diff options
| -rw-r--r-- | notmuch-new.c | 29 |
1 files changed, 29 insertions, 0 deletions
diff --git a/notmuch-new.c b/notmuch-new.c index faa33f1f..ba05cb41 100644 --- a/notmuch-new.c +++ b/notmuch-new.c @@ -323,6 +323,35 @@ add_files (notmuch_database_t *notmuch, } db_mtime = directory ? notmuch_directory_get_mtime (directory) : 0; + /* If the directory is unchanged from our last scan and has no + * sub-directories, then return without scanning it at all. In + * some situations, skipping the scan can substantially reduce the + * cost of notmuch new, especially since the huge numbers of files + * in Maildirs make scans expensive, but all files live in leaf + * directories. + * + * To check for sub-directories, we borrow a trick from find, + * kpathsea, and many other UNIX tools: since a directory's link + * count is the number of sub-directories (specifically, their + * '..' entries) plus 2 (the link from the parent and the link for + * '.'). This check is safe even on weird file systems, since + * file systems that can't compute this will return 0 or 1. This + * is safe even on *really* weird file systems like HFS+ that + * mistakenly return the total number of directory entries, since + * that only inflates the count beyond 2. + */ + if (directory && fs_mtime == db_mtime && st.st_nlink == 2) { + /* There's one catch: pass 1 below considers symlinks to + * directories to be directories, but these don't increase the + * file system link count. So, only bail early if the + * database agrees that there are no sub-directories. */ + db_subdirs = notmuch_directory_get_child_directories (directory); + if (!notmuch_filenames_valid (db_subdirs)) + goto DONE; + notmuch_filenames_destroy (db_subdirs); + db_subdirs = NULL; + } + /* If the database knows about this directory, then we sort based * on strcmp to match the database sorting. Otherwise, we can do * inode-based sorting for faster filesystem operation. */ |