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[PATCH v6 5/6] blame: optionally track line fingerprints during fill_blame_origin()

From
BRBarret Rhoden <brho@google.com>
Date
Apr 10, 2019, 16:24 UTC
Message-ID
<20190410162409.117264-6-brho@google.com>
In-Reply-To
<20190410162409.117264-1-brho@google.com>

fill_blame_origin() is a convenient place to store data that we will use throughout the lifetime of a blame_origin. Some heuristics for ignoring commits during a blame session can make use of this storage. In particular, we will calculate a fingerprint for each line of a file for blame_origins involved in an ignored commit.

In this commit, we only calculate the line_starts, reusing the existing code from the scoreboard's line_starts. In an upcoming commit, we will actually compute the fingerprints.

This feature will be used when we attempt to pass blame entries to parents when we "ignore" a commit. Most uses of fill_blame_origin() will not require this feature, hence the flag parameter. Multiple calls to fill_blame_origin() are idempotent, and any of them can request the creation of the fingerprints structure.

Suggested-by: Michael Platings <michael@platin.gs>
Signed-off-by: Barret Rhoden <brho@google.com>
---
 blame.c | 95 +++++++++++++++++++++++++++++++++++++++------------------
 blame.h |  2 ++
 2 files changed, 67 insertions(+), 30 deletions(-)
diff --git a/blame.c b/blame.c
index a98ae00e2cfc..a42dff80b1a5 100644
--- a/blame.c
+++ b/blame.c
@@ -311,12 +311,63 @@ static int diff_hunks(mmfile_t *file_a, mmfile_t *file_b,
 	return xdi_diff(file_a, file_b, &xpp, &xecfg, &ecb);
 }
 
+static const char *get_next_line(const char *start, const char *end)
+{
+	const char *nl = memchr(start, '\n', end - start);
+
+	return nl ? nl + 1 : end;
+}
+
+static int find_line_starts(int **line_starts, const char *buf,
+			    unsigned long len)
+{
+	const char *end = buf + len;
+	const char *p;
+	int *lineno;
+	int num = 0;
+
+	for (p = buf; p < end; p = get_next_line(p, end))
+		num++;
+
+	ALLOC_ARRAY(*line_starts, num + 1);
+	lineno = *line_starts;
+
+	for (p = buf; p < end; p = get_next_line(p, end))
+		*lineno++ = p - buf;
+
+	*lineno = len;
+
+	return num;
+}
+
+static void fill_origin_fingerprints(struct blame_origin *o, mmfile_t *file)
+{
+	int *line_starts;
+
+	if (o->fingerprints)
+		return;
+	o->num_lines = find_line_starts(&line_starts, o->file.ptr,
+					o->file.size);
+	/* TODO: Will fill in fingerprints in a future commit */
+	o->fingerprints = xcalloc(sizeof(struct fingerprint), o->num_lines);
+	free(line_starts);
+}
+
+static void drop_origin_fingerprints(struct blame_origin *o)
+{
+	if (o->fingerprints) {
+		o->num_lines = 0;
+		FREE_AND_NULL(o->fingerprints);
+	}
+}
+
 /*
  * Given an origin, prepare mmfile_t structure to be used by the
  * diff machinery
  */
 static void fill_origin_blob(struct diff_options *opt,
-			     struct blame_origin *o, mmfile_t *file, int *num_read_blob)
+			     struct blame_origin *o, mmfile_t *file,
+			     int *num_read_blob, int fill_fingerprints)
 {
 	if (!o->file.ptr) {
 		enum object_type type;
@@ -340,11 +391,14 @@ static void fill_origin_blob(struct diff_options *opt,
 	}
 	else
 		*file = o->file;
+	if (fill_fingerprints)
+		fill_origin_fingerprints(o, file);
 }
 
 static void drop_origin_blob(struct blame_origin *o)
 {
 	FREE_AND_NULL(o->file.ptr);
+	drop_origin_fingerprints(o);
 }
 
 /*
@@ -1136,8 +1190,10 @@ static void pass_blame_to_parent(struct blame_scoreboard *sb,
 	d.ignore_diffs = ignore_diffs;
 	d.dstq = &newdest; d.srcq = &target->suspects;
 
-	fill_origin_blob(&sb->revs->diffopt, parent, &file_p, &sb->num_read_blob);
-	fill_origin_blob(&sb->revs->diffopt, target, &file_o, &sb->num_read_blob);
+	fill_origin_blob(&sb->revs->diffopt, parent, &file_p,
+			 &sb->num_read_blob, ignore_diffs);
+	fill_origin_blob(&sb->revs->diffopt, target, &file_o,
+			 &sb->num_read_blob, ignore_diffs);
 	sb->num_get_patch++;
 
 	if (diff_hunks(&file_p, &file_o, blame_chunk_cb, &d, sb->xdl_opts))
@@ -1348,7 +1404,8 @@ static void find_move_in_parent(struct blame_scoreboard *sb,
 	if (!unblamed)
 		return; /* nothing remains for this target */
 
