Mornington

What is Mornington?

Mornington is a subway simulator.

Put another way, Mornington is a sort of simulation, or zero-player game, in the vein of Blaseball. Instead of simulating games of baseball, Mornington simulates games of Mornington Crescent.

Setup

Have NodeJS and yarn installed on your machine, as well as Postgres.

Clone the mornington repo. cd mornington

# Setup backend prerequisites
pushd api
yarn install

# Create the database
yarn db:drop
yarn db:create
yarn db:sync
yarn db:seed
# Or...
yarn db:all

# Import an SVG map
yarn game:import --file=../assets/map1.svg
yarn game:import --file=../assets/map2.svg

popd

# Setup frontend prerequisites
pushd app
yarn install
popd

# Start the API service
# In another terminal,
cd api
yarn api:start

# Start the clock, which runs the simulation
# In another terminal,
cd api
yarn clock:start
# Or, to just run once:
yarn clock:tick

# Start the frontend app
# In another terminal,
cd app
yarn dev

Structure

flowchart LR
    clock[Clock Process]
    api[API Service]
    db[(PostgreSQL)]
    web[Web Client]
    clock --- db
    api --- db
    web --- api

Clock

The clock runs every ten seconds currently, meaning a tick of the simulation happens every ten seconds.

Every ten seconds, the clock iterates through each game.

For each game:

A transaction is opened
Trains and agents are updated in the database
The game state is precomputed and stored in a "game turn" table

Future enhancements include:

It would be straightforward to enqueue a job per-game per-tick. This would allow each game to be processed roughly in parallel.
All game objects are scoped to a specific game ID, which would make splitting games across databases in some way is a possibility.

API Service

The API service is an Express app which can pull latest game state (precalculated and stored in a "game turn" row in the DB) and serve it to the user.

This endpoint is designed for frequent access.

Future enhancements include:

Use a dedicated caching solution for storing state for a given game
Use websockets to notify a user when a turn has taken place (notification can be sent from the clock after update)

Frontend App

A NextJS app which renders games using React and SVG. Designed to be fast and lightweight.

Quick Codebase Tour

app/
- package.json lists the dependencies as well as the scripts that can be run
- src/page.tsx is the primary page that shows the game board
- src/gameboard.tsx is the component that renders game state
- src/graph.tsx renders the game view using SVG
api/
- package.json lists the dependencies as well as the scripts that can be run
- src/index.ts is the primary script for the API service
- src/clock.ts is the primary script for the Clock

Deployment

Heroku

Once Heroku is setup,

# Deploy backend
git subtree push --prefix api backend main
# Or, to force-push (preferred for CI)
git push backend `git subtree split --prefix api main`:main --force

# Sync and seed the DB
heroku run -a mornington-backend yarn db:sync
heroku run -a mornington-backend yarn db:seed

# Get the logs for the API and clock process
heroku logs --tail -a mornington-backend

# Dump and load the DB
heroku pg:backups:capture -a $api
heroku pg:backups:download -a $api

# Deploy frontend
git subtree push --prefix app frontend main
# Or, to force-push (preferred for CI)
git push frontend `git subtree split --prefix app main`:main --force

Credits

Subway icon from SVG Repo. Generated favicon with RealFaviconGenerator.

rjungemann / mornington