Make task implementation for async configurable

guides/telemetry.md

@@ -89,3 +89,13 @@ 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
+```
+
+This is a compile-time option, so it cannot be configured in `runtime.exs`.
+Instead, place it in `config.exs` or build-specific configs (`dev.exs`,
+`prod.exs`, etc.). 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 +151,19 @@ defmodule Absinthe.Utils do
     #{types ++ directives}
     """
   end
+
+  task_module = Application.compile_env(:absinthe, :task_module)
+
+  @spec async((-> any)) :: Task.t()
+  cond do
+    is_atom(task_module) and task_module != nil ->
+      def async(fun), do: unquote(task_module).async(fun)
+
+    # Optionally use `async/1` function from `opentelemetry_process_propagator` if available
+    Code.ensure_loaded?(OpentelemetryProcessPropagator.Task) ->
+      defdelegate async(fun), to: OpentelemetryProcessPropagator.Task
+
+    true ->
+      defdelegate async(fun), to: Task
+  end
 end