From caf4e6de78a7b685376fc983036d3c3484543c6b Mon Sep 17 00:00:00 2001
From: Ayrat Badykov <ayratin555@gmail.com>
Date: Thu, 16 May 2019 09:57:02 +0300
Subject: [PATCH] remove period based update

---
 .../lib/explorer/chain/block_number_cache.ex  | 46 +++------------
 .../chain/block_number_cache_test.exs         | 56 +++++--------------
 apps/explorer/test/support/data_case.ex       |  2 +-
 3 files changed, 22 insertions(+), 82 deletions(-)

diff --git a/apps/explorer/lib/explorer/chain/block_number_cache.ex b/apps/explorer/lib/explorer/chain/block_number_cache.ex
index d15d6781e6..b74e0999bf 100644
--- a/apps/explorer/lib/explorer/chain/block_number_cache.ex
+++ b/apps/explorer/lib/explorer/chain/block_number_cache.ex
@@ -6,13 +6,10 @@ defmodule Explorer.Chain.BlockNumberCache do
   alias Explorer.Chain
 
   @tab :block_number_cache
-  # 30 minutes
-  @cache_period 1_000 * 60 * 30
   @key "min_max"
-  @opts_key "opts"
 
-  @spec setup(Keyword.t()) :: :ok
-  def setup(opts \\ []) do
+  @spec setup() :: :ok
+  def setup do
     if :ets.whereis(@tab) == :undefined do
       :ets.new(@tab, [
         :set,
@@ -22,7 +19,6 @@ defmodule Explorer.Chain.BlockNumberCache do
       ])
     end
 
-    setup_opts(opts)
     update_cache()
 
     :ok
@@ -41,16 +37,7 @@ defmodule Explorer.Chain.BlockNumberCache do
   end
 
   defp value(type) do
-    initial_cache = {_min, _max, old_current_time} = cached_values()
-
-    {min, max, _current_time} =
-      if current_time() - old_current_time > cache_period() do
-        update_cache()
-
-        cached_values()
-      else
-        initial_cache
-      end
+    {min, max} = cached_values()
 
     case type do
       :max -> max
@@ -61,15 +48,15 @@ defmodule Explorer.Chain.BlockNumberCache do
 
   @spec update(non_neg_integer()) :: boolean()
   def update(number) do
-    {old_min, old_max, time} = cached_values()
+    {old_min, old_max} = cached_values()
 
     cond do
       number > old_max ->
-        tuple = {old_min, number, time}
+        tuple = {old_min, number}
         :ets.insert(@tab, {@key, tuple})
 
       number < old_min ->
-        tuple = {number, old_max, time}
+        tuple = {number, old_max}
         :ets.insert(@tab, {@key, tuple})
 
       true ->
@@ -78,41 +65,22 @@ defmodule Explorer.Chain.BlockNumberCache do
   end
 
   defp update_cache do
-    current_time = current_time()
     {min, max} = min_and_max_from_db()
-    tuple = {min, max, current_time}
+    tuple = {min, max}
 
     :ets.insert(@tab, {@key, tuple})
   end
 
-  defp setup_opts(opts) do
-    cache_period = opts[:cache_period] || @cache_period
-
-    :ets.insert(@tab, {@opts_key, cache_period})
-  end
-
   defp cached_values do
     [{_, cached_values}] = :ets.lookup(@tab, @key)
 
     cached_values
   end
 
-  defp cache_period do
-    [{_, cache_period}] = :ets.lookup(@tab, @opts_key)
-
-    cache_period
-  end
-
   defp min_and_max_from_db do
     Chain.fetch_min_and_max_block_numbers()
   rescue
     _e ->
       {0, 0}
   end
-
-  defp current_time do
-    utc_now = DateTime.utc_now()
-
-    DateTime.to_unix(utc_now, :millisecond)
-  end
 end
diff --git a/apps/explorer/test/explorer/chain/block_number_cache_test.exs b/apps/explorer/test/explorer/chain/block_number_cache_test.exs
index a33263293c..870b1b4240 100644
--- a/apps/explorer/test/explorer/chain/block_number_cache_test.exs
+++ b/apps/explorer/test/explorer/chain/block_number_cache_test.exs
@@ -11,33 +11,6 @@ defmodule Explorer.Chain.BlockNumberCacheTest do
 
       assert BlockNumberCache.max_number() == 5
     end
-
-    test "invalidates cache if period did pass" do
-      insert(:block, number: 5)
-
-      BlockNumberCache.setup(cache_period: 2_000)
-
-      assert BlockNumberCache.max_number() == 5
-
-      insert(:block, number: 10)
-
-      Process.sleep(2_000)
-
-      assert BlockNumberCache.max_number() == 10
-      assert BlockNumberCache.min_number() == 5
-    end
-
-    test "does not invalidate cache if period time did not pass" do
-      insert(:block, number: 5)
-
-      BlockNumberCache.setup(cache_period: 10_000)
-
-      assert BlockNumberCache.max_number() == 5
-
-      insert(:block, number: 10)
-
-      assert BlockNumberCache.max_number() == 5
-    end
   end
 
   describe "min_number/1" do
@@ -48,32 +21,31 @@ defmodule Explorer.Chain.BlockNumberCacheTest do
 
       assert BlockNumberCache.max_number() == 2
     end
+  end
 
-    test "invalidates cache" do
-      insert(:block, number: 5)
-
-      BlockNumberCache.setup(cache_period: 2_000)
+  describe "update/1" do
+    test "updates max number" do
+      insert(:block, number: 2)
 
-      assert BlockNumberCache.min_number() == 5
+      BlockNumberCache.setup()
 
-      insert(:block, number: 2)
+      assert BlockNumberCache.max_number() == 2
 
-      Process.sleep(2_000)
+      assert BlockNumberCache.update(3)
 
-      assert BlockNumberCache.min_number() == 2
-      assert BlockNumberCache.max_number() == 5
+      assert BlockNumberCache.max_number() == 3
     end
 
-    test "does not invalidate cache if period time did not pass" do
-      insert(:block, number: 5)
+    test "updates min number" do
+      insert(:block, number: 2)
 
-      BlockNumberCache.setup(cache_period: 10_000)
+      BlockNumberCache.setup()
 
-      assert BlockNumberCache.max_number() == 5
+      assert BlockNumberCache.min_number() == 2
 
-      insert(:block, number: 2)
+      assert BlockNumberCache.update(1)
 
-      assert BlockNumberCache.max_number() == 5
+      assert BlockNumberCache.min_number() == 1
     end
   end
 end
diff --git a/apps/explorer/test/support/data_case.ex b/apps/explorer/test/support/data_case.ex
index 75d3429e70..68bb21434c 100644
--- a/apps/explorer/test/support/data_case.ex
+++ b/apps/explorer/test/support/data_case.ex
@@ -39,7 +39,7 @@ defmodule Explorer.DataCase do
       Ecto.Adapters.SQL.Sandbox.mode(Explorer.Repo, {:shared, self()})
     end
 
-    Explorer.Chain.BlockNumberCache.setup(cache_period: 0)
+    Explorer.Chain.BlockNumberCache.setup()
 
     :ok
   end