summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
Diffstat
-rw-r--r--pack-objects.c367
-rw-r--r--pack.h4
-rw-r--r--sha1_file.c19
3 files changed, 332 insertions, 58 deletions
diff --git a/pack-objects.c b/pack-objects.c
index c5a5e61605..70fb2afeb8 100644
--- a/pack-objects.c
+++ b/pack-objects.c
@@ -9,15 +9,31 @@ static const char pack_usage[] = "git-pack-objects [-q] [--non-empty] [--local]
struct object_entry {
unsigned char sha1[20];
- unsigned long size;
- unsigned long offset;
- unsigned int depth;
- unsigned int hash;
+ unsigned long size; /* uncompressed size */
+ unsigned long offset; /* offset into the final pack file (nonzero if already written) */
+ unsigned int depth; /* delta depth */
+ unsigned int hash; /* name hint hash */
enum object_type type;
- unsigned long delta_size;
- struct object_entry *delta;
+ unsigned long delta_size; /* delta data size (uncompressed) */
+ struct object_entry *delta; /* delta base object */
+ struct packed_git *in_pack; /* already in pack */
+ enum object_type in_pack_type; /* could be delta */
+ unsigned int in_pack_offset;
};
+/*
+ * Objects we are going to pack are colected in objects array (dynamically
+ * expanded). nr_objects & nr_alloc controls this array. They are stored
+ * in the order we see -- typically rev-list --objects order that gives us
+ * nice "minimum seek" order.
+ *
+ * sorted-by-sha ans sorted-by-type are arrays of pointers that point at
+ * elements in the objects array. The former is used to build the pack
+ * index (lists object names in the ascending order to help offset lookup),
+ * and the latter is used to group similar things together by try_delta()
+ * heuristics.
+ */
+
static unsigned char object_list_sha1[20];
static int non_empty = 0;
static int local = 0;
@@ -29,6 +45,135 @@ static const char *base_name;
static unsigned char pack_file_sha1[20];
static int progress = 1;
+/*
+ * The object names in objects array are hashed with this hashtable,
+ * to help looking up the entry by object name. Binary search from
+ * sorted_by_sha is also possible but this was easier to code and faster.
+ * This hashtable is built after all the objects are seen.
+ */
+static int *object_ix = NULL;
+static int object_ix_hashsz = 0;
+
+/*
+ * Pack index for existing packs give us easy access to the offsets into
+ * corresponding pack file where each object's data starts, but the entries
+ * do not store the size of the compressed representation (uncompressed
+ * size is easily available by examining the pack entry header). We build
+ * a hashtable of existing packs (pack_revindex), and keep reverse index
+ * here -- pack index file is sorted by object name mapping to offset; this
+ * pack_revindex[].revindex array is an ordered list of offsets, so if you
+ * know the offset of an object, next offset is where its packed
+ * representation ends.
+ */
+struct pack_revindex {
+ struct packed_git *p;
+ unsigned long *revindex;
+} *pack_revindex = NULL;
+static int pack_revindex_hashsz = 0;
+
+/*
+ * stats
+ */
+static int written = 0;
+static int reused = 0;
+
+static int pack_revindex_ix(struct packed_git *p)
+{
+ unsigned int ui = (unsigned int) p;
+ int i;
+
+ ui = ui ^ (ui >> 16); /* defeat structure alignment */
+ i = (int)(ui % pack_revindex_hashsz);
+ while (pack_revindex[i].p) {
+ if (pack_revindex[i].p == p)
+ return i;
+ if (++i == pack_revindex_hashsz)
+ i = 0;
+ }
+ return -1 - i;
+}
+
+static void prepare_pack_ix(void)
+{
+ int num;
+ struct packed_git *p;
+ for (num = 0, p = packed_git; p; p = p->next)
+ num++;
+ if (!num)
+ return;
+ pack_revindex_hashsz = num * 11;
+ pack_revindex = xcalloc(sizeof(*pack_revindex), pack_revindex_hashsz);
+ for (p = packed_git; p; p = p->next) {
+ num = pack_revindex_ix(p);
+ num = - 1 - num;
+ pack_revindex[num].p = p;
+ }
+ /* revindex elements are lazily initialized */
+}
+
+static int cmp_offset(const void *a_, const void *b_)
+{
+ unsigned long a = *(unsigned long *) a_;
+ unsigned long b = *(unsigned long *) b_;
+ if (a < b)
+ return -1;
+ else if (a == b)
+ return 0;
+ else
+ return 1;
+}
+
+/*
+ * Ordered list of offsets of objects in the pack.
