From ddd752336c178b3544f21547c37fd8fcce4af138 Mon Sep 17 00:00:00 2001
From: Ayrat Badykov <ayratin555@gmail.com>
Date: Thu, 3 Oct 2019 17:31:01 +0300
Subject: [PATCH 01/30] fix opt 22.1 support

---
 .circleci/config.yml          |  3 ---
 apps/ethereum_jsonrpc/mix.exs |  3 ++-
 mix.lock                      | 14 +++++++-------
 3 files changed, 9 insertions(+), 11 deletions(-)

diff --git a/.circleci/config.yml b/.circleci/config.yml
index a2b372d416..8fd55cb8d7 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -39,9 +39,6 @@ jobs:
 
       - run: mix deps.get
 
-      - run:
-          command: sed -i '68,68 s/^/%/' ./deps/hackney/src/hackney_ssl.erl
-
       - restore_cache:
           keys:
             - v7-npm-install-{{ .Branch }}-{{ checksum "apps/block_scout_web/assets/package-lock.json" }}
diff --git a/apps/ethereum_jsonrpc/mix.exs b/apps/ethereum_jsonrpc/mix.exs
index e3949457e9..240a3aca52 100644
--- a/apps/ethereum_jsonrpc/mix.exs
+++ b/apps/ethereum_jsonrpc/mix.exs
@@ -90,7 +90,8 @@ defmodule EthereumJsonrpc.MixProject do
       # `EthereumJSONRPC.WebSocket`
       {:websocket_client, "~> 1.3"},
       {:decimal, "~> 1.0"},
-      {:decorator, "~> 1.2"}
+      {:decorator, "~> 1.2"},
+      {:hackney, "~> 1.15.2"}
     ]
   end
 end
diff --git a/mix.lock b/mix.lock
index 87f6e4e2f0..081e2eec49 100644
--- a/mix.lock
+++ b/mix.lock
@@ -11,7 +11,7 @@
   "briefly": {:git, "https://github.com/CargoSense/briefly.git", "2526e9674a4e6996137e066a1295ea60962712b8", []},
   "bunt": {:hex, :bunt, "0.2.0", "951c6e801e8b1d2cbe58ebbd3e616a869061ddadcc4863d0a2182541acae9a38", [:mix], [], "hexpm"},
   "bypass": {:hex, :bypass, "1.0.0", "b78b3dcb832a71aca5259c1a704b2e14b55fd4e1327ff942598b4e7d1a7ad83d", [:mix], [{:plug, "~> 1.7", [hex: :plug, repo: "hexpm", optional: false]}, {:plug_cowboy, "~> 1.0 or ~> 2.0", [hex: :plug_cowboy, repo: "hexpm", optional: false]}], "hexpm"},
-  "certifi": {:hex, :certifi, "2.3.1", "d0f424232390bf47d82da8478022301c561cf6445b5b5fb6a84d49a9e76d2639", [:rebar3], [{:parse_trans, "3.2.0", [hex: :parse_trans, repo: "hexpm", optional: false]}], "hexpm"},
+  "certifi": {:hex, :certifi, "2.5.1", "867ce347f7c7d78563450a18a6a28a8090331e77fa02380b4a21962a65d36ee5", [:rebar3], [{:parse_trans, "~>3.3", [hex: :parse_trans, repo: "hexpm", optional: false]}], "hexpm"},
   "cldr_utils": {:hex, :cldr_utils, "2.3.0", "e7e8b5ad7494a929c1b620cc489c3aa3f6e7e5299584c1a934bbdb56d1a53c70", [:mix], [{:decimal, "~> 1.5", [hex: :decimal, repo: "hexpm", optional: false]}], "hexpm"},
   "combine": {:hex, :combine, "0.10.0", "eff8224eeb56498a2af13011d142c5e7997a80c8f5b97c499f84c841032e429f", [:mix], [], "hexpm"},
