Cleaning code with the help of Credo

Credo helps us identify code style issues.  Missing spaces or extra
parens and all that.  We're read the advice and we've done our best to
apply it.

Our goal was to execute a partial refactoring of the code but this
shouldn't have sipled through in the current implementation.

Author: madnificent

lib/cache/cache.ex

@@ -1,131 +1,138 @@
-defmodule UsePlugProxy.Cache do
+defmodule Cache.Registry do
+  @moduledoc """
+  Maintains all cached requests and can clean them if needed.
+  """
+
   use GenServer
 
-  def find_cache( { _method, _full_path, _get_params, _allowed_groups } = key ) do
-    case GenServer.call( __MODULE__, { :find_cache, key } ) do
-      { :ok, response } -> response
-      { :not_found } -> nil
+  @type header :: {String.t(), String.t(), any, allowed_groups}
+  @type cache_key :: any
+  @doc "Allowed groups is currently treated as a string, if none were supplied, we can use nil instead."
+  @type allowed_groups :: String.t() | nil
+
+  def find_cache({_method, _full_path, _get_params, _allowed_groups} = key) do
+    case GenServer.call(__MODULE__, {:find_cache, key}) do
+      {:ok, response} -> response
+      {:not_found} -> nil
     end
   end
 
-  def store( { _method, _full_path, _get_params, _allowed_groups } = key, response ) do
+  def store({_method, _full_path, _get_params, _allowed_groups} = key, response) do
     # IO.puts "Going to store new content"
     # IO.inspect( key, label: "Key to store under" )
     # IO.inspect( response, label: "Response to save" )
-    GenServer.call( __MODULE__, {:store, key, response } )
+    GenServer.call(__MODULE__, {:store, key, response})
   end
 
-  def clear_keys( keys ) do
-    GenServer.call( __MODULE__, {:clear_keys, keys} )
+  def clear_keys(keys) do
+    GenServer.call(__MODULE__, {:clear_keys, keys})
   end
 
   ###
   # GenServer API
   ###
   def start_link(_) do
-    GenServer.start_link( __MODULE__, [%{cache: %{}, caches_by_key: %{}}], name: __MODULE__ )
+    GenServer.start_link(__MODULE__, [%{cache: %{}, caches_by_key: %{}}], name: __MODULE__)
   end
 
   def init(_) do
     {:ok, %{cache: %{}, caches_by_key: %{}}}
   end
 
   def handle_call({:find_cache, key}, _from, state) do
-    if has_key? state, key do
-      { :reply, { :ok, Map.get( state.cache, key ) }, state }
+    if has_key?(state, key) do
+      {:reply, {:ok, Map.get(state.cache, key)}, state}
     else
-      { :reply, { :not_found }, state }
+      {:reply, {:not_found}, state}
     end
   end
 
   def handle_call({:store, request_key, response}, _from, state) do
     # IO.inspect( request_key, label: "Request key" )
     # IO.inspect( response, label: "Response" )
 
-    %{ cache_keys: cache_keys, clear_keys: clear_keys } = response
+    %{cache_keys: cache_keys, clear_keys: clear_keys} = response
 
     # IO.inspect { :cache_keys, cache_keys }
     # IO.inspect { :clear_keys, clear_keys }
 
     state =
       state
       # update state for clear_keys
-      |> clear_keys!( clear_keys )
+      |> clear_keys!(clear_keys)
 
     # IO.puts "Executed clear keys"
 
     if cache_keys == [] do
-      {:reply, :ok, state }
+      {:reply, :ok, state}
     else
       # IO.puts "Caching request"
       # update state for new cache
       state =
         state
-        |> add_cache_key_dependency!( cache_keys, request_key )
-        |> add_cached_value!( request_key, response )
+        |> add_cache_key_dependency!(cache_keys, request_key)
+        |> add_cached_value!(request_key, response)
 
