From 91089c93ada742ff2b709601e9f0ea217c9f5a06 Mon Sep 17 00:00:00 2001
From: Lain Soykaf <lain@lain.com>
Date: Sun, 26 Jul 2026 11:38:24 +0400
Subject: [PATCH] feat(search): add resumable runtime backfill

---
 lib/mix/tasks/pleroma/search/indexer.ex |  58 ++++------
 lib/pleroma/search/backfill.ex          | 137 ++++++++++++++++++++++++
 test/pleroma/search/backfill_test.exs   |  79 ++++++++++++++
 3 files changed, 234 insertions(+), 40 deletions(-)
 create mode 100644 lib/pleroma/search/backfill.ex
 create mode 100644 test/pleroma/search/backfill_test.exs

diff --git a/lib/mix/tasks/pleroma/search/indexer.ex b/lib/mix/tasks/pleroma/search/indexer.ex
index 2a52472f9..62cbf2e50 100644
--- a/lib/mix/tasks/pleroma/search/indexer.ex
+++ b/lib/mix/tasks/pleroma/search/indexer.ex
@@ -4,9 +4,6 @@
 
 defmodule Mix.Tasks.Pleroma.Search.Indexer do
   import Mix.Pleroma
-  import Ecto.Query
-
-  alias Pleroma.Workers.SearchIndexingWorker
 
   def run(["create_index"]) do
     start_pleroma()
@@ -35,49 +32,30 @@ defmodule Mix.Tasks.Pleroma.Search.Indexer do
         strict: [
           chunk: :integer,
           limit: :integer,
-          step: :integer
+          step: :integer,
+          before: :string
         ]
       )
 
     start_pleroma()
 
-    chunk_size = Keyword.get(options, :chunk, 100)
-    limit = Keyword.get(options, :limit, 100_000)
-    per_step = Keyword.get(options, :step, 1000)
+    result =
+      Pleroma.Search.Backfill.run(
+        options ++
+          [
+            on_page: fn page ->
+              IO.puts(
+                "Queued #{page.count} activities (#{page.enqueued} total), " <>
+                  "checkpoint: #{page.next_cursor}"
+              )
+            end
+          ]
+      )
 
-    chunks = max(div(limit, per_step), 1)
+    IO.puts("Queued #{result.enqueued} activities")
 