   "comeonin": {:hex, :comeonin, "4.1.2", "3eb5620fd8e35508991664b4c2b04dd41e52f1620b36957be837c1d7784b7592", [:mix], [{:argon2_elixir, "~> 1.2", [hex: :argon2_elixir, repo: "hexpm", optional: true]}, {:bcrypt_elixir, "~> 0.12.1 or ~> 1.0", [hex: :bcrypt_elixir, repo: "hexpm", optional: true]}, {:pbkdf2_elixir, "~> 0.12", [hex: :pbkdf2_elixir, repo: "hexpm", optional: true]}], "hexpm"},
@@ -53,10 +53,10 @@
   "flow": {:hex, :flow, "0.14.3", "0d92991fe53035894d24aa8dec10dcfccf0ae00c4ed436ace3efa9813a646902", [:mix], [{:gen_stage, "~> 0.14.0", [hex: :gen_stage, repo: "hexpm", optional: false]}], "hexpm"},
   "gen_stage": {:hex, :gen_stage, "0.14.2", "6a2a578a510c5bfca8a45e6b27552f613b41cf584b58210f017088d3d17d0b14", [:mix], [], "hexpm"},
   "gettext": {:hex, :gettext, "0.16.1", "e2130b25eebcbe02bb343b119a07ae2c7e28bd4b146c4a154da2ffb2b3507af2", [:mix], [], "hexpm"},
-  "hackney": {:hex, :hackney, "1.13.0", "24edc8cd2b28e1c652593833862435c80661834f6c9344e84b6a2255e7aeef03", [:rebar3], [{:certifi, "2.3.1", [hex: :certifi, repo: "hexpm", optional: false]}, {:idna, "5.1.2", [hex: :idna, repo: "hexpm", optional: false]}, {:metrics, "1.0.1", [hex: :metrics, repo: "hexpm", optional: false]}, {:mimerl, "1.0.2", [hex: :mimerl, repo: "hexpm", optional: false]}, {:ssl_verify_fun, "1.1.1", [hex: :ssl_verify_fun, repo: "hexpm", optional: false]}], "hexpm"},
+  "hackney": {:hex, :hackney, "1.15.2", "07e33c794f8f8964ee86cebec1a8ed88db5070e52e904b8f12209773c1036085", [:rebar3], [{:certifi, "2.5.1", [hex: :certifi, repo: "hexpm", optional: false]}, {:idna, "6.0.0", [hex: :idna, repo: "hexpm", optional: false]}, {:metrics, "1.0.1", [hex: :metrics, repo: "hexpm", optional: false]}, {:mimerl, "~>1.1", [hex: :mimerl, repo: "hexpm", optional: false]}, {:ssl_verify_fun, "1.1.5", [hex: :ssl_verify_fun, repo: "hexpm", optional: false]}], "hexpm"},
   "html_entities": {:hex, :html_entities, "0.4.0", "f2fee876858cf6aaa9db608820a3209e45a087c5177332799592142b50e89a6b", [:mix], [], "hexpm"},
   "httpoison": {:hex, :httpoison, "1.0.0", "1f02f827148d945d40b24f0b0a89afe40bfe037171a6cf70f2486976d86921cd", [:mix], [{:hackney, "~> 1.8", [hex: :hackney, repo: "hexpm", optional: false]}], "hexpm"},
-  "idna": {:hex, :idna, "5.1.2", "e21cb58a09f0228a9e0b95eaa1217f1bcfc31a1aaa6e1fdf2f53a33f7dbd9494", [:rebar3], [{:unicode_util_compat, "0.3.1", [hex: :unicode_util_compat, repo: "hexpm", optional: false]}], "hexpm"},
+  "idna": {:hex, :idna, "6.0.0", "689c46cbcdf3524c44d5f3dde8001f364cd7608a99556d8fbd8239a5798d4c10", [:rebar3], [{:unicode_util_compat, "0.4.1", [hex: :unicode_util_compat, repo: "hexpm", optional: false]}], "hexpm"},
   "jason": {:hex, :jason, "1.1.2", "b03dedea67a99223a2eaf9f1264ce37154564de899fd3d8b9a21b1a6fd64afe7", [:mix], [{:decimal, "~> 1.0", [hex: :decimal, repo: "hexpm", optional: true]}], "hexpm"},
   "jsx": {:hex, :jsx, "2.8.3", "a05252d381885240744d955fbe3cf810504eb2567164824e19303ea59eef62cf", [:mix, :rebar3], [], "hexpm"},
   "junit_formatter": {:hex, :junit_formatter, "3.0.1", "4ed76a50886717a6d683a978cec775abdcb88d9d51cfddd3d8fbf8e6af4625da", [:mix], [], "hexpm"},
