asobi_discovery (asobi v0.75.1)

Shared enumeration for the discovery surfaces.

Worlds and matches both register as {ServerMod, Id} in the nova_scope pg scope and both expose get_info/2 (the listing variant, asobi#194) plus listing_info/1, so browsing either is the same walk: enumerate the live processes, apply the caller's filter to the listing info, and return the listing projection.

Enumeration is a pull, not a push. Worlds churn on attributes — the set of worlds is near-static while occupancy changes constantly — so a delta stream would fan out at a rate set by other players' behaviour, with no ceiling. The 500ms cache in front of this is a hard ceiling of two refreshes per second regardless of load. See asobi_world_lobby.

Summary

Functions

cache_lookup(Key, Now)

Read a cached listing, or miss if absent or expired.

enumerate(ServerMod, Filters, FilterFun)

List live ServerMod processes whose info satisfies FilterFun, each as its ServerMod:listing_info/1 projection.

Functions

cache_lookup(Key, Now)

-spec cache_lookup(term(), integer()) -> {hit, [map()]} | miss.

Read a cached listing, or miss if absent or expired.

The table is owned and written by asobi_world_lobby_server; reads are direct (the table is protected) so a browse costs no round-trip. badarg before the owner has started is a miss, not a crash.

enumerate(ServerMod, Filters, FilterFun)

-spec enumerate(module(), map(), fun((map(), map()) -> boolean())) -> [map()].

List live ServerMod processes whose info satisfies FilterFun, each as its ServerMod:listing_info/1 projection.

ServerMod is both the pg group tag and the module supplying get_info/2 and listing_info/1. A process that dies mid-enumeration, or whose get_info/2 fails, is skipped rather than failing the whole listing.

asobi#194: uses get_info(Pid, listing), not get_info/1 - the roster (players) is not read by any consumer here (FilterFun only reads scalar fields like player_count; listing_info/1 never projects players into its output either), so fanning it out to every process just to discard it was copying up to max_players binaries per process, per call, for nothing. At up to 1000 worlds of up to 500 players that is up to 500k discarded binaries per enumeration.