-    1..chunks
-    |> Enum.each(fn step ->
-      q =
-        from(a in Pleroma.Activity,
-          limit: ^per_step,
-          offset: ^per_step * (^step - 1),
-          select: [:id],
-          order_by: [desc: :id]
-        )
-
-      {:ok, ids} =
-        Pleroma.Repo.transaction(fn ->
-          Pleroma.Repo.stream(q, timeout: :infinity)
-          |> Enum.map(fn a ->
-            a.id
-          end)
-        end)
-
-      IO.puts("Got #{length(ids)} activities, adding to indexer")
-
-      ids
-      |> Enum.chunk_every(chunk_size)
-      |> Enum.each(fn chunk ->
-        IO.puts("Adding #{length(chunk)} activities to indexing queue")
-
-        chunk
-        |> Enum.map(fn id ->
-          SearchIndexingWorker.new(%{"op" => "add_to_index", "activity" => id})
-        end)
-        |> Oban.insert_all()
-      end)
-    end)
+    unless result.exhausted do
+      IO.puts("Resume with --before #{result.next_cursor}")
+    end
   end
 end
diff --git a/lib/pleroma/search/backfill.ex b/lib/pleroma/search/backfill.ex
new file mode 100644
index 000000000..1b986bb59
--- /dev/null
+++ b/lib/pleroma/search/backfill.ex
@@ -0,0 +1,137 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2026 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Search.Backfill do
+  import Ecto.Query
+
+  alias Pleroma.Activity
+  alias Pleroma.Workers.SearchIndexingWorker
+
+  @default_chunk_size 100
+  @default_step_size 1_000
+  @default_limit 100_000
+
+  @doc """
+  Enqueues existing Create activities for search indexing.
+
+  The returned `next_cursor` can be passed as `before` to resume a bounded run.
+  Pass `limit: :infinity` to continue until the oldest activity is reached.
+  """
+  def run(options \\ []) do
+    options =
+      Keyword.validate!(options,
+        chunk: @default_chunk_size,
+        step: @default_step_size,
+        limit: @default_limit,
+        before: nil,
+        on_page: nil
+      )
+
+    chunk_size = positive_option!(options, :chunk, @default_chunk_size)
+    step_size = positive_option!(options, :step, @default_step_size)
+    limit = limit_option!(options)
+    before = cursor_option!(options[:before])
+    on_page = callback_option!(options[:on_page])
+
+    do_run(before, limit, step_size, chunk_size, on_page, 0)
+  end
+
+  defp do_run(before, remaining, step_size, chunk_size, on_page, enqueued) do
+    page_size = page_size(remaining, step_size)
+    ids = fetch_ids(before, page_size)
+
+    case ids do
+      [] ->
+        result(enqueued, before, true)
+
+      ids ->
+        enqueue(ids, chunk_size)
+
+        page_count = length(ids)
+        next_cursor = List.last(ids)
+        total = enqueued + page_count
+        remaining = decrement(remaining, page_count)
+
+        on_page.(%{count: page_count, enqueued: total, next_cursor: next_cursor})
+
+        cond do
+          remaining == 0 -> result(total, next_cursor, false)
+          page_count < page_size -> result(total, next_cursor, true)
+          true -> do_run(next_cursor, remaining, step_size, chunk_size, on_page, total)
+        end
+    end
+  end
+
+  defp fetch_ids(before, limit) do
+    Activity
+    |> where([a], fragment("?->>'type' = 'Create'", a.data))
+    |> maybe_before(before)
+    |> order_by([a], desc: a.id)
+    |> limit(^limit)
+    |> select([a], a.id)
+    |> Pleroma.Repo.all()
+  end
+
+  defp maybe_before(query, nil), do: query
+  defp maybe_before(query, before), do: where(query, [a], a.id < ^before)
+
+  defp enqueue(ids, chunk_size) do
+    ids
+    |> Enum.chunk_every(chunk_size)
+    |> Enum.each(fn chunk ->
+      chunk
+      |> Enum.map(&SearchIndexingWorker.new(%{"op" => "add_to_index", "activity" => &1}))
+      |> Oban.insert_all()
+    end)
+  end
+
+  defp page_size(:infinity, step_size), do: step_size
+  defp page_size(remaining, step_size), do: min(remaining, step_size)
+
+  defp decrement(:infinity, _count), do: :infinity
+  defp decrement(remaining, count), do: remaining - count
+
+  defp result(enqueued, next_cursor, exhausted) do
+    %{enqueued: enqueued, next_cursor: next_cursor, exhausted: exhausted}
+  end
+
+  defp positive_option!(options, key, default) do
+    case Keyword.get(options, key, default) do
+      value when is_integer(value) and value > 0 -> value
+      value -> raise ArgumentError, "#{key} must be a positive integer, got: #{inspect(value)}"
+    end
+  end
+
+  defp limit_option!(options) do
+    case Keyword.fetch!(options, :limit) do
+      :infinity -> :infinity
+      value when is_integer(value) and value > 0 -> value
+      value -> raise ArgumentError, "limit must be a positive integer, got: #{inspect(value)}"
+    end
+  end
+
+  defp cursor_option!(nil), do: nil
+
+  defp cursor_option!(cursor) do
+    valid? =
+      try do
+        match?({:ok, <<_::binary-size(16)>>}, FlakeId.Ecto.CompatType.dump(cursor))
+      rescue
+        _ -> false
+      end
+
+    if valid? do
+      cursor
+    else
+      raise ArgumentError, "before must be a valid activity id, got: #{inspect(cursor)}"
+    end
+  end
+
+  defp callback_option!(nil), do: fn _ -> :ok end
+  defp callback_option!(callback) when is_function(callback, 1), do: callback
+
+  defp callback_option!(callback) do
+    raise ArgumentError, "on_page must be a function of arity 1, got: #{inspect(callback)}"
+  end
+end
diff --git a/test/pleroma/search/backfill_test.exs b/test/pleroma/search/backfill_test.exs
new file mode 100644
index 000000000..d707524c3
--- /dev/null
+++ b/test/pleroma/search/backfill_test.exs
@@ -0,0 +1,79 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2026 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Search.BackfillTest do
+  use Pleroma.DataCase, async: false
+  use Oban.Testing, repo: Pleroma.Repo
+
+  import Pleroma.Factory
+
+  alias Pleroma.Search.Backfill
+  alias Pleroma.Workers.SearchIndexingWorker
+
+  test "enqueues the exact requested number across partial pages" do
+    activities = insert_list(5, :note_activity) |> Enum.sort_by(& &1.id, :desc)
+
+    assert %{enqueued: 3, exhausted: false, next_cursor: cursor} =
+             Backfill.run(limit: 3, step: 2, chunk: 2)
+
+    assert search_indexing_ids() == Enum.map(Enum.take(activities, 3), & &1.id)
+    assert cursor == Enum.at(activities, 2).id
+  end
+
+  test "resumes after the last processed activity without duplicates" do
+    activities = insert_list(5, :note_activity) |> Enum.sort_by(& &1.id, :desc)
+
+    assert %{enqueued: 2, next_cursor: cursor} = Backfill.run(limit: 2, step: 1)
+
+    Pleroma.Repo.delete_all(Oban.Job)
+
+    assert %{enqueued: 2, next_cursor: next_cursor} =
+             Backfill.run(before: cursor, limit: 2, step: 1)
+
+    assert search_indexing_ids() ==
+             activities
+             |> Enum.slice(2, 2)
+             |> Enum.map(& &1.id)
+
+    assert next_cursor == Enum.at(activities, 3).id
+  end
+
+  test "only queues Create activities" do
+    create = insert(:note_activity)
+    insert(:like_activity, note_activity: create)
+
+    assert %{enqueued: 1, exhausted: true, next_cursor: cursor} = Backfill.run(step: 2)
+    assert search_indexing_ids() == [create.id]
+    assert cursor == create.id
+  end
+
+  test "rejects unknown options and malformed cursors before enqueueing" do
+    assert_raise ArgumentError, fn -> Backfill.run(limt: 1) end
+    assert_raise ArgumentError, fn -> Backfill.run(before: "not-an-activity-id") end
+    assert_raise ArgumentError, fn -> Backfill.run(on_page: :invalid) end
+
+    assert all_enqueued(worker: SearchIndexingWorker) == []
+  end
+
+  test "does not duplicate or skip the initial activities when newer rows are inserted" do
+    activities = insert_list(3, :note_activity) |> Enum.sort_by(& &1.id, :desc)
+
+    assert %{enqueued: 3, exhausted: true} =
+             Backfill.run(
+               limit: :infinity,
+               step: 1,
+               on_page: fn %{enqueued: enqueued} ->
+                 if enqueued == 1, do: insert(:note_activity)
+               end
+             )
+
+    assert search_indexing_ids() == Enum.map(activities, & &1.id)
+  end
+
+  defp search_indexing_ids do
+    all_enqueued(worker: SearchIndexingWorker)
+    |> Enum.sort_by(& &1.id)
+    |> Enum.map(& &1.args["activity"])
+  end
+end