Add "--depth=N" parameter to git-pack-objects to limit maximum delta depth

It too defaults to 10. A nice round random number.

diff --git a/pack-objects.c b/pack-objects.c
index 6c24f64..9d87a64 100644 (file)
--- a/pack-objects.c
+++ b/pack-objects.c
@@ -2,7 +2,7 @@
 #include "object.h"
 #include "delta.h"
 
-static const char pack_usage[] = "git-pack-objects [--window=N] base-name < object-list";
+static const char pack_usage[] = "git-pack-objects [--window=N] [--depth=N] base-name < object-list";
 
 enum object_type {
        OBJ_NONE,
@@ -286,7 +286,7 @@ struct unpacked {
  * going to be even smaller or of a different type. So return -1
  * once we determine that there's no point even trying.
  */
-static int try_delta(struct unpacked *cur, struct unpacked *old)
+static int try_delta(struct unpacked *cur, struct unpacked *old, unsigned max_depth)
 {
        struct object_entry *cur_entry = cur->entry;
        struct object_entry *old_entry = old->entry;
@@ -305,6 +305,8 @@ static int try_delta(struct unpacked *cur, struct unpacked *old)
        oldsize = old_entry->size;
        if (size - oldsize > oldsize / 4)
                return -1;
+       if (old_entry->depth >= max_depth)
+               return 0;
 
        /*
         * NOTE!
@@ -321,11 +323,12 @@ static int try_delta(struct unpacked *cur, struct unpacked *old)
                return 0;
        cur_entry->delta = old_entry;
        cur_entry->delta_size = delta_size;
+       cur_entry->depth = old_entry->depth + 1;
        free(delta_buf);
        return 0;
 }
 
-static void find_deltas(struct object_entry **list, int window)
+static void find_deltas(struct object_entry **list, int window, int depth)
 {
        unsigned int i;
        unsigned int array_size = window * sizeof(struct unpacked);
@@ -354,7 +357,7 @@ static void find_deltas(struct object_entry **list, int window)
                        m = array + other_idx;
                        if (!m->entry)
                                break;
-                       if (try_delta(n, m) < 0)
+                       if (try_delta(n, m, depth) < 0)
                                break;
                }
        }
@@ -363,7 +366,7 @@ static void find_deltas(struct object_entry **list, int window)
 int main(int argc, char **argv)
 {
        char line[128];
-       int window = 10;
+       int window = 10, depth = 10;
        int i;
 
        for (i = 1; i < argc; i++) {
@@ -377,6 +380,13 @@ int main(int argc, char **argv)
                                        usage(pack_usage);
                                continue;
                        }
+                       if (!strncmp("--depth=", arg, 8)) {
+                               char *end;
+                               depth = strtoul(arg+8, &end, 0);
+                               if (!arg[8] || *end)
+                                       usage(pack_usage);
+                               continue;
+                       }
                        usage(pack_usage);
                }
                if (base_name)
@@ -399,8 +409,8 @@ int main(int argc, char **argv)
 
        sorted_by_sha = create_sorted_list(sha1_sort);
        sorted_by_type = create_sorted_list(type_size_sort);
-       if (window)
-               find_deltas(sorted_by_type, window+1);
+       if (window && depth)
+               find_deltas(sorted_by_type, window+1, depth);
 
        write_pack_file();
        write_index_file();