Simplify event handling & remove GenStage

Author: adriankumpf

lib/telegram_logger_backend.ex

@@ -6,21 +6,23 @@ defmodule LoggerTelegramBackend do
   @behaviour :gen_event
 
   defstruct [:name, :level, :metadata, :metadata_filter, :sender, :sender_args]
+  alias __MODULE__, as: State
 
-  alias LoggerTelegramBackend.Sender.Telegram
-  alias LoggerTelegramBackend.Manager
+  alias LoggerTelegramBackend.{Formatter, Telegram}
 
   @default_name :telegram
   @default_sender {Telegram, [:token, :chat_id]}
   @default_metadata [:line, :function, :module, :application, :file]
 
   @impl :gen_event
-  def init(__MODULE__), do: init({__MODULE__, @default_name})
+  def init(__MODULE__) do
+    init({__MODULE__, @default_name})
+  end
 
   def init({__MODULE__, name}) when is_atom(name) do
     state =
       Application.get_env(:logger, name)
-      |> initialize(%__MODULE__{})
+      |> initialize(%State{})
 
     {:ok, state}
   end
@@ -35,12 +37,9 @@ defmodule LoggerTelegramBackend do
     {:ok, state}
   end
 
-  def handle_event(
-        {level, _gl, {Logger, msg, ts, md}},
-        %{level: log_lvl, metadata_filter: filter} = state
-      ) do
-    if meet_level?(level, log_lvl) and metadata_matches?(md, filter) do
-      :ok = log_event(level, msg, ts, md, state)
+  def handle_event({level, _gl, {Logger, message, timestamp, metadata}}, state) do
+    if meet_level?(level, state.level) and metadata_matches?(metadata, state.metadata_filter) do
+      :ok = log_event(level, message, timestamp, metadata, state)
     end
 
     {:ok, state}
@@ -55,7 +54,7 @@ defmodule LoggerTelegramBackend do
     {:ok, state}
   end
 
-  ## Helpers
+  ## Private
 
   defp meet_level?(_lvl, nil), do: true
   defp meet_level?(lvl, min), do: Logger.compare_levels(lvl, min) != :lt
@@ -83,10 +82,10 @@ defmodule LoggerTelegramBackend do
     metadata = Keyword.get(config, :metadata, @default_metadata)
     metadata_filter = Keyword.get(config, :metadata_filter)
 
-    %{
+    %State{
       state
       | sender: sender,
-        sender_args: Enum.map(sender_args, &Keyword.get(config, &1)),
+        sender_args: Keyword.take(config, sender_args),
         metadata: configure_metadata(metadata),
         level: level,
         metadata_filter: metadata_filter
@@ -96,15 +95,11 @@ defmodule LoggerTelegramBackend do
   defp configure_metadata(:all), do: :all
   defp configure_metadata(metadata), do: Enum.reverse(metadata)
 
-  defp log_event(lvl, msg, ts, md, %{sender: sender, sender_args: sender_args, metadata: keys}) do
-    event = %{
-      level: lvl,
-      message: msg,
-      metadata: take_metadata(md, keys),
-      timestamp: ts
-    }
+  defp log_event(lvl, msg, _ts, md, %State{sender: sender, sender_args: args, metadata: keys}) do
+    metadata = take_metadata(md, keys)
 
-    Manager.add_event({sender, sender_args, event})
+    Formatter.format_event(msg, lvl, metadata)
+    |> sender.send_message(args)
   end
 
   defp take_metadata(metadata, :all), do: metadata

lib/telegram_logger_backend/application.ex

@@ -1,66 +1,35 @@
 defmodule LoggerTelegramBackend.Formatter do
   @moduledoc false
 
