Merge branch 'jc/pack'

* jc/pack:
Keep last used delta base in the delta window

diff --git a/builtin-pack-objects.c b/builtin-pack-objects.c
index 12509faa777bb2903e98c79a98be151380911b87..e64e3a03a0f0c81c45557fc1181d8af1945ad8d8 100644 (file)
--- a/builtin-pack-objects.c
+++ b/builtin-pack-objects.c
@@ -1460,7 +1460,7 @@ static void find_deltas(struct object_entry **list, int window, int depth)
        do {
                struct object_entry *entry = list[--i];
                struct unpacked *n = array + idx;
-               int j;
+               int j, best_base = -1;
 
                if (!entry->preferred_base)
                        processed++;
@@ -1505,6 +1505,7 @@ static void find_deltas(struct object_entry **list, int window, int depth)
 
                j = window;
                while (--j > 0) {
+                       int ret;
                        uint32_t other_idx = idx + j;
                        struct unpacked *m;
                        if (other_idx >= window)
@@ -1512,8 +1513,11 @@ static void find_deltas(struct object_entry **list, int window, int depth)
                        m = array + other_idx;
                        if (!m->entry)
                                break;
-                       if (try_delta(n, m, max_depth) < 0)
+                       ret = try_delta(n, m, max_depth);
+                       if (ret < 0)
                                break;
+                       else if (ret > 0)
+                               best_base = other_idx;
                }
 
                /* if we made n a delta, and if n is already at max
@@ -1523,6 +1527,23 @@ static void find_deltas(struct object_entry **list, int window, int depth)
                if (entry->delta && depth <= n->depth)
                        continue;
 
+               /*
+                * Move the best delta base up in the window, after the
+                * currently deltified object, to keep it longer.  It will
+                * be the first base object to be attempted next.
+                */
+               if (entry->delta) {
+                       struct unpacked swap = array[best_base];
+                       int dist = (window + idx - best_base) % window;
+                       int dst = best_base;
+                       while (dist--) {
+                               int src = (dst + 1) % window;
+                               array[dst] = array[src];
+                               dst = src;
+                       }
+                       array[dst] = swap;
+               }
+
                next:
                idx++;
                if (count + 1 < window)