@@ -70,7 +70,7 @@
   "memento": {:hex, :memento, "0.3.1", "b2909390820550d8b90b68ec96f9e15ff8a45a28b6f97fa4a62ef50e87c2f9d9", [:mix], [], "hexpm"},
   "metrics": {:hex, :metrics, "1.0.1", "25f094dea2cda98213cecc3aeff09e940299d950904393b2a29d191c346a8486", [:rebar3], [], "hexpm"},
   "mime": {:hex, :mime, "1.3.1", "30ce04ab3175b6ad0bdce0035cba77bba68b813d523d1aac73d9781b4d193cf8", [:mix], [], "hexpm"},
-  "mimerl": {:hex, :mimerl, "1.0.2", "993f9b0e084083405ed8252b99460c4f0563e41729ab42d9074fd5e52439be88", [:rebar3], [], "hexpm"},
+  "mimerl": {:hex, :mimerl, "1.2.0", "67e2d3f571088d5cfd3e550c383094b47159f3eee8ffa08e64106cdf5e981be3", [:rebar3], [], "hexpm"},
   "mix_erlang_tasks": {:hex, :mix_erlang_tasks, "0.1.0", "36819fec60b80689eb1380938675af215565a89320a9e29c72c70d97512e4649", [:mix], [], "hexpm"},
   "mochiweb": {:hex, :mochiweb, "2.18.0", "eb55f1db3e6e960fac4e6db4e2db9ec3602cc9f30b86cd1481d56545c3145d2e", [:rebar3], [], "hexpm"},
   "mock": {:hex, :mock, "0.3.3", "42a433794b1291a9cf1525c6d26b38e039e0d3a360732b5e467bfc77ef26c914", [:mix], [{:meck, "~> 0.8.13", [hex: :meck, repo: "hexpm", optional: false]}], "hexpm"},
@@ -80,7 +80,7 @@
   "nimble_parsec": {:hex, :nimble_parsec, "0.5.1", "c90796ecee0289dbb5ad16d3ad06f957b0cd1199769641c961cfe0b97db190e0", [:mix], [], "hexpm"},
   "optimal": {:hex, :optimal, "0.3.6", "46bbf52fbbbd238cda81e02560caa84f93a53c75620f1fe19e81e4ae7b07d1dd", [:mix], [], "hexpm"},
   "parallel_stream": {:hex, :parallel_stream, "1.0.6", "b967be2b23f0f6787fab7ed681b4c45a215a81481fb62b01a5b750fa8f30f76c", [:mix], [], "hexpm"},
-  "parse_trans": {:hex, :parse_trans, "3.2.0", "2adfa4daf80c14dc36f522cf190eb5c4ee3e28008fc6394397c16f62a26258c2", [:rebar3], [], "hexpm"},
+  "parse_trans": {:hex, :parse_trans, "3.3.0", "09765507a3c7590a784615cfd421d101aec25098d50b89d7aa1d66646bc571c1", [:rebar3], [], "hexpm"},
   "phoenix": {:hex, :phoenix, "1.4.0", "56fe9a809e0e735f3e3b9b31c1b749d4b436e466d8da627b8d82f90eaae714d2", [:mix], [{:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: true]}, {:phoenix_pubsub, "~> 1.1", [hex: :phoenix_pubsub, repo: "hexpm", optional: false]}, {:plug, "~> 1.7", [hex: :plug, repo: "hexpm", optional: false]}, {:plug_cowboy, "~> 1.0 or ~> 2.0", [hex: :plug_cowboy, repo: "hexpm", optional: true]}], "hexpm"},
   "phoenix_ecto": {:hex, :phoenix_ecto, "4.0.0", "c43117a136e7399ea04ecaac73f8f23ee0ffe3e07acfcb8062fe5f4c9f0f6531", [:mix], [{:ecto, "~> 3.0", [hex: :ecto, repo: "hexpm", optional: false]}, {:phoenix_html, "~> 2.9", [hex: :phoenix_html, repo: "hexpm", optional: true]}, {:plug, "~> 1.0", [hex: :plug, repo: "hexpm", optional: false]}], "hexpm"},
   "phoenix_form_awesomplete": {:hex, :phoenix_form_awesomplete, "0.1.5", "d09aade160b584e3428e1e095645482396f17bddda4f566f1118f12d2598d11c", [:mix], [{:phoenix_html, "~> 2.10", [hex: :phoenix_html, repo: "hexpm", optional: false]}], "hexpm"},
