From 599f8bb152ca0669d17baa5f313f00f0791209b6 Mon Sep 17 00:00:00 2001
From: Maksim Pechnikov <parallel588@gmail.com>
Date: Wed, 16 Sep 2020 09:47:18 +0300
Subject: [PATCH] RepoStreamer.chunk_stream ->  Repo.chunk_stream

---
 lib/mix/tasks/pleroma/database.ex |  4 ++--
 lib/mix/tasks/pleroma/user.ex     |  4 ++--
 lib/pleroma/repo.ex               | 14 +++++++++++++
 lib/pleroma/repo_streamer.ex      | 34 -------------------------------
 lib/pleroma/user.ex               |  3 +--
 test/repo_test.exs                | 28 +++++++++++++++++++++++++
 6 files changed, 47 insertions(+), 40 deletions(-)
 delete mode 100644 lib/pleroma/repo_streamer.ex

diff --git a/lib/mix/tasks/pleroma/database.ex b/lib/mix/tasks/pleroma/database.ex
index 7f1108dcf..a01c36ece 100644
--- a/lib/mix/tasks/pleroma/database.ex
+++ b/lib/mix/tasks/pleroma/database.ex
@@ -99,7 +99,7 @@ defmodule Mix.Tasks.Pleroma.Database do
       where: fragment("(?)->>'likes' is not null", object.data),
       select: %{id: object.id, likes: fragment("(?)->>'likes'", object.data)}
     )
-    |> Pleroma.RepoStreamer.chunk_stream(100)
+    |> Pleroma.Repo.chunk_stream(100, :batches)
     |> Stream.each(fn objects ->
       ids =
         objects
@@ -145,7 +145,7 @@ defmodule Mix.Tasks.Pleroma.Database do
     |> where(local: true)
     |> where([a], fragment("(? ->> 'type'::text) = 'Create'", a.data))
     |> where([_a, o], fragment("?->>'type' = 'Note'", o.data))
-    |> Pleroma.RepoStreamer.chunk_stream(100)
+    |> Pleroma.Repo.chunk_stream(100, :batches)
     |> Stream.each(fn activities ->
       Enum.each(activities, fn activity ->
         expires_at =
diff --git a/lib/mix/tasks/pleroma/user.ex b/lib/mix/tasks/pleroma/user.ex
index 01824aa18..b20c49d89 100644
--- a/lib/mix/tasks/pleroma/user.ex
+++ b/lib/mix/tasks/pleroma/user.ex
@@ -179,7 +179,7 @@ defmodule Mix.Tasks.Pleroma.User do
     start_pleroma()
 
     Pleroma.User.Query.build(%{nickname: "@#{instance}"})
-    |> Pleroma.RepoStreamer.chunk_stream(500)
+    |> Pleroma.Repo.chunk_stream(500, :batches)
     |> Stream.each(fn users ->
       users
       |> Enum.each(fn user ->
@@ -370,7 +370,7 @@ defmodule Mix.Tasks.Pleroma.User do
     start_pleroma()
 
     Pleroma.User.Query.build(%{local: true})
-    |> Pleroma.RepoStreamer.chunk_stream(500)
+    |> Pleroma.Repo.chunk_stream(500, :batches)
     |> Stream.each(fn users ->
       users
       |> Enum.each(fn user ->
diff --git a/lib/pleroma/repo.ex b/lib/pleroma/repo.ex
index a75610879..4524bd5e2 100644
--- a/lib/pleroma/repo.ex
+++ b/lib/pleroma/repo.ex
@@ -49,6 +49,20 @@ defmodule Pleroma.Repo do
     end
   end
 
+  @doc """
+  Returns a lazy enumerable that emits all entries from the data store matching the given query.
+
+  `returns_as` use to group records. use the `batches` option to fetch records in bulk.
+
+  ## Examples
+
+  # fetch records one-by-one
+  iex> Pleroma.Repo.chunk_stream(Pleroma.Activity.Queries.by_actor(ap_id), 500)
+
+  # fetch records in bulk
+  iex> Pleroma.Repo.chunk_stream(Pleroma.Activity.Queries.by_actor(ap_id), 500, :batches)
+  """
+  @spec chunk_stream(Ecto.Query.t(), integer(), atom()) :: Enumerable.t()
   def chunk_stream(query, chunk_size, returns_as \\ :one) do
     # We don't actually need start and end funcitons of resource streaming,
     # but it seems to be the only way to not fetch records one-by-one and
diff --git a/lib/pleroma/repo_streamer.ex b/lib/pleroma/repo_streamer.ex
deleted file mode 100644
index cb4d7bb7a..000000000
--- a/lib/pleroma/repo_streamer.ex
+++ /dev/null
@@ -1,34 +0,0 @@
-# Pleroma: A lightweight social networking server
-# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
-# SPDX-License-Identifier: AGPL-3.0-only
-
-defmodule Pleroma.RepoStreamer do
-  alias Pleroma.Repo
-  import Ecto.Query
-
-  def chunk_stream(query, chunk_size) do
-    Stream.unfold(0, fn
-      :halt ->
-        {[], :halt}
-
-      last_id ->
-        query
-        |> order_by(asc: :id)
-        |> where([r], r.id > ^last_id)
-        |> limit(^chunk_size)
-        |> Repo.all()
-        |> case do
-          [] ->
-            {[], :halt}
-
-          records ->
-            last_id = List.last(records).id
-            {records, last_id}
-        end
-    end)
-    |> Stream.take_while(fn
-      [] -> false
-      _ -> true
-    end)
-  end
-end
diff --git a/lib/pleroma/user.ex b/lib/pleroma/user.ex
index e73d19964..57497eb83 100644
--- a/lib/pleroma/user.ex
+++ b/lib/pleroma/user.ex
@@ -25,7 +25,6 @@ defmodule Pleroma.User do
   alias Pleroma.Object
   alias Pleroma.Registration
   alias Pleroma.Repo
-  alias Pleroma.RepoStreamer
   alias Pleroma.User
   alias Pleroma.UserRelationship
   alias Pleroma.Web
@@ -1775,7 +1774,7 @@ defmodule Pleroma.User do
   def delete_user_activities(%User{ap_id: ap_id} = user) do
     ap_id
     |> Activity.Queries.by_actor()
-    |> RepoStreamer.chunk_stream(50)
+    |> Repo.chunk_stream(50, :batches)
     |> Stream.each(fn activities ->
       Enum.each(activities, fn activity -> delete_activity(activity, user) end)
     end)
diff --git a/test/repo_test.exs b/test/repo_test.exs
index 72c0b5071..155791be2 100644
--- a/test/repo_test.exs
+++ b/test/repo_test.exs
@@ -49,4 +49,32 @@ defmodule Pleroma.RepoTest do
       assert Repo.get_assoc(token, :user) == {:error, :not_found}
     end
   end
+
+  describe "chunk_stream/3" do
+    test "fetch records one-by-one" do
+      users = insert_list(50, :user)
+
+      {fetch_users, 50} =
+        from(t in User)
+        |> Repo.chunk_stream(5)
+        |> Enum.reduce({[], 0}, fn %User{} = user, {acc, count} ->
+          {acc ++ [user], count + 1}
+        end)
+
+      assert users == fetch_users
+    end
+
+    test "fetch records in bulk" do
+      users = insert_list(50, :user)
+
+      {fetch_users, 10} =
+        from(t in User)
+        |> Repo.chunk_stream(5, :batches)
+        |> Enum.reduce({[], 0}, fn users, {acc, count} ->
+          {acc ++ users, count + 1}
+        end)
+
+      assert users == fetch_users
+    end
+  end
 end