Graham McIntire
d67186176f
Type spec fixes: - duct_usable_* return boolean→float (delegate to duct_usable_for_band) - sanitize/1 spec includes :unicode error tuples - match_delete/1 broadened from :ets.match_spec() - telemetry_event local type replaces :telemetry.event/0 - wgrib2 parse_lon_val_segment corrected to tuple spec - preloaded Ecto assoc types in get_mission/get_contact! specs Unmatched returns: - _ = prefix on Task.start, Oban.insert, Repo.query!, PubSub.subscribe, :ets.new, and if-expression returns across 18 files Pattern match fixes: - markdown: restructure acc!=[] guard as direct pattern match - path_compute/pskr/skewt_location_resolver: remove dead clauses - calibrate.aprs_144: remove unreachable format_float catch-all - unused.ex: suppress MapSet.union no_opaque Also: remove unused unicode_util_compat from mix.lock
87 lines
2.6 KiB
Elixir
87 lines
2.6 KiB
Elixir
defmodule Microwaveprop.Weather.NexradCache do
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@moduledoc """
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Node-local ETS cache of decoded NEXRAD n0q composite reflectivity frames.
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Keyed by a 5-minute rounded timestamp. Stores the raw pixel buffer + image
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width so per-point rain-cell extraction can skip the HTTP fetch + PNG decode
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(which take 1-5 seconds for a ~5 MB CONUS-wide image).
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The cache is populated by `Microwaveprop.Weather.NexradClient.fetch_rain_cells/4`
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on its first call per 5-min window, then reused by every concurrent click
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until the window rolls over.
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"""
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use GenServer
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@table :nexrad_frame_cache
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# Each frame is ~66 MB (12,200 × 5,400 palette-index bytes). 20 frames
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# caps at ~1.3 GB — comfortable headroom under a 2 GB pod limit, and
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# enough to hit on the common backfill pattern where a worker chews
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# through contacts in one timestamp window before moving on. Adjust
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# if pod memory limits change or the n0q geometry changes.
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@max_entries 20
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@type pixels :: binary()
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@type width :: pos_integer()
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@spec start_link(keyword()) :: GenServer.on_start()
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def start_link(opts) do
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GenServer.start_link(__MODULE__, opts, name: __MODULE__)
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end
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@spec fetch(DateTime.t()) :: {:ok, pixels(), width()} | :miss
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def fetch(rounded_ts) do
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case :ets.lookup(@table, rounded_ts) do
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[{_, pixels, width}] -> {:ok, pixels, width}
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[] -> :miss
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end
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end
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@spec put(DateTime.t(), pixels(), width()) :: :ok
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def put(rounded_ts, pixels, width) do
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:ets.insert(@table, {rounded_ts, pixels, width})
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enforce_size_cap()
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:ok
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end
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defp enforce_size_cap do
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if :ets.info(@table, :size) > @max_entries do
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case oldest_key() do
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nil -> :ok
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ts -> :ets.delete(@table, ts)
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end
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enforce_size_cap()
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end
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end
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# Iterate ETS with foldl so frame payloads (~66 MB each) never land on the
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# calling process's heap — :ets.tab2list() at capacity would allocate ~1.3 GB.
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defp oldest_key do
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:ets.foldl(
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fn
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{ts, _, _}, nil -> ts
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{ts, _, _}, oldest -> if DateTime.before?(ts, oldest), do: ts, else: oldest
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end,
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nil,
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@table
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)
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end
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@spec prune_older_than(DateTime.t()) :: non_neg_integer()
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def prune_older_than(cutoff_ts) do
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match_spec = [{{:"$1", :_, :_}, [{:<, :"$1", {:const, cutoff_ts}}], [true]}]
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:ets.select_delete(@table, match_spec)
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end
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@spec clear() :: :ok
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def clear do
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:ets.delete_all_objects(@table)
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:ok
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end
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@impl true
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def init(_opts) do
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_ = :ets.new(@table, [:set, :named_table, :public, :compressed, read_concurrency: true])
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{:ok, %{}}
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end
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end
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