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-rw-r--r--Documentation/git-pack-objects.txt21
-rw-r--r--pack-objects.c102
2 files changed, 91 insertions, 32 deletions
diff --git a/Documentation/git-pack-objects.txt b/Documentation/git-pack-objects.txt
index 2d67d3911..4cb2e83fa 100644
--- a/Documentation/git-pack-objects.txt
+++ b/Documentation/git-pack-objects.txt
@@ -8,7 +8,10 @@ git-pack-objects - Create a packed archive of objects.
SYNOPSIS
--------
-'git-pack-objects' [--non-empty] [--local] [--incremental] [--window=N] [--depth=N] {--stdout | base-name} < object-list
+[verse]
+'git-pack-objects' [-q] [--no-reuse-delta] [--non-empty]
+ [--local] [--incremental] [--window=N] [--depth=N]
+ {--stdout | base-name} < object-list
DESCRIPTION
@@ -32,6 +35,10 @@ Placing both in the pack/ subdirectory of $GIT_OBJECT_DIRECTORY (or
any of the directories on $GIT_ALTERNATE_OBJECT_DIRECTORIES)
enables git to read from such an archive.
+In a packed archive, an object is either stored as a compressed
+whole, or as a difference from some other object. The latter is
+often called a delta.
+
OPTIONS
-------
@@ -74,6 +81,18 @@ base-name::
Only create a packed archive if it would contain at
least one object.
+-q::
+ This flag makes the command not to report its progress
+ on the standard error stream.
+
+--no-reuse-delta::
+ When creating a packed archive in a repository that
+ has existing packs, the command reuses existing deltas.
+ This sometimes results in a slightly suboptimal pack.
+ This flag tells the command not to reuse existing deltas
+ but compute them from scratch.
+
+
Author
------
Written by Linus Torvalds <torvalds@osdl.org>
diff --git a/pack-objects.c b/pack-objects.c
index 70fb2afeb..38e1c9921 100644
--- a/pack-objects.c
+++ b/pack-objects.c
@@ -5,7 +5,7 @@
#include "csum-file.h"
#include <sys/time.h>
-static const char pack_usage[] = "git-pack-objects [-q] [--non-empty] [--local] [--incremental] [--window=N] [--depth=N] {--stdout | base-name} < object-list";
+static const char pack_usage[] = "git-pack-objects [-q] [--no-reuse-delta] [--non-empty] [--local] [--incremental] [--window=N] [--depth=N] {--stdout | base-name} < object-list";
struct object_entry {
unsigned char sha1[20];
@@ -14,10 +14,11 @@ struct object_entry {
unsigned int depth; /* delta depth */
unsigned int hash; /* name hint hash */
enum object_type type;
+ unsigned char edge; /* reused delta chain points at this entry. */
+ enum object_type in_pack_type; /* could be 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;
};
@@ -36,6 +37,7 @@ struct object_entry {
static unsigned char object_list_sha1[20];
static int non_empty = 0;
+static int no_reuse_delta = 0;
static int local = 0;
static int incremental = 0;
static struct object_entry **sorted_by_sha, **sorted_by_type;
@@ -75,7 +77,9 @@ static int pack_revindex_hashsz = 0;
* stats
*/
static int written = 0;
+static int written_delta = 0;
static int reused = 0;
+static int reused_delta = 0;
static int pack_revindex_ix(struct packed_git *p)
{
@@ -227,10 +231,23 @@ static unsigned long write_object(struct sha1file *f, struct object_entry *entry
unsigned char header[10];
unsigned hdrlen, datalen;
enum object_type obj_type;
+ int to_reuse = 0;
obj_type = entry->type;
- if (!entry->in_pack ||
- (obj_type != entry->in_pack_type)) {
+ if (! entry->in_pack)
+ to_reuse = 0; /* can't reuse what we don't have */
+ else if (obj_type == OBJ_DELTA)
+ to_reuse = 1; /* check_object() decided it for us */
+ else if (obj_type != entry->in_pack_type)
+ to_reuse = 0; /* pack has delta which is unusable */
+ else if (entry->delta)
+ to_reuse = 0; /* we want to pack afresh */
+ else
+ to_reuse = 1; /* we have it in-pack undeltified,
+ * and we do not need to deltify it.
