survey: add pathname of blob or tree to large_item_vec

Include the pathname of each blob or tree in the large_item_vec
to help identify the file or directory associated with the OID
and size information.

This pathname is computed during the path walk, so it reflects the
first observed pathname seen for that OID during the traversal over
all of the refs.  Since the file or directory could have moved
(without being modified), there may be multiple "correct" pathnames
for a particular OID.  Since we do not control the ref traversal
order, we should consider it to be a "suggested pathname" for the OID.

Signed-off-by: Jeff Hostetler <jeffhostetler@github.com>

Author: jeffhostetler

Diff for: builtin/survey.c

@@ -156,6 +156,7 @@ static void incr_obj_hist_bin(struct obj_hist_bin *pbin,
 struct large_item {
 	uint64_t size;
 	struct object_id oid;
+	struct strbuf name;
 };
 
 struct large_item_vec {
@@ -171,6 +172,7 @@ static struct large_item_vec *alloc_large_item_vec(const char *dimension_label,
 {
 	struct large_item_vec *vec;
 	size_t flex_len = nr_items * sizeof(struct large_item);
+	size_t k;
 
 	if (!nr_items)
 		return NULL;
@@ -180,6 +182,9 @@ static struct large_item_vec *alloc_large_item_vec(const char *dimension_label,
 	vec->item_label = strdup(item_label);
 	vec->nr_items = nr_items;
 
+	for (k = 0; k < nr_items; k++)
+		strbuf_init(&vec->items[k].name, 0);
+
 	return vec;
 }
 
@@ -188,14 +193,18 @@ static void free_large_item_vec(struct large_item_vec *vec)
 	if (!vec)
 		return;
 
+	for (size_t k = 0; k < vec->nr_items; k++)
+		strbuf_release(&vec->items[k].name);
+
 	free(vec->dimension_label);
 	free(vec->item_label);
 	free(vec);
 }
 
 static void maybe_insert_large_item(struct large_item_vec *vec,
 				    uint64_t size,
-				    struct object_id *oid)
+				    struct object_id *oid,
+				    const char *name)
 {
 	size_t rest_len;
 	size_t k;
@@ -215,7 +224,14 @@ static void maybe_insert_large_item(struct large_item_vec *vec,
 		if (size < vec->items[k].size)
 			continue;
 
-		/* push items[k..] down one and insert it here */
+		/*
+		 * The last large_item in the vector is about to be
+		 * overwritten by the previous one during the shift.
+		 * Steal its allocated strbuf and reuse it.
+		 */
+		strbuf_release(&vec->items[vec->nr_items - 1].name);
+
+		/* push items[k..] down one and insert data for this item here */
 
 		rest_len = (vec->nr_items - k - 1) * sizeof(struct large_item);
 		if (rest_len)
@@ -224,6 +240,10 @@ static void maybe_insert_large_item(struct large_item_vec *vec,
 		memset(&vec->items[k], 0, sizeof(struct large_item));
 		vec->items[k].size = size;
 		oidcpy(&vec->items[k].oid, oid);
+		strbuf_init(&vec->items[k].name, 0);
+		if (name && *name)
+			strbuf_addstr(&vec->items[k].name, name);
+
 		return;
 	}
 }
@@ -728,15 +748,15 @@ static void survey_report_largest_vec(struct large_item_vec *vec)
 		return;
 
 	table.table_name = vec->dimension_label;
-	strvec_pushl(&table.header, "Size", "OID", NULL);
+	strvec_pushl(&table.header, "Size", "OID", "Name", NULL);
 
 	for (size_t k = 0; k < vec->nr_items; k++) {
 		struct large_item *pk = &vec->items[k];
 		if (!is_null_oid(&pk->oid)) {
 			strbuf_reset(&size);
 			strbuf_addf(&size, "%"PRIuMAX, (uintmax_t)pk->size);
 
-			insert_table_rowv(&table, size.buf, oid_to_hex(&pk->oid), NULL);
+			insert_table_rowv(&table, size.buf, oid_to_hex(&pk->oid), pk->name.buf, NULL);
 		}
 	}
 	strbuf_release(&size);
@@ -1197,7 +1217,8 @@ static void increment_object_counts(
 
 static void increment_totals(struct survey_context *ctx,
 			     struct oid_array *oids,
-			     struct survey_report_object_size_summary *summary)
+			     struct survey_report_object_size_summary *summary,
+			     const char *path)
 {
 	for (size_t i = 0; i < oids->nr; i++) {
 		struct object_info oi = OBJECT_INFO_INIT;
@@ -1233,8 +1254,8 @@ static void increment_totals(struct survey_context *ctx,
 			ctx->report.reachable_objects.commits.parent_cnt_pbin[k]++;
 			base = &ctx->report.reachable_objects.commits.base;
 
-			maybe_insert_large_item(ctx->report.reachable_objects.commits.vec_largest_by_nr_parents, k, &commit->object.oid);
-			maybe_insert_large_item(ctx->report.reachable_objects.commits.vec_largest_by_size_bytes, object_length, &commit->object.oid);
+			maybe_insert_large_item(ctx->report.reachable_objects.commits.vec_largest_by_nr_parents, k, &commit->object.oid, NULL);
+			maybe_insert_large_item(ctx->report.reachable_objects.commits.vec_largest_by_size_bytes, object_length, &commit->object.oid, NULL);
 			break;
 		}
 		case OBJ_TREE: {
@@ -1254,8 +1275,8 @@ static void increment_totals(struct survey_context *ctx,
 
 				pst->sum_entries += nr_entries;
 
-				maybe_insert_large_item(pst->vec_largest_by_nr_entries, nr_entries, &tree->object.oid);
-				maybe_insert_large_item(pst->vec_largest_by_size_bytes, object_length, &tree->object.oid);
+				maybe_insert_large_item(pst->vec_largest_by_nr_entries, nr_entries, &tree->object.oid, path);
+				maybe_insert_large_item(pst->vec_largest_by_size_bytes, object_length, &tree->object.oid, path);
 
 				qb = qbin(nr_entries);
 				incr_obj_hist_bin(&pst->entry_qbin[qb], object_length, disk_sizep);
@@ -1266,7 +1287,7 @@ static void increment_totals(struct survey_context *ctx,
 		case OBJ_BLOB:
 			base = &ctx->report.reachable_objects.blobs.base;
 
-			maybe_insert_large_item(ctx->report.reachable_objects.blobs.vec_largest_by_size_bytes, object_length, &oids->oid[i]);
+			maybe_insert_large_item(ctx->report.reachable_objects.blobs.vec_largest_by_size_bytes, object_length, &oids->oid[i], path);
 			break;
 		default:
 			continue;
@@ -1306,7 +1327,7 @@ static void increment_object_totals(struct survey_context *ctx,
 	struct survey_report_object_size_summary *total;
 	struct survey_report_object_size_summary summary = { 0 };
 
-	increment_totals(ctx, oids, &summary);
+	increment_totals(ctx, oids, &summary, path);
 
 	switch (type) {
 	case OBJ_COMMIT: