From 94b7005e7ba4c94a1aac7b97013233fd97e6c322 Mon Sep 17 00:00:00 2001
From: Viktor Baranov <baranov.viktor.27@gmail.com>
Date: Fri, 20 Aug 2021 14:47:07 +0300
Subject: [PATCH] Eliminate multiple Updates of the same token in mint/burn
 token transfers

---
 CHANGELOG.md                                  |  1 +
 .../lib/indexer/transform/token_transfers.ex  | 53 +++++++++++--------
 2 files changed, 32 insertions(+), 22 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 89c6916c46..9389f02bf1 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,7 @@
 - [#4452](https://github.com/blockscout/blockscout/pull/4452) - Add names for smart-conrtact's function response
 
 ### Fixes
+- [#4535](https://github.com/blockscout/blockscout/pull/4535) - Indexer performance update:: Eliminate multiple updates of the same token while parsing mint/burn token transfers batch
 - [#4527](https://github.com/blockscout/blockscout/pull/4527) - Indexer performance update: refactor coin balance daily fetcher
 - [#4525](https://github.com/blockscout/blockscout/pull/4525) - Uncataloged token transfers query performance improvement
 - [#4513](https://github.com/blockscout/blockscout/pull/4513) - Fix installation with custom default path: add NETWORK_PATH variable to the current_path
diff --git a/apps/indexer/lib/indexer/transform/token_transfers.ex b/apps/indexer/lib/indexer/transform/token_transfers.ex
index 33ca2e0136..aaec1e8ca5 100644
--- a/apps/indexer/lib/indexer/transform/token_transfers.ex
+++ b/apps/indexer/lib/indexer/transform/token_transfers.ex
@@ -18,9 +18,24 @@ defmodule Indexer.Transform.TokenTransfers do
   def parse(logs) do
     initial_acc = %{tokens: [], token_transfers: []}
 
-    logs
-    |> Enum.filter(&(&1.first_topic == unquote(TokenTransfer.constant())))
-    |> Enum.reduce(initial_acc, &do_parse/2)
+    token_transfers_from_logs =
+      logs
+      |> Enum.filter(&(&1.first_topic == unquote(TokenTransfer.constant())))
+      |> Enum.reduce(initial_acc, &do_parse/2)
+
+    token_transfers = token_transfers_from_logs.token_transfers
+
+    token_transfers
+    |> Enum.filter(fn token_transfer ->
+      token_transfer.to_address_hash == @burn_address || token_transfer.from_address_hash == @burn_address
+    end)
+    |> Enum.map(fn token_transfer ->
+      token_transfer.token_contract_address_hash
+    end)
+    |> Enum.dedup()
+    |> Enum.each(&update_token/1)
+
+    token_transfers_from_logs
   end
 
   defp do_parse(log, %{tokens: tokens, token_transfers: token_transfers} = acc) do
@@ -58,8 +73,6 @@ defmodule Indexer.Transform.TokenTransfers do
       type: "ERC-20"
     }
 
-    update_token(log.address_hash, token_transfer)
-
     {token, token_transfer}
   end
 
@@ -85,8 +98,6 @@ defmodule Indexer.Transform.TokenTransfers do
       type: "ERC-721"
     }
 
-    update_token(log.address_hash, token_transfer)
-
     {token, token_transfer}
   end
 
@@ -112,28 +123,26 @@ defmodule Indexer.Transform.TokenTransfers do
       type: "ERC-721"
     }
 
-    update_token(log.address_hash, token_transfer)
-
     {token, token_transfer}
   end
 
-  defp update_token(address_hash_string, token_transfer) do
-    if token_transfer.to_address_hash == @burn_address || token_transfer.from_address_hash == @burn_address do
-      {:ok, address_hash} = Chain.string_to_address_hash(address_hash_string)
+  defp update_token(nil), do: :ok
+
+  defp update_token(address_hash_string) do
+    {:ok, address_hash} = Chain.string_to_address_hash(address_hash_string)
 
-      token_params =
-        address_hash_string
-        |> MetadataRetriever.get_functions_of()
+    token_params =
+      address_hash_string
+      |> MetadataRetriever.get_functions_of()
 
-      token = Repo.get_by(Token, contract_address_hash: address_hash)
+    token = Repo.get_by(Token, contract_address_hash: address_hash)
 
-      if token do
-        token_to_update =
-          token
-          |> Repo.preload([:contract_address])
+    if token do
+      token_to_update =
+        token
+        |> Repo.preload([:contract_address])
 
-        {:ok, _} = Chain.update_token(%{token_to_update | updated_at: DateTime.utc_now()}, token_params)
-      end
+      {:ok, _} = Chain.update_token(%{token_to_update | updated_at: DateTime.utc_now()}, token_params)
     end
 
     :ok