git-commit-vandalism/trace2/tr2_dst.h
Jeff Hostetler ee4512ed48 trace2: create new combined trace facility
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: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-02-22 15:27:59 -08:00

37 lines
787 B
C

#ifndef TR2_DST_H
#define TR2_DST_H
struct strbuf;
struct tr2_dst {
const char *const env_var_name;
int fd;
unsigned int initialized : 1;
unsigned int need_close : 1;
};
/*
* Disable TRACE2 on the destination. In TRACE2 a destination (DST)
* wraps a file descriptor; it is associated with a TARGET which
* defines the formatting.
*/
void tr2_dst_trace_disable(struct tr2_dst *dst);
/*
* Return the file descriptor for the DST.
* If 0, the dst is closed or disabled.
*/
int tr2_dst_get_trace_fd(struct tr2_dst *dst);
/*
* Return true if the DST is opened for writing.
*/
int tr2_dst_trace_want(struct tr2_dst *dst);
/*
* Write a single line/message to the trace file.
*/
void tr2_dst_write_line(struct tr2_dst *dst, struct strbuf *buf_line);
#endif /* TR2_DST_H */