[PATCH 2/3] common-main: delay trace2 initialization

From: Jeff King <peff@peff.net>
Date: Aug 6, 2019, 12:27 UTC
Message-ID: <20190806122725.GB13513@sigill.intra.peff.net>
In-Reply-To: <20190806122601.GA21475@sigill.intra.peff.net>

We initialize the trace2 system in the common main() function so that all programs (even ones that aren't builtins) will enable tracing. But trace2 startup is relatively heavy-weight, as we have to actually read on-disk config to decide whether to trace. This can cause unexpected interactions with other common-main initialization. For instance, we'll end up in the config code before calling initialize_the_repository(), and the usual invariant that the_repository is never NULL will not hold.

Let's push the trace2 initialization further down in common-main, to just before we execute cmd_main(). The other parts of the initialization are much more self-contained and less likely to call library code that depends on those kinds of invariants.

Originally the trace2 code tried to start as early as possible to get accurate timings. But the timer initialization was split out from the config reading in a089724958 (trace2: refactor setting process starting time, 2019-04-15), so there shouldn't be any impact from this patch.

Signed-off-by: Jeff King <peff@peff.net>
---
 common-main.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/common-main.c b/common-main.c
index 582a7b1886..71e21dd20a 100644
--- a/common-main.c
+++ b/common-main.c
@@ -39,16 +39,16 @@ int main(int argc, const char **argv)
 
 	git_resolve_executable_dir(argv[0]);
 
-	trace2_initialize();
-	trace2_cmd_start(argv);
-	trace2_collect_process_info(TRACE2_PROCESS_INFO_STARTUP);
-
 	git_setup_gettext();
 
 	initialize_the_repository();
 
 	attr_start();
 
+	trace2_initialize();
+	trace2_cmd_start(argv);
+	trace2_collect_process_info(TRACE2_PROCESS_INFO_STARTUP);
+
 	result = cmd_main(argc, argv);
 
 	trace2_cmd_exit(result);

-- 
2.23.0.rc1.436.g24d2e81391