-      {:reply, :ok, state }
+      {:reply, :ok, state}
     end
   end
 
   def handle_call({:clear_keys, keys}, _from, state) do
-    {:reply, :ok, clear_keys!( state, keys )}
+    {:reply, :ok, clear_keys!(state, keys)}
   end
 
-  defp has_key?( state, key ) do
-    Map.has_key?( state.cache, key )
+  defp has_key?(state, key) do
+    Map.has_key?(state.cache, key)
   end
 
-  defp clear_keys!( state, [] ) do
+  defp clear_keys!(state, []) do
     state
   end
-  defp clear_keys!( state, clear_keys ) do
+
+  defp clear_keys!(state, clear_keys) do
     # We have multiple clear_keys and need to update the state for it.
-    %{ cache: cache, caches_by_key: caches_by_key } = state
+    %{cache: cache, caches_by_key: caches_by_key} = state
 
     cache =
-      Enum.reduce( clear_keys, cache, fn (clear_key, cache) ->
-        keys_to_remove = Map.get( caches_by_key, clear_key, [] )
-        cache = Map.drop( cache, keys_to_remove )
+      Enum.reduce(clear_keys, cache, fn clear_key, cache ->
+        keys_to_remove = Map.get(caches_by_key, clear_key, [])
+        cache = Map.drop(cache, keys_to_remove)
         cache
-      end )
+      end)
 
-    caches_by_key =
-      Map.drop( caches_by_key, clear_keys )
+    caches_by_key = Map.drop(caches_by_key, clear_keys)
 
-    %{ state |
-       cache: cache,
-       caches_by_key: caches_by_key }
+    %{state | cache: cache, caches_by_key: caches_by_key}
   end
 
-  defp add_cache_key_dependency!( state, [], _request_key ) do
+  defp add_cache_key_dependency!(state, [], _request_key) do
     state
   end
-  defp add_cache_key_dependency!( state, cache_keys, request_key ) do
+
+  defp add_cache_key_dependency!(state, cache_keys, request_key) do
     # For each cache_key, we need to see if the request_key is already
     # in the cache_keys and add it if it is not there.
-    %{ caches_by_key: caches_by_key } = state
+    %{caches_by_key: caches_by_key} = state
 
     caches_by_key =
-      Enum.reduce( cache_keys, caches_by_key, fn (cache_key, caches_by_key) ->
-        relevant_keys = Map.get( caches_by_key, cache_key, [] )
+      Enum.reduce(cache_keys, caches_by_key, fn cache_key, caches_by_key ->
+        relevant_keys = Map.get(caches_by_key, cache_key, [])
 
-        if Enum.member?( relevant_keys, request_key ) do
+        if Enum.member?(relevant_keys, request_key) do
           caches_by_key
         else
-          Map.put( caches_by_key, cache_key, [ request_key | relevant_keys ] )
+          Map.put(caches_by_key, cache_key, [request_key | relevant_keys])
         end
-      end )
+      end)
 
-    %{ state | caches_by_key: caches_by_key }
+    %{state | caches_by_key: caches_by_key}
   end
 
-  defp add_cached_value!( state, request_key, response ) do
-    %{ cache: cache } = state
+  defp add_cached_value!(state, request_key, response) do
+    %{cache: cache} = state
 
-    cache = Map.put( cache, request_key, response )
+    cache = Map.put(cache, request_key, response)
 
-    %{ state | cache: cache }
+    %{state | cache: cache}
   end
-
 end

lib/mu_elixir_cache.ex

@@ -1,11 +1,14 @@
 defmodule MuElixirCache do
+  @moduledoc """
+  Main supervisor for the cache.
+  """
   use Application
 
   def start(_type, _args) do
     IO.puts("Starting application")
     # List all child processes to be supervised
     children = [
-      {UsePlugProxy.Cache, %{}},
+      {Cache.Registry, %{}},
       {Plug.Cowboy,
        scheme: :http,
        plug: UsePlugProxy,

lib/use_plug_proxy.ex

@@ -1,6 +1,9 @@
-alias UsePlugProxy.Cache, as: Cache
+alias Cache.Registry, as: Cache
 
 defmodule UsePlugProxy do
+  @moduledoc """
+  Router for receiving cache requests.
+  """
   use Plug.Router
 
   plug(Plug.Logger)
@@ -47,6 +50,7 @@ defmodule UsePlugProxy do
 
   defp maybe_log_clear_keys(clear_keys) do
     if Application.get_env(:use_plug_proxy, :log_clear_keys) do
+      # credo:disable-for-next-line Credo.Check.Warning.IoInspect
       IO.inspect(clear_keys, label: "Clear keys")
     end
 
