pack-objects: refactor the packing list

The hash table that stores the packing list for a given `pack-objects`
run was tightly coupled to the pack-objects code.

In this commit, we refactor the hash table and the underlying storage
array into a `packing_data` struct. The functionality for accessing and
adding entries to the packing list is hence accessible from other parts
of Git besides the `pack-objects` builtin.

This refactoring is a requirement for further patches in this series
that will require accessing the commit packing list from outside of
`pack-objects`.

The hash table implementation has been minimally altered: we now
use table sizes which are always a power of two, to ensure a uniform
index distribution in the array.

Signed-off-by: Vicent Marti <tanoku@gmail.com>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 47 insertions, 0 deletions

diff --git a/pack-objects.h b/pack-objects.h
new file mode 100644
index 0000000..f528215
--- /dev/null
+++ b/pack-objects.h
@@ -0,0 +1,47 @@
+#ifndef PACK_OBJECTS_H
+#define PACK_OBJECTS_H
+
+struct object_entry {
+	struct pack_idx_entry idx;
+	unsigned long size;	/* uncompressed size */
+	struct packed_git *in_pack;	/* already in pack */
+	off_t in_pack_offset;
+	struct object_entry *delta;	/* delta base object */
+	struct object_entry *delta_child; /* deltified objects who bases me */
+	struct object_entry *delta_sibling; /* other deltified objects who
+					     * uses the same base as me
+					     */
+	void *delta_data;	/* cached delta (uncompressed) */
+	unsigned long delta_size;	/* delta data size (uncompressed) */
+	unsigned long z_delta_size;	/* delta data size (compressed) */
+	enum object_type type;
+	enum object_type in_pack_type;	/* could be delta */
+	uint32_t hash;			/* name hint hash */
+	unsigned char in_pack_header_size;
+	unsigned preferred_base:1; /*
+				    * we do not pack this, but is available
+				    * to be used as the base object to delta
+				    * objects against.
+				    */
+	unsigned no_try_delta:1;
+	unsigned tagged:1; /* near the very tip of refs */
+	unsigned filled:1; /* assigned write-order */
+};
+
+struct packing_data {
+	struct object_entry *objects;
+	uint32_t nr_objects, nr_alloc;
+
+	int32_t *index;
+	uint32_t index_size;
+};
+
+struct object_entry *packlist_alloc(struct packing_data *pdata,
+				    const unsigned char *sha1,
+				    uint32_t index_pos);
+
+struct object_entry *packlist_find(struct packing_data *pdata,
+				   const unsigned char *sha1,
+				   uint32_t *index_pos);
+
+#endif