+ */
+static void prepare_pack_revindex(struct pack_revindex *rix)
+{
+ struct packed_git *p = rix->p;
+ int num_ent = num_packed_objects(p);
+ int i;
+ void *index = p->index_base + 256;
+
+ rix->revindex = xmalloc(sizeof(unsigned long) * (num_ent + 1));
+ for (i = 0; i < num_ent; i++) {
+ long hl = *((long *)(index + 24 * i));
+ rix->revindex[i] = ntohl(hl);
+ }
+ /* This knows the pack format -- the 20-byte trailer
+ * follows immediately after the last object data.
+ */
+ rix->revindex[num_ent] = p->pack_size - 20;
+ qsort(rix->revindex, num_ent, sizeof(unsigned long), cmp_offset);
+}
+
+static unsigned long find_packed_object_size(struct packed_git *p,
+ unsigned long ofs)
+{
+ int num;
+ int lo, hi;
+ struct pack_revindex *rix;
+ unsigned long *revindex;
+ num = pack_revindex_ix(p);
+ if (num < 0)
+ die("internal error: pack revindex uninitialized");
+ rix = &pack_revindex[num];
+ if (!rix->revindex)
+ prepare_pack_revindex(rix);
+ revindex = rix->revindex;
+ lo = 0;
+ hi = num_packed_objects(p) + 1;
+ do {
+ int mi = (lo + hi) / 2;
+ if (revindex[mi] == ofs) {
+ return revindex[mi+1] - ofs;
+ }
+ else if (ofs < revindex[mi])
+ hi = mi;
+ else
+ lo = mi + 1;
+ } while (lo < hi);
+ die("internal error: pack revindex corrupt");
+}
+
static void *delta_against(void *buf, unsigned long size, struct object_entry *entry)
{
unsigned long othersize, delta_size;
@@ -78,35 +223,52 @@ static unsigned long write_object(struct sha1file *f, struct object_entry *entry
{
unsigned long size;
char type[10];
- void *buf = read_sha1_file(entry->sha1, type, &size);
+ void *buf;
unsigned char header[10];
unsigned hdrlen, datalen;
enum object_type obj_type;
- if (!buf)
- die("unable to read %s", sha1_to_hex(entry->sha1));
- if (size != entry->size)
- die("object %s size inconsistency (%lu vs %lu)", sha1_to_hex(entry->sha1), size, entry->size);
-
- /*
- * The object header is a byte of 'type' followed by zero or
- * more bytes of length. For deltas, the 20 bytes of delta sha1
- * follows that.
- */
obj_type = entry->type;
- if (entry->delta) {
- buf = delta_against(buf, size, entry);
- size = entry->delta_size;
- obj_type = OBJ_DELTA;
+ if (!entry->in_pack ||
+ (obj_type != entry->in_pack_type)) {
+ buf = read_sha1_file(entry->sha1, type, &size);
+ if (!buf)
+ die("unable to read %s", sha1_to_hex(entry->sha1));
+ if (size != entry->size)
+ die("object %s size inconsistency (%lu vs %lu)",
+ sha1_to_hex(entry->sha1), size, entry->size);
+ if (entry->delta) {
+ buf = delta_against(buf, size, entry);
+ size = entry->delta_size;
+ obj_type = OBJ_DELTA;
+ }
+ /*
+ * The object header is a byte of 'type' followed by zero or
+ * more bytes of length. For deltas, the 20 bytes of delta
+ * sha1 follows that.
