Claudio Ortolina
45 lines
1.1 KiB
Elixir
45 lines
1.1 KiB
Elixir
defmodule LastFm.Feed do
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@moduledoc """
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Holds a in-memory cache of scrobbled tracks.
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Tracks are keyed and ASC ordered by their scrobbling unix timestamp. While this
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is technically prone to collision, it's very unlikely for that to happen due to the
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nature of the data.
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"""
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@spec create_table!() :: :ok | no_return
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def create_table! do
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__MODULE__ = :ets.new(__MODULE__, [:ordered_set, :named_table, :public])
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:ok
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end
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@spec update([LastFm.Track.t()]) :: :ok | no_return
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def update(tracks) do
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data = Enum.map(tracks, fn t -> {t.scrobbled_at_uts, t} end)
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:ets.delete_all_objects(__MODULE__)
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:ets.insert(__MODULE__, data)
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Phoenix.PubSub.broadcast(LastFm.PubSub, "feed:update", %{tracks: tracks})
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end
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@spec all_tracks() :: [LastFm.Track.t()]
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def all_tracks do
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m = [
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{
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{:_, :_},
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[],
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[{:element, 2, :"$_"}]
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}
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]
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# reversing to get tracks in DESC order
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:ets.select_reverse(__MODULE__, m)
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end
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@spec subscribe() :: :ok
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def subscribe do
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Phoenix.PubSub.subscribe(LastFm.PubSub, "feed:update")
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end
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end
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