Divide up refreshing credits and debits

lib/explorer/workers/refresh_balance.ex

@@ -3,15 +3,30 @@ defmodule Explorer.Workers.RefreshBalance do
     Refreshes the Credit and Debit balance views.
   """
 
+  alias Ecto.Adapters.SQL
   alias Explorer.Credit
   alias Explorer.Debit
+  alias Explorer.Repo
+
+  def perform("credit"), do: unless refreshing("credits"), do: Credit.refresh()
+  def perform("debit"), do: unless refreshing("debits"), do: Debit.refresh()
 
   def perform do
-    Credit.refresh()
-    Debit.refresh()
+    perform_later("credit")
+    perform_later("debit")
+  end
+
+  def perform_later(args \\ []) do
+    Exq.enqueue(Exq.Enqueuer, "default", __MODULE__, args)
   end
 
-  def perform_later do
-    Exq.enqueue(Exq.Enqueuer, "default", __MODULE__, [])
+  def refreshing(table) do
+    query = "REFRESH MATERIALIZED VIEW CONCURRENTLY #{table}%"
+    result = SQL.query!(
+      Repo,
+      "SELECT TRUE FROM pg_stat_activity WHERE query ILIKE '$#{query}'",
+      []
+    )
+    Enum.count(result.rows) > 0
   end
 end

test/explorer/workers/refresh_balance_test.exs

@@ -1,25 +1,31 @@
 defmodule Explorer.Workers.RefreshBalanceTest do
   use Explorer.DataCase
 
+  import Mock
+
   alias Explorer.Credit
   alias Explorer.Debit
   alias Explorer.Workers.RefreshBalance
 
   describe "perform/1" do
     test "refreshes credit balances" do
-      address = insert(:address)
-      transaction = insert(:transaction, value: 20)
-      insert(:to_address, address: address, transaction: transaction)
-      RefreshBalance.perform
-      assert Repo.one(Credit).value == Decimal.new(20)
+      with_mock Exq, [enqueue: fn (_, _, _, _) -> Credit.refresh() end] do
+        address = insert(:address)
+        transaction = insert(:transaction, value: 20)
+        insert(:to_address, address: address, transaction: transaction)
+        RefreshBalance.perform
+        assert Repo.one(Credit).value == Decimal.new(20)
+      end
     end
 
     test "refreshes debit balances" do
-      address = insert(:address)
-      transaction = insert(:transaction, value: 20)
-      insert(:from_address, address: address, transaction: transaction)
-      RefreshBalance.perform
-      assert Repo.one(Debit).value == Decimal.new(20)
+      with_mock Exq, [enqueue: fn (_, _, _, _) -> Debit.refresh() end] do
+        address = insert(:address)
+        transaction = insert(:transaction, value: 20)
+        insert(:from_address, address: address, transaction: transaction)
+        RefreshBalance.perform
+        assert Repo.one(Debit).value == Decimal.new(20)
+      end
     end
   end
 end