path: root/trace2/tr2_dst.h
diff options
authorJeff Hostetler <>2019-02-22 22:25:01 (GMT)
committerJunio C Hamano <>2019-02-22 23:27:59 (GMT)
commitee4512ed481a126dadd33334186e0e759d7f2f47 (patch)
tree4bc0418115d44b1833c1d24d2ac1c92f067b7ad3 /trace2/tr2_dst.h
parente544221d97a57a9be7ba18a0df52a15b4cc76f97 (diff)
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 <> Signed-off-by: Junio C Hamano <>
Diffstat (limited to 'trace2/tr2_dst.h')
1 files changed, 36 insertions, 0 deletions
diff --git a/trace2/tr2_dst.h b/trace2/tr2_dst.h
new file mode 100644
index 0000000..9a64f05
--- /dev/null
+++ b/trace2/tr2_dst.h
@@ -0,0 +1,36 @@
+#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 */