~emersion/soju

soju/doc/architecture.md -rw-r--r-- 1.4 KiB
62f12074Simon Ser Forward ISUPPORT NETWORK token 15 hours ago

#soju architecture

soju manages two types of connections:

  • Upstream connections: soju maintains persistent connections to user-configured IRC servers
  • Downstream connections: soju accepts connections from IRC clients

On startup, soju will iterate over the list of networks stored in the database and try to open an upstream connection for each network.

#Ring buffer

In order to correctly send history to each downstream client, soju maintains for each upstream channel a single-producer multiple-consumer ring buffer. The network's upstream connection produces messages and multiple downstream connections consume these messages. Each downstream client may have a different cursor in the history: for instance a client may be 10 messages late while another has consumed all pending messages.

#Goroutines

Each type of connection has two dedicated goroutines: the first one reads incoming messages, the second one writes outgoing messages.

Each user has a dedicated goroutine responsible for dispatching all messages. It communicates via channels with the per-connection reader and writer goroutines. This allows to keep the dispatching logic simple (by avoiding any race condition or inconsistent state) and to rate-limit each user.

The user dispatcher goroutine receives from the user.events channel. Upstream and downstream message handlers are called from this goroutine, thus they can safely access both upstream and downstream state.