PhiaUi.Application (phia_ui v0.1.5)

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OTP Application entry-point for PhiaUi.

Supervision Tree

PhiaUi runs a minimal supervision tree with a :one_for_one strategy — meaning each worker is restarted independently if it crashes, without affecting siblings.

PhiaUi.Supervisor  (strategy: :one_for_one)
└── PhiaUi.ClassMerger.Cache  (GenServer + ETS table owner)

Why a Supervision Tree for a UI Library?

PhiaUI ships ClassMerger.Cache, an ETS-backed memoisation table for resolved Tailwind class strings. ETS tables in Erlang/OTP are owned by the process that created them: if the owning process exits, the table is garbage-collected. To keep the table alive for the lifetime of the application, it must be owned by a supervised, long-running process.

ClassMerger.Cache is that process. It is a GenServer whose sole initialisation side-effect is creating the ETS table. The GenServer itself holds no meaningful state — the ETS table is the state. All reads and the majority of writes go directly to ETS without passing through the GenServer message queue, ensuring lock-free concurrent access from every LiveView process in the application.

Why ETS?

cn/1 is called on every component render. In a busy LiveView application a single page diff may trigger hundreds of cn/1 calls. Without caching, each call would re-tokenise strings, walk the prefix-rule table, and rebuild the output string. ETS provides:

  • O(1) key lookup regardless of table size.
  • read_concurrency: true — read operations use a lock-free path optimised for tables that are read far more than they are written.
  • Process isolation — no single bottleneck process; every caller reads directly from the shared table.
  • Zero serialisation — because the table is :public, writers also bypass the GenServer queue (:ets.insert/2 is a direct NIF call).

Extending the Supervision Tree

If you eject PhiaUI components into your own application and add processes (e.g. a theme registry), you can add them as siblings here by modifying the ejected Application module rather than the upstream package.