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[PATCH 15/16] bisect: compute best bisection in compute_relevant_weights()

From
Stephan Beyer <s-beyer@gmx.net>
Date
Feb 26, 2016, 02:04 UTC
Message-ID
<1456452282-10325-16-git-send-email-s-beyer@gmx.net>
In-Reply-To
<1456452282-10325-1-git-send-email-s-beyer@gmx.net>

This commit gets rid of the O(#commits) extra overhead of the best_bisection() function.

Signed-off-by: Stephan Beyer <s-beyer@gmx.net>
---
 bisect.c | 43 ++++++++++++++++++-------------------------
 1 file changed, 18 insertions(+), 25 deletions(-)
diff --git a/bisect.c b/bisect.c
index 827a82a..185a3cf 100644
--- a/bisect.c
+++ b/bisect.c
@@ -27,6 +27,8 @@ static int total;
 
 static unsigned marker;
 
+static struct commit_list best_bisection;
+
 struct node_data {
 	int weight;
 	unsigned marked;
@@ -73,6 +75,14 @@ static inline int distance_direction(struct commit *commit)
 	return 0;
 }
 
+static inline void update_best_bisection(struct commit *commit)
+{
+	if (distance_direction(commit) >= 0
+	 && node_data(commit)->weight > node_data(best_bisection.item)->weight) {
+		best_bisection.item = commit;
+	}
+}
+
 static int compute_weight(struct commit *entry)
 {
 	int nr = 0;
@@ -153,29 +163,6 @@ static void show_list(const char *debug, int counted,
 }
 #endif /* DEBUG_BISECT */
 
-static struct commit_list *best_bisection(struct commit_list *list)
-{
-	struct commit_list *p, *best;
-	int best_distance = -1;
-
-	best = list;
-	for (p = list; p; p = p->next) {
-		int distance;
-		unsigned flags = p->item->object.flags;
-
-		if (flags & TREESAME)
-			continue;
-		distance = get_distance(p->item);
-		if (distance > best_distance) {
-			best = p;
-			best_distance = distance;
-		}
-	}
-
-	best->next = NULL;
-	return best;
-}
-
 struct commit_dist {
 	struct commit *commit;
 	int distance;
@@ -403,6 +390,7 @@ static void bfs_up_to_merges(struct commit_list *queue,
 			}
 		}
 
+		update_best_bisection(top);
 		pop_commit(&queue);
 	}
 }
@@ -459,8 +447,10 @@ static int find_new_queue_from_merges(struct commit_list **queue,
 static void compute_merge_weights(struct commit_list *merges)
 {
 	struct commit_list *p;
-	for (p = merges; p; p = p->next)
+	for (p = merges; p; p = p->next) {
 		compute_weight(p->item);
+		update_best_bisection(p->item);
+	}
 }
 
 static void modified_bfs(struct commit_list *queue)
@@ -489,6 +479,9 @@ static void compute_relevant_weights(struct commit_list *list,
 	struct commit_list *p;
 	struct commit_list *sources = build_reversed_dag(list, weights);
 
+	best_bisection.item = sources->item;
+	best_bisection.next = NULL;
+
 	for (p = sources; p; p = p->next)
 		node_data(p->item)->weight = 1;
 	modified_bfs(sources);
@@ -541,7 +534,7 @@ struct commit_list *find_bisection(struct commit_list *list,
 		best = best_bisection_sorted(list);
 	} else {
 		compute_relevant_weights(list, weights);
-		best = best_bisection(list);
+		best = &best_bisection;
 	}
 	assert(best);
 	*reaches = node_data(best->item)->weight;
-- 
2.7.1.354.gd492730.dirty
Previous: Stephan BeyerNext: Stephan Beyer
Message 29 of 34 in “git bisect improvements”
  1. 00/16 git bisect improvementsStephan Beyer, Feb 26, 2016
  2. 01/16 bisect: write about `bisect next` in documentationStephan Beyer, Feb 26, 2016
  3. Jacob KellerFeb 26, 2016
  4. Junio C HamanoFeb 26, 2016
  5. Stephan BeyerFeb 27, 2016
  6. Junio C HamanoFeb 27, 2016
  7. Stephan BeyerFeb 27, 2016
  8. Junio C HamanoFeb 28, 2016
  9. 02/16 bisect: add test for the bisect algorithmStephan Beyer, Feb 26, 2016
  10. Christian CouderFeb 26, 2016
  11. Stephan BeyerFeb 26, 2016
  12. Christian CouderFeb 27, 2016
  13. Matthieu MoyFeb 27, 2016
  14. 03/16 bisect: make bisect compile if DEBUG_BISECT is setStephan Beyer, Feb 26, 2016
  15. 04/16 bisect: make algorithm behavior independent of DEBUG_BISECTStephan Beyer, Feb 26, 2016
  16. 05/16 bisect: get rid of recursion in count_distance()Stephan Beyer, Feb 26, 2016
  17. 06/16 bisect: use struct node_data array instead of int arrayStephan Beyer, Feb 26, 2016
  18. 07/16 bisect: replace clear_distance() by unique markersStephan Beyer, Feb 26, 2016
  19. 08/16 bisect: use commit instead of commit list as arguments when appropriateStephan Beyer, Feb 26, 2016
  20. Junio C HamanoFeb 26, 2016
  21. 09/16 bisect: extract get_distance() function from code duplicationStephan Beyer, Feb 26, 2016
  22. 10/16 bisect: introduce distance_direction()Stephan Beyer, Feb 26, 2016
  23. 11/16 bisect: make total number of commits globalStephan Beyer, Feb 26, 2016
  24. 12/16 bisect: rename count_distance() to compute_weight()Stephan Beyer, Feb 26, 2016
  25. 13/16 bisect: prepare for different algorithms based on find_allStephan Beyer, Feb 26, 2016
  26. 14/16 bisect: use a modified breadth-first search to find relevant weightsStephan Beyer, Feb 26, 2016
  27. Junio C HamanoFeb 26, 2016
  28. Stephan BeyerFeb 26, 2016
  29. 15/16 bisect: compute best bisection in compute_relevant_weights()Stephan Beyer, Feb 26, 2016
  30. 16/16 bisect: get back halfway shortcutStephan Beyer, Feb 26, 2016
  31. Pranit BauvaMar 20, 2016
  32. Stephan BeyerMar 21, 2016
  33. Christian CouderMar 22, 2016
  34. Pranit BauvaMar 22, 2016

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