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[PATCH/RFC v2 3/9] pack-objects: use bitfield for object_entry::dfs_state




Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@xxxxxxxxx>
---
 builtin/pack-objects.c |  3 +++
 pack-objects.h         | 33 ++++++++++++++++++++-------------
 2 files changed, 23 insertions(+), 13 deletions(-)

diff --git a/builtin/pack-objects.c b/builtin/pack-objects.c
index fd217cb51f..a4dbb40824 100644
--- a/builtin/pack-objects.c
+++ b/builtin/pack-objects.c
@@ -3049,6 +3049,9 @@ int cmd_pack_objects(int argc, const char **argv, const char *prefix)
 		OPT_END(),
 	};
 
+	if (DFS_NUM_STATES > (1 << OE_DFS_STATE_BITS))
+		die("BUG: too many dfs states, increase OE_DFS_STATE_BITS");
+
 	check_replace_refs = 0;
 
 	reset_pack_idx_option(&pack_idx_opts);
diff --git a/pack-objects.h b/pack-objects.h
index f8b06e2521..6a85cc60c9 100644
--- a/pack-objects.h
+++ b/pack-objects.h
@@ -1,6 +1,21 @@
 #ifndef PACK_OBJECTS_H
 #define PACK_OBJECTS_H
 
+#define OE_DFS_STATE_BITS 2
+
+/*
+ * State flags for depth-first search used for analyzing delta cycles.
+ *
+ * The depth is measured in delta-links to the base (so if A is a delta
+ * against B, then A has a depth of 1, and B a depth of 0).
+ */
+enum dfs_state {
+	DFS_NONE = 0,
+	DFS_ACTIVE,
+	DFS_DONE,
+	DFS_NUM_STATES
+};
+
 struct object_entry {
 	struct pack_idx_entry idx;
 	unsigned long size;	/* uncompressed size */
@@ -27,21 +42,13 @@ struct object_entry {
 	unsigned no_try_delta:1;
 	unsigned tagged:1; /* near the very tip of refs */
 	unsigned filled:1; /* assigned write-order */
+	unsigned dfs_state:OE_DFS_STATE_BITS;
+
+	/* XXX 20 bits hole, try to pack */
 
-	/* XXX 22 bits hole, try to pack */
-	/*
-	 * State flags for depth-first search used for analyzing delta cycles.
-	 *
-	 * The depth is measured in delta-links to the base (so if A is a delta
-	 * against B, then A has a depth of 1, and B a depth of 0).
-	 */
-	enum {
-		DFS_NONE = 0,
-		DFS_ACTIVE,
-		DFS_DONE
-	} dfs_state;
 	int depth;
-	/* size: 128, padding: 4 */
+
+	/* size: 120 */
 };
 
 struct packing_data {
-- 
2.16.1.435.g8f24da2e1a