@@ -107,11 +107,11 @@
   "spandex_datadog": {:hex, :spandex_datadog, "0.4.0", "75113a73e843123074886a2e31994af07d6e0632749a8d97e9ca6157b120c287", [:mix], [{:msgpax, "~> 2.2.1", [hex: :msgpax, repo: "hexpm", optional: false]}, {:spandex, "~> 2.3", [hex: :spandex, repo: "hexpm", optional: false]}], "hexpm"},
   "spandex_ecto": {:hex, :spandex_ecto, "0.4.0", "deaeaddc11a35f1c551206c53d09bb93a0da5808dbef751430e465c8c7de01d3", [:mix], [{:spandex, "~> 2.2", [hex: :spandex, repo: "hexpm", optional: false]}], "hexpm"},
   "spandex_phoenix": {:hex, :spandex_phoenix, "0.3.2", "e81889d80852a895cf62ce2e25181b15766d21e8647962e0a4458414b935feb3", [:mix], [{:plug, "~> 1.3", [hex: :plug, repo: "hexpm", optional: false]}, {:spandex, "~> 2.2", [hex: :spandex, repo: "hexpm", optional: false]}], "hexpm"},
-  "ssl_verify_fun": {:hex, :ssl_verify_fun, "1.1.1", "28a4d65b7f59893bc2c7de786dec1e1555bd742d336043fe644ae956c3497fbe", [:make, :rebar], [], "hexpm"},
+  "ssl_verify_fun": {:hex, :ssl_verify_fun, "1.1.5", "6eaf7ad16cb568bb01753dbbd7a95ff8b91c7979482b95f38443fe2c8852a79b", [:make, :mix, :rebar3], [], "hexpm"},
   "telemetry": {:hex, :telemetry, "0.4.0", "8339bee3fa8b91cb84d14c2935f8ecf399ccd87301ad6da6b71c09553834b2ab", [:rebar3], [], "hexpm"},
   "timex": {:hex, :timex, "3.6.1", "efdf56d0e67a6b956cc57774353b0329c8ab7726766a11547e529357ffdc1d56", [:mix], [{:combine, "~> 0.10", [hex: :combine, repo: "hexpm", optional: false]}, {:gettext, "~> 0.10", [hex: :gettext, repo: "hexpm", optional: false]}, {:tzdata, "~> 0.1.8 or ~> 0.5 or ~> 1.0.0", [hex: :tzdata, repo: "hexpm", optional: false]}], "hexpm"},
   "tzdata": {:hex, :tzdata, "1.0.1", "f6027a331af7d837471248e62733c6ebee86a72e57c613aa071ebb1f750fc71a", [:mix], [{:hackney, "~> 1.0", [hex: :hackney, repo: "hexpm", optional: false]}], "hexpm"},
-  "unicode_util_compat": {:hex, :unicode_util_compat, "0.3.1", "a1f612a7b512638634a603c8f401892afbf99b8ce93a45041f8aaca99cadb85e", [:rebar3], [], "hexpm"},
+  "unicode_util_compat": {:hex, :unicode_util_compat, "0.4.1", "d869e4c68901dd9531385bb0c8c40444ebf624e60b6962d95952775cac5e90cd", [:rebar3], [], "hexpm"},
   "wallaby": {:hex, :wallaby, "0.22.0", "e5d16bfa7ab23562c8a6e3b0a31445a2fd470ca622082a910114807ba823780d", [:mix], [{:httpoison, "~> 0.12 or ~> 1.0", [hex: :httpoison, repo: "hexpm", optional: false]}, {:poison, ">= 1.4.0", [hex: :poison, repo: "hexpm", optional: false]}, {:poolboy, "~> 1.5", [hex: :poolboy, repo: "hexpm", optional: false]}], "hexpm"},
   "websocket_client": {:hex, :websocket_client, "1.3.0", "2275d7daaa1cdacebf2068891c9844b15f4fdc3de3ec2602420c2fb486db59b6", [:rebar3], [], "hexpm"},
   "wobserver": {:git, "https://github.com/poanetwork/wobserver.git", "13bcda30a87f4f0be1878920a79433ad831eefbe", [branch: "support-https"]},