-  use GenStage
-
-  alias LoggerTelegramBackend.Manager
-
-  def start_link([min_demand, max_demand]) do
-    GenStage.start_link(__MODULE__, {min_demand, max_demand}, name: __MODULE__)
-  end
-
-  # Callbacks
-
-  def init({min_demand, max_demand}) do
-    {
-      :producer_consumer,
-      %{},
-      subscribe_to: [{Manager, min_demand: min_demand, max_demand: max_demand}]
-    }
-  end
-
-  def handle_events(events, _from, state) do
-    formatted_events =
-      events
-      |> Enum.reverse()
-      |> Enum.map(&format_event/1)
-
-    {:noreply, formatted_events, state}
-  end
-
-  # Private
-
-  defp format_event({sender, args, %{level: lvl, message: msg, metadata: md}}) do
-    text = """
-    <b>[#{lvl}]</b> #{format_message(msg)}
-    <pre>#{format_metadata(md)}</pre>
+  def format_event(message, level, metadata) do
+    """
+    <b>[#{level}]</b> #{format_message(message)}
+    <pre>#{format_metadata(metadata)}</pre>
     """
-
-    {sender, args, text}
   end
 
-  defp format_message(msg) do
-    msg
+  defp format_message(message) do
+    message
     |> to_string
     |> String.trim()
     |> escape_special_chars()
     |> highlight_title()
   end
 
-  defp escape_special_chars(msg) do
+  defp escape_special_chars(message) do
     special_chars = [
       {"&", "&amp;"},
       {"<", "&lt;"},
       {">", "&gt;"}
     ]
 
-    Enum.reduce(special_chars, msg, fn {c, r}, acc ->
+    Enum.reduce(special_chars, message, fn {c, r}, acc ->
       String.replace(acc, c, r)
     end)
   end
 
-  defp highlight_title(msg) do
-    msg
+  defp highlight_title(message) do
+    message
     |> String.split("\n")
     |> do_highlight_title()
     |> Enum.join("\n")

lib/telegram_logger_backend/formatter.ex

@@ -1,12 +1,12 @@
-defmodule LoggerTelegramBackend.Sender.Telegram do
+defmodule LoggerTelegramBackend.Telegram do
   @moduledoc false
 
   alias HTTPoison.{Response, Error}
 
-  def send_message(text, token, chat_id) when is_binary(text) do
-    post("https://api.telegram.org/bot#{token}/sendMessage",
+  def send_message(text, opts) when is_binary(text) and is_list(opts) do
+    post("https://api.telegram.org/bot#{Keyword.fetch!(opts, :token)}/sendMessage",
       text: text,
-      chat_id: chat_id,
+      chat_id: Keyword.fetch!(opts, :chat_id),
       parse_mode: "HTML"
     )
   end

lib/telegram_logger_backend/manager.ex

@@ -4,13 +4,11 @@ defmodule LoggerTelegramBackend.Mixfile do
   def project do
     [
       app: :logger_telegram_backend,
-      version: "1.1.0-beta",
+      version: "1.1.0-beta.1",
       elixir: "~> 1.5",
       start_permanent: Mix.env() == :prod,
       deps: deps(),
       package: package(),
-
-      # Docs
       name: "LoggerTelegramBackend",
       description: "A Logger backend for Telegram",
       source_url: "https://github.com/adriankumpf/logger-telegram-backend",
@@ -21,16 +19,14 @@ defmodule LoggerTelegramBackend.Mixfile do
 
   def application do
     [
-      extra_applications: [:logger],
-      mod: {LoggerTelegramBackend.Application, []}
+      extra_applications: [:logger]
     ]
   end
 
   defp deps do
     [
       {:ex_doc, "~> 0.18", only: :dev, runtime: false},
       {:exvcr, "~> 0.10", only: :test},
-      {:gen_stage, "~> 0.13"},
       {:httpoison, "~> 1.0"}
     ]
   end

