MapFleet

Remarks

The stateful half of doc 27 § Placement, and it is stateful for exactly two reasons: a spawn is debounced against the last one, and a merge has to have been true for a while. Everything else it decides is a function of the shards it is shown.

⚠ One action per observation, and a spawn beats a drain. A fleet that returned both would be asked to grow and shrink in the same breath; and a map that is saturating while one of its shards is nearly empty wants the shard, not the tidiness.

⚠ The clock is a parameter. Every method takes now, so a test can run a flash crowd, a slow bleed and a sawtooth through half an hour of simulated traffic in milliseconds — which is what doc 27 § Testing asks of this.

Fields and properties (3)

• public ShardKey Key

  What this fleet is for.

• public FleetPolicy Policy

  The thresholds in force.

• public int ArrivalsInWindow

  How many arrivals are inside the window, as of the last call.

Methods (4)

• public MapFleet(ShardKey key, FleetPolicy? policy = null)

  Stands one up.

• public void Arrived(DateTimeOffset now, int count = 1)

  Records people arriving, which is what the spawn projection is made of.

• public double ArrivalRate(DateTimeOffset now)

  Arrivals per second, over the span they landed in.

• public FleetAction Observe(DateTimeOffset now, IReadOnlyList<ShardCandidate> shards)

  Decides what to do about the map, given what it currently is.

Used by (3)

• FleetSimulationVixen.Live.Orchestrator.Tests
• MapCoordinatorVixen.Live.Orchestrator
• MapFleetTestsVixen.Live.Orchestrator.Tests