odyssey/INTERNALS.md

Odissey architecture and internals

Odissey heavily depends on two libraries, which were originally created during its development: Machinarium and Shapito.

Machinarium

Machinarium extensively used for organization of multi-thread processing, cooperative multi-tasking and networking IO. All Odissey threads are run in context of machinarium machines - pthreads with coroutine schedulers placed on top of epoll(2) event loop.

Odissey does not directly use or create multi-tasking primitives such as OS threads and mutexes. All synchronization is done using message passing and transparently handled by machinarium.

Repository: github/machinarium

Shapito

Shapito provides resizable buffers (streams) and methods for constructing, reading and validating PostgreSQL protocol requests. By design, all PostgreSQL specific details should be provided by Shapito library.

Repository: github/shapito.

Core components

                      main()
                   ┌──────────┐
                   │ instance │
    thread         └──────────┘
  ┌────────┐                       ┌────────────┐
  │ pooler │                       │ relay_pool │
  └────────┘                       └────────────┘
      ┌─────────┐           ┌────────┐         ┌────────┐
      │ servers │           │ relay0 │   ...   │ relayN │
      └─────────┘           └────────┘         └────────┘
      ┌────────┐              thread             thread
      │ router │
      └────────┘
      ┌──────────┐
      │ periodic │
      └──────────┘
      ┌─────────┐
      │ console │
      └─────────┘

Instance Pooler Servers Router Periodic Console and signal handling Relay pool