Many trace2 targets ignore the absolute elapsed time parameters.
However, the virtual interface needs to retain the parameter since it is
used by others (e.g., the perf target).
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
There is a code path starting from trace2_def_param_fl() that eventually
calls current_config_scope(), and thus it needs to have "kvi" plumbed
through it. Additional plumbing is also needed to get "kvi" to
trace2_def_param_fl(), which gets called by two code paths:
- Through tr2_cfg_cb(), which is a config callback, so it trivially
receives "kvi" via the "struct config_context ctx" parameter.
- Through tr2_list_env_vars_fl(), which is a high level function that
lists environment variables for tracing. This has been secretly
behaving like git_config_from_parameters() (in that it parses config
from environment variables/the CLI), but does not set config source
information.
Teach tr2_list_env_vars_fl() to be well-behaved by using
kvi_from_param(), which is used elsewhere for CLI/environment
variable-based config.
As a result, current_config_scope() has no more callers, so remove it.
Signed-off-by: Glen Choo <chooglen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
hash.h depends upon and includes repository.h, due to the definition and
use of the_hash_algo (defined as the_repository->hash_algo). However,
most headers trying to include hash.h are only interested in the layout
of the structs like object_id. Move the parts of hash.h that do not
depend upon repository.h into a new file hash-ll.h (the "low level"
parts of hash.h), and adjust other files to use this new header where
the convenience inline functions aren't needed.
This allows hash.h and object.h to be fairly small, minimal headers. It
also exposes a lot of hidden dependencies on both path.h (which was
brought in by repository.h) and repository.h (which was previously
implicitly brought in by object.h), so also adjust other files to be
more explicit about what they depend upon.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We had several C files include cache.h unnecessarily. Replace those
with an include of "git-compat-util.h" instead. Much like the previous
commit, these have all been verified via both ensuring that
gcc -E $SOURCE_FILE | grep '"cache.h"'
found no hits and that
make DEVELOPER=1 ${OBJECT_FILE_FOR_SOURCE_FILE}
successfully compiles without warnings.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Add global counters mechanism to Trace2.
The Trace2 counters mechanism adds the ability to create a set of
global counter variables and an API to increment them efficiently.
Counters can optionally report per-thread usage in addition to the sum
across all threads.
Counter events are emitted to the Trace2 logs when a thread exits and
at process exit.
Counters are an alternative to `data` and `data_json` events.
Counters are useful when you want to measure something across the life
of the process, when you don't want per-measurement events for
performance reasons, when the data does not fit conveniently within a
region, or when your control flow does not easily let you write the
final total. For example, you might use this to report the number of
calls to unzip() or the number of de-delta steps during a checkout.
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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>
When we specify GIT_TRACE2_CONFIG_PARAMS or trace2.configparams,
trace2 will prints "interesting" config values to log. Sometimes,
when a config set in multiple scope files, the following output
looks like (the irrelevant fields are omitted here as "..."):
...| def_param | ... | core.multipackindex:false
...| def_param | ... | core.multipackindex:false
...| def_param | ... | core.multipackindex:false
As the log shows, even each config in different scope is dumped, but
we don't know which scope it comes from. Therefore, it's better to
add the scope names as well to make them be more recognizable. For
example, when execute:
$ GIT_TRACE2_PERF=1 \
> GIT_TRACE2_CONFIG_PARAMS=core.multipackIndex \
> git rev-list --test-bitmap HEAD"
The following is the ouput (the irrelevant fields are omitted here
as "..."):
Format normal:
... git.c:461 ... def_param scope:system core.multipackindex=false
... git.c:461 ... def_param scope:global core.multipackindex=false
... git.c:461 ... def_param scope:local core.multipackindex=false
Format perf:
... | def_param | ... | scope:system | core.multipackindex:false
... | def_param | ... | scope:global | core.multipackindex:false
... | def_param | ... | scope:local | core.multipackindex:false
Format event:
{"event":"def_param", ... ,"scope":"system","param":"core.multipackindex","value":"false"}
{"event":"def_param", ... ,"scope":"global","param":"core.multipackindex","value":"false"}
{"event":"def_param", ... ,"scope":"local","param":"core.multipackindex","value":"false"}
Signed-off-by: Teng Long <dyroneteng@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Convert the "static struct tr2_dst" assignments in trace2/* to use
designated initializers. I don't think it improves readability to
include the explicit 0-ing out of the
fd/initialized/need_close/too_many_files members, so let's have those
be initialized implicitly by the compiler.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
As with the preceding commit, change another set of file-level struct
assignments to use designated initializers.
As before the "= NULL" assignments are redundant, but we're keeping
them for self-documentation purposes. The comments left to explain the
pre-image can now be removed in favor of working code that relays the
same information to the reader.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Remove the "argv" member from the run-command API, ever since "args"
was added in c460c0ecdc (run-command: store an optional argv_array,
2014-05-15) being able to provide either "argv" or "args" has led to
some confusion and bugs.
If we hadn't gone in that direction and only had an "argv" our
problems wouldn't have been solved either, as noted in [1] (and in the
documentation amended here) it comes with inherent memory management
issues: The caller would have to hang on to the "argv" until the
run-command API was finished. If the "argv" was an argument to main()
this wasn't an issue, but if it it was manually constructed using the
API might be painful.
We also have a recent report[2] of a user of the API segfaulting,
which is a direct result of it being complex to use. This commit
addresses the root cause of that bug.