lib/telegram_logger_backend/sender.ex

@@ -5,9 +5,8 @@
   "exactor": {:hex, :exactor, "2.2.4", "5efb4ddeb2c48d9a1d7c9b465a6fffdd82300eb9618ece5d34c3334d5d7245b1", [:mix], [], "hexpm"},
   "exjsx": {:hex, :exjsx, "4.0.0", "60548841e0212df401e38e63c0078ec57b33e7ea49b032c796ccad8cde794b5c", [:mix], [{:jsx, "~> 2.8.0", [hex: :jsx, repo: "hexpm", optional: false]}], "hexpm"},
   "exvcr": {:hex, :exvcr, "0.10.3", "1ae3b97560430acfa88ebc737c85b2b7a9dbacd8a2b26789a19718b51ae3522c", [:mix], [{:exactor, "~> 2.2", [hex: :exactor, repo: "hexpm", optional: false]}, {:exjsx, "~> 4.0", [hex: :exjsx, repo: "hexpm", optional: false]}, {:httpoison, "~> 1.0", [hex: :httpoison, repo: "hexpm", optional: true]}, {:httpotion, "~> 3.1", [hex: :httpotion, repo: "hexpm", optional: true]}, {:ibrowse, "~> 4.4", [hex: :ibrowse, repo: "hexpm", optional: true]}, {:meck, "~> 0.8", [hex: :meck, repo: "hexpm", optional: false]}], "hexpm"},
-  "gen_stage": {:hex, :gen_stage, "0.14.1", "9d46723fda072d4f4bb31a102560013f7960f5d80ea44dcb96fd6304ed61e7a4", [:mix], [], "hexpm"},
   "hackney": {:hex, :hackney, "1.14.3", "b5f6f5dcc4f1fba340762738759209e21914516df6be440d85772542d4a5e412", [:rebar3], [{:certifi, "2.4.2", [hex: :certifi, repo: "hexpm", optional: false]}, {:idna, "6.0.0", [hex: :idna, repo: "hexpm", optional: false]}, {:metrics, "1.0.1", [hex: :metrics, repo: "hexpm", optional: false]}, {:mimerl, "1.0.2", [hex: :mimerl, repo: "hexpm", optional: false]}, {:ssl_verify_fun, "1.1.4", [hex: :ssl_verify_fun, repo: "hexpm", optional: false]}], "hexpm"},
-  "httpoison": {:hex, :httpoison, "1.3.1", "7ac607311f5f706b44e8b3fab736d0737f2f62a31910ccd9afe7227b43edb7f0", [:mix], [{:hackney, "~> 1.8", [hex: :hackney, repo: "hexpm", optional: false]}], "hexpm"},
+  "httpoison": {:hex, :httpoison, "1.4.0", "e0b3c2ad6fa573134e42194d13e925acfa8f89d138bc621ffb7b1989e6d22e73", [:mix], [{:hackney, "~> 1.8", [hex: :hackney, repo: "hexpm", optional: false]}], "hexpm"},
   "idna": {:hex, :idna, "6.0.0", "689c46cbcdf3524c44d5f3dde8001f364cd7608a99556d8fbd8239a5798d4c10", [:rebar3], [{:unicode_util_compat, "0.4.1", [hex: :unicode_util_compat, repo: "hexpm", optional: false]}], "hexpm"},
   "jsx": {:hex, :jsx, "2.8.3", "a05252d381885240744d955fbe3cf810504eb2567164824e19303ea59eef62cf", [:mix, :rebar3], [], "hexpm"},
   "makeup": {:hex, :makeup, "0.5.5", "9e08dfc45280c5684d771ad58159f718a7b5788596099bdfb0284597d368a882", [:mix], [{:nimble_parsec, "~> 0.4", [hex: :nimble_parsec, repo: "hexpm", optional: false]}], "hexpm"},

…legram_logger_backend/sender/telegram.ex lib/telegram_logger_backend/telegram.exlib/telegram_logger_backend/sender/telegram.ex renamed to lib/telegram_logger_backend/telegram.ex lib/telegram_logger_backend/sender/telegram.ex renamed to lib/telegram_logger_backend/telegram.ex

@@ -16,7 +16,7 @@ defmodule SenderTelegramTest do
 
   test "send_message" do
     use_cassette "send_message" do
-      assert Telegram.send_message("tach", "$token", "$chatId") == :ok
+      assert :ok = Telegram.send_message("tach", token: "$token", chat_id: "$chatId")
     end
   end
 end

mix.exs

@@ -89,7 +89,7 @@ defmodule LoggerTelegramBackendTest do
 end
 
 defmodule TestSender do
-  def send_message(text) do
+  def send_message(text, _opts) do
     send(:logger_telegram_backend_test, {:text, text})
     :ok
   end