commit-graph: rename "large edges" to "extra edges"

The optional 'Large Edge List' chunk of the commit graph file stores
parent information for commits with more than two parents, and the
names of most of the macros, variables, struct fields, and functions
related to this chunk contain the term "large edges", e.g.
write_graph_chunk_large_edges().  However, it's not a really great
term, as the edges to the second and subsequent parents stored in this
chunk are not any larger than the edges to the first and second
parents stored in the "main" 'Commit Data' chunk.  It's the number of
edges, IOW number of parents, that is larger compared to non-merge and
"regular" two-parent merge commits.  And indeed, two functions in
'commit-graph.c' have a local variable called 'num_extra_edges' that
refer to the same thing, and this "extra edges" term is much better at
describing these edges.

So let's rename all these references to "large edges" in macro,
variable, function, etc. names to "extra edges".  There is a
GRAPH_OCTOPUS_EDGES_NEEDED macro as well; for the sake of consistency
rename it to GRAPH_EXTRA_EDGES_NEEDED.

We can do so safely without causing any incompatibility issues,
because the term "large edges" doesn't come up in the file format
itself in any form (the chunk's magic is {'E', 'D', 'G', 'E'}, there
is no 'L' in there), but only in the specification text.  The string
"large edges", however, does come up in the output of 'git
commit-graph read' and in tests looking at its input, but that command
is explicitly documented as debugging aid, so we can change its output
and the affected tests safely.

Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/technical/commit-graph-format.txt

@@ -76,7 +76,7 @@ CHUNK DATA:
       of the ith commit. Stores value 0x7000000 if no parent in that
       position. If there are more than two parents, the second value
       has its most-significant bit on and the other bits store an array
-      position into the Large Edge List chunk.
+      position into the Extra Edge List chunk.
     * The next 8 bytes store the generation number of the commit and
       the commit time in seconds since EPOCH. The generation number
       uses the higher 30 bits of the first 4 bytes, while the commit
@@ -84,7 +84,7 @@ CHUNK DATA:
       2 bits of the lowest byte, storing the 33rd and 34th bit of the
       commit time.
 
-  Large Edge List (ID: {'E', 'D', 'G', 'E'}) [Optional]
+  Extra Edge List (ID: {'E', 'D', 'G', 'E'}) [Optional]
       This list of 4-byte values store the second through nth parents for
       all octopus merges. The second parent value in the commit data stores
       an array position within this list along with the most-significant bit

builtin/commit-graph.c

@@ -110,8 +110,8 @@ static int graph_read(int argc, const char **argv)
 		printf(" oid_lookup");
 	if (graph->chunk_commit_data)
 		printf(" commit_metadata");
-	if (graph->chunk_large_edges)
-		printf(" large_edges");
+	if (graph->chunk_extra_edges)
+		printf(" extra_edges");
 	printf("\n");
 
 	UNLEAK(graph);

commit-graph.c

@@ -21,7 +21,7 @@
 #define GRAPH_CHUNKID_OIDFANOUT 0x4f494446 /* "OIDF" */
 #define GRAPH_CHUNKID_OIDLOOKUP 0x4f49444c /* "OIDL" */
 #define GRAPH_CHUNKID_DATA 0x43444154 /* "CDAT" */
-#define GRAPH_CHUNKID_LARGEEDGES 0x45444745 /* "EDGE" */
+#define GRAPH_CHUNKID_EXTRAEDGES 0x45444745 /* "EDGE" */
 
 #define GRAPH_DATA_WIDTH 36
 
@@ -33,7 +33,7 @@
 #define GRAPH_OID_VERSION GRAPH_OID_VERSION_SHA1
 #define GRAPH_OID_LEN GRAPH_OID_LEN_SHA1
 
-#define GRAPH_OCTOPUS_EDGES_NEEDED 0x80000000
+#define GRAPH_EXTRA_EDGES_NEEDED 0x80000000
 #define GRAPH_PARENT_MISSING 0x7fffffff
 #define GRAPH_EDGE_LAST_MASK 0x7fffffff
 #define GRAPH_PARENT_NONE 0x70000000
@@ -177,11 +177,11 @@ struct commit_graph *load_commit_graph_one(const char *graph_file)
 				graph->chunk_commit_data = data + chunk_offset;
 			break;
 
