add an agent to store distributino state (and avoid multiple pem deco…

…des when runtime configured)

lib/cloudfront_signer/application.ex

@@ -0,0 +1,12 @@
+defmodule CloudfrontSigner.Application do
+  use Application
+  import Supervisor.Spec
+
+  def start(_type, _args) do
+    children = [
+      worker(CloudfrontSigner.DistributionRegistry, [])
+    ]
+    opts = [strategy: :one_for_one, name: CloudfrontSigner.Application.Supervisor]
+    Supervisor.start_link(children, opts)
+  end
+end

lib/cloudfront_signer/distribution_registry.ex

@@ -0,0 +1,20 @@
+defmodule CloudfrontSigner.DistributionRegistry do
+  @moduledoc """
+  Agent to store and fetch cloudfront distributions, to avoid expensive runtime pem decodes
+  """
+  use Agent
+  alias CloudfrontSigner.Distribution
+
+  def start_link() do
+    Agent.start_link(fn -> %{} end, name: __MODULE__)
+  end
+
+  def get_distribution(scope, key) do
+    Agent.get_and_update(__MODULE__, &Map.get_and_update(&1, {scope, key}, fn 
+      nil -> 
+        dist = Distribution.from_config(scope, key)
+        {dist, dist}
+      dist -> {dist, dist}
+    end))
+  end
+end

mix.exs

@@ -13,7 +13,8 @@ defmodule CloudfrontSigner.MixProject do
 
   def application do
     [
-      extra_applications: [:logger]
+      extra_applications: [:logger],
+      mod: {CloudfrontSigner.Application, []}
     ]
   end
 

test/cloudfront_signer/distribution_registry_test.exs

@@ -0,0 +1,11 @@
+defmodule CloudfrontSigner.DistributionRegistryTest do
+  use ExUnit.Case, async: true
+
+  describe "#get_distribution/2" do
+    test "It will get a registry and save it internally" do
+      distribution = CloudfrontSigner.DistributionRegistry.get_distribution(:cloudfront_signer, CloudfrontSignerTest)
+
+      assert distribution.domain == "https://somewhere.cloudfront.com"
+    end
+  end
+end

test/cloudfront_signer/signature_test.exs

@@ -1,5 +1,5 @@
 defmodule CloudfrontSigner.SignatureTest do
-  use ExUnit.Case
+  use ExUnit.Case, async: true
 
   @correct_signature """
 ToshDrR-FhIhiStqrp8kAEyQ3YGsz-P5Nh9~~lu0m5l4V-qg3K9Pp~pjYCIYR4yC

test/cloudfront_signer_test.exs

@@ -1,5 +1,5 @@
 defmodule CloudfrontSignerTest do
-  use ExUnit.Case
+  use ExUnit.Case, async: true
   doctest CloudfrontSigner
 
   describe "#sign/3" do