resolved bug where source metadata worker could call itself in an infinite loop

lib/pinchflat/metadata/source_metadata_storage_worker.ex

@@ -4,7 +4,10 @@ defmodule Pinchflat.Metadata.SourceMetadataStorageWorker do
   use Oban.Worker,
     queue: :remote_metadata,
     tags: ["media_source", "source_metadata", "remote_metadata"],
-    max_attempts: 1
+    max_attempts: 1,
+    # This is the only thing stopping this job from calling itself
+    # in an infinite loop.
+    unique: [period: 600]
 
   alias __MODULE__
   alias Pinchflat.Repo
@@ -27,16 +30,19 @@ defmodule Pinchflat.Metadata.SourceMetadataStorageWorker do
     |> Tasks.create_job_with_task(source)
   end
 
-  @impl Oban.Worker
   @doc """
   Fetches and stores metadata for a source in the secret metadata location.
 
   Returns :ok
   """
+  @impl Oban.Worker
   def perform(%Oban.Job{args: %{"id" => source_id}}) do
     source = Repo.preload(Sources.get_source!(source_id), :metadata)
     {:ok, metadata} = MediaCollection.get_source_metadata(source.original_url)
 
+    # Since updating a source kicks this job off again, we enforce job uniqueness (above)
+    # to once, per source, per x minutes. This is to prevent a job from calling itself
+    # in an infinite loop.
     Sources.update_source(source, %{
       metadata: %{
         metadata_filepath: MetadataFileHelpers.compress_and_store_metadata_for(source, metadata)

test/pinchflat/metadata/source_metadata_storage_worker_test.exs

@@ -51,5 +51,28 @@ defmodule Pinchflat.Metadata.SourceMetadataStorageWorkerTest do
 
       assert metadata == %{"title" => "test"}
     end
+
+    test "won't call itself in an infinite loop" do
+      stub(YtDlpRunnerMock, :run, fn _url, _opts, _ot -> {:ok, "{}"} end)
+      source = source_fixture()
+
+      perform_job(SourceMetadataStorageWorker, %{id: source.id})
+      perform_job(SourceMetadataStorageWorker, %{id: source.id})
+
+      assert [_] = all_enqueued(worker: SourceMetadataStorageWorker)
+    end
+
+    test "doesn't prevent over source jobs from running" do
+      stub(YtDlpRunnerMock, :run, fn _url, _opts, _ot -> {:ok, "{}"} end)
+      source_1 = source_fixture()
+      source_2 = source_fixture()
+
+      perform_job(SourceMetadataStorageWorker, %{id: source_1.id})
+      perform_job(SourceMetadataStorageWorker, %{id: source_1.id})
+      perform_job(SourceMetadataStorageWorker, %{id: source_2.id})
+      perform_job(SourceMetadataStorageWorker, %{id: source_2.id})
+
+      assert [_, _] = all_enqueued(worker: SourceMetadataStorageWorker)
+    end
   end
 end