From ec3cacb8d903f9c782536758a334685a045195b9 Mon Sep 17 00:00:00 2001
From: Ayrat Badykov <ayratin555@gmail.com>
Date: Thu, 3 Oct 2019 17:33:25 +0300
Subject: [PATCH 02/30] add CHANGELOG entry

---
 CHANGELOG.md | 1 +
 1 file changed, 1 insertion(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1ab11179aa..b371ffdf5d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -39,6 +39,7 @@ fixed menu hovers in dark mode desktop view
 - [#2738](https://github.com/poanetwork/blockscout/pull/2738) - do not fail block `internal_transactions_indexed_at` field update
 
 ### Chore
+- [#2749](https://github.com/poanetwork/blockscout/pull/2749) - fix opt 22.1 support
 - [#2724](https://github.com/poanetwork/blockscout/pull/2724) - fix ci by commenting a line in hackney library
 - [#2708](https://github.com/poanetwork/blockscout/pull/2708) - add log index to logs view
 - [#2723](https://github.com/poanetwork/blockscout/pull/2723) - get rid of ex_json_schema warnings

From 82f4eb4a24a8a412d6bad12561450876bc269560 Mon Sep 17 00:00:00 2001
From: Ayrat Badykov <ayratin555@gmail.com>
Date: Fri, 4 Oct 2019 17:23:06 +0300
Subject: [PATCH 03/30] various token instance fethcer fixes

1. Handle invalid json / uri
2. Do not fetch instance metadata for empty token id
---
 apps/explorer/lib/explorer/chain.ex           |  2 +-
 .../token/instance_metadata_retriever.ex      |  5 +++++
 apps/explorer/test/explorer/chain_test.exs    | 22 +++++++++++++++++++
 3 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/apps/explorer/lib/explorer/chain.ex b/apps/explorer/lib/explorer/chain.ex
index b83b3fe3e3..d7b031cd51 100644
--- a/apps/explorer/lib/explorer/chain.ex
+++ b/apps/explorer/lib/explorer/chain.ex
@@ -2946,7 +2946,7 @@ defmodule Explorer.Chain do
         on: token.contract_address_hash == token_transfer.token_contract_address_hash,
         left_join: instance in Instance,
         on: token_transfer.token_id == instance.token_id,
-        where: token.type == ^"ERC-721" and is_nil(instance.token_id),
+        where: token.type == ^"ERC-721" and is_nil(instance.token_id) and not is_nil(token_transfer.token_id),
         distinct: [token_transfer.token_contract_address_hash, token_transfer.token_id],
         select: %{contract_address_hash: token_transfer.token_contract_address_hash, token_id: token_transfer.token_id}
       )
diff --git a/apps/explorer/lib/explorer/token/instance_metadata_retriever.ex b/apps/explorer/lib/explorer/token/instance_metadata_retriever.ex
index a4cf460e74..f1472c7a38 100644
--- a/apps/explorer/lib/explorer/token/instance_metadata_retriever.ex
+++ b/apps/explorer/lib/explorer/token/instance_metadata_retriever.ex
@@ -61,6 +61,11 @@ defmodule Explorer.Token.InstanceMetadataRetriever do
       {:error, %Error{reason: reason}} ->
         {:error, reason}
     end
+  rescue
+    e ->
+      Logger.error(fn -> ["Could not send request to token uri #{inspect(token_uri)}. error #{inspect(e)}"] end)
+
+      {:error, :request_error}
   end
 
   defp fetch_json(result) do
diff --git a/apps/explorer/test/explorer/chain_test.exs b/apps/explorer/test/explorer/chain_test.exs
index c623ea2d4c..4556153b09 100644
--- a/apps/explorer/test/explorer/chain_test.exs
+++ b/apps/explorer/test/explorer/chain_test.exs
@@ -3645,6 +3645,28 @@ defmodule Explorer.ChainTest do
       assert result.contract_address_hash == token_transfer.token_contract_address_hash
     end
 
