* feat(backend/sink): write big messages directly to file * feat(backend/sink): manually sync all files on partitions rebalanced event (#847) * feat(backend): fix vulnerability in /x/net
* feat(backend): use channel of changed sessions instead of sync.Map * feat(backend): avoid memory alloc for message body in message iterator * feat(backend): removed unnecessary locks in file syncer * feat(backend): sync.Map with prev updates * feat(backend): improved write algorith (added bufio.Writer) * feat(backend): session writer refactoring * feat(backend): removed unnecessary type definition * feat(backend): added write retrier to avoid data losing * feat(backend): refactoring * feat(backend): added session file implementation
