git-fetch-pack: avoid unnecessary zero packing

diff --git a/fetch-pack.c b/fetch-pack.c
index 953c0cf441c282bcfb50ce36299c4da3c90e290f..459736909cb3b16348b5dab893461e41b98f89aa 100644 (file)
--- a/fetch-pack.c
+++ b/fetch-pack.c
@@ -12,6 +12,7 @@ static const char *exec = "git-upload-pack";
 static int find_common(int fd[2], unsigned char *result_sha1,
                       struct ref *refs)
 {
+       int fetching;
        static char line[1000];
        int count = 0, flushes = 0, retval;
        FILE *revs;
@@ -20,16 +21,19 @@ static int find_common(int fd[2], unsigned char *result_sha1,
        if (!revs)
                die("unable to run 'git-rev-list'");
 
-       while (refs) {
+       fetching = 0;
+       for ( ; refs ; refs = refs->next) {
                unsigned char *remote = refs->old_sha1;
-               if (verbose)
-                       fprintf(stderr,
-                               "want %s (%s)\n", sha1_to_hex(remote),
-                               refs->name);
+               unsigned char *local = refs->new_sha1;
+
+               if (!memcmp(remote, local, 20))
+                       continue;
                packet_write(fd[1], "want %s\n", sha1_to_hex(remote));
-               refs = refs->next;
+               fetching++;
        }
        packet_flush(fd[1]);
+       if (!fetching)
+               return 1;
        flushes = 1;
        retval = -1;
        while (fgets(line, sizeof(line), revs) != NULL) {
@@ -74,6 +78,35 @@ static int find_common(int fd[2], unsigned char *result_sha1,
        return retval;
 }
 
+static int everything_local(struct ref *refs)
+{
+       int retval;
+
+       for (retval = 1; refs ; refs = refs->next) {
+               const unsigned char *remote = refs->old_sha1;
+               unsigned char local[20];
+
+               if (read_ref(git_path("%s", refs->name), local) < 0 ||
+                   memcmp(remote, local, 20)) {
+                       retval = 0;
+                       if (!verbose)
+                               continue;
+                       fprintf(stderr,
+                               "want %s (%s)\n", sha1_to_hex(remote),
+                               refs->name);
+                       continue;
+               }
+
+               memcpy(refs->new_sha1, local, 20);
+               if (!verbose)
+                       continue;
+               fprintf(stderr,
+                       "already have %s (%s)\n", sha1_to_hex(remote),
+                       refs->name);
+       }
+       return retval;
+}
+
 static int fetch_pack(int fd[2], int nr_match, char **match)
 {
        struct ref *ref;
@@ -86,6 +119,10 @@ static int fetch_pack(int fd[2], int nr_match, char **match)
                packet_flush(fd[1]);
                die("no matching remote head");
        }
+       if (everything_local(ref)) {
+               packet_flush(fd[1]);
+               goto all_done;
+       }
        if (find_common(fd, sha1, ref) < 0)
                fprintf(stderr, "warning: no common commits\n");
        pid = fork();
@@ -109,6 +146,7 @@ static int fetch_pack(int fd[2], int nr_match, char **match)
                int code = WEXITSTATUS(status);
                if (code)
                        die("git-unpack-objects died with error code %d", code);
+all_done:
                while (ref) {
                        printf("%s %s\n",
                               sha1_to_hex(ref->old_sha1), ref->name);