+    test "does not fetch token transfers without token id" do
+      token_contract_address = insert(:contract_address)
+      token = insert(:token, contract_address: token_contract_address, type: "ERC-721")
+
+      transaction =
+        :transaction
+        |> insert()
+        |> with_block(insert(:block, number: 1))
+
+      insert(
+        :token_transfer,
+        block_number: 1000,
+        to_address: build(:address),
+        transaction: transaction,
+        token_contract_address: token_contract_address,
+        token: token,
+        token_id: nil
+      )
+
+      assert {:ok, []} = Chain.stream_unfetched_token_instances([], &[&1 | &2])
+    end
+
     test "do not fetch records with token instances" do
       token_contract_address = insert(:contract_address)
       token = insert(:token, contract_address: token_contract_address, type: "ERC-721")

From faab55ed824f6bdcec18100a5ca01b5e9c1fbb84 Mon Sep 17 00:00:00 2001
From: Ayrat Badykov <ayratin555@gmail.com>
Date: Fri, 4 Oct 2019 17:26:37 +0300
Subject: [PATCH 04/30] add CHANGELOG entry

---
 CHANGELOG.md | 1 +
 1 file changed, 1 insertion(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 21543cfb98..328485ef65 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -15,6 +15,7 @@
 - [#2642](https://github.com/poanetwork/blockscout/pull/2642) - add ERC721 coin instance page
 
 ### Fixes
+- [#2755](https://github.com/poanetwork/blockscout/pull/2755) - various token instance fetcher fixes
 - [#2750](https://github.com/poanetwork/blockscout/pull/2750) - fixed contract buttons color for NFT token instance on each theme
 - [#2746](https://github.com/poanetwork/blockscout/pull/2746) - fixed wrong alignment in logs decoded view
 - [#2745](https://github.com/poanetwork/blockscout/pull/2745) - optimize addresses page

From 57abb0047ccace1935b8f30184260250fa32364d Mon Sep 17 00:00:00 2001
From: Ayrat Badykov <ayratin555@gmail.com>
Date: Fri, 4 Oct 2019 18:58:52 +0300
Subject: [PATCH 05/30] handle metadata in token uri

---
 .../token/instance_metadata_retriever.ex      | 29 +++++++++++++++----
 1 file changed, 24 insertions(+), 5 deletions(-)

diff --git a/apps/explorer/lib/explorer/token/instance_metadata_retriever.ex b/apps/explorer/lib/explorer/token/instance_metadata_retriever.ex
index f1472c7a38..8b530934aa 100644
--- a/apps/explorer/lib/explorer/token/instance_metadata_retriever.ex
+++ b/apps/explorer/lib/explorer/token/instance_metadata_retriever.ex
@@ -50,7 +50,30 @@ defmodule Explorer.Token.InstanceMetadataRetriever do
     {:error, :no_uri}
   end
 
-  defp fetch_json(%{"tokenURI" => {:ok, [token_uri]}}) do
+  defp fetch_json(%{"tokenURI" => {:ok, ["http://" <> _ = token_uri]}}) do
+    fetch_metadata(token_uri)
+  end
+
+  defp fetch_json(%{"tokenURI" => {:ok, ["https://" <> _ = token_uri]}}) do
+    fetch_metadata(token_uri)
+  end
+
+  defp fetch_json(%{"tokenURI" => {:ok, [json]}}) do
+    Jason.decode(json)
+  rescue
+    e ->
+      Logger.error(fn -> ["Unknown metadata format #{inspect(json)}. error #{inspect(e)}"] end)
+
+    {:error, json}
+  end
+
+  defp fetch_json(result) do
+    Logger.error(fn -> ["Unknown metadata format #{result}."] end)
+
+    {:error, result}
+  end
+
+  defp fetch_metadata(token_uri) do
     case HTTPoison.get(token_uri) do
       {:ok, %Response{body: body, status_code: 200}} ->
         Jason.decode(body)
@@ -67,8 +90,4 @@ defmodule Explorer.Token.InstanceMetadataRetriever do
 
       {:error, :request_error}
   end
-
-  defp fetch_json(result) do
-    {:error, result}
-  end
 end

From df38c83ca3ddcf19536ef3c6d57317cccd8fcf47 Mon Sep 17 00:00:00 2001
From: Ayrat Badykov <ayratin555@gmail.com>
Date: Fri, 4 Oct 2019 19:00:33 +0300
Subject: [PATCH 06/30] mix format

