Fix average block time

CHANGELOG.md

@@ -6,6 +6,8 @@
 
 ### Fixes
 
+- [#8891](https://github.com/blockscout/blockscout/pull/8891) - Fix average block time
+
 ### Chore
 
 ## 5.3.2-beta

apps/explorer/lib/explorer/counters/average_block_time.ex

@@ -84,7 +84,7 @@ defmodule Explorer.Counters.AverageBlockTime do
 
     timestamps =
       timestamps_row
-      |> Enum.sort_by(fn {_, timestamp} -> timestamp end, &>=/2)
+      |> Enum.sort_by(fn {_, timestamp} -> timestamp end, &Timex.after?/2)
       |> Enum.map(fn {number, timestamp} ->
         {number, DateTime.to_unix(timestamp, :millisecond)}
       end)
@@ -125,7 +125,7 @@ defmodule Explorer.Counters.AverageBlockTime do
   defp compose_durations(durations, block_number, last_block_number, last_timestamp, timestamp) do
     block_numbers_range = last_block_number - block_number
 
-    if block_numbers_range == 0 do
+    if block_numbers_range <= 0 do
       {durations, block_number, timestamp}
     else
       duration = (last_timestamp - timestamp) / block_numbers_range

apps/explorer/test/explorer/counters/average_block_time_test.exs

@@ -129,5 +129,55 @@ defmodule Explorer.Counters.AverageBlockTimeTest do
 
       assert AverageBlockTime.average_block_time() == Timex.Duration.parse!("PT3S")
     end
+
+    test "timestamps are compared correctly" do
+      block_number = 99_999_999
+
+      first_timestamp = ~U[2023-08-23 19:04:59.000000Z]
+      pseudo_after_timestamp = ~U[2022-08-23 19:05:59.000000Z]
+
+      insert(:block, number: block_number, consensus: true, timestamp: pseudo_after_timestamp)
+      insert(:block, number: block_number + 1, consensus: true, timestamp: Timex.shift(first_timestamp, seconds: 3))
+      insert(:block, number: block_number + 2, consensus: true, timestamp: Timex.shift(first_timestamp, seconds: 6))
+
+      Enum.each(1..100, fn i ->
+        insert(:block,
+          number: block_number + i + 2,
+          consensus: true,
+          timestamp: Timex.shift(first_timestamp, seconds: -(101 - i) - 9)
+        )
+      end)
+
+      AverageBlockTime.refresh()
+
+      %{timestamps: timestamps} = :sys.get_state(AverageBlockTime)
+
+      assert Enum.sort_by(timestamps, fn {_bn, ts} -> ts end, &>=/2) == timestamps
+    end
+
+    test "average time are calculated correctly for blocks that are not in chronological order" do
+      block_number = 99_999_999
+
+      first_timestamp = Timex.now()
+
+      insert(:block, number: block_number, consensus: true, timestamp: Timex.shift(first_timestamp, seconds: 3))
+      insert(:block, number: block_number + 1, consensus: true, timestamp: Timex.shift(first_timestamp, seconds: 6))
+      insert(:block, number: block_number + 2, consensus: true, timestamp: Timex.shift(first_timestamp, seconds: 9))
+      insert(:block, number: block_number + 3, consensus: true, timestamp: Timex.shift(first_timestamp, seconds: -69))
+      insert(:block, number: block_number + 4, consensus: true, timestamp: Timex.shift(first_timestamp, seconds: -66))
+      insert(:block, number: block_number + 5, consensus: true, timestamp: Timex.shift(first_timestamp, seconds: -63))
+
+      Enum.each(1..100, fn i ->
+        insert(:block,
+          number: block_number + i + 5,
+          consensus: true,
+          timestamp: Timex.shift(first_timestamp, seconds: -(101 - i) - 9)
+        )
+      end)
+
+      AverageBlockTime.refresh()
+
+      assert Timex.Duration.to_milliseconds(AverageBlockTime.average_block_time()) == 3000
+    end
   end
 end