@@ -55,15 +59,17 @@ defmodule UsePlugProxy do
 
   defp maybe_log_cache_keys(cache_keys) do
     if Application.get_env(:use_plug_proxy, :log_cache_keys) do
+      # credo:disable-for-next-line Credo.Check.Warning.IoInspect
       IO.inspect(cache_keys, label: "Cache keys")
     end
 
     cache_keys
   end
 
-  @spec calculate_response_from_backend(String.t, Plug.Conn.t) :: Plug.Conn.t
+  @spec calculate_response_from_backend(String.t(), Plug.Conn.t()) :: Plug.Conn.t()
   defp calculate_response_from_backend(full_path, conn) do
-    url = "http://backend" <> full_path #Full path starts with /
+    # Full path starts with /
+    url = "http://backend" <> full_path
 
     url =
       case conn.query_string do
@@ -80,8 +86,8 @@ defmodule UsePlugProxy do
         {headers, cache_keys} = extract_json_header(headers, "cache-keys")
         {headers, clear_keys} = extract_json_header(headers, "clear-keys")
 
-        maybe_log_cache_keys( cache_keys )
-        maybe_log_clear_keys( clear_keys )
+        maybe_log_cache_keys(cache_keys)
+        maybe_log_clear_keys(clear_keys)
 
         {headers,
          %{

mix.exs

@@ -2,13 +2,15 @@ defmodule UsePlugProxy.Mixfile do
   use Mix.Project
 
   def project do
-    [app: :use_plug_proxy,
-     version: "2.0.2",
-     elixir: "~> 1.5",
-     build_embedded: Mix.env == :prod,
-     start_permanent: Mix.env == :prod,
-     deps: deps(),
-     aliases: aliases()]
+    [
+      app: :use_plug_proxy,
+      version: "2.0.2",
+      elixir: "~> 1.5",
+      build_embedded: Mix.env() == :prod,
+      start_permanent: Mix.env() == :prod,
+      deps: deps(),
+      aliases: aliases()
+    ]
   end
 
   def aliases do
@@ -40,8 +42,12 @@ defmodule UsePlugProxy.Mixfile do
   #
   # Type "mix help deps" for more examples and options
   defp deps do
-    [{:plug_proxy, git: "https://github.com/madnificent/plug-proxy.git"},
-     {:plug_cowboy, "~> 1.0"},
-     {:poison, "~> 2.0"}]
+    [
+      {:plug_proxy, git: "https://github.com/madnificent/plug-proxy.git"},
+      {:plug_cowboy, "~> 1.0"},
+      {:dialyxir, "~> 1.0", only: [:dev], runtime: false},
+      {:credo, "~> 1.5", only: [:dev, :test], runtime: false},
+      {:poison, "~> 2.0"}
+    ]
   end
 end

