Impl. config based dep. injection for ets;

- Check for extant url ids
- Various minor refactors

Dockerfile

@@ -11,7 +11,7 @@ RUN env MIX_ENV=prod mix release
 FROM debian:buster-20191014-slim
 
 WORKDIR /home/shortnr
-COPY --from=build /root/shortnr/_build/prod/rel/service/ .
+COPY --from=build /root/shortnr/_build/prod/rel/shortnr/ .
 
 RUN apt-get update && apt-get install -y --no-install-recommends \
     libtinfo5=6.1+20181013-2+deb10u2 \
@@ -29,5 +29,5 @@ RUN groupadd -r shortnr && useradd --no-log-init -r -g shortnr shortnr
 RUN chown -R shortnr:shortnr /home/shortnr
 USER shortnr
 
-ENTRYPOINT ["bin/service", "start"]
+ENTRYPOINT ["bin/shortnr", "start"]
 EXPOSE 8080

config/config.exs

@@ -1,7 +1,12 @@
 import Config
 
-config :service,
-  port: 8080
+config :shortnr,
+  port: 8080,
+  ets_implementation:
+    (fn
+       :test -> :ets
+       _ -> :dets
+     end).(Mix.env())
 
 config :logger, :console,
   format: "date=$date time=$time level=$level$levelpad message=\"$message\" $metadata\n",

lib/router.ex

@@ -4,7 +4,7 @@ defmodule Shortnr.Router do
 
   require Logger
 
-  alias Shortnr.Transport.{Text, Http}
+  alias Shortnr.Transport.{Text, HTTP}
   alias Shortnr.URL
 
   plug(Plug.Logger, log: :debug)
@@ -13,36 +13,36 @@ defmodule Shortnr.Router do
 
   post "/urls/:url" do
     {:ok, url, conn}
-    |> Http.handle(&URL.create(&1, URL.Repo.DETS))
+    |> HTTP.handle(&URL.create(&1, URL.Repo.ETS))
     |> Text.encode_response()
-    |> Http.send(:created, conn)
+    |> HTTP.send(:created, conn)
   end
 
   get "/urls" do
     {:ok, :ignore, conn}
-    |> Http.handle(fn -> URL.list(URL.Repo.DETS) end)
+    |> HTTP.handle(fn -> URL.list(URL.Repo.ETS) end)
     |> Text.encode_response()
-    |> Http.send(:ok, conn)
+    |> HTTP.send(:ok, conn)
   end
 
   get "/:id" do
     {:ok, id, conn}
-    |> Http.handle(&URL.get(&1, URL.Repo.DETS))
+    |> HTTP.handle(&URL.get(&1, URL.Repo.ETS))
     |> Text.encode_response()
-    |> Http.send(:found, conn)
+    |> HTTP.send(:found, conn)
   end
 
   delete "/:id" do
     {:ok, id, conn}
-    |> Http.handle(&URL.delete(&1, URL.Repo.DETS))
+    |> HTTP.handle(&URL.delete(&1, URL.Repo.ETS))
     |> Text.encode_response()
-    |> Http.send(:ok, conn)
+    |> HTTP.send(:ok, conn)
   end
 
   match _ do
     {:error, {:not_found, "route not found"}, conn}
     |> Text.encode_response()
-    |> Http.send(:ignore, conn)
+    |> HTTP.send(:ignore, conn)
   end
 
   def handle_errors(conn, %{kind: _kind, reason: reason, stack: stack}) do
@@ -50,6 +50,6 @@ defmodule Shortnr.Router do
 
     {:error, {:internal_server_error, "internal server error"}, conn}
     |> Text.encode_response()
-    |> Http.send(:ignore, conn)
+    |> HTTP.send(:ignore, conn)
   end
 end

lib/shortnr.ex

@@ -14,17 +14,29 @@ defmodule Shortnr do
       {Plug.Cowboy, scheme: :http, plug: Shortnr.Router, options: [port: port]}
     ]
 
-    :dets.open_file(:urls, type: :set)
+    if ets_implementation() == :dets do
+      {:ok, _} = :dets.open_file(:urls, type: :set)
+    else
+      :ets.new(:urls, [:set, :named_table])
+    end
 
     Logger.info("server starting", port: port)
     Supervisor.start_link(children, strategy: :one_for_one)
   end
 
+  @impl true
+  def stop(_state) do
+    if ets_implementation() == :dets, do: :dets.close(:urls)
+  end
+
   @spec port() :: integer()
   defp port do
-    case Application.fetch_env(:service, :port) do
+    case Application.fetch_env(:shortnr, :port) do
       {:ok, port} -> port
       _ -> 4000
     end
   end
+
+  @spec ets_implementation() :: atom()
+  defp ets_implementation, do: Application.fetch_env!(:shortnr, :ets_implementation)
 end

lib/transport/http.ex

@@ -1,4 +1,4 @@
-defmodule Shortnr.Transport.Http do
+defmodule Shortnr.Transport.HTTP do
   import Plug.Conn
 
   @type ok_error :: {:ok, term(), Plug.Conn.t()} | error()

lib/transport/json.ex

@@ -1,8 +1,8 @@
 defmodule Shortnr.Transport.Json do
   import Plug.Conn
-  alias Shortnr.Transport.Http
+  alias Shortnr.Transport.HTTP
 