-		case GRAPH_CHUNKID_LARGEEDGES:
-			if (graph->chunk_large_edges)
+		case GRAPH_CHUNKID_EXTRAEDGES:
+			if (graph->chunk_extra_edges)
 				chunk_repeated = 1;
 			else
-				graph->chunk_large_edges = data + chunk_offset;
+				graph->chunk_extra_edges = data + chunk_offset;
 			break;
 		}
 
@@ -343,12 +343,12 @@ static int fill_commit_in_graph(struct commit *item, struct commit_graph *g, uin
 	edge_value = get_be32(commit_data + g->hash_len + 4);
 	if (edge_value == GRAPH_PARENT_NONE)
 		return 1;
-	if (!(edge_value & GRAPH_OCTOPUS_EDGES_NEEDED)) {
+	if (!(edge_value & GRAPH_EXTRA_EDGES_NEEDED)) {
 		pptr = insert_parent_or_die(g, edge_value, pptr);
 		return 1;
 	}
 
-	parent_data_ptr = (uint32_t*)(g->chunk_large_edges +
+	parent_data_ptr = (uint32_t*)(g->chunk_extra_edges +
 			  4 * (uint64_t)(edge_value & GRAPH_EDGE_LAST_MASK));
 	do {
 		edge_value = get_be32(parent_data_ptr);
@@ -504,7 +504,7 @@ static void write_graph_chunk_data(struct hashfile *f, int hash_len,
 		if (!parent)
 			edge_value = GRAPH_PARENT_NONE;
 		else if (parent->next)
-			edge_value = GRAPH_OCTOPUS_EDGES_NEEDED | num_extra_edges;
+			edge_value = GRAPH_EXTRA_EDGES_NEEDED | num_extra_edges;
 		else {
 			edge_value = sha1_pos(parent->item->object.oid.hash,
 					      commits,
@@ -516,7 +516,7 @@ static void write_graph_chunk_data(struct hashfile *f, int hash_len,
 
 		hashwrite_be32(f, edge_value);
 
-		if (edge_value & GRAPH_OCTOPUS_EDGES_NEEDED) {
+		if (edge_value & GRAPH_EXTRA_EDGES_NEEDED) {
 			do {
 				num_extra_edges++;
 				parent = parent->next;
@@ -537,7 +537,7 @@ static void write_graph_chunk_data(struct hashfile *f, int hash_len,
 	}
 }
 
-static void write_graph_chunk_large_edges(struct hashfile *f,
+static void write_graph_chunk_extra_edges(struct hashfile *f,
 					  struct commit **commits,
 					  int nr_commits)
 {
@@ -923,7 +923,7 @@ void write_commit_graph(const char *obj_dir,
 	chunk_ids[1] = GRAPH_CHUNKID_OIDLOOKUP;
 	chunk_ids[2] = GRAPH_CHUNKID_DATA;
 	if (num_extra_edges)
-		chunk_ids[3] = GRAPH_CHUNKID_LARGEEDGES;
+		chunk_ids[3] = GRAPH_CHUNKID_EXTRAEDGES;
 	else
 		chunk_ids[3] = 0;
 	chunk_ids[4] = 0;
@@ -946,7 +946,7 @@ void write_commit_graph(const char *obj_dir,
 	write_graph_chunk_fanout(f, commits.list, commits.nr);
 	write_graph_chunk_oids(f, GRAPH_OID_LEN, commits.list, commits.nr);
 	write_graph_chunk_data(f, GRAPH_OID_LEN, commits.list, commits.nr);
-	write_graph_chunk_large_edges(f, commits.list, commits.nr);
+	write_graph_chunk_extra_edges(f, commits.list, commits.nr);
 
