recompile articles on change

Author: robsonperassoli

config/config.exs

@@ -0,0 +1,4 @@
+import Config
+
+config :exsync,
+  addition_dirs: ["/priv"]

lib/boc/application.ex

@@ -7,7 +7,8 @@ defmodule Boc.Application do
   def start(_type, _args) do
     children = [
       {Bandit, plug: Boc.Router},
-      {Boc.Articles.DB, []}
+      {Boc.Articles.DB, []},
+      {Boc.ArticlesMonitor, []}
     ]
 
     opts = [strategy: :one_for_one, name: Boc.Supervisor]

lib/boc/articles/db.ex

@@ -2,14 +2,7 @@ defmodule Boc.Articles.DB do
   use Agent
 
   def start_link(_initial_value) do
-    Agent.start_link(
-      fn ->
-        Boc.Articles.compile_articles()
-        |> Enum.map(&{&1.key, &1})
-        |> Map.new()
-      end,
-      name: __MODULE__
-    )
+    Agent.start_link(&prepare_articles/0, name: __MODULE__)
   end
 
   def get_article(key) do
@@ -19,4 +12,14 @@ defmodule Boc.Articles.DB do
   def put_article(%{key: key} = article) do
     Agent.update(__MODULE__, &Map.put(&1, key, article))
   end
+
+  def reset() do
+    Agent.update(__MODULE__, fn _ -> prepare_articles() end)
+  end
+
+  defp prepare_articles() do
+    Boc.Articles.compile_articles()
+    |> Enum.map(&{&1.key, &1})
+    |> Map.new()
+  end
 end

lib/boc/articles_monitor.ex

@@ -0,0 +1,60 @@
+defmodule Boc.ArticlesMonitor do
+  use GenServer
+
+  require Logger
+
+  @throttle_timeout_ms 100
+
+  defmodule State do
+    defstruct [:throttle_timer, :file_events, :watcher_pid]
+  end
+
+  def start_link(_opts \\ []) do
+    GenServer.start_link(__MODULE__, [])
+  end
+
+  @impl GenServer
+  def init([]) do
+    {:ok, watcher_pid} =
+      FileSystem.start_link(dirs: [Boc.articles_path()])
+
+    FileSystem.subscribe(watcher_pid)
+    Logger.debug("Boc articles monitor started.")
+    {:ok, %State{watcher_pid: watcher_pid}}
+  end
+
+  @impl GenServer
+  def handle_info({:file_event, watcher_pid, {path, events}}, %{watcher_pid: watcher_pid} = state) do
+    matching_extension? = Path.extname(path) === ".md"
+
+    matching_event? = :modified in events
+
+    state =
+      if matching_extension? && matching_event? do
+        maybe_recomplete(state)
+      else
+        state
+      end
+
+    {:noreply, state}
+  end
+
+  def handle_info({:file_event, watcher_pid, :stop}, %{watcher_pid: watcher_pid} = state) do
+    Logger.debug("Boc articles monitor stopped.")
+    {:noreply, state}
+  end
+
+  def handle_info(:throttle_timer_complete, state) do
+    Boc.Articles.DB.reset()
+
+    state = %State{state | throttle_timer: nil}
+    {:noreply, state}
+  end
+
+  defp maybe_recomplete(%State{throttle_timer: nil} = state) do
+    throttle_timer = Process.send_after(self(), :throttle_timer_complete, @throttle_timeout_ms)
+    %State{state | throttle_timer: throttle_timer}
+  end
+
+  defp maybe_recomplete(%State{} = state), do: state
+end

mix.exs

@@ -31,7 +31,9 @@ defmodule Boc.MixProject do
       {:plug, "~> 1.18"},
       {:bandit, "~> 1.8"},
       {:earmark, "~> 1.4"},
-      {:yaml_elixir, "~> 2.11"}
+      {:yaml_elixir, "~> 2.11"},
+      {:exsync, "~> 0.4", only: :dev},
+      {:file_system, "~> 1.1", only: :dev}
     ]
   end
 end

mix.lock

@@ -1,6 +1,8 @@
 %{
   "bandit": {:hex, :bandit, "1.8.0", "c2e93d7e3c5c794272fa4623124f827c6f24b643acc822be64c826f9447d92fb", [:mix], [{:hpax, "~> 1.0", [hex: :hpax, repo: "hexpm", optional: false]}, {:plug, "~> 1.18", [hex: :plug, repo: "hexpm", optional: false]}, {:telemetry, "~> 0.4 or ~> 1.0", [hex: :telemetry, repo: "hexpm", optional: false]}, {:thousand_island, "~> 1.0", [hex: :thousand_island, repo: "hexpm", optional: false]}, {:websock, "~> 0.5", [hex: :websock, repo: "hexpm", optional: false]}], "hexpm", "8458ff4eed20ff2a2ea69d4854883a077c33ea42b51f6811b044ceee0fa15422"},
   "earmark": {:hex, :earmark, "1.4.48", "5f41e579d85ef812351211842b6e005f6e0cef111216dea7d4b9d58af4608434", [:mix], [], "hexpm", "a461a0ddfdc5432381c876af1c86c411fd78a25790c75023c7a4c035fdc858f9"},
+  "exsync": {:hex, :exsync, "0.4.1", "0a14fe4bfcb80a509d8a0856be3dd070fffe619b9ba90fec13c58b316c176594", [:mix], [{:file_system, "~> 0.2 or ~> 1.0", [hex: :file_system, repo: "hexpm", optional: false]}], "hexpm", "cefb22aa805ec97ffc5b75a4e1dc54bcaf781e8b32564bf74abbe5803d1b5178"},
+  "file_system": {:hex, :file_system, "1.1.0", "08d232062284546c6c34426997dd7ef6ec9f8bbd090eb91780283c9016840e8f", [:mix], [], "hexpm", "bfcf81244f416871f2a2e15c1b515287faa5db9c6bcf290222206d120b3d43f6"},
   "hpax": {:hex, :hpax, "1.0.3", "ed67ef51ad4df91e75cc6a1494f851850c0bd98ebc0be6e81b026e765ee535aa", [:mix], [], "hexpm", "8eab6e1cfa8d5918c2ce4ba43588e894af35dbd8e91e6e55c817bca5847df34a"},
   "mime": {:hex, :mime, "2.0.7", "b8d739037be7cd402aee1ba0306edfdef982687ee7e9859bee6198c1e7e2f128", [:mix], [], "hexpm", "6171188e399ee16023ffc5b76ce445eb6d9672e2e241d2df6050f3c771e80ccd"},
   "plug": {:hex, :plug, "1.18.1", "5067f26f7745b7e31bc3368bc1a2b818b9779faa959b49c934c17730efc911cf", [:mix], [{:mime, "~> 1.0 or ~> 2.0", [hex: :mime, repo: "hexpm", optional: false]}, {:plug_crypto, "~> 1.1.1 or ~> 1.2 or ~> 2.0", [hex: :plug_crypto, repo: "hexpm", optional: false]}, {:telemetry, "~> 0.4.3 or ~> 1.0", [hex: :telemetry, repo: "hexpm", optional: false]}], "hexpm", "57a57db70df2b422b564437d2d33cf8d33cd16339c1edb190cd11b1a3a546cc2"},

priv/articles/dev.md

@@ -5,3 +5,4 @@ title: "My dev Tools"
  - alacritty
  - starship
  - zellij
+ - zsh