Add stopwatch timer mechanism to Trace2.
Timers are an alternative to Trace2 Regions. Regions are useful for
measuring the time spent in various computation phases, such as the
time to read the index, time to scan for unstaged files, time to scan
for untracked files, and etc.
However, regions are not appropriate in all places. For example,
during a checkout, it would be very inefficient to use regions to
measure the total time spent inflating objects from the ODB from
across the entire lifetime of the process; a per-unzip() region would
flood the output and significantly slow the command; and some form of
post-processing would be requried to compute the time spent in unzip().
Timers can be used to measure a series of timer intervals and emit
a single summary event (at thread and/or process exit).
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Convert the `tr2tls_thread_ctx.thread_name` field from a `strbuf`
to a "const char*" pointer.
The `thread_name` field is a constant string that is constructed when
the context is created. Using a (non-const) `strbuf` structure for it
caused some confusion in the past because it implied that someone
could rename a thread after it was created. That usage was not
intended. Change it to a const pointer to make the intent more clear.
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Rename the `thread_name` argument in `tr2tls_create_self()` and
`trace2_thread_start()` to be `thread_base_name` to make it clearer
that the passed argument is a component used in the construction of
the actual `struct tr2tls_thread_ctx.thread_name` variable.
The base name will be used along with the thread id to create a
unique thread name.
This commit does not change how the `thread_name` field is
allocated or stored within the `tr2tls_thread_ctx` structure.
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Reduce or eliminate use of the term "TLS" in the Trace2 code.
The term "TLS" has two popular meanings: "thread-local storage" and
"transport layer security". In the Trace2 source, the term is associated
with the former. There was concern on the mailing list about it refering
to the latter.
Update the source and documentation to eliminate the use of the "TLS" term
or replace it with the phrase "thread-local storage" to reduce ambiguity.
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Fix a memory leak introduced in ee4512ed48 (trace2: create new
combined trace facility, 2019-02-22), we were doing a free() of other
memory allocated in tr2tls_create_self(), but not the "thread_name"
"struct strbuf".
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Acked-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Teach trace2 TLS code to not rely on pthread_getspecific() when NO_PTHREADS
is defined. Instead, always assume the context data of the main thread.
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio 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: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio 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: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
