdr_histogram_nif.o
      __hh_log_csv in hdr_histogram_nif.o
  "_enif_get_tuple", referenced from:
      _parse_opt in hdr_histogram_nif.o
  "_enif_get_uint", referenced from:
      _parse_opt in hdr_histogram_nif.o
      __hi_open in hdr_histogram_nif.o
  "_enif_inspect_binary", referenced from:
      __hh_from_binary in hdr_histogram_nif.o
  "_enif_is_list", referenced from:
      __hi_init in hdr_histogram_nif.o
  "_enif_make_atom", referenced from:
      __hh_open in hdr_histogram_nif.o
      __hh_get_memory_size in hdr_histogram_nif.o
      __hh_get_total_count in hdr_histogram_nif.o
      __hh_record in hdr_histogram_nif.o
      __hh_record_corrected in hdr_histogram_nif.o
      __hh_record_many in hdr_histogram_nif.o
      __hh_add in hdr_histogram_nif.o
      ...
  "_enif_make_badarg", referenced from:
      __hh_open in hdr_histogram_nif.o
      __hh_get_memory_size in hdr_histogram_nif.o
      __hh_get_total_count in hdr_histogram_nif.o
      __hh_record in hdr_histogram_nif.o
      __hh_record_corrected in hdr_histogram_nif.o
      __hh_record_many in hdr_histogram_nif.o
      __hh_add in hdr_histogram_nif.o
      ...
  "_enif_make_binary", referenced from:
      __hh_to_binary in hdr_histogram_nif.o
      __hh_to_binary_uncompressed in hdr_histogram_nif.o
  "_enif_make_double", referenced from:
      __hh_mean in hdr_histogram_nif.o
      __hh_median in hdr_histogram_nif.o
      __hh_stddev in hdr_histogram_nif.o
      __hh_percentile in hdr_histogram_nif.o
      __hi_next in hdr_histogram_nif.o
  "_enif_make_int", referenced from:
      __hi_next in hdr_histogram_nif.o
  "_enif_make_list", referenced from:
      __hi_next in hdr_histogram_nif.o
  "_enif_make_long", referenced from:
      __hh_add in hdr_histogram_nif.o
      __hh_min in hdr_histogram_nif.o
      __hh_max in hdr_histogram_nif.o
      __hh_lowest_at in hdr_histogram_nif.o
      __hh_count_at in hdr_histogram_nif.o
      __hi_next in hdr_histogram_nif.o
  "_enif_make_resource", referenced from:
      __hh_open in hdr_histogram_nif.o
      __hh_from_binary in hdr_histogram_nif.o
      __hi_open in hdr_histogram_nif.o
  "_enif_make_tuple", referenced from:
      __hh_open in hdr_histogram_nif.o
      __hh_get_memory_size in hdr_histogram_nif.o
      __hh_get_total_count in hdr_histogram_nif.o
      __hh_record in hdr_histogram_nif.o
      __hh_record_corrected in hdr_histogram_nif.o
      __hh_record_many in hdr_histogram_nif.o
      __hh_add in hdr_histogram_nif.o
      ...
  "_enif_make_ulong", referenced from:
      __hh_get_memory_size in hdr_histogram_nif.o
      __hh_get_total_count in hdr_histogram_nif.o
  "_enif_open_resource_type", referenced from:
     _on_load in hdr_histogram_nif.o
  "_enif_priv_data", referenced from:
      __hh_open in hdr_histogram_nif.o
      __hh_get_memory_size in hdr_histogram_nif.o
      __hh_get_total_count in hdr_histogram_nif.o
      __hh_record in hdr_histogram_nif.o
     __hh_record_corrected in hdr_histogram_nif.o
      __hh_record_many in hdr_histogram_nif.o
      __hh_add in hdr_histogram_nif.o
      ...
  "_enif_release_resource", referenced from:
      __hh_open in hdr_histogram_nif.o
      __hh_from_binary in hdr_histogram_nif.o
      __hi_open in hdr_histogram_nif.o
  "_inflate", referenced from:
      _hdr_decode_compressed in hdr_histogram_log.o
  "_inflateEnd", referenced from:
      _hdr_decode_compressed in hdr_histogram_log.o
  "_inflateInit_", referenced from:
      _hdr_decode_compressed in hdr_histogram_log.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make: *** [/.../customized_hdr_histogram/c_src/../priv/hdr_histogram_nif.so] Error 1
===> Hook for compile failed!
 
** (Mix) Could not compile dependency :customized_hdr_histogram, ...

[karlseguin]

Someone linked this issue in Elixir's #general slack channel. I wrote https://github.com/2nd/histogrex a while ago, if it helps (pure Elixir HDR histogram)

[gomoripeti]

hi Karl,

thanks for bringing to our attention that someone had this issue. And even more for the pointer to your pure Elixir implementation. Currently there is a requirement that we need to compile and run XProf in an env without Elixir, so cannot include your lib straight away, but it's a good starting point (maybe porting it to Erlang) and motivation to tackle this issue sooner rather than later.