fix address sum cache

on the first call address sum cache starts task to
fetch a value from the DB and return nil

CHANGELOG.md

@@ -3,6 +3,7 @@
 ### Features
 
 ### Fixes
+- [#2901](https://github.com/poanetwork/blockscout/pull/2901) - fix address sum cache
 
 ### Chore
 

apps/block_scout_web/test/block_scout_web/controllers/api/rpc/stats_controller_test.exs

@@ -7,6 +7,12 @@ defmodule BlockScoutWeb.API.RPC.StatsControllerTest do
   alias Explorer.ExchangeRates.Token
   alias Explorer.ExchangeRates.Source.TestSource
 
+  setup do
+    Supervisor.terminate_child(Explorer.Supervisor, Explorer.Chain.Cache.AddressSum.child_id())
+    Supervisor.restart_child(Explorer.Supervisor, Explorer.Chain.Cache.AddressSum.child_id())
+    :ok
+  end
+
   describe "tokensupply" do
     test "with missing contract address", %{conn: conn} do
       params = %{
@@ -106,6 +112,8 @@ defmodule BlockScoutWeb.API.RPC.StatsControllerTest do
 
   describe "ethsupply" do
     test "returns total supply from DB", %{conn: conn} do
+      insert(:address, fetched_coin_balance: 6)
+
       params = %{
         "module" => "stats",
         "action" => "ethsupply"

apps/explorer/lib/explorer/chain/cache/address_sum.ex

@@ -16,11 +16,13 @@ defmodule Explorer.Chain.Cache.AddressSum do
   alias Explorer.Chain
 
   defp handle_fallback(:sum) do
-    # This will get the task PID if one exists and launch a new task if not
-    # See next `handle_fallback` definition
-    get_async_task()
+    result = fetch_from_db()
 
-    {:return, nil}
+    if Application.get_env(:explorer, __MODULE__)[:enabled] do
+      {:update, result}
+    else
+      {:return, result}
+    end
   end
 
   defp handle_fallback(:async_task) do
@@ -29,7 +31,7 @@ defmodule Explorer.Chain.Cache.AddressSum do
     {:ok, task} =
       Task.start(fn ->
         try do
-          result = Chain.fetch_sum_coin_total_supply()
+          result = fetch_from_db()
 
           set_sum(result)
         rescue
@@ -45,6 +47,10 @@ defmodule Explorer.Chain.Cache.AddressSum do
     {:update, task}
   end
 
+  defp fetch_from_db do
+    Chain.fetch_sum_coin_total_supply()
+  end
+
   # By setting this as a `callback` an async task will be started each time the
   # `sum` expires (unless there is one already running)
   defp async_task_on_deletion({:delete, _, :sum}), do: get_async_task()

apps/explorer/test/explorer/chain/cache/address_sum_test.exs

@@ -12,7 +12,7 @@ defmodule Explorer.Chain.Cache.AddressSumTest do
   test "returns default address sum" do
     result = AddressSum.get_sum()
 
-    assert is_nil(result)
+    assert result == 0
   end
 
   test "updates cache if initial value is zero" do

apps/explorer/test/explorer/chain/import/runner/address/token_balances_test.exs

@@ -93,7 +93,7 @@ defmodule Explorer.Chain.Import.Runner.Address.TokenBalancesTest do
         value_fetched_at: DateTime.utc_now()
       }
 
-      run_changes(new_changes, options) |> IO.inspect()
+      run_changes(new_changes, options)
     end
   end