Module event_log

Client Event Log

The goal here is to maintain a single, ordered, append only log of all important client-side events: low or high level, and move as much of coordination between different parts of the system in a natural and decomposed way.

Any event log “follower” can just keep going through all events and react to ones it is interested in (and understands), potentially emitting events of its own, and atomically updating persisted event log position (“cursor”) of events that were already processed.

Structs

• EventKind
• EventLogEntry
• EventLogId
  Ordered, contiguous ID space, which is easy for event log followers to track.
• EventLogIdPrefix
• EventLogIdPrefixAll
• UnordedEventLogId
  A self-allocated ID that is mostly ordered
• UnorderedEventLogIdPrefixAll

Statics

• UNORDEREDED_EVENT_LOG_ID_COUNTER 🔒
  An counter that resets on every restart, that guarantees that UnordedEventLogIds don’t conflict with each other.

Traits

• DBTransactionEventLogExt
• Event

Functions

• handle_events
• run_event_log_ordering_task 🔒
  The code that handles new unordered events and rewriters them fully ordered into the final event log.