169 lines
4 KiB
Elixir
169 lines
4 KiB
Elixir
defmodule Floof.SessionManager do
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use GenServer
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require Logger
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require Record
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# structure of data := %{dets file, subscription Map}
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# dets data := {sesskey, hash} (via bag)
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defstruct dets_file: :sessions, subs: %{}
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def start_link({file, opts}) do
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GenServer.start_link(__MODULE__, {file, opts}, name: __MODULE__)
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end
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@impl true
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def init({file, opts}) do
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{:ok, file} = :dets.open_file(file, opts ++ [type: :bag])
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{:ok, %Floof.SessionManager{dets_file: file}}
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end
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### client interface
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def attach(key, pid) do
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GenServer.cast(
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__MODULE__,
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{:modify_subscription, key,
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fn oldpid, dets_file ->
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if oldpid != pid do
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Floof.Distributor.unregister(pid)
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if oldpid != nil do
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Floof.Distributor.register(oldpid)
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send(oldpid, {:SessionDetached, key})
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end
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end
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case :dets.lookup(dets_file, key) do
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[] -> nil
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{:error, _} -> nil
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_ -> send(pid, {:SessionPushed, key})
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end
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pid
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end}
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)
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end
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def detach(key, pid) do
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GenServer.cast(
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__MODULE__,
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{:modify_subscription, key,
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fn oldpid, _ ->
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if oldpid == pid do
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send(pid, {:SessionDetached, key})
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nil
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else
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oldpid
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end
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end}
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)
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end
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def set_for_all(subkey, value, origin) do
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GenServer.cast(__MODULE__, {:set_for_all, subkey, value, origin})
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end
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def set_soft_multi(key, subkeys) do
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GenServer.cast(__MODULE__, {:set_soft_multi, key, subkeys})
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end
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def peek(key) do
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GenServer.call(__MODULE__, {:peek, key})
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end
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def drop(key, subkeys) do
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GenServer.cast(__MODULE__, {:drop, key, subkeys})
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end
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@impl true
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def handle_cast({:modify_subscription, key, handler}, state) do
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{_, subs2} =
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Map.get_and_update(state.subs, key, fn oldpid ->
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{nil, handler.(oldpid, state.dets_file)}
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end)
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{:noreply, %Floof.SessionManager{state | subs: subs2}}
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end
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@impl true
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def handle_cast({:set_for_all, subkey, value, origin}, state) do
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filter_keys =
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MapSet.new(
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for {key, sub} <- state.subs do
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if origin != sub and sub != nil do
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send(sub, {:SessionPushed, key})
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key
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else
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nil
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end
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end
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)
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{:ok, all_keys} = all_session_keys(state)
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# filter_keys contains all subscribed sessions
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# all_keys contains all non-empty sessions
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added_dets_ents =
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for key <- MapSet.union(MapSet.new(all_keys), filter_keys), do: {key, subkey}
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if not Enum.empty?(added_dets_ents) do
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# only store packets when we have any sessions
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:ok = Floof.PacketSpool.store(subkey, value)
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:ok = :dets.insert(state.dets_file, added_dets_ents)
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end
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{:noreply, state}
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end
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@impl true
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def handle_cast({:set_soft_multi, key, subkeys}, state) do
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:ok = :dets.insert(state.dets_file, for(subkey <- subkeys, do: {key, subkey}))
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{:noreply, state}
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end
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@impl true
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def handle_cast({:drop, key, subkeys}, state) do
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dets_file = state.dets_file
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for x <- subkeys do
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:ok = :dets.delete_object(dets_file, {key, x})
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end
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{:noreply, state}
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end
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@impl true
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def handle_call({:peek, key}, _, state) do
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{:reply,
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case :dets.lookup(state.dets_file, key) do
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{:error, _} -> []
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items -> Enum.map(items, fn {_, x} -> x end)
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end, state}
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end
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@impl true
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def handle_call(:get_keep_only, _, state) do
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{:reply,
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case :dets.match(state.dets_file, {'_', '$2'}) do
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{:error, e} ->
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Logger.error("garbage collection error: #{inspect(e)}")
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:error
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keys ->
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{:ok, Enum.map(keys, fn [x] -> x end)}
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end, state}
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end
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defp all_session_keys(state) do
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case :dets.match(state.dets_file, {'_', '$1'}) do
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{:error, e} ->
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Logger.error("unable to fetch list of session keys: #{inspect(e)}")
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{:error, e}
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keys ->
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{:ok, Enum.map(keys, fn [x] -> x end)}
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end
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end
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end
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