1. 22 Feb, 2019 1 commit
    • Jeff Hostetler's avatar
      trace2: create new combined trace facility · ee4512ed
      Jeff Hostetler authored
      Create a new unified tracing facility for git.  The eventual intent is to
      replace the current trace_printf* and trace_performance* routines with a
      unified set of git_trace2* routines.
      
      In addition to the usual printf-style API, trace2 provides higer-level
      event verbs with fixed-fields allowing structured data to be written.
      This makes post-processing and analysis easier for external tools.
      
      Trace2 defines 3 output targets.  These are set using the environment
      variables "GIT_TR2", "GIT_TR2_PERF", and "GIT_TR2_EVENT".  These may be
      set to "1" or to an absolute pathname (just like the current GIT_TRACE).
      
      * GIT_TR2 is intended to be a replacement for GIT_TRACE and logs command
        summary data.
      
      * GIT_TR2_PERF is intended as a replacement for GIT_TRACE_PERFORMANCE.
        It extends the output with columns for the command process, thread,
        repo, absolute and relative elapsed times.  It reports events for
        child process start/stop, thread start/stop, and per-thread function
        nesting.
      
      * GIT_TR2_EVENT is a new structured format. It writes event data as a
        series of JSON records.
      
      Calls to trace2 functions log to any of the 3 output targets enabled
      without the need to call different trace_printf* or trace_performance*
      routines.
      Signed-off-by: default avatarJeff Hostetler <jeffhost@microsoft.com>
      Signed-off-by: default avatarJunio C Hamano <gitster@pobox.com>
      ee4512ed