This change is larger than I'd like, but there's no easy way to avoid
it that wouldn't involve even more verbose intermediate steps. We use
the "argv" as the source of truth over the "args", so we need to
change all parts of run-command.[ch] itself, as well as the trace2
logging at the same time.
The resulting Windows-specific code in start_command() is a bit nasty,
as we're now assigning to a strvec's "v" member, instead of to our own
"argv". There was a suggestion of some alternate approaches in reply
to an earlier version of this commit[3], but let's leave larger a
larger and needless refactoring of this code for now.
1. http://lore.kernel.org/git/YT6BnnXeAWn8BycF@coredump.intra.peff.net
2. https://lore.kernel.org/git/20211120194048.12125-1-ematsumiya@suse.de/
3. https://lore.kernel.org/git/patch-5.5-ea1011f7473-20211122T153605Z-avarab@gmail.com/
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In 64bc752 (trace2: add trace2_child_ready() to report on background
children, 2021-09-20), we added a new "child_ready" event. In
Documentation/technical/api-trace2.txt, we promise that adding a new
event type will result in incrementing the trace2 event format version
number, but this was not done. Correct this in code & docs.
Signed-off-by: Josh Steadmon <steadmon@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Create "child_ready" event to capture the state of a child process
created in the background.
When a child command is started a "child_start" event is generated in
the Trace2 log. For normal synchronous children, a "child_exit" event
is later generated when the child exits or is terminated. The two events
include information, such as the "child_id" and "pid", to allow post
analysis to match-up the command line and exit status.
When a child is started in the background (and may outlive the parent
process), it is not possible for the parent to emit a "child_exit"
event. Create a new "child_ready" event to indicate whether the
child was successfully started. Also include the "child_id" and "pid"
to allow similar post processing.
This will be used in a later commit with the new "start_bg_command()".
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
It can be useful to tell who invoked Git - was it invoked manually by a
user via CLI or script? By an IDE? In some cases - like 'repo' tool -
we can influence the source code and set the GIT_TRACE2_PARENT_SID
environment variable from the caller process. In 'repo''s case, that
parent SID is manipulated to include the string "repo", which means we
can positively identify when Git was invoked by 'repo' tool. However,
identifying parents that way requires both that we know which tools
invoke Git and that we have the ability to modify the source code of
those tools. It cannot scale to keep up with the various IDEs and
wrappers which use Git, most of which we don't know about. Learning
which tools and wrappers invoke Git, and how, would give us insight to
decide where to improve Git's usability and performance.
Unfortunately, there's no cross-platform reliable way to gather the name
of the parent process. If procfs is present, we can use that; otherwise
we will need to discover the name another way. However, the process ID
should be sufficient to look up the process name on most platforms, so
that code may be shareable.
Git for Windows gathers similar information and logs it as a "data_json"
event. However, since "data_json" has a variable format, it is difficult
to parse effectively in some languages; instead, let's pursue a
dedicated "cmd_ancestry" event to record information about the ancestry
of the current process and a consistent, parseable way.
Git for Windows also gathers information about more than one generation
of parent. In Linux further ancestry info can be gathered with procfs,
but it's unwieldy to do so. In the interest of later moving Git for
Windows ancestry logging to the 'cmd_ancestry' event, and in the
interest of later adding more ancestry to the Linux implementation - or
of adding this functionality to other platforms which have an easier
time walking the process tree - let's make 'cmd_ancestry' accept an
array of parentage.
Signed-off-by: Emily Shaffer <emilyshaffer@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Add a new "discard" event type for trace2 event destinations. When the
trace2 file count check creates a sentinel file, it will include the
normal trace2 output in the sentinel, along with this new discard
event.
Writing this message into the sentinel file is useful for tracking how
often the file count check triggers in practice.
Bump up the event format version since we've added a new event type.
Signed-off-by: Josh Steadmon <steadmon@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Remove an unnecessary "if" block in maybe_add_string_va().
Commit "ad006fe419e trace2: NULL is not allowed for va_list"
changed "if (fmt && *fmt && ap)" to just "if (fmt && *fmt)"
because it isn't safe to treat 'ap' as a pointer. This made
the "if" block following it unnecessary.
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Polishing of the new trace2 facility continues. The system-level
configuration can specify site-wide trace2 settings, which can be
overridden with per-user configuration and environment variables.
* jh/trace2-sid-fix:
trace2: fixup access problem on /etc/gitconfig in read_very_early_config
trace2: update docs to describe system/global config settings
trace2: make SIDs more unique
trace2: clarify UTC datetime formatting
trace2: report peak memory usage of the process
trace2: use system/global config for default trace2 settings
config: add read_very_early_config()
trace2: find exec-dir before trace2 initialization
trace2: add absolute elapsed time to start event
trace2: refactor setting process starting time
config: initialize opts structure in repo_read_config()
Update tr2_tbuf_utc_datetime to generate extended UTC format.
Update tr2_tgt_event target to use extended format in 'time' columns.
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio 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: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Add elapsed process time to "start" event to measure
the performance of early process startup.
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio 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: Torsten Bögershausen <tboegi@web.de>
Acked-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>
Jeff King
Glen Choo
Elijah Newren
Jeff Hostetler
Teng Long
Ævar Arnfjörð Bjarmason
Josh Steadmon
Emily Shaffer
Junio C Hamano
Torsten Bögershausen