+ */
+ hdrlen = encode_header(obj_type, size, header);
+ sha1write(f, header, hdrlen);
+
+ if (entry->delta) {
+ sha1write(f, entry->delta, 20);
+ hdrlen += 20;
+ }
+ datalen = sha1write_compressed(f, buf, size);
+ free(buf);
}
- hdrlen = encode_header(obj_type, size, header);
- sha1write(f, header, hdrlen);
- if (entry->delta) {
- sha1write(f, entry->delta, 20);
- hdrlen += 20;
+ else {
+ struct packed_git *p = entry->in_pack;
+ use_packed_git(p);
+
+ datalen = find_packed_object_size(p, entry->in_pack_offset);
+ buf = p->pack_base + entry->in_pack_offset;
+ sha1write(f, buf, datalen);
+ unuse_packed_git(p);
+ hdrlen = 0; /* not really */
+ reused++;
}
- datalen = sha1write_compressed(f, buf, size);
- free(buf);
+ written++;
return hdrlen + datalen;
}
@@ -148,8 +310,6 @@ static void write_pack_file(void)
offset = write_one(f, objects + i, offset);
sha1close(f, pack_file_sha1, 1);
- mb = offset >> 20;
- offset &= 0xfffff;
}
static void write_index_file(void)
@@ -196,18 +356,21 @@ static int add_object_entry(unsigned char *sha1, unsigned int hash)
{
unsigned int idx = nr_objects;
struct object_entry *entry;
-
- if (incremental || local) {
- struct packed_git *p;
-
- for (p = packed_git; p; p = p->next) {
- struct pack_entry e;
-
- if (find_pack_entry_one(sha1, &e, p)) {
- if (incremental)
- return 0;
- if (local && !p->pack_local)
- return 0;
+ struct packed_git *p;
+ unsigned int found_offset;
+ struct packed_git *found_pack;
+
+ found_pack = NULL;
+ for (p = packed_git; p; p = p->next) {
+ struct pack_entry e;
+ if (find_pack_entry_one(sha1, &e, p)) {
+ if (incremental)
+ return 0;
+ if (local && !p->pack_local)
+ return 0;
+ if (!found_pack) {
+ found_offset = e.offset;
+ found_pack = e.p;
}
}
}
@@ -221,30 +384,107 @@ static int add_object_entry(unsigned char *sha1, unsigned int hash)
memset(entry, 0, sizeof(*entry));
memcpy(entry->sha1, sha1, 20);
entry->hash = hash;
+ if (found_pack) {
+ entry->in_pack = found_pack;
+ entry->in_pack_offset = found_offset;
+ }
nr_objects = idx+1;
return 1;
}
+static int locate_object_entry_hash(unsigned char *sha1)
+{
+ int i;
+ unsigned int ui;
+ memcpy(&ui, sha1, sizeof(unsigned int));
+ i = ui % object_ix_hashsz;
+ while (0 < object_ix[i]) {
+ if (!memcmp(sha1, objects[object_ix[i]-1].sha1, 20))
+ return i;
+ if (++i == object_ix_hashsz)
+ i = 0;
+ }
+ return -1 - i;
+}
+
+static struct object_entry *locate_object_entry(unsigned char *sha1)
+{
+ int i = locate_object_entry_hash(sha1);
+ if (0 <= i)
+ return &objects[object_ix[i]-1];
+ return NULL;
+}
+
static void check_object(struct object_entry *entry)
{
char type[20];
- if (!sha1_object_info(entry->sha1, type, &entry->size)) {
- if (!strcmp(type, "commit")) {
- entry->type = OBJ_COMMIT;
- } else if (!strcmp(type, "tree")) {
- entry->type = OBJ_TREE;
- } else if (!strcmp(type, "blob")) {
- entry->type = OBJ_BLOB;
- } else if (!strcmp(type, "tag")) {
- entry->type = OBJ_TAG;
- } else
- die("unable to pack object %s of type %s",
- sha1_to_hex(entry->sha1), type);
+ if (entry->in_pack) {
+ /* Check if it is delta, and the base is also an object
+ * we are going to pack. If so we will reuse the existing
+ * delta.
+ */
+ unsigned char base[20];
+ unsigned long size;
+ struct object_entry *base_entry;
+ if (!check_reuse_pack_delta(entry->in_pack,
+ entry->in_pack_offset,
+ base, &size,
+ &entry->in_pack_type) &&
+ (base_entry = locate_object_entry(base))) {
+ /* We do not know depth at this point, but it
+ * does not matter. Getting delta_chain_length
+ * with packed_object_info_detail() is not so
+ * expensive, so we could do that later if we
+ * wanted to. Calling sha1_object_info to get
+ * the true size (and later an uncompressed
+ * representation) of deeply deltified object
+ * is quite expensive.