---
 apps/explorer/lib/explorer/token/instance_metadata_retriever.ex | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/apps/explorer/lib/explorer/token/instance_metadata_retriever.ex b/apps/explorer/lib/explorer/token/instance_metadata_retriever.ex
index 8b530934aa..9210bd0857 100644
--- a/apps/explorer/lib/explorer/token/instance_metadata_retriever.ex
+++ b/apps/explorer/lib/explorer/token/instance_metadata_retriever.ex
@@ -64,7 +64,7 @@ defmodule Explorer.Token.InstanceMetadataRetriever do
     e ->
       Logger.error(fn -> ["Unknown metadata format #{inspect(json)}. error #{inspect(e)}"] end)
 
-    {:error, json}
+      {:error, json}
   end
 
   defp fetch_json(result) do

From 2de98bf627b400996d00d32bcf8b4255a35e4d8c Mon Sep 17 00:00:00 2001
From: Ayrat Badykov <ayratin555@gmail.com>
Date: Mon, 7 Oct 2019 11:58:59 +0300
Subject: [PATCH 07/30] add indexes for token instances fetching queries

Without these indexes the query can not be finished.

But on staging requests for `tokenURI` are timing out.
That's why we have so many records with empty metadata.
---
 ...191007082500_add_indexes_for_token_instances_query.exs | 8 ++++++++
 1 file changed, 8 insertions(+)
 create mode 100644 apps/explorer/priv/repo/migrations/20191007082500_add_indexes_for_token_instances_query.exs

diff --git a/apps/explorer/priv/repo/migrations/20191007082500_add_indexes_for_token_instances_query.exs b/apps/explorer/priv/repo/migrations/20191007082500_add_indexes_for_token_instances_query.exs
new file mode 100644
index 0000000000..310f0fed02
--- /dev/null
+++ b/apps/explorer/priv/repo/migrations/20191007082500_add_indexes_for_token_instances_query.exs
@@ -0,0 +1,8 @@
+defmodule Explorer.Repo.Migrations.AddIndexesForTokenInstrancesQuery do
+  use Ecto.Migration
+
+  def change do
+    create_if_not_exists(index(:token_instances, [:token_id]))
+    create_if_not_exists(index(:tokens, [:type]))
+  end
+end

From 7fdd0496ae46647f3197fed4c60cf7e2dc060f45 Mon Sep 17 00:00:00 2001
From: Ayrat Badykov <ayratin555@gmail.com>
Date: Mon, 7 Oct 2019 12:08:24 +0300
Subject: [PATCH 08/30] add CHANGELOG entry

---
 CHANGELOG.md | 1 +
 1 file changed, 1 insertion(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 21543cfb98..fa519eba98 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -15,6 +15,7 @@
 - [#2642](https://github.com/poanetwork/blockscout/pull/2642) - add ERC721 coin instance page
 
 ### Fixes
+- [#2761](https://github.com/poanetwork/blockscout/pull/2761) - add indexes for token instances fetching queries
 - [#2750](https://github.com/poanetwork/blockscout/pull/2750) - fixed contract buttons color for NFT token instance on each theme
 - [#2746](https://github.com/poanetwork/blockscout/pull/2746) - fixed wrong alignment in logs decoded view
 - [#2745](https://github.com/poanetwork/blockscout/pull/2745) - optimize addresses page

From d34275d2feeb556b5efcd90e9c18e58874c0923f Mon Sep 17 00:00:00 2001
From: Ayrat Badykov <ayratin555@gmail.com>
Date: Mon, 7 Oct 2019 15:19:29 +0300
Subject: [PATCH 09/30] on-fly fetching of token instances

Currently, we have to restart indexer to fetch metadata
for newly imported ERC-721 token instances.

