Delegate to JSON and fallback to Jason

Adds a new `Oban.JSON` module that detects whether the new JSON module
is available at compile time. If it isn't available, then it falls back
to Jason, and if Jason isn't available (which is extremely rare) then it
warns about a missing module.

This approach was chosen over a config option for backward compatibility
because Oban will only support the JSON module once the minimum
supported Elixir version is v1.18.

Closes #1213

guides/advanced/release_configuration.md

@@ -32,12 +32,10 @@ defmodule MyApp.ConfigProvider do
   end
 
   defp parse_json(path) do
-    {:ok, _} = Application.ensure_all_started(:jason)
-
     if File.exists?(path) do
       path
       |> File.read!()
-      |> Jason.decode!()
+      |> JSON.decode!()
       |> Map.fetch!("queues")
       |> Keyword.new(fn {key, value} -> {String.to_atom(key), value} end)
     end

lib/oban/engines/inline.ex

@@ -14,7 +14,7 @@ defmodule Oban.Engines.Inline do
   import DateTime, only: [utc_now: 0]
 
   alias Ecto.Changeset
-  alias Oban.{Config, Engine, Job}
+  alias Oban.{Config, Engine, Job, JSON}
   alias Oban.Queue.Executor
 
   @impl Engine
@@ -87,8 +87,8 @@ defmodule Oban.Engines.Inline do
       |> Changeset.put_change(:attempted_by, [conf.node])
       |> Changeset.put_change(:attempted_at, utc_now())
       |> Changeset.put_change(:scheduled_at, utc_now())
-      |> Changeset.update_change(:args, &json_encode_decode/1)
-      |> Changeset.update_change(:meta, &json_encode_decode/1)
+      |> Changeset.update_change(:args, &json_recode/1)
+      |> Changeset.update_change(:meta, &json_recode/1)
 
     case Changeset.apply_action(changeset, :insert) do
       {:ok, job} ->
@@ -102,10 +102,10 @@ defmodule Oban.Engines.Inline do
     end
   end
 
-  defp json_encode_decode(map) do
+  defp json_recode(map) do
     map
-    |> Jason.encode!()
-    |> Jason.decode!()
+    |> JSON.encode!()
+    |> JSON.decode!()
   end
 
   defp complete_job(%{job: job, state: :failure}) do

lib/oban/engines/lite.ex

@@ -22,7 +22,7 @@ defmodule Oban.Engines.Lite do
 
   alias Ecto.Changeset
   alias Oban.Engines.Basic
-  alias Oban.{Config, Engine, Job, Repo}
+  alias Oban.{Config, Engine, Job, JSON, Repo}
 
   @forever 60 * 60 * 24 * 365 * 99
 
@@ -327,7 +327,7 @@ defmodule Oban.Engines.Lite do
               dynamic([j], field(j, ^field) == ^value and ^acc)
 
             keys == [] ->
-              encoded = Jason.encode!(value)
+              encoded = JSON.encode!(value)
 
               dynamic(
                 [j],
@@ -336,7 +336,7 @@ defmodule Oban.Engines.Lite do
               )
 
             true ->
-              dynamic([j], json_contains(field(j, ^field), ^Jason.encode!(value)) and ^acc)
+              dynamic([j], json_contains(field(j, ^field), ^JSON.encode!(value)) and ^acc)
           end
 
         field, acc ->
@@ -385,6 +385,6 @@ defmodule Oban.Engines.Lite do
   defp encode_unsaved(job) do
     job
     |> Job.format_attempt()
-    |> Jason.encode!()
+    |> JSON.encode!()
   end
 end

lib/oban/json.ex

@@ -0,0 +1,22 @@
+defmodule Oban.JSON do
+  @moduledoc false
+
+  # Delegates to JSON in Elixir v1.18+ or Jason for earlier versions
+
+  cond do
+    Code.ensure_loaded?(JSON) ->
+      defdelegate decode!(data), to: JSON
+      defdelegate encode!(data), to: JSON
+      defdelegate encode_to_iodata!(data), to: JSON
+
+    Code.ensure_loaded?(Jason) ->
+      defdelegate decode!(data), to: Jason
+      defdelegate encode!(data), to: Jason
+      defdelegate encode_to_iodata!(data), to: Jason
+
+    true ->
+      message = "Missing a compatible JSON library, add `:jason` to your deps."
+
+      IO.warn(message, Macro.Env.stacktrace(__ENV__))
+  end
+end

lib/oban/notifier.ex

@@ -77,7 +77,7 @@ defmodule Oban.Notifier do
       end
   """
 
-  alias Oban.{Config, Registry, Sonar}
+  alias Oban.{Config, JSON, Registry, Sonar}
 
   require Logger
 
@@ -304,7 +304,7 @@ defmodule Oban.Notifier do
   defp encode(payload) do
     payload
     |> to_encodable()
-    |> Jason.encode!()
+    |> JSON.encode_to_iodata!()
     |> :zlib.gzip()
     |> Base.encode64()
   end
@@ -314,11 +314,11 @@ defmodule Oban.Notifier do
       {:ok, decoded} ->
         decoded
         |> :zlib.gunzip()
-        |> Jason.decode!()
+        |> JSON.decode!()
 
       # Messages emitted by the insert trigger aren't compressed.
       :error ->
-        Jason.decode!(payload)
+        JSON.decode!(payload)
     end
   end
 

lib/oban/telemetry.ex

@@ -618,7 +618,7 @@ defmodule Oban.Telemetry do
       output = Map.put(fun.(), :source, "oban")
 
       if Keyword.fetch!(opts, :encode) do
-        Jason.encode_to_iodata!(output)
+        JSON.encode_to_iodata!(output)
       else
         output
       end

lib/oban/testing.ex

@@ -572,8 +572,8 @@ defmodule Oban.Testing do
 
   defp json_recode(map) do
     map
-    |> Jason.encode!()
-    |> Jason.decode!()
+    |> JSON.encode!()
+    |> JSON.decode!()
   end
 
   defp assert_valid_result(result) do

mix.exs

@@ -178,7 +178,7 @@ defmodule Oban.MixProject do
     [
       {:ecto_sql, "~> 3.10"},
       {:ecto_sqlite3, "~> 0.9", optional: true},
-      {:jason, "~> 1.1"},
+      {:jason, "~> 1.1", optional: true},
       {:igniter, "~> 0.5", optional: true},
       {:myxql, "~> 0.7", optional: true},
       {:postgrex, "~> 0.16", optional: true},