Subject: [PATCH 1/1] fetch: add trace2 instrumentation

From: "Erik Chen via GitGitGadget" <[email-masked]>
Date: Tue, 05 Nov 2019 19:26:20 +0000

From: Erik Chen <[email-masked]>

Add trace2 regions to fetch-pack.c to better track time spent in the various
phases of a fetch:

    * matching common remote and local refs
    * marking local refs as complete (part of the matching process)

Both of these stages can be slow for repositories with many refs.

Signed-off-by: Erik Chen <[email-masked]>
---
 fetch-pack.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/fetch-pack.c b/fetch-pack.c
index 0130b44112..f2f3365bbe 100644
--- a/fetch-pack.c
+++ b/fetch-pack.c
@@ -666,9 +666,10 @@ static void mark_complete_and_common_ref(struct fetch_negotiator *negotiator,
 	struct ref *ref;
 	int old_save_commit_buffer = save_commit_buffer;
 	timestamp_t cutoff = 0;
-
 	save_commit_buffer = 0;
 
+	trace2_region_enter("fetch-pack", "mark_complete_and_common_ref", NULL);
+
 	for (ref = *refs; ref; ref = ref->next) {
 		struct object *o;
 
@@ -690,6 +691,10 @@ static void mark_complete_and_common_ref(struct fetch_negotiator *negotiator,
 		}
 	}
 
+	/* This block marks all local refs as COMPLETE, and then recursively marks all
+	 * parents of those refs as COMPLETE.
+	 */
+	trace2_region_enter("fetch-pack", "mark_complete_local_refs", NULL);
 	if (!args->deepen) {
 		for_each_ref(mark_complete_oid, NULL);
 		for_each_cached_alternate(NULL, mark_alternate_complete);
@@ -697,6 +702,7 @@ static void mark_complete_and_common_ref(struct fetch_negotiator *negotiator,
 		if (cutoff)
 			mark_recent_complete_commits(args, cutoff);
 	}
+	trace2_region_leave("fetch-pack", "mark_complete_local_refs", NULL);
 
 	/*
 	 * Mark all complete remote refs as common refs.
@@ -716,6 +722,7 @@ static void mark_complete_and_common_ref(struct fetch_negotiator *negotiator,
 	}
 
 	save_commit_buffer = old_save_commit_buffer;
+	trace2_region_leave("fetch-pack", "mark_complete_and_common_ref", NULL);
 }
 
 /*
-- 
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