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150 lines
4.3 KiB
Elixir
150 lines
4.3 KiB
Elixir
defmodule Phoenix.Presence.Client do
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use GenServer
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@doc """
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TODO
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## Options
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* `:pubsub` - The required name of the pubsub server
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* `:presence` - The required name of the presence module
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* `:client` - The required callback module
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"""
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def start_link(opts) do
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GenServer.start_link(__MODULE__, opts, name: PresenceClient)
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end
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def track(topic, key, meta) do
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GenServer.call(PresenceClient, {:track, self(), topic, to_string(key), meta})
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end
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def untrack(topic, key) do
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GenServer.call(PresenceClient, {:untrack, self(), topic, to_string(key)})
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end
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def init(opts) do
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client = Keyword.fetch!(opts, :client)
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client_state = client.init(%{})
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state = %{
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topics: %{},
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client: client,
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pubsub: Keyword.fetch!(opts, :pubsub),
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presence_mod: Keyword.fetch!(opts, :presence),
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client_state: client_state
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}
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{:ok, state}
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end
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def handle_info(%{topic: topic, event: "presence_diff", payload: diff}, state) do
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{:noreply, merge_diff(state, topic, diff)}
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end
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def handle_call(:state, _from, state) do
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{:reply, state, state}
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end
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def handle_call({:track, pid, topic, key, meta}, _from, state) do
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{:reply, :ok, track_pid(state, pid, topic, key, meta)}
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end
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def handle_call({:untrack, pid, topic, key}, _from, state) do
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{:reply, :ok, untrack_pid(state, pid, topic, key)}
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end
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defp track_pid(state, pid, topic, key, meta) do
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# presences are handled when the presence_diff event is received
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case Map.fetch(state.topics, topic) do
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{:ok, _topic_content} ->
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state.presence_mod.track(pid, topic, key, meta)
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state
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:error ->
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# subscribe to topic we weren't yet tracking
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Phoenix.PubSub.subscribe(state.pubsub, topic)
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state.presence_mod.track(pid, topic, key, meta)
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state
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end
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end
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defp untrack_pid(state, pid, topic, key) do
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if Map.has_key?(state.topics, topic) do
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state.presence_mod.untrack(pid, topic, key)
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else
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state
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end
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end
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defp merge_diff(state, topic, %{leaves: leaves, joins: joins}) do
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# add new topic if needed
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updated_state =
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if Map.has_key?(state.topics, topic) do
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state
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else
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update_topics_state(:add_new_topic, state, topic)
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end
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# merge diff into state.topics
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{updated_state, _topic} = Enum.reduce(joins, {updated_state, topic}, &handle_join/2)
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{updated_state, _topic} = Enum.reduce(leaves, {updated_state, topic}, &handle_leave/2)
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# if no more presences for given topic, unsubscribe and remove topic
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if topic_presences_count(updated_state, topic) == 0 do
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Phoenix.PubSub.unsubscribe(state.pubsub, topic)
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update_topics_state(:remove_topic, updated_state, topic)
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else
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updated_state
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end
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end
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defp handle_join({joined_key, meta}, {state, topic}) do
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joined_meta = Map.get(meta, :metas, [])
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updated_state = update_topics_state(:add_new_presence, state, topic, joined_key, joined_meta)
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state.client.handle_join(topic, joined_key, joined_meta, state)
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{updated_state, topic}
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end
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defp handle_leave({left_key, meta}, {state, topic}) do
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updated_state = update_topics_state(:remove_presence, state, topic, left_key)
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state.client.handle_leave(topic, left_key, meta, state)
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{updated_state, topic}
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end
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defp update_topics_state(:add_new_topic, %{topics: topics} = state, topic) do
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updated_topics = Map.put_new(topics, topic, %{})
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Map.put(state, :topics, updated_topics)
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end
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defp update_topics_state(:remove_topic, %{topics: topics} = state, topic) do
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updated_topics = Map.delete(topics, topic)
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Map.put(state, :topics, updated_topics)
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end
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defp update_topics_state(:add_new_presence, %{topics: topics} = state, topic, key, meta) do
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updated_topic =
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topics[topic]
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|> Map.put(key, meta)
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updated_topics = Map.put(topics, topic, updated_topic)
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Map.put(state, :topics, updated_topics)
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end
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defp update_topics_state(:remove_presence, %{topics: topics} = state, topic, key) do
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updated_presences =
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topics[topic]
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|> Map.delete(key)
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updated_topics = Map.put(topics, topic, updated_presences)
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Map.put(state, :topics, updated_topics)
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end
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defp topic_presences_count(state, topic) do
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state.topics[topic]
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|> Map.keys()
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|> Enum.count()
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end
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end
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