From 8c39e8d6fbc1202605494d481b27be6bcccaf500 Mon Sep 17 00:00:00 2001 From: Austin Clements Date: Wed, 29 Jun 2011 03:10:54 -0400 Subject: [PATCH] new: Don't update DB mtime if FS mtime equals wall-clock time. This fixes a race where multiple message deliveries in the same second with an intervening notmuch new could result in messages being ignored by notmuch (at least, until a later delivery forced a rescan). Because mtimes only have second granularity, later deliveries in the same second won't change the directory mtime, and hence won't trigger notmuch new to rescan the directory. This situation can only occur when notmuch new is being run at the same second as the directory's modification time, so simply don't update the saved mtime in this case. This very race happens all over the test suite, and is currently compensated for with increment_mtime (and, occasionally, luck). With this change, increment_mtime becomes unnecessary. --- notmuch-new.c | 20 +++++++++++++++++++- 1 file changed, 19 insertions(+), 1 deletion(-) diff --git a/notmuch-new.c b/notmuch-new.c index 0fa2a3cb..c1805916 100644 --- a/notmuch-new.c +++ b/notmuch-new.c @@ -213,6 +213,7 @@ _entries_resemble_maildir (struct dirent **entries, int count) * information is lost from the database). * * o Tell the database to update its time of 'path' to 'fs_mtime' + * if fs_mtime isn't the current wall-clock time. */ static notmuch_status_t add_files_recursive (notmuch_database_t *notmuch, @@ -230,6 +231,7 @@ add_files_recursive (notmuch_database_t *notmuch, notmuch_directory_t *directory; notmuch_filenames_t *db_files = NULL; notmuch_filenames_t *db_subdirs = NULL; + time_t stat_time; struct stat st; notmuch_bool_t is_maildir, new_directory; const char **tag; @@ -239,6 +241,7 @@ add_files_recursive (notmuch_database_t *notmuch, path, strerror (errno)); return NOTMUCH_STATUS_FILE_ERROR; } + stat_time = time (NULL); /* This is not an error since we may have recursed based on a * symlink to a regular file, not a directory, and we don't know @@ -509,7 +512,22 @@ add_files_recursive (notmuch_database_t *notmuch, notmuch_filenames_move_to_next (db_subdirs); } - if (! interrupted) { + /* If the directory's mtime is the same as the wall-clock time + * when we stat'ed the directory, we skip updating the mtime in + * the database because a message could be delivered later in this + * same second. This may lead to unnecessary re-scans, but it + * avoids overlooking messages. + * + * XXX Bug workaround: If this is a new directory, we *must* + * update the mtime; otherwise the next run will see the 0 mtime + * and think this is still a new directory containing no files or + * subdirs (which is unsound in general). If fs_mtime == + * stat_time, we set the database mtime to a bogus (but non-zero!) + * value to force a rescan. + */ + if (new_directory && fs_mtime == stat_time) + fs_mtime = 1; + if (! interrupted && fs_mtime != stat_time) { status = notmuch_directory_set_mtime (directory, fs_mtime); if (status && ret == NOTMUCH_STATUS_SUCCESS) ret = status;