Handle review comments

lib/live_book/application.ex

@@ -11,10 +11,10 @@ defmodule LiveBook.Application do
       LiveBookWeb.Telemetry,
       # Start the PubSub system
       {Phoenix.PubSub, name: LiveBook.PubSub},
-      # Start the Endpoint (http/https)
-      LiveBookWeb.Endpoint,
       # Start the supervisor dynamically managing sessions
-      LiveBook.SessionSupervisor
+      LiveBook.SessionSupervisor,
+      # Start the Endpoint (http/https)
+      LiveBookWeb.Endpoint
     ]
 
     # See https://hexdocs.pm/elixir/Supervisor.html

lib/live_book/session.ex

@@ -1,19 +1,19 @@
 defmodule LiveBook.Session do
-  @moduledoc """
-  Server corresponding to a single notebook session.
+  @moduledoc false
 
-  The process keeps the current notebook state and serves
-  as a source of truth that multiple clients talk to.
-  Receives update requests from the clients and notifies
-  them of any changes applied to the notebook.
-  """
+  # Server corresponding to a single notebook session.
+  #
+  # The process keeps the current notebook state and serves
+  # as a source of truth that multiple clients talk to.
+  # Receives update requests from the clients and notifies
+  # them of any changes applied to the notebook.
 
   use GenServer, restart: :temporary
 
   @typedoc """
-  A UUID assigned to every running session process.
+  An id assigned to every running session process.
   """
-  @type session_id :: String.t()
+  @type session_id :: LiveBook.Utils.id()
 
   ## API
 

lib/live_book/session_supervisor.ex

@@ -1,14 +1,14 @@
 defmodule LiveBook.SessionSupervisor do
-  @moduledoc """
-  Supervisor responsible for managing running notebook sessions.
+  @moduledoc false
 
-  Allows for creating new session processes on demand
-  and managing them using UUIDs.
-  """
+  # Supervisor responsible for managing running notebook sessions.
+  #
+  # Allows for creating new session processes on demand
+  # and managing them using random ids.
 
   use DynamicSupervisor
 
-  alias LiveBook.Session
+  alias LiveBook.{Session, Utils}
 
   @name __MODULE__
 
@@ -28,7 +28,7 @@ defmodule LiveBook.SessionSupervisor do
   """
   @spec create_session() :: {:ok, Session.session_id()} | {:error, any()}
   def create_session() do
-    id = UUID.uuid4()
+    id = Utils.random_id()
 
     case DynamicSupervisor.start_child(@name, {Session, id}) do
       {:ok, _} ->

lib/live_book/utils.ex

@@ -0,0 +1,13 @@
+defmodule LiveBook.Utils do
+  @moduledoc false
+
+  @type id :: binary()
+
+  @doc """
+  Generates a random binary id.
+  """
+  @spec random_id() :: binary()
+  def random_id() do
+    :crypto.strong_rand_bytes(20) |> Base.encode32(case: :lower)
+  end
+end

mix.exs

@@ -41,8 +41,7 @@ defmodule LiveBook.MixProject do
       {:telemetry_metrics, "~> 0.4"},
       {:telemetry_poller, "~> 0.4"},
       {:jason, "~> 1.0"},
-      {:plug_cowboy, "~> 2.0"},
-      {:elixir_uuid, "~> 1.2"}
+      {:plug_cowboy, "~> 2.0"}
     ]
   end
 

mix.lock

@@ -2,7 +2,6 @@
   "cowboy": {:hex, :cowboy, "2.8.0", "f3dc62e35797ecd9ac1b50db74611193c29815401e53bac9a5c0577bd7bc667d", [:rebar3], [{:cowlib, "~> 2.9.1", [hex: :cowlib, repo: "hexpm", optional: false]}, {:ranch, "~> 1.7.1", [hex: :ranch, repo: "hexpm", optional: false]}], "hexpm", "4643e4fba74ac96d4d152c75803de6fad0b3fa5df354c71afdd6cbeeb15fac8a"},
   "cowboy_telemetry": {:hex, :cowboy_telemetry, "0.3.1", "ebd1a1d7aff97f27c66654e78ece187abdc646992714164380d8a041eda16754", [:rebar3], [{:cowboy, "~> 2.7", [hex: :cowboy, repo: "hexpm", optional: false]}, {:telemetry, "~> 0.4", [hex: :telemetry, repo: "hexpm", optional: false]}], "hexpm", "3a6efd3366130eab84ca372cbd4a7d3c3a97bdfcfb4911233b035d117063f0af"},
   "cowlib": {:hex, :cowlib, "2.9.1", "61a6c7c50cf07fdd24b2f45b89500bb93b6686579b069a89f88cb211e1125c78", [:rebar3], [], "hexpm", "e4175dc240a70d996156160891e1c62238ede1729e45740bdd38064dad476170"},
-  "elixir_uuid": {:hex, :elixir_uuid, "1.2.1", "dce506597acb7e6b0daeaff52ff6a9043f5919a4c3315abb4143f0b00378c097", [:mix], [], "hexpm", "f7eba2ea6c3555cea09706492716b0d87397b88946e6380898c2889d68585752"},
   "file_system": {:hex, :file_system, "0.2.10", "fb082005a9cd1711c05b5248710f8826b02d7d1784e7c3451f9c1231d4fc162d", [:mix], [], "hexpm", "41195edbfb562a593726eda3b3e8b103a309b733ad25f3d642ba49696bf715dc"},
   "floki": {:hex, :floki, "0.29.0", "b1710d8c93a2f860dc2d7adc390dd808dc2fb8f78ee562304457b75f4c640881", [:mix], [{:html_entities, "~> 0.5.0", [hex: :html_entities, repo: "hexpm", optional: false]}], "hexpm", "008585ce64b9f74c07d32958ec9866f4b8a124bf4da1e2941b28e41384edaaad"},
   "html_entities": {:hex, :html_entities, "0.5.1", "1c9715058b42c35a2ab65edc5b36d0ea66dd083767bef6e3edb57870ef556549", [:mix], [], "hexpm", "30efab070904eb897ff05cd52fa61c1025d7f8ef3a9ca250bc4e6513d16c32de"},