+ */
+
+ if (! to_reuse) {
buf = read_sha1_file(entry->sha1, type, &size);
if (!buf)
die("unable to read %s", sha1_to_hex(entry->sha1));
@@ -266,8 +283,12 @@ static unsigned long write_object(struct sha1file *f, struct object_entry *entry
sha1write(f, buf, datalen);
unuse_packed_git(p);
hdrlen = 0; /* not really */
+ if (obj_type == OBJ_DELTA)
+ reused_delta++;
reused++;
}
+ if (obj_type == OBJ_DELTA)
+ written_delta++;
written++;
return hdrlen + datalen;
}
@@ -294,7 +315,6 @@ static void write_pack_file(void)
int i;
struct sha1file *f;
unsigned long offset;
- unsigned long mb;
struct pack_header hdr;
if (!base_name)
@@ -357,10 +377,9 @@ static int add_object_entry(unsigned char *sha1, unsigned int hash)
unsigned int idx = nr_objects;
struct object_entry *entry;
struct packed_git *p;
- unsigned int found_offset;
- struct packed_git *found_pack;
+ unsigned int found_offset = 0;
+ struct packed_git *found_pack = NULL;
- found_pack = NULL;
for (p = packed_git; p; p = p->next) {
struct pack_entry e;
if (find_pack_entry_one(sha1, &e, p)) {
@@ -420,32 +439,39 @@ static void check_object(struct object_entry *entry)
char type[20];
if (entry->in_pack) {
+ unsigned char base[20];
+ unsigned long size;
+ struct object_entry *base_entry;
+
+ /* We want in_pack_type even if we do not reuse delta.
+ * There is no point not reusing non-delta representations.
+ */
+ check_reuse_pack_delta(entry->in_pack,
+ entry->in_pack_offset,
+ base, &size,
+ &entry->in_pack_type);
+
/* 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) &&
+ if (!no_reuse_delta &&
+ entry->in_pack_type == OBJ_DELTA &&
(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.
+
+ /* Depth value does not matter - find_deltas()
+ * will never consider reused delta as the
+ * base object to deltify other objects
+ * against, in order to avoid circular deltas.
*/
- entry->depth = 1;
- /* uncompressed size */
+
+ /* uncompressed size of the delta data */
entry->size = entry->delta_size = size;
entry->delta = base_entry;
entry->type = OBJ_DELTA;
+
+ base_entry->edge = 1;
+
return;
}
/* Otherwise we would do the usual */
@@ -568,6 +594,13 @@ static int try_delta(struct unpacked *cur, struct unpacked *old, unsigned max_de
if (cur_entry->type != old_entry->type)
return -1;
+ /* If the current object is at edge, take the depth the objects
+ * that depend on the current object into account -- otherwise
+ * they would become too deep.
+ */
+ if (cur_entry->edge)
+ max_depth /= 4;
+
size = cur_entry->size;
if (size < 50)
return -1;
@@ -627,7 +660,7 @@ static void find_deltas(struct object_entry **list, int window, int depth)
if (entry->delta)
/* This happens if we decided to reuse existing
- * delta from a pack.
+ * delta from a pack. "!no_reuse_delta &&" is implied.
*/
continue;
@@ -636,6 +669,7 @@ static void find_deltas(struct object_entry **list, int window, int depth)
n->data = read_sha1_file(entry->sha1, type, &size);
if (size != entry->size)
die("object %s inconsistent object length (%lu vs %lu)", sha1_to_hex(entry->sha1), size, entry->size);
+
j = window;
while (--j > 0) {
unsigned int other_idx = idx + j;
@@ -664,7 +698,7 @@ static void prepare_pack(int window, int depth)
fprintf(stderr, "Packing %d objects", nr_objects);
get_object_details();
if (progress)
- fprintf(stderr, ".");
+ fputc('.', stderr);
sorted_by_type = create_sorted_list(type_size_sort);
if (window && depth)
@@ -694,8 +728,9 @@ static int reuse_cached_pack(unsigned char *sha1, int pack_to_stdout)
}
}
- fprintf(stderr, "Reusing %d objects pack %s\n", nr_objects,
- sha1_to_hex(sha1));
+ if (progress)
+ fprintf(stderr, "Reusing %d objects pack %s\n", nr_objects,
+ sha1_to_hex(sha1));
if (pack_to_stdout) {
if (copy_fd(ifd, 1))
@@ -775,6 +810,10 @@ int main(int argc, char **argv)
progress = 0;
continue;
}
+ if (!strcmp("--no-reuse-delta", arg)) {
+ no_reuse_delta = 1;
+ continue;
+ }
if (!strcmp("--stdout", arg)) {
pack_to_stdout = 1;
continue;
@@ -850,7 +889,8 @@ 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);
+ if (progress)
+ fprintf(stderr, "Total %d, written %d (delta %d), reused %d (delta %d)\n",
+ nr_objects, written, written_delta, reused, reused_delta);
return 0;
}