Incremental updates like mlocate.

[freedit-dev]

mlocate implements incremental updates compared to its predecessor slocate. Overall, mlocate determines whether to further index the contents of a directory based on whether the directory’s mtime (modification time) or ctime (change time) has changed.

 1   /* "relative" may now become a symlink to somewhere else.  So we use it only
 2      in safe_chdir (). */
 3   entries_mark = obstack_alloc (&scan_dir_state.data_obstack, 0);
 4   dir.path = path;
 5   time_get_ctime (&dir.time, &st);
 6   time_get_mtime (&mtime, &st);
 7   if (time_compare (&dir.time, &mtime) < 0)
 8     dir.time = mtime;
 9   while (old_dir.path != NULL && (cmp = dir_path_cmp (old_dir.path, path)) < 0)
10     {
11       old_dir_skip ();
12       old_dir_next_header ();
13     }
14   did_chdir = false;
15   have_subdir = false;
16   if (old_dir.path != NULL && cmp == 0
17       && time_compare (&dir.time, &old_dir.time) == 0
18       && (dir.time.sec != 0 || dir.time.nsec != 0))
19     {
20       res = copy_old_dir (&dir);
21       if (res != -1)
22     {
23       have_subdir = res;
24       old_dir_next_header ();
25       goto have_dir;
26     }
27     }
28   if (time_is_current (&dir.time))
29     {
30       /* The directory might be changing right now and we can't be sure the
31      timestamp will be changed again if more changes happen very soon, mark
32      the timestamp as invalid to force rescanning the directory next time
33      updatedb is run. */
34       dir.time.sec = 0;
35       dir.time.nsec = 0;
36     }
37   did_chdir = true;
38   if (safe_chdir (cwd_fd, relative, &st) != 0)
39     goto err_chdir;
40   res = scan_cwd (&dir);
41   if (res == -1)
42     goto err_chdir;
43   have_subdir = res;
44  have_dir:
45   write_directory (&dir);
46   if (have_subdir != false)
47     {
48       if (did_chdir == false)
49     {
50       did_chdir = true;
51       if (safe_chdir (cwd_fd, relative, &st) != 0)
52         goto err_entries;
53     }
54       scan_subdirs (&dir, &st);
55     }