Make task implementation for async configurable

guides/telemetry.md

@@ -89,3 +89,11 @@ Instead, you can add the `:opentelemetry_process_propagator` package to your
 dependencies, which has a `Task.async/1` wrapper that will attach the context
 automatically. If the package is installed, the middleware will use it in place
 of the default `Task.async/1`.
+
+Alternatively, you can configure the `Task` implementation to use:
+
+```elixir
+config :absinthe, task_module: MyTaskModule
+```
+
+The provided module must support the `async/1` function.

lib/absinthe/middleware/async.ex

@@ -38,6 +38,8 @@ defmodule Absinthe.Middleware.Async do
   @behaviour Absinthe.Middleware
   @behaviour Absinthe.Plugin
 
+  import Absinthe.Utils, only: [async: 1]
+
   # A function has handed resolution off to this middleware. The first argument
   # is the current resolution struct. The second argument is the function to
   # execute asynchronously, and opts we'll want to use when it is time to await
@@ -110,13 +112,4 @@ defmodule Absinthe.Middleware.Async do
         pipeline
     end
   end
-
-  # Optionally use `async/1` function from `opentelemetry_process_propagator` if available
-  if Code.ensure_loaded?(OpentelemetryProcessPropagator.Task) do
-    @spec async((-> any)) :: Task.t()
-    defdelegate async(fun), to: OpentelemetryProcessPropagator.Task
-  else
-    @spec async((-> any)) :: Task.t()
-    defdelegate async(fun), to: Task
-  end
 end

lib/absinthe/middleware/batch.ex

@@ -62,6 +62,8 @@ defmodule Absinthe.Middleware.Batch do
 
   require Logger
 
+  import Absinthe.Utils, only: [async: 1]
+
   @typedoc """
   The function to be called with the aggregate batch information.
 
@@ -226,13 +228,4 @@ defmodule Absinthe.Middleware.Batch do
         pipeline
     end
   end
-
-  # Optionally use `async/1` function from `opentelemetry_process_propagator` if available
-  if Code.ensure_loaded?(OpentelemetryProcessPropagator.Task) do
-    @spec async((-> any)) :: Task.t()
-    defdelegate async(fun), to: OpentelemetryProcessPropagator.Task
-  else
-    @spec async((-> any)) :: Task.t()
-    defdelegate async(fun), to: Task
-  end
 end

lib/absinthe/utils.ex

@@ -151,4 +151,24 @@ defmodule Absinthe.Utils do
     #{types ++ directives}
     """
   end
+
+  @spec async((-> any)) :: Task.t()
+  def async(fun) do
+    case Application.fetch_env(:absinthe, :task_module) do
+      {:ok, module} when is_atom(module) ->
+        module.async(fun)
+
+      _ ->
+        async_default(fun)
+    end
+  end
+
+  # Optionally use `async/1` function from `opentelemetry_process_propagator` if available
+  if Code.ensure_loaded?(OpentelemetryProcessPropagator.Task) do
+    @spec async_default((-> any)) :: Task.t()
+    defdelegate async_default(fun), to: OpentelemetryProcessPropagator.Task, as: :async
+  else
+    @spec async_default((-> any)) :: Task.t()
+    defdelegate async_default(fun), to: Task, as: :async
+  end
 end