Because there is no delta object cache for tree objects yet, walking
tree entries may result in a lot of recursion.
Let's add --min-tree-copy=N where N is the minimum number of copied
entries in a single copy sequence allowed for encoding tree deltas.
The default is 1. Specifying 0 disables tree deltas entirely.
This allows for experiments with the delta width and see the influence
on pack size vs runtime access cost.
Signed-off-by: Nicolas Pitre <nico@xxxxxxxxxxx>
---
packv4-create.c | 27 ++++++++++++++++++++-------
1 file changed, 20 insertions(+), 7 deletions(-)
diff --git a/packv4-create.c b/packv4-create.c
index 9d6ffc0..34dcebf 100644
--- a/packv4-create.c
+++ b/packv4-create.c
@@ -19,6 +19,7 @@
static int pack_compression_seen;
static int pack_compression_level = Z_DEFAULT_COMPRESSION;
+static int min_tree_copy = 1;
struct data_entry {
unsigned offset;
@@ -441,7 +442,7 @@ void *pv4_encode_tree(void *_buffer, unsigned long *sizep,
if (!size)
return NULL;
- if (!delta_size)
+ if (!delta_size || !min_tree_copy)
delta = NULL;
/*
@@ -530,7 +531,6 @@ void *pv4_encode_tree(void *_buffer, unsigned long *sizep,
cp += encode_varint(copy_count, cp);
if (first_delta)
cp += encode_sha1ref(delta_sha1, cp);
- copy_count = 0;
/*
* Now let's make sure this is going to take less
@@ -538,12 +538,14 @@ void *pv4_encode_tree(void *_buffer, unsigned long *sizep,
* created in parallel. If so we dump the copy
* sequence over those entries in the output buffer.
*/
- if (cp - copy_buf < out - &buffer[copy_pos]) {
+ if (copy_count >= min_tree_copy &&
+ cp - copy_buf < out - &buffer[copy_pos]) {
out = buffer + copy_pos;
memcpy(out, copy_buf, cp - copy_buf);
out += cp - copy_buf;
first_delta = 0;
}
+ copy_count = 0;
}
if (end - out < 48) {
@@ -574,7 +576,8 @@ void *pv4_encode_tree(void *_buffer, unsigned long *sizep,
cp += encode_varint(copy_count, cp);
if (first_delta)
cp += encode_sha1ref(delta_sha1, cp);
- if (cp - copy_buf < out - &buffer[copy_pos]) {
+ if (copy_count >= min_tree_copy &&
+ cp - copy_buf < out - &buffer[copy_pos]) {
out = buffer + copy_pos;
memcpy(out, copy_buf, cp - copy_buf);
out += cp - copy_buf;
@@ -1078,14 +1081,24 @@ static int git_pack_config(const char *k, const char *v, void *cb)
int main(int argc, char *argv[])
{
- if (argc != 3) {
- fprintf(stderr, "Usage: %s <src_packfile> <dst_packfile>\n", argv[0]);
+ char *src_pack, *dst_pack;
+
+ if (argc == 3) {
+ src_pack = argv[1];
+ dst_pack = argv[2];
+ } else if (argc == 4 && !prefixcmp(argv[1], "--min-tree-copy=")) {
+ min_tree_copy = atoi(argv[1] + strlen("--min-tree-copy="));
+ src_pack = argv[2];
+ dst_pack = argv[3];
+ } else {
+ fprintf(stderr, "Usage: %s [--min-tree-copy=<n>] <src_packfile> <dst_packfile>\n", argv[0]);
exit(1);
}
+
git_config(git_pack_config, NULL);
if (!pack_compression_seen && core_compression_seen)
pack_compression_level = core_compression_level;
- process_one_pack(argv[1], argv[2]);
+ process_one_pack(src_pack, dst_pack);
if (0)
dict_dump();
return 0;
--
1.8.4.38.g317e65b
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