facebook/hhvm — pull request #3082 by rrh (2014-07-01 22:51:16+00:00)
Title: Add a new class SystemProfiler and a default null singleton instance.

This class implements hookpoints of interest to a system profiler,
currently hooking file load and PHP errors. This list may grow.

The new class also supplies a HotProfiler.

The instance of a SystemProfiler may be made and bound during the initialization
phase of a 3rd party DSO.

While I'm at it, plumb in instantiation of the pre-existing experimental MemoProfiler.