-	fill_origin_blob(&sb->revs->diffopt, parent, &file_p, &sb->num_read_blob);
+	fill_origin_blob(&sb->revs->diffopt, parent, &file_p,
+			 &sb->num_read_blob, 0);
 	if (!file_p.ptr)
 		return;
 
@@ -1477,7 +1534,8 @@ static void find_copy_in_parent(struct blame_scoreboard *sb,
 			norigin = get_origin(parent, p->one->path);
 			oidcpy(&norigin->blob_oid, &p->one->oid);
 			norigin->mode = p->one->mode;
-			fill_origin_blob(&sb->revs->diffopt, norigin, &file_p, &sb->num_read_blob);
+			fill_origin_blob(&sb->revs->diffopt, norigin, &file_p,
+					 &sb->num_read_blob, 0);
 			if (!file_p.ptr)
 				continue;
 
@@ -1816,37 +1874,14 @@ void assign_blame(struct blame_scoreboard *sb, int opt)
 	}
 }
 
-static const char *get_next_line(const char *start, const char *end)
-{
-	const char *nl = memchr(start, '\n', end - start);
-	return nl ? nl + 1 : end;
-}
-
 /*
  * To allow quick access to the contents of nth line in the
  * final image, prepare an index in the scoreboard.
  */
 static int prepare_lines(struct blame_scoreboard *sb)
 {
-	const char *buf = sb->final_buf;
-	unsigned long len = sb->final_buf_size;
-	const char *end = buf + len;
-	const char *p;
-	int *lineno;
-	int num = 0;
-
-	for (p = buf; p < end; p = get_next_line(p, end))
-		num++;
-
-	ALLOC_ARRAY(sb->lineno, num + 1);
-	lineno = sb->lineno;
-
-	for (p = buf; p < end; p = get_next_line(p, end))
-		*lineno++ = p - buf;
-
-	*lineno = len;
-
-	sb->num_lines = num;
+	sb->num_lines = find_line_starts(&sb->lineno, sb->final_buf,
+					 sb->final_buf_size);
 	return sb->num_lines;
 }
 
diff --git a/blame.h b/blame.h
index 53df8b4c5b3f..5dd877bb78fc 100644
--- a/blame.h
+++ b/blame.h
@@ -51,6 +51,8 @@ struct blame_origin {
 	 */
 	struct blame_entry *suspects;
 	mmfile_t file;
+	int num_lines;
+	void *fingerprints;
 	struct object_id blob_oid;
 	unsigned mode;
 	/* guilty gets set when shipping any suspects to the final

-- 
2.21.0.392.gf8f6787159e-goog
Previous: Barret RhodenNext: Barret Rhoden
Message 17 of 25 in “blame: add the ability to ignore commits”
  1. 0/6 blame: add the ability to ignore commitsBarret Rhoden, Apr 10, 2019
  2. 1/6 Move init_skiplist() outside of fsckBarret Rhoden, Apr 10, 2019
  3. Ævar Arnfjörð BjarmasonApr 10, 2019
  4. Barret RhodenApr 15, 2019
  5. 2/6 blame: use a helper function in blame_chunk()Barret Rhoden, Apr 10, 2019
  6. 3/6 blame: add the ability to ignore commits and their changesBarret Rhoden, Apr 10, 2019
  7. Ævar Arnfjörð BjarmasonApr 10, 2019
  8. Michael PlatingsApr 14, 2019
  9. Barret RhodenApr 15, 2019
  10. Barret RhodenApr 15, 2019
  11. 4/6 blame: add config options to handle output for ignored linesBarret Rhoden, Apr 10, 2019
  12. Junio C HamanoApr 14, 2019
  13. Michael PlatingsApr 14, 2019
  14. Junio C HamanoApr 14, 2019
  15. Michael PlatingsApr 14, 2019
  16. Barret RhodenApr 15, 2019
  17. 5/6 blame: optionally track line fingerprints during fill_blame_origin()Barret Rhoden, Apr 10, 2019
  18. 6/6 blame: use a fingerprint heuristic to match ignored linesBarret Rhoden, Apr 10, 2019
  19. Junio C HamanoApr 14, 2019
  20. Michael PlatingsApr 14, 2019
  21. Barret RhodenApr 15, 2019
  22. Junio C HamanoApr 16, 2019
  23. Michael PlatingsApr 14, 2019
  24. Barret RhodenApr 15, 2019
  25. Michael PlatingsApr 15, 2019

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