 	close_commit_graph(the_repository);
 	finalize_hashfile(f, NULL, CSUM_HASH_IN_STREAM | CSUM_FSYNC);

commit-graph.h

@@ -49,7 +49,7 @@ struct commit_graph {
 	const uint32_t *chunk_oid_fanout;
 	const unsigned char *chunk_oid_lookup;
 	const unsigned char *chunk_commit_data;
-	const unsigned char *chunk_large_edges;
+	const unsigned char *chunk_extra_edges;
 };
 
 struct commit_graph *load_commit_graph_one(const char *graph_file);

t/t5318-commit-graph.sh

@@ -122,7 +122,7 @@ test_expect_success 'write graph with merges' '
 	cd "$TRASH_DIRECTORY/full" &&
 	git commit-graph write &&
 	test_path_is_file $objdir/info/commit-graph &&
-	graph_read_expect "10" "large_edges"
+	graph_read_expect "10" "extra_edges"
 '
 
 graph_git_behavior 'merge 1 vs 2' full merge/1 merge/2
@@ -157,7 +157,7 @@ test_expect_success 'write graph with new commit' '
 	cd "$TRASH_DIRECTORY/full" &&
 	git commit-graph write &&
 	test_path_is_file $objdir/info/commit-graph &&
-	graph_read_expect "11" "large_edges"
+	graph_read_expect "11" "extra_edges"
 '
 
 graph_git_behavior 'full graph, commit 8 vs merge 1' full commits/8 merge/1
@@ -167,7 +167,7 @@ test_expect_success 'write graph with nothing new' '
 	cd "$TRASH_DIRECTORY/full" &&
 	git commit-graph write &&
 	test_path_is_file $objdir/info/commit-graph &&
-	graph_read_expect "11" "large_edges"
+	graph_read_expect "11" "extra_edges"
 '
 
 graph_git_behavior 'cleared graph, commit 8 vs merge 1' full commits/8 merge/1
@@ -177,7 +177,7 @@ test_expect_success 'build graph from latest pack with closure' '
 	cd "$TRASH_DIRECTORY/full" &&
 	cat new-idx | git commit-graph write --stdin-packs &&
 	test_path_is_file $objdir/info/commit-graph &&
-	graph_read_expect "9" "large_edges"
+	graph_read_expect "9" "extra_edges"
 '
 
 graph_git_behavior 'graph from pack, commit 8 vs merge 1' full commits/8 merge/1
@@ -200,7 +200,7 @@ test_expect_success 'build graph from commits with append' '
 	cd "$TRASH_DIRECTORY/full" &&
 	git rev-parse merge/3 | git commit-graph write --stdin-commits --append &&
 	test_path_is_file $objdir/info/commit-graph &&
-	graph_read_expect "10" "large_edges"
+	graph_read_expect "10" "extra_edges"
 '
 
 graph_git_behavior 'append graph, commit 8 vs merge 1' full commits/8 merge/1
@@ -210,7 +210,7 @@ test_expect_success 'build graph using --reachable' '
 	cd "$TRASH_DIRECTORY/full" &&
 	git commit-graph write --reachable &&
 	test_path_is_file $objdir/info/commit-graph &&
-	graph_read_expect "11" "large_edges"
+	graph_read_expect "11" "extra_edges"
 '
 
 graph_git_behavior 'append graph, commit 8 vs merge 1' full commits/8 merge/1
@@ -231,7 +231,7 @@ test_expect_success 'write graph in bare repo' '
 	cd "$TRASH_DIRECTORY/bare" &&
 	git commit-graph write &&
 	test_path_is_file $baredir/info/commit-graph &&
-	graph_read_expect "11" "large_edges"
+	graph_read_expect "11" "extra_edges"
 '
 
 graph_git_behavior 'bare repo with graph, commit 8 vs merge 1' bare commits/8 merge/1