implement alternative match-making approach with Lua scripts in Redis

main-server/config/initializers/matchmaking.rb

@@ -0,0 +1,25 @@
+# Matchmaking configuration. All values can be overridden via environment variables.
+mm = Rails.application.config.x.matchmaking = ActiveSupport::OrderedOptions.new
+
+mm.game_server_url  = ENV.fetch("GAME_SERVER_URL", "ws://localhost:8080")
+mm.default_rating   = ENV.fetch("MATCHMAKING_DEFAULT_RATING", 1000).to_i
+
+# How long a found match (and its game token) stays valid, in seconds.
+mm.match_ttl        = ENV.fetch("MATCHMAKING_MATCH_TTL", 120).to_i
+mm.token_ttl        = ENV.fetch("MATCHMAKING_TOKEN_TTL", 120).to_i
+
+# How long a player waits in the queue before a timeout, in seconds.
+mm.queue_ttl        = ENV.fetch("MATCHMAKING_QUEUE_TTL", 60).to_i
+
+# How long a found (but not yet finalized) pair is kept in the "pending"
+# state before the players are put back into the queue, in seconds.
+mm.pending_ttl      = ENV.fetch("MATCHMAKING_PENDING_TTL", 15).to_i
+
+# Rating tolerance: players within `base_range` are matched immediately;
+# the tolerance grows by `range_per_second` of waiting up to `max_range`.
+mm.base_range       = ENV.fetch("MATCHMAKING_BASE_RANGE", 100).to_i
+mm.range_per_second = ENV.fetch("MATCHMAKING_RANGE_PER_SECOND", 50).to_i
+mm.max_range        = ENV.fetch("MATCHMAKING_MAX_RANGE", 1000).to_i
+
+# How often the background sweep job re-checks the queue, in seconds.
+mm.sweep_interval   = ENV.fetch("MATCHMAKING_SWEEP_INTERVAL", 2).to_i

main-server/config/initializers/redis.rb

@@ -2,6 +2,10 @@
 # Development/test: localhost:6379 (default)
 # Production: set REDIS_URL env variable, e.g. redis://redis.example.com:6379/0
 
+# Use an isolated Redis logical database in tests to avoid clobbering dev data.
+url = ENV.fetch("REDIS_URL", "redis://localhost:6380/0")
+url = url.sub(%r{/\d+$}, "/15") if Rails.env.test?
+
 RedisConnection = ConnectionPool.new(size: 5, timeout: 5) do
-  Redis.new(url: ENV.fetch("REDIS_URL", "redis://localhost:6380/0"))
+  Redis.new(url: url)
 end