Merge branch 'jk/fetch-pack-remove-dups-optim'

The way "fetch-pack" that is given multiple references to fetch tried to
remove duplicates was very inefficient.

By Jeff King
* jk/fetch-pack-remove-dups-optim:
fetch-pack: sort incoming heads list earlier
fetch-pack: avoid quadratic loop in filter_refs
fetch-pack: sort the list of incoming refs
add sorting infrastructure for list refs
fetch-pack: avoid quadratic behavior in remove_duplicates
fetch-pack: sort incoming heads

diff --git a/builtin/fetch-pack.c b/builtin/fetch-pack.c
index 7ad9e54a75892390d6ec670df9b5af2e1c70bf6f..149db88726b8b5f924e6d136828008ec952bc88e 100644 (file)
--- a/builtin/fetch-pack.c
+++ b/builtin/fetch-pack.c
@@ -528,6 +528,7 @@ static void filter_refs(struct ref **refs, int nr_match, char **match)
        struct ref **newtail = &newlist;
        struct ref *ref, *next;
        struct ref *fastarray[32];
+       int match_pos;
 
        if (nr_match && !args.fetch_all) {
                if (ARRAY_SIZE(fastarray) < nr_match)
@@ -540,6 +541,7 @@ static void filter_refs(struct ref **refs, int nr_match, char **match)
        else
                return_refs = NULL;
 
+       match_pos = 0;
        for (ref = *refs; ref; ref = next) {
                next = ref->next;
                if (!memcmp(ref->name, "refs/", 5) &&
@@ -553,15 +555,20 @@ static void filter_refs(struct ref **refs, int nr_match, char **match)
                        continue;
                }
                else {
-                       int i;
-                       for (i = 0; i < nr_match; i++) {
-                               if (!strcmp(ref->name, match[i])) {
-                                       match[i][0] = '\0';
-                                       return_refs[i] = ref;
+                       int cmp = -1;
+                       while (match_pos < nr_match) {
+                               cmp = strcmp(ref->name, match[match_pos]);
+                               if (cmp < 0) /* definitely do not have it */
+                                       break;
+                               else if (cmp == 0) { /* definitely have it */
+                                       match[match_pos][0] = '\0';
+                                       return_refs[match_pos] = ref;
                                        break;
                                }
+                               else /* might have it; keep looking */
+                                       match_pos++;
                        }
-                       if (i < nr_match)
+                       if (!cmp)
                                continue; /* we will link it later */
                }
                free(ref);
@@ -777,6 +784,8 @@ static struct ref *do_fetch_pack(int fd[2],
        struct ref *ref = copy_ref_list(orig_ref);
        unsigned char sha1[20];
 
+       sort_ref_list(&ref, ref_compare_name);
+
        if (is_repository_shallow() && !server_supports("shallow"))
                die("Server does not support shallow clients");
        if (server_supports("multi_ack_detailed")) {
@@ -834,21 +843,12 @@ static int remove_duplicates(int nr_heads, char **heads)
 {
        int src, dst;
 
-       for (src = dst = 0; src < nr_heads; src++) {
-               /* If heads[src] is different from any of
-                * heads[0..dst], push it in.
-                */
-               int i;
-               for (i = 0; i < dst; i++) {
-                       if (!strcmp(heads[i], heads[src]))
-                               break;
-               }
-               if (i < dst)
-                       continue;
-               if (src != dst)
-                       heads[dst] = heads[src];
-               dst++;
-       }
+       if (!nr_heads)
+               return 0;
+
+       for (src = dst = 1; src < nr_heads; src++)
+               if (strcmp(heads[src], heads[dst-1]))
+                       heads[dst++] = heads[src];
        return dst;
 }
 
@@ -1054,6 +1054,11 @@ int cmd_fetch_pack(int argc, const char **argv, const char *prefix)
        return ret;
 }
 
+static int compare_heads(const void *a, const void *b)
+{
+       return strcmp(*(const char **)a, *(const char **)b);
+}
+
 struct ref *fetch_pack(struct fetch_pack_args *my_args,
                       int fd[], struct child_process *conn,
                       const struct ref *ref,
@@ -1073,8 +1078,11 @@ struct ref *fetch_pack(struct fetch_pack_args *my_args,
                        st.st_mtime = 0;
        }
 
-       if (heads && nr_heads)
+       if (heads && nr_heads) {
+               qsort(heads, nr_heads, sizeof(*heads), compare_heads);
                nr_heads = remove_duplicates(nr_heads, heads);
+       }
+
        if (!ref) {
                packet_flush(fd[1]);
                die("no matching remote head");

diff --git a/remote.c b/remote.c
index b296d174043b5e5a11aceb9940ba6ba035e77678..6833538829e1d3e5fe4a525a1b44cbebd9f96efb 100644 (file)
--- a/remote.c
+++ b/remote.c
@@ -7,6 +7,7 @@
 #include "dir.h"
 #include "tag.h"
 #include "string-list.h"
+#include "mergesort.h"
 
 enum map_direction { FROM_SRC, FROM_DST };
 
@@ -918,6 +919,27 @@ void free_refs(struct ref *ref)
        }
 }
 
+int ref_compare_name(const void *va, const void *vb)
+{
+       const struct ref *a = va, *b = vb;
+       return strcmp(a->name, b->name);
+}
+
+static void *ref_list_get_next(const void *a)
+{
+       return ((const struct ref *)a)->next;
+}
+
+static void ref_list_set_next(void *a, void *next)
+{
+       ((struct ref *)a)->next = next;
+}
+
+void sort_ref_list(struct ref **l, int (*cmp)(const void *, const void *))
+{
+       *l = llist_mergesort(*l, ref_list_get_next, ref_list_set_next, cmp);
+}
+
 static int count_refspec_match(const char *pattern,
                               struct ref *refs,
                               struct ref **matched_ref)

diff --git a/remote.h b/remote.h
index 9ad8eb6cc68b0842d8dc2aef9a65c25524739d97..251d8fd9654f23e7a131765742803492fb0d9041 100644 (file)
--- a/remote.h
+++ b/remote.h
@@ -72,6 +72,8 @@ extern const struct refspec *tag_refspec;
 struct ref *alloc_ref(const char *name);
 struct ref *copy_ref(const struct ref *ref);
 struct ref *copy_ref_list(const struct ref *ref);
+void sort_ref_list(struct ref **, int (*cmp)(const void *, const void *));
+int ref_compare_name(const void *, const void *);
 
 int check_ref_type(const struct ref *ref, int flags);