Documentation/hooks: add pre-auto-gc hook

diff --git a/builtin-pack-objects.c b/builtin-pack-objects.c
index f504cff7566159332c89f830a871da0ea05868fe..777f272668c39931b330be555f41399adfbce397 100644 (file)
--- a/builtin-pack-objects.c
+++ b/builtin-pack-objects.c
@@ -454,6 +454,7 @@ static void write_pack_file(void)
        struct pack_header hdr;
        int do_progress = progress >> pack_to_stdout;
        uint32_t nr_remaining = nr_result;
+       time_t last_mtime = 0;
 
        if (do_progress)
                progress_state = start_progress("Writing objects", nr_result);
@@ -504,6 +505,7 @@ static void write_pack_file(void)
 
                if (!pack_to_stdout) {
                        mode_t mode = umask(0);
+                       struct stat st;
                        char *idx_tmp_name, tmpname[PATH_MAX];
 
                        umask(mode);
@@ -511,6 +513,7 @@ static void write_pack_file(void)
 
                        idx_tmp_name = write_idx_file(NULL, written_list,
                                                      nr_written, sha1);
+
                        snprintf(tmpname, sizeof(tmpname), "%s-%s.pack",
                                 base_name, sha1_to_hex(sha1));
                        if (adjust_perm(pack_tmp_name, mode))
@@ -519,6 +522,28 @@ static void write_pack_file(void)
                        if (rename(pack_tmp_name, tmpname))
                                die("unable to rename temporary pack file: %s",
                                    strerror(errno));
+
+                       /*
+                        * Packs are runtime accessed in their mtime
+                        * order since newer packs are more likely to contain
+                        * younger objects.  So if we are creating multiple
+                        * packs then we should modify the mtime of later ones
+                        * to preserve this property.
+                        */
+                       if (stat(tmpname, &st) < 0) {
+                               warning("failed to stat %s: %s",
+                                       tmpname, strerror(errno));
+                       } else if (!last_mtime) {
+                               last_mtime = st.st_mtime;
+                       } else {
+                               struct utimbuf utb;
+                               utb.actime = st.st_atime;
+                               utb.modtime = --last_mtime;
+                               if (utime(tmpname, &utb) < 0)
+                                       warning("failed utime() on %s: %s",
+                                               tmpname, strerror(errno));
+                       }
+
                        snprintf(tmpname, sizeof(tmpname), "%s-%s.idx",
                                 base_name, sha1_to_hex(sha1));
                        if (adjust_perm(idx_tmp_name, mode))
@@ -527,6 +552,7 @@ static void write_pack_file(void)
                        if (rename(idx_tmp_name, tmpname))
                                die("unable to rename temporary index file: %s",
                                    strerror(errno));
+
                        free(idx_tmp_name);
                        free(pack_tmp_name);
                        puts(sha1_to_hex(sha1));