+ */
+ entry->depth = 1;
+ /* uncompressed size */
+ entry->size = entry->delta_size = size;
+ entry->delta = base_entry;
+ entry->type = OBJ_DELTA;
+ return;
+ }
+ /* Otherwise we would do the usual */
}
- else
+
+ if (sha1_object_info(entry->sha1, type, &entry->size))
die("unable to get type of object %s",
sha1_to_hex(entry->sha1));
+
+ if (!strcmp(type, "commit")) {
+ entry->type = OBJ_COMMIT;
+ } else if (!strcmp(type, "tree")) {
+ entry->type = OBJ_TREE;
+ } else if (!strcmp(type, "blob")) {
+ entry->type = OBJ_BLOB;
+ } else if (!strcmp(type, "tag")) {
+ entry->type = OBJ_TAG;
+ } else
+ die("unable to pack object %s of type %s",
+ sha1_to_hex(entry->sha1), type);
+}
+
+static void hash_objects(void)
+{
+ int i;
+ struct object_entry *oe;
+
+ object_ix_hashsz = nr_objects * 2;
+ object_ix = xcalloc(sizeof(int), object_ix_hashsz);
+ for (i = 0, oe = objects; i < nr_objects; i++, oe++) {
+ int ix = locate_object_entry_hash(oe->sha1);
+ if (0 <= ix) {
+ error("the same object '%s' added twice",
+ sha1_to_hex(oe->sha1));
+ continue;
+ }
+ ix = -1 - ix;
+ object_ix[ix] = i + 1;
+ }
}
static void get_object_details(void)
@@ -252,6 +492,8 @@ static void get_object_details(void)
int i;
struct object_entry *entry = objects;
+ hash_objects();
+ prepare_pack_ix();
for (i = 0; i < nr_objects; i++)
check_object(entry++);
}
@@ -382,6 +624,13 @@ static void find_deltas(struct object_entry **list, int window, int depth)
eye_candy -= nr_objects / 20;
fputc('.', stderr);
}
+
+ if (entry->delta)
+ /* This happens if we decided to reuse existing
+ * delta from a pack.
+ */
+ continue;
+
free(n->data);
n->entry = entry;
n->data = read_sha1_file(entry->sha1, type, &size);
@@ -411,10 +660,12 @@ static void find_deltas(struct object_entry **list, int window, int depth)
static void prepare_pack(int window, int depth)
{
- get_object_details();
-
if (progress)
fprintf(stderr, "Packing %d objects", nr_objects);
+ get_object_details();
+ if (progress)
+ fprintf(stderr, ".");
+
sorted_by_type = create_sorted_list(type_size_sort);
if (window && depth)
find_deltas(sorted_by_type, window+1, depth);
@@ -599,5 +850,7 @@ int main(int argc, char **argv)
puts(sha1_to_hex(object_list_sha1));
}
}
+ fprintf(stderr, "Total %d, written %d, reused %d\n",
+ nr_objects, written, reused);
return 0;
}
diff --git a/pack.h b/pack.h
index 9dafa2b6d2..694e0c56f0 100644
--- a/pack.h
+++ b/pack.h
@@ -29,5 +29,7 @@ struct pack_header {
};
extern int verify_pack(struct packed_git *, int);
-
+extern int check_reuse_pack_delta(struct packed_git *, unsigned long,
+ unsigned char *, unsigned long *,
+ enum object_type *);
#endif
diff --git a/sha1_file.c b/sha1_file.c
index c08da35d8a..f4b10894c8 100644
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -841,6 +841,25 @@ static unsigned long unpack_object_header(struct packed_git *p, unsigned long of
return offset;
}
+int check_reuse_pack_delta(struct packed_git *p, unsigned long offset,
+ unsigned char *base, unsigned long *sizep,
+ enum object_type *kindp)
+{
+ unsigned long ptr;
+ int status = -1;
+
+ use_packed_git(p);
+ ptr = offset;
+ ptr = unpack_object_header(p, ptr, kindp, sizep);
+ if (*kindp != OBJ_DELTA)
+ goto done;
+ memcpy(base, p->pack_base + ptr, 20);
+ status = 0;
+ done:
+ unuse_packed_git(p);
+ return status;
+}
+
void packed_object_info_detail(struct pack_entry *e,
char *type,
unsigned long *size,
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-11 04:46:22 +0000