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.)

director: Avoid USER loops when ring latency is over 1 second Do this by adding a timestamp parameter to USER events. This way if it takes over 1 second for the USER event to traverse the ring, it won't get into an infinite loop getting the user updated over and over again.

director: Code cleanup - typedef user_free_hook This is done because user_free_hook needs to be also used in mail_host. If it changes, this reduces the places that need touching.

director: Code cleanup - moved username_hash generation to director.h It's not really user_directory specific. This is especially important in the following patches that add per-tag user_directories. It's also not always known which tag the username_hash refers to, so there can't be different tag-specific username_hash generators.

lib: API change - var_expand*() now returns error string. This allows callers to fail properly if the format string is invalid.

director: Moved all user killing state to struct director_kill_context This should make it a bit easier to understand the life time of user killing. It also simplifies code by removing struct director_user_kill_finish_ctx. Finally, this already reduces memory usage with 32bit systems, and would make it possible to reduce also on 64bit systems if timestamp is shrank to 31 bits and weak bit moved after it. I'm not sure if that would be better for performance though. In any case it would provide free space for 4 extra bytes if that were needed in future.

director: Code cleanup - added USER_IS_BEING_KILLED() macro

director: Code cleanup - move enum user_kill_state to director.h This will be needed by following commits

director: Execute director_flush_socket only from one director. Having each director do it would be redundant since they're all supposed to be performing the same flush task to the same backend.

director: Prevent race conditions by adding USER_KILL_STATE_FLUSHING In theory it's possible that a user is freed during a flush and added back before flush is finished, possibly even being moved again. This check makes sure that we don't finish such move unless we're actually at the correct flushing state. (If there's another flush also running for the user it'll be ignored.) This is also useful for logging purposes.

director: HOST-RESET-USERS moves users more slowly now. By default only 100 users can be moved in parallel. This can be overridden with HOST-RESET-USERS parameter. This delaying is especially useful when director_flush_socket is used to avoid huge floods to the script service. Even without the socket it's still good for avoiding unnecessary load spikes when all users are kicked at once and they reconnect back at the same time.

director: Log user's kill_state with a human-readable string.

global: unsigned int:1 -> bool:1 perl -i -pe 's/unsigned int ([^,:;]+):1;/bool $1:1;/' **/*.[ch]

director: Moving a user to another host sometimes caused the move to fail. It could have given "User hash .. is being redirected to two hosts" error and afterwards moved the user back to its original host.

director: Include useful statistics in process title.

director: Update existing users' timestamps during handshake.

director: Removed special (time_t)-1 code, it's not actually needed. Also this fixes a user refreshing issue.

director: Optimized adding users to linked list during handshake.

director: Avoid user getting redirected to different servers near its expiration. Fixes a problem when user is logging in at the same time on director1 which thinks the user is expired, and on director2 which thinks the user expires only in 1 second.

Added director_username_hash setting to specify what part of the username is hashed. The default is "%u" meaning the full username. Another potentially useful value is "%d" for hashing only the domain (i.e. redirect users from the same domain always to same server so they can safely access each others' shared mailboxes).

director: Added support for moving user to another server with "doveadm director move".

Added initial implementation of a director process (for NFS users). There are still some unimplemented features and bugs. Also changing mail server list doesn't yet make sure that other directors won't assign the same user to a different server at the same time. --HG-- branch : HEAD