mix.lock

@@ -1,19 +1,25 @@
 %{
-  "certifi": {:hex, :certifi, "2.4.2", "75424ff0f3baaccfd34b1214184b6ef616d89e420b258bb0a5ea7d7bc628f7f0", [:rebar3], [{:parse_trans, "~>3.3", [hex: :parse_trans, repo: "hexpm", optional: false]}], "hexpm"},
-  "cowboy": {:hex, :cowboy, "1.1.2", "61ac29ea970389a88eca5a65601460162d370a70018afe6f949a29dca91f3bb0", [:rebar3], [{:cowlib, "~> 1.0.2", [hex: :cowlib, repo: "hexpm", optional: false]}, {:ranch, "~> 1.3.2", [hex: :ranch, repo: "hexpm", optional: false]}], "hexpm"},
-  "cowlib": {:hex, :cowlib, "1.0.2", "9d769a1d062c9c3ac753096f868ca121e2730b9a377de23dec0f7e08b1df84ee", [:make], [], "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"},
-  "idna": {:hex, :idna, "6.0.0", "689c46cbcdf3524c44d5f3dde8001f364cd7608a99556d8fbd8239a5798d4c10", [:rebar3], [{:unicode_util_compat, "0.4.1", [hex: :unicode_util_compat, repo: "hexpm", optional: false]}], "hexpm"},
-  "metrics": {:hex, :metrics, "1.0.1", "25f094dea2cda98213cecc3aeff09e940299d950904393b2a29d191c346a8486", [:rebar3], [], "hexpm"},
-  "mime": {:hex, :mime, "1.3.1", "30ce04ab3175b6ad0bdce0035cba77bba68b813d523d1aac73d9781b4d193cf8", [:mix], [], "hexpm"},
-  "mimerl": {:hex, :mimerl, "1.0.2", "993f9b0e084083405ed8252b99460c4f0563e41729ab42d9074fd5e52439be88", [:rebar3], [], "hexpm"},
-  "parse_trans": {:hex, :parse_trans, "3.3.0", "09765507a3c7590a784615cfd421d101aec25098d50b89d7aa1d66646bc571c1", [:rebar3], [], "hexpm"},
-  "plug": {:hex, :plug, "1.7.1", "8516d565fb84a6a8b2ca722e74e2cd25ca0fc9d64f364ec9dbec09d33eb78ccd", [:mix], [{:mime, "~> 1.0", [hex: :mime, repo: "hexpm", optional: false]}, {:plug_crypto, "~> 1.0", [hex: :plug_crypto, repo: "hexpm", optional: false]}], "hexpm"},
-  "plug_cowboy": {:hex, :plug_cowboy, "1.0.0", "2e2a7d3409746d335f451218b8bb0858301c3de6d668c3052716c909936eb57a", [:mix], [{:cowboy, "~> 1.0", [hex: :cowboy, repo: "hexpm", optional: false]}, {:plug, "~> 1.7", [hex: :plug, repo: "hexpm", optional: false]}], "hexpm"},
-  "plug_crypto": {:hex, :plug_crypto, "1.0.0", "18e49317d3fa343f24620ed22795ec29d4a5e602d52d1513ccea0b07d8ea7d4d", [:mix], [], "hexpm"},
+  "bunt": {:hex, :bunt, "0.2.0", "951c6e801e8b1d2cbe58ebbd3e616a869061ddadcc4863d0a2182541acae9a38", [:mix], [], "hexpm", "7af5c7e09fe1d40f76c8e4f9dd2be7cebd83909f31fee7cd0e9eadc567da8353"},
+  "certifi": {:hex, :certifi, "2.4.2", "75424ff0f3baaccfd34b1214184b6ef616d89e420b258bb0a5ea7d7bc628f7f0", [:rebar3], [{:parse_trans, "~>3.3", [hex: :parse_trans, repo: "hexpm", optional: false]}], "hexpm", "01d479edba0569a7b7a2c8bf923feeb6dc6a358edc2965ef69aea9ba288bb243"},
