concurrent reindexing for faster dev startup

lib/mix/tasks/reindex_all.ex

@@ -18,6 +18,15 @@ defmodule Mix.Tasks.ReindexAll do
   alias Philomena.Repo
   import Ecto.Query
 
+  @indices [
+    {Images, Image},
+    {Comments, Comment},
+    {Galleries, Gallery},
+    {Tags, Tag},
+    {Posts, Post},
+    {Filters, Filter}
+  ]
+
   @shortdoc "Destroys and recreates all Elasticsearch indices."
   @requirements ["app.start"]
   @impl Mix.Task
@@ -26,19 +35,16 @@ defmodule Mix.Tasks.ReindexAll do
       raise "do not run this task unless you know what you're doing"
     end
 
-    for {context, schema} <- [
-          {Images, Image},
-          {Comments, Comment},
-          {Galleries, Gallery},
-          {Tags, Tag},
-          {Posts, Post},
-          {Filters, Filter}
-        ] do
+    @indices
+    |> Enum.map(fn {context, schema} ->
+      Task.async(fn ->
         Elasticsearch.delete_index!(schema)
         Elasticsearch.create_index!(schema)
 
         Elasticsearch.reindex(preload(schema, ^context.indexing_preloads()), schema)
-    end
+      end)
+    end)
+    |> Task.await_many(:infinity)
 
     # Reports are a bit special