-  @spec decode_request(Plug.Conn.t(), module()) :: Http.ok_error()
+  @spec decode_request(Plug.Conn.t(), module()) :: HTTP.ok_error()
   def decode_request(conn, struct_module) do
     {:ok, body, conn} = read_body(conn)
     {:ok, params} = Jason.decode(body)
@@ -15,7 +15,7 @@ defmodule Shortnr.Transport.Json do
     {:ok, struct(struct_module, params_list), conn}
   end
 
-  @spec encode_response(Http.ok_error()) :: Http.ok_error()
+  @spec encode_response(HTTP.ok_error()) :: HTTP.ok_error()
   def encode_response({:error, {status, response}, conn}) do
     {:ok, json_body} = Jason.encode(%{data: response})
     {:error, {status, json_body}, conn}

lib/transport/text.ex

@@ -1,15 +1,15 @@
 defmodule Shortnr.Transport.Text do
   import Plug.Conn
-  alias Shortnr.Transport.Http
+  alias Shortnr.Transport.HTTP
   alias Shortnr.URL
 
-  @spec decode_request(Plug.Conn.t()) :: Http.ok_error()
+  @spec decode_request(Plug.Conn.t()) :: HTTP.ok_error()
   def decode_request(conn) do
     {:ok, body, conn} = read_body(conn)
     {:ok, body, conn}
   end
 
-  @spec encode_response(Http.ok_error()) :: Http.ok_error()
+  @spec encode_response(HTTP.ok_error()) :: HTTP.ok_error()
   def encode_response(ok_error = {:error, _, _}), do: ok_error
 
   def encode_response({:ok, [], conn}) do

lib/url/repo/dets.ex

@@ -1,29 +0,0 @@
-defmodule Shortnr.URL.Repo.DETS do
-  @behaviour Shortnr.URL.Repo
-
-  @impl true
-  def get(key) do
-    case :dets.lookup(:urls, key) |> List.first() do
-      {_, url} -> {:ok, url}
-      nil -> {:ok, nil}
-    end
-  end
-
-  @impl true
-  def put(url) do
-    :ok = :dets.insert(:urls, {url.id, url})
-    :ok
-  end
-
-  @impl true
-  def list() do
-    resp = :dets.select(:urls, [{:"$1", [], [:"$1"]}])
-    {:ok, resp |> Enum.map(&elem(&1, 1))}
-  end
-
-  @impl true
-  def delete(key) do
-    :ok = :dets.delete(:urls, key)
-    :ok
-  end
-end

lib/url/repo/ets.ex

@@ -0,0 +1,36 @@
+defmodule Shortnr.URL.Repo.ETS do
+  @behaviour Shortnr.URL.Repo
+
+  @impl true
+  def get(key) do
+    case ets().lookup(:urls, key) |> List.first() do
+      {_, url} -> {:ok, url}
+      nil -> {:ok, nil}
+    end
+  end
+
+  @impl true
+  def put(url) do
+    :ok = ets().insert(:urls, {url.id, url})
+    :ok
+  end
+
+  @impl true
+  def list() do
+    resp = ets().select(:urls, [{:"$1", [], [:"$1"]}])
+    {:ok, resp |> Enum.map(&elem(&1, 1))}
+  end
+
+  @impl true
+  def delete(key) do
+    :ok = ets().delete(:urls, key)
+    :ok
+  end
+
+  @impl true
+  def reset do
+    :ok = ets().delete_all_objects(:urls)
+  end
+
+  defp ets, do: Application.fetch_env!(:shortnr, :ets_implementation)
+end

lib/url/repo/repo.ex

@@ -6,4 +6,5 @@ defmodule Shortnr.URL.Repo do
   @callback get(String.t()) :: {:ok, URL.t()} | Transport.error()
   @callback delete(String.t()) :: :ok | Transport.error()
   @callback list() :: {:ok, list(URL.t())} | Transport.error()
+  @callback reset() :: :ok | Transport.error()
 end

lib/url/url.ex

@@ -10,16 +10,23 @@ defmodule Shortnr.URL do
 
   @type t :: %__MODULE__{
           id: String.t(),
-          url: URI.t(),
           created_at: DateTime.t(),
-          updated_at: DateTime.t()
+          updated_at: DateTime.t(),
+          url: URI.t()
         }
 
   @spec create(String.t(), module()) :: {:ok, String.t()} | Transport.error()
   def create(url, repo) do
     url_struct = %URL{id: Util.gen_id(), url: URI.parse(url)}
-    :ok = repo.put(url_struct)
-    {:ok, url_struct.id}
+
+    {:ok, extant_url} = repo.get(url_struct.id)
+
+    if is_nil(extant_url) do
+      :ok = repo.put(url_struct)
+      {:ok, url_struct.id}
+    else
+      create(url, repo)
+    end
   end
 
   @spec get(String.t(), module()) :: {:ok, URL.t()} | Transport.error()

mix.exs

@@ -3,7 +3,7 @@ defmodule Shortnr.MixProject do
 
   def project do
     [
-      app: :service,
+      app: :shortnr,
       version: "0.1.0",
       elixir: "~> 1.9",
       start_permanent: Mix.env() == :prod,