+  "cowboy": {:hex, :cowboy, "1.1.2", "61ac29ea970389a88eca5a65601460162d370a70018afe6f949a29dca91f3bb0", [:rebar3], [{:cowlib, "~> 1.0.2", [hex: :cowlib, repo: "hexpm", optional: false]}, {:ranch, "~> 1.3.2", [hex: :ranch, repo: "hexpm", optional: false]}], "hexpm", "f4763bbe08233eceed6f24bc4fcc8d71c17cfeafa6439157c57349aa1bb4f17c"},
+  "cowlib": {:hex, :cowlib, "1.0.2", "9d769a1d062c9c3ac753096f868ca121e2730b9a377de23dec0f7e08b1df84ee", [:make], [], "hexpm", "db622da03aa039e6366ab953e31186cc8190d32905e33788a1acb22744e6abd2"},
+  "credo": {:hex, :credo, "1.5.5", "e8f422026f553bc3bebb81c8e8bf1932f498ca03339856c7fec63d3faac8424b", [:mix], [{:bunt, "~> 0.2.0", [hex: :bunt, repo: "hexpm", optional: false]}, {:file_system, "~> 0.2.8", [hex: :file_system, repo: "hexpm", optional: false]}, {:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: false]}], "hexpm", "dd8623ab7091956a855dc9f3062486add9c52d310dfd62748779c4315d8247de"},
+  "dialyxir": {:hex, :dialyxir, "1.1.0", "c5aab0d6e71e5522e77beff7ba9e08f8e02bad90dfbeffae60eaf0cb47e29488", [:mix], [{:erlex, ">= 0.2.6", [hex: :erlex, repo: "hexpm", optional: false]}], "hexpm", "07ea8e49c45f15264ebe6d5b93799d4dd56a44036cf42d0ad9c960bc266c0b9a"},
+  "erlex": {:hex, :erlex, "0.2.6", "c7987d15e899c7a2f34f5420d2a2ea0d659682c06ac607572df55a43753aa12e", [:mix], [], "hexpm", "2ed2e25711feb44d52b17d2780eabf998452f6efda104877a3881c2f8c0c0c75"},
+  "file_system": {:hex, :file_system, "0.2.10", "fb082005a9cd1711c05b5248710f8826b02d7d1784e7c3451f9c1231d4fc162d", [:mix], [], "hexpm", "41195edbfb562a593726eda3b3e8b103a309b733ad25f3d642ba49696bf715dc"},
+  "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", "ed15491f324aa0e95647dca8ef4340418dac479d1204d57e455d52dcfba3f705"},
+  "idna": {:hex, :idna, "6.0.0", "689c46cbcdf3524c44d5f3dde8001f364cd7608a99556d8fbd8239a5798d4c10", [:rebar3], [{:unicode_util_compat, "0.4.1", [hex: :unicode_util_compat, repo: "hexpm", optional: false]}], "hexpm", "4bdd305eb64e18b0273864920695cb18d7a2021f31a11b9c5fbcd9a253f936e2"},
+  "jason": {:hex, :jason, "1.2.2", "ba43e3f2709fd1aa1dce90aaabfd039d000469c05c56f0b8e31978e03fa39052", [:mix], [{:decimal, "~> 1.0 or ~> 2.0", [hex: :decimal, repo: "hexpm", optional: true]}], "hexpm", "18a228f5f0058ee183f29f9eae0805c6e59d61c3b006760668d8d18ff0d12179"},
+  "metrics": {:hex, :metrics, "1.0.1", "25f094dea2cda98213cecc3aeff09e940299d950904393b2a29d191c346a8486", [:rebar3], [], "hexpm", "69b09adddc4f74a40716ae54d140f93beb0fb8978d8636eaded0c31b6f099f16"},
+  "mime": {:hex, :mime, "1.3.1", "30ce04ab3175b6ad0bdce0035cba77bba68b813d523d1aac73d9781b4d193cf8", [:mix], [], "hexpm", "6cbe761d6a0ca5a31a0931bf4c63204bceb64538e664a8ecf784a9a6f3b875f1"},
+  "mimerl": {:hex, :mimerl, "1.0.2", "993f9b0e084083405ed8252b99460c4f0563e41729ab42d9074fd5e52439be88", [:rebar3], [], "hexpm", "7a4c8e1115a2732a67d7624e28cf6c9f30c66711a9e92928e745c255887ba465"},
