[EXPORTER] Do not use regex in CleanUpString because some implementations of STL may crash.

[owent]

Fixes #2463

Changes

• Remove the usage of regex in PrometheusExporterUtils::CleanUpString
  • I didn't tested but it should have better performance than using std::regex_replace, because it allocate less std::string objects.
• Use explicit std::string constructor in std::regex_replace because some versions of gcc can not detect the types correctly.

For significant contributions please make sure you have completed the following items:

• CHANGELOG.md updated for non-trivial changes
• Unit tests have been added
• Changes in public API reviewed

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (0dd5eed) 87.04% compared to head (c231c82) 87.06%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2464      +/-   ##
==========================================
+ Coverage   87.04%   87.06%   +0.02%     
==========================================
  Files         199      199              
  Lines        6087     6087              
==========================================
+ Hits         5298     5299       +1     
+ Misses        789      788       -1     

see 1 file with indirect coverage changes

[marcalff]

There is a known issue with gcc and regexp:

// Regex support
#if (__GNUC__ == 4 && (__GNUC_MINOR__ == 8 || __GNUC_MINOR__ == 9))
#  define OPENTELEMETRY_HAVE_WORKING_REGEX 0
#else
#  define OPENTELEMETRY_HAVE_WORKING_REGEX 1
#endif

The code in exporter_utils.cc did not check for OPENTELEMETRY_HAVE_WORKING_REGEX, probably causing the bug found.

About the fix,

For PrometheusExporterUtils::CleanUpString, I totally agree that using 4 regexp in a row was overkill, and replacing regexp with custom code is much better.

About PrometheusExporterUtils::RemoveUnitPortionInBraces,
leaving the code as is with the regexp will still fail in gcc 4.8 and 4.9.

Could the fix also reimplement RemoveUnitPortionInBraces(), to remove the usage of regex completely ?

[owent]

There is a known issue with gcc and regexp:

// Regex support
#if (__GNUC__ == 4 && (__GNUC_MINOR__ == 8 || __GNUC_MINOR__ == 9))
#  define OPENTELEMETRY_HAVE_WORKING_REGEX 0
#else
#  define OPENTELEMETRY_HAVE_WORKING_REGEX 1
#endif

The code in exporter_utils.cc did not check for OPENTELEMETRY_HAVE_WORKING_REGEX, probably causing the bug found.

About the fix,

For PrometheusExporterUtils::CleanUpString, I totally agree that using 4 regexp in a row was overkill, and replacing regexp with custom code is much better.

About PrometheusExporterUtils::RemoveUnitPortionInBraces, leaving the code as is with the regexp will still fail in gcc 4.8 and 4.9.

Could the fix also reimplement RemoveUnitPortionInBraces(), to remove the usage of regex completely ?

Thanks, it use OPENTELEMETRY_HAVE_WORKING_REGEX to decide whether to use the fallback implantation now, and I also add a fallback implantation for PrometheusExporterUtils::RemoveUnitPortionInBraces. This function won't crash but it have a wrong result before, sorry for the missing.

[lalitb]

Thanks for the fix.

[marcalff]

LGTM, thanks for the fix.