Fix trace2_data_json_fl() to check for the presence of pfn_data_json_fl
in its targets, rather than pfn_data_fl, which is not actually called.
Signed-off-by: NJosh Steadmon <steadmon@google.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Teach Windows version of git to report peak memory usage
during exit() processing.
Signed-off-by: NJeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Teach git to read the system and global config files for
default Trace2 settings.  This allows system-wide Trace2 settings to
be installed and inherited to make it easier to manage a collection of
systems.

The original GIT_TR2* environment variables are loaded afterwards and
can be used to override the system settings.

Only the system and global config files are used.  Repo and worktree
local config files are ignored.  Likewise, the "-c" command line
arguments are also ignored.  These limits are for performance reasons.

(1) For users not using Trace2, there should be minimal overhead to
detect that Trace2 is not enabled.  In particular, Trace2 should not
allocate lots of otherwise unused data strucutres.

(2) For accurate performance measurements, Trace2 should be initialized
as early in the git process as possible, and before most of the normal
git process initialization (which involves discovering the .git directory
and reading a hierarchy of config files).
Signed-off-by: NJeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Add elapsed process time to "start" event to measure
the performance of early process startup.
Signed-off-by: NJeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Create trace2_initialize_clock() and call from main() to capture
process start time in isolation and before other sub-systems are
ready.
Signed-off-by: NJeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Some compilers don't allow NULL to be passed for a va_list,
and e.g. "gcc (Raspbian 6.3.0-18+rpi1+deb9u1) 6.3.0 20170516"
errors out like this:
 trace2/tr2_tgt_event.c:193:18:
   error: invalid operands to binary &&
   (have ‘int’ and ‘va_list {aka __va_list}’)
    if (fmt && *fmt && ap) {
                       ^^
I couldn't find any hints that va_list and pointers can be mixed,
and no hints that they can't either. Morten Welinder comments:

"C99, Section 7.15, simply says that va_list "is an object type suitable for
holding information needed by the macros va_start, va_end, and
va_copy". So clearly not guaranteed to be mixable with pointers...

The portable solution is to use "va_list" everywhere in the callchain.
As a consequence, both trace2_region_enter_fl() and trace2_region_leave_fl()
now take a variable argument list.
Signed-off-by: NTorsten Bögershausen <tboegi@web.de>
Acked-by: NJeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

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: NJeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>