+  "parse_trans": {:hex, :parse_trans, "3.3.0", "09765507a3c7590a784615cfd421d101aec25098d50b89d7aa1d66646bc571c1", [:rebar3], [], "hexpm", "17ef63abde837ad30680ea7f857dd9e7ced9476cdd7b0394432af4bfc241b960"},
+  "plug": {:hex, :plug, "1.7.1", "8516d565fb84a6a8b2ca722e74e2cd25ca0fc9d64f364ec9dbec09d33eb78ccd", [:mix], [{:mime, "~> 1.0", [hex: :mime, repo: "hexpm", optional: false]}, {:plug_crypto, "~> 1.0", [hex: :plug_crypto, repo: "hexpm", optional: false]}], "hexpm", "daa5fee4209c12c3c48b05a96cf88c320b627c9575f987554dcdc1fdcdf2c15e"},
+  "plug_cowboy": {:hex, :plug_cowboy, "1.0.0", "2e2a7d3409746d335f451218b8bb0858301c3de6d668c3052716c909936eb57a", [:mix], [{:cowboy, "~> 1.0", [hex: :cowboy, repo: "hexpm", optional: false]}, {:plug, "~> 1.7", [hex: :plug, repo: "hexpm", optional: false]}], "hexpm", "01d201427a8a1f4483be2465a98b45f5e82263327507fe93404a61c51eb9e9a8"},
+  "plug_crypto": {:hex, :plug_crypto, "1.0.0", "18e49317d3fa343f24620ed22795ec29d4a5e602d52d1513ccea0b07d8ea7d4d", [:mix], [], "hexpm", "73c1682f0e414cfb5d9b95c8e8cd6ffcfdae699e3b05e1db744e58b7be857759"},
   "plug_proxy": {:git, "https://github.com/madnificent/plug-proxy.git", "201b26a05eb869cb3773549e67606756c3b9cd8a", []},
-  "poison": {:hex, :poison, "2.2.0", "4763b69a8a77bd77d26f477d196428b741261a761257ff1cf92753a0d4d24a63", [:mix], [], "hexpm"},
-  "ranch": {:hex, :ranch, "1.3.2", "e4965a144dc9fbe70e5c077c65e73c57165416a901bd02ea899cfd95aa890986", [:rebar3], [], "hexpm"},
-  "ssl_verify_fun": {:hex, :ssl_verify_fun, "1.1.4", "f0eafff810d2041e93f915ef59899c923f4568f4585904d010387ed74988e77b", [:make, :mix, :rebar3], [], "hexpm"},
-  "unicode_util_compat": {:hex, :unicode_util_compat, "0.4.1", "d869e4c68901dd9531385bb0c8c40444ebf624e60b6962d95952775cac5e90cd", [:rebar3], [], "hexpm"},
+  "poison": {:hex, :poison, "2.2.0", "4763b69a8a77bd77d26f477d196428b741261a761257ff1cf92753a0d4d24a63", [:mix], [], "hexpm", "519bc209e4433961284174c497c8524c001e285b79bdf80212b47a1f898084cc"},
+  "ranch": {:hex, :ranch, "1.3.2", "e4965a144dc9fbe70e5c077c65e73c57165416a901bd02ea899cfd95aa890986", [:rebar3], [], "hexpm", "6e56493a862433fccc3aca3025c946d6720d8eedf6e3e6fb911952a7071c357f"},
+  "ssl_verify_fun": {:hex, :ssl_verify_fun, "1.1.4", "f0eafff810d2041e93f915ef59899c923f4568f4585904d010387ed74988e77b", [:make, :mix, :rebar3], [], "hexpm", "603561dc0fd62f4f2ea9b890f4e20e1a0d388746d6e20557cafb1b16950de88c"},
+  "unicode_util_compat": {:hex, :unicode_util_compat, "0.4.1", "d869e4c68901dd9531385bb0c8c40444ebf624e60b6962d95952775cac5e90cd", [:rebar3], [], "hexpm", "1d1848c40487cdb0b30e8ed975e34e025860c02e419cb615d255849f3427439d"},
 }