fix(indexer): keep one flush timer per BufferedTask and defer days without blocks

apps/indexer/lib/indexer/buffered_task.ex

@@ -1285,6 +1285,12 @@ defmodule Indexer.BufferedTask do
     if state.flush_interval == :infinity do
       state
     else
+      # Keep one flush timer per worker. Overwriting a live reference leaves
+      # the previous timer running and starts another repeating flush chain.
+      if is_reference(state.flush_timer) do
+        Process.cancel_timer(state.flush_timer)
+      end
+
       timer = Process.send_after(self(), :flush, state.flush_interval)
       %__MODULE__{state | flush_timer: timer}
     end

apps/indexer/lib/indexer/fetcher/stats/hot_smart_contracts.ex

@@ -44,6 +44,17 @@ defmodule Indexer.Fetcher.Stats.HotSmartContracts do
 
       Logger.info("Hot contracts fetched for #{date}")
     else
+      {:error, {:error, :not_found}} ->
+        if Date.diff(Date.utc_today(), date) < @max_days_ago do
+          schedule_message_on_the_next_day({:fetch_for_date, date, false})
+        end
+
+        if new_day? do
+          schedule_next_day_fetch()
+        end
+
+        Logger.info("No indexed blocks for hot contracts on #{date}")
+
       {:error, error} ->
         Process.send_after(self(), {:fetch_for_date, date, new_day?}, @retry_interval)
         Logger.error("Error fetching hot contracts for #{date}: #{inspect(error)}")

apps/indexer/test/indexer/buffered_task_test.exs

@@ -239,6 +239,7 @@ defmodule Indexer.BufferedTaskTest do
 
     test "with 0 size without maximum size schedules next flush and hibernates" do
       bound_queue = %BoundQueue{}
+      old_timer = Process.send_after(self(), :flush, :timer.minutes(5))
 
       refute BoundQueue.shrunk?(bound_queue)
 
@@ -249,15 +250,16 @@ defmodule Indexer.BufferedTaskTest do
                  callback_module: ShrinkableTask,
                  callback_module_state: nil,
                  bound_queue: bound_queue,
-                 flush_interval: 50,
-                 flush_timer: nil,
+                 flush_interval: :timer.minutes(5),
+                 flush_timer: old_timer,
                  task_supervisor: BufferedTaskSup,
                  max_batch_size: 1,
                  max_concurrency: 1,
                  poll: false
                })
 
-      refute flush_timer == nil
+      assert Process.read_timer(old_timer) == false
+      assert is_integer(Process.read_timer(flush_timer))
     end
 
     test "with 0 size with maximum size calls init/2 to get work that was shed before scheduling next flush and hibernates" do

apps/indexer/test/indexer/fetcher/stats/hot_smart_contracts_test.exs

@@ -356,6 +356,19 @@ defmodule Indexer.Fetcher.Stats.HotSmartContractsTest do
     end
   end
 
+  test "logs an unavailable date without an error" do
+    insert(:block, number: 0, timestamp: DateTime.add(DateTime.utc_now(), -40, :day))
+    date = Date.add(Date.utc_today(), -1)
+
+    log =
+      capture_log([level: :info], fn ->
+        assert {:noreply, :ok} = HotSmartContracts.handle_info({:fetch_for_date, date, false}, :ok)
+      end)
+
+    assert log =~ "No indexed blocks for hot contracts on #{date}"
+    refute log =~ "Error fetching hot contracts"
+  end
+
   describe "handle_continue/2" do
     test "processes chain age check on startup" do
       # Create blocks older than 30 days