Mercurial > dovecot > core-2.2
changeset 22676:c9549bea9106
director: Don't send USERs in handshake that were already sent between handshake
If the user was refreshed since the handshake was started, it means that
the same user was already sent to the other side (added to the stream
immediately after it was received/handled). There's no need to send it
again.
This fixes a potentally infinite handshake when users are rapidly changing
and the handshake iterator never sees the end of the list. (Each refreshed
user is moved to the end of the list, so handshaking can keep sending the
same user over and over again.)
| author | Timo Sirainen <timo.sirainen@dovecot.fi> |
|---|---|
| date | Sat, 25 Nov 2017 10:01:31 +0200 |
| parents | d689d7d99b4f |
| children | 2fa7cadb2e58 |
| files | src/director/director-connection.c src/director/director.c src/director/director.h src/director/doveadm-connection.c src/director/test-user-directory.c src/director/user-directory.c src/director/user-directory.h |
| diffstat | 7 files changed, 41 insertions(+), 12 deletions(-) [+] |
line wrap: on
line diff
--- a/src/director/director-connection.c Sat Nov 25 10:05:27 2017 +0200 +++ b/src/director/director-connection.c Sat Nov 25 10:01:31 2017 +0200 @@ -2255,7 +2255,16 @@ director_connection_send_hosts(conn); i_assert(conn->user_iter == NULL); - conn->user_iter = director_iterate_users_init(conn->dir); + /* Iterate only through users that aren't refreshed since the + iteration started. The refreshed users will already be sent as + regular USER updates, so they don't need to be sent again. + + We especially don't want to send these users again, because + otherwise in a rapidly changing director we might never end up + sending all the users when they constantly keep being added to the + end of the list. (The iteration lists users in order from older to + newer.) */ + conn->user_iter = director_iterate_users_init(conn->dir, TRUE); if (director_connection_send_users(conn) == 0) o_stream_set_flush_pending(conn->output, TRUE);
--- a/src/director/director.c Sat Nov 25 10:05:27 2017 +0200 +++ b/src/director/director.c Sat Nov 25 10:01:31 2017 +0200 @@ -1520,12 +1520,15 @@ struct director *dir; unsigned int tag_idx; struct user_directory_iter *user_iter; + bool iter_until_current_tail; }; -struct director_user_iter *director_iterate_users_init(struct director *dir) +struct director_user_iter * +director_iterate_users_init(struct director *dir, bool iter_until_current_tail) { struct director_user_iter *iter = i_new(struct director_user_iter, 1); iter->dir = dir; + iter->iter_until_current_tail = iter_until_current_tail; return iter; } @@ -1541,7 +1544,8 @@ if (iter->tag_idx >= array_count(tags)) return NULL; struct mail_tag *const *tagp = array_idx(tags, iter->tag_idx); - iter->user_iter = user_directory_iter_init((*tagp)->users); + iter->user_iter = user_directory_iter_init((*tagp)->users, + iter->iter_until_current_tail); } user = user_directory_iter_next(iter->user_iter); if (user == NULL) {
--- a/src/director/director.h Sat Nov 25 10:05:27 2017 +0200 +++ b/src/director/director.h Sat Nov 25 10:01:31 2017 +0200 @@ -266,7 +266,8 @@ void dir_debug(const char *fmt, ...) ATTR_FORMAT(1, 2); -struct director_user_iter *director_iterate_users_init(struct director *dir); +struct director_user_iter * +director_iterate_users_init(struct director *dir, bool iter_until_current_tail); struct user *director_iterate_users_next(struct director_user_iter *iter); void director_iterate_users_deinit(struct director_user_iter **_iter);
--- a/src/director/doveadm-connection.c Sat Nov 25 10:05:27 2017 +0200 +++ b/src/director/doveadm-connection.c Sat Nov 25 10:01:31 2017 +0200 @@ -522,7 +522,7 @@ director_connection_cork(dir->right); if (cmd->iter == NULL) { - cmd->iter = director_iterate_users_init(dir); + cmd->iter = director_iterate_users_init(dir, FALSE); cmd->users_killed = FALSE; } @@ -715,7 +715,7 @@ ip.family = 0; } - iter = director_iterate_users_init(conn->dir); + iter = director_iterate_users_init(conn->dir, FALSE); while ((user = director_iterate_users_next(iter)) != NULL) { if (ip.family == 0 || net_ip_compare(&ip, &user->host->ip)) T_BEGIN {
--- a/src/director/test-user-directory.c Sat Nov 25 10:05:27 2017 +0200 +++ b/src/director/test-user-directory.c Sat Nov 25 10:01:31 2017 +0200 @@ -19,7 +19,7 @@ struct user *user, *prev = NULL; unsigned int prev_stamp = 0, iter_count = 0; - iter = user_directory_iter_init(dir); + iter = user_directory_iter_init(dir, FALSE); while ((user = user_directory_iter_next(iter)) != NULL) { test_assert(prev_stamp <= user->timestamp); test_assert(user->prev == prev);
--- a/src/director/user-directory.c Sat Nov 25 10:05:27 2017 +0200 +++ b/src/director/user-directory.c Sat Nov 25 10:01:31 2017 +0200 @@ -17,7 +17,7 @@ struct user_directory_iter { struct user_directory *dir; - struct user *pos; + struct user *pos, *stop_after_tail; }; struct user_directory { @@ -46,6 +46,10 @@ array_foreach(&dir->iters, iterp) { if ((*iterp)->pos == user) (*iterp)->pos = user->next; + if ((*iterp)->stop_after_tail == user) { + (*iterp)->stop_after_tail = + user->prev != NULL ? user->prev : user->next; + } } } @@ -291,13 +295,15 @@ } struct user_directory_iter * -user_directory_iter_init(struct user_directory *dir) +user_directory_iter_init(struct user_directory *dir, + bool iter_until_current_tail) { struct user_directory_iter *iter; iter = i_new(struct user_directory_iter, 1); iter->dir = dir; iter->pos = dir->head; + iter->stop_after_tail = iter_until_current_tail ? dir->tail : NULL; array_append(&dir->iters, &iter, 1); user_directory_drop_expired(dir); return iter; @@ -312,6 +318,10 @@ return NULL; iter->pos = user->next; + if (user == iter->stop_after_tail) { + /* this is the last user we want to iterate */ + iter->pos = NULL; + } return user; }
--- a/src/director/user-directory.h Sat Nov 25 10:05:27 2017 +0200 +++ b/src/director/user-directory.h Sat Nov 25 10:01:31 2017 +0200 @@ -62,10 +62,15 @@ struct user *user); /* Iterate through users in the directory. It's safe to modify user directory - while iterators are running. The moved/removed users will just be skipped - over. */ + while iterators are running. The removed users will just be skipped over. + Users that are refreshed (= moved to end of list) may be processed twice. + + Using iter_until_current_tail=TRUE causes the iterator to not iterate + through any users that were added/refreshed since the iteration began. + Note that this may skip some users entirely. */ struct user_directory_iter * -user_directory_iter_init(struct user_directory *dir); +user_directory_iter_init(struct user_directory *dir, + bool iter_until_current_tail); struct user *user_directory_iter_next(struct user_directory_iter *iter); void user_directory_iter_deinit(struct user_directory_iter **iter);