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2019-05-30Merge branch 'sg/trace2-rename'Junio C Hamano
Rename environment variables that are used to control the "trace2" mechanism to a more readable name. * sg/trace2-rename: trace2: document the supported values of GIT_TRACE2* env variables trace2: rename environment variables to GIT_TRACE2*
2019-05-30Merge branch 'jh/trace2'Junio C Hamano
* jh/trace2: trace2: fix tracing when NO_PTHREADS is defined
2019-05-28trace2: fix tracing when NO_PTHREADS is definedJeff Hostetler
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>
2019-05-28trace2: rename environment variables to GIT_TRACE2*SZEDER Gábor
For an environment variable that is supposed to be set by users, the GIT_TR2* env vars are just too unclear, inconsistent, and ugly. Most of the established GIT_* environment variables don't use abbreviations, and in case of the few that do (GIT_DIR, GIT_COMMON_DIR, GIT_DIFF_OPTS) it's quite obvious what the abbreviations (DIR and OPTS) stand for. But what does TR stand for? Track, traditional, trailer, transaction, transfer, transformation, transition, translation, transplant, transport, traversal, tree, trigger, truncate, trust, or ...?! The trace2 facility, as the '2' suffix in its name suggests, is supposed to eventually supercede Git's original trace facility. It's reasonable to expect that the corresponding environment variables follow suit, and after the original GIT_TRACE variables they are called GIT_TRACE2; there is no such thing is 'GIT_TR'. All trace2-specific config variables are, very sensibly, in the 'trace2' section, not in 'tr2'. OTOH, we don't gain anything at all by omitting the last three characters of "trace" from the names of these environment variables. So let's rename all GIT_TR2* environment variables to GIT_TRACE2*, before they make their way into a stable release. Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-05-13Merge branch 'jh/trace2-sid-fix'Junio C Hamano
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()
2019-05-08Merge branch 'js/trace2-to-directory'Junio C Hamano
The trace2 tracing facility learned to auto-generate a filename when told to log to a directory. * js/trace2-to-directory: trace2: write to directory targets
2019-04-16trace2: make SIDs more uniqueJeff Hostetler
Update SID component construction to use the current UTC datetime and a portion of the SHA1 of the hostname. Use an simplified date/time format to make it easier to use the SID component as a logfile filename. Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-04-16trace2: clarify UTC datetime formattingJeff Hostetler
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>
2019-04-16trace2: use system/global config for default trace2 settingsJeff Hostetler
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>
2019-04-16trace2: add absolute elapsed time to start eventJeff Hostetler
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>
2019-04-16trace2: refactor setting process starting timeJeff Hostetler
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>
2019-03-22trace2: write to directory targetsJosh Steadmon
When the value of a trace2 environment variable is an absolute path referring to an existing directory, write output to files (one per process) underneath the given directory. Files will be named according to the final component of the trace2 SID, followed by a counter to avoid potential collisions. This makes it more convenient to collect traces for every git invocation by unconditionally setting the relevant trace2 envvar to a constant directory name. Signed-off-by: Josh Steadmon <steadmon@google.com> Reviewed-by: Jeff Hostetler <jeffhost@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-03-20trace2: NULL is not allowed for va_listTorsten Bögershausen
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>
2019-02-22trace2: create new combined trace facilityJeff Hostetler
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>