This PR triggers fetching of new token instances after blocks
imports in Catchup and Realtime fetchers.
---
 apps/explorer/lib/explorer/chain.ex           | 23 +++++++++++++++++++
 .../lib/indexer/block/catchup/fetcher.ex      |  2 ++
 apps/indexer/lib/indexer/block/fetcher.ex     |  7 ++++++
 .../lib/indexer/block/realtime/fetcher.ex     |  2 ++
 .../lib/indexer/fetcher/token_instance.ex     |  6 +++++
 5 files changed, 40 insertions(+)

diff --git a/apps/explorer/lib/explorer/chain.ex b/apps/explorer/lib/explorer/chain.ex
index b83b3fe3e3..468c969399 100644
--- a/apps/explorer/lib/explorer/chain.ex
+++ b/apps/explorer/lib/explorer/chain.ex
@@ -2954,6 +2954,29 @@ defmodule Explorer.Chain do
     Repo.stream_reduce(query, initial, reducer)
   end
 
+  def token_transfers_without_instances(token_transfers) do
+    token_contract_address_hashes =
+      token_transfers
+      |> Enum.map(fn token_transfer -> token_transfer.token_contract_address_hash end)
+      |> Enum.uniq()
+
+    query =
+      from(
+        token_transfer in TokenTransfer,
+        inner_join: token in Token,
+        on: token.contract_address_hash == token_transfer.token_contract_address_hash,
+        left_join: instance in Instance,
+        on: token_transfer.token_id == instance.token_id,
+        where:
+          token.type == ^"ERC-721" and is_nil(instance.token_id) and
+            token_transfer.token_contract_address_hash in ^token_contract_address_hashes,
+        distinct: [token_transfer.token_contract_address_hash, token_transfer.token_id],
+        select: %{contract_address_hash: token_transfer.token_contract_address_hash, token_id: token_transfer.token_id}
+      )
+
+    Repo.all(query)
+  end
+
   @doc """
   Streams a list of token contract addresses that have been cataloged.
   """
diff --git a/apps/indexer/lib/indexer/block/catchup/fetcher.ex b/apps/indexer/lib/indexer/block/catchup/fetcher.ex
index f228551a37..fb83147594 100644
--- a/apps/indexer/lib/indexer/block/catchup/fetcher.ex
+++ b/apps/indexer/lib/indexer/block/catchup/fetcher.ex
@@ -16,6 +16,7 @@ defmodule Indexer.Block.Catchup.Fetcher do
       async_import_replaced_transactions: 1,
       async_import_tokens: 1,
       async_import_token_balances: 1,
+      async_import_token_instances: 1,
       async_import_uncles: 1,
       fetch_and_import_range: 2
     ]
@@ -164,6 +165,7 @@ defmodule Indexer.Block.Catchup.Fetcher do
     async_import_token_balances(imported)
     async_import_uncles(imported)
     async_import_replaced_transactions(imported)
+    async_import_token_instances(imported)
   end
 
   defp stream_fetch_and_import(%__MODULE__{blocks_concurrency: blocks_concurrency} = state, sequence)
diff --git a/apps/indexer/lib/indexer/block/fetcher.ex b/apps/indexer/lib/indexer/block/fetcher.ex
index 7b51602ddf..9a2127ae15 100644
--- a/apps/indexer/lib/indexer/block/fetcher.ex
+++ b/apps/indexer/lib/indexer/block/fetcher.ex
@@ -25,6 +25,7 @@ defmodule Indexer.Block.Fetcher do
     StakingPools,
     Token,
     TokenBalance,
+    TokenInstance,
     UncleBlock
   }
 
@@ -229,6 +230,12 @@ defmodule Indexer.Block.Fetcher do
     callback_module.import(state, options_with_broadcast)
   end
 
+  def async_import_token_instances(%{token_transfers: token_transfers}) do
+    TokenInstance.async_fetch(token_transfers)
+  end
+
+  def async_import_token_instances(_), do: :ok
+
   def async_import_block_rewards([]), do: :ok
 
   def async_import_block_rewards(errors) when is_list(errors) do
diff --git a/apps/indexer/lib/indexer/block/realtime/fetcher.ex b/apps/indexer/lib/indexer/block/realtime/fetcher.ex
index 897eab2cff..c2ab8ea8d7 100644
--- a/apps/indexer/lib/indexer/block/realtime/fetcher.ex
+++ b/apps/indexer/lib/indexer/block/realtime/fetcher.ex
@@ -19,6 +19,7 @@ defmodule Indexer.Block.Realtime.Fetcher do
       async_import_replaced_transactions: 1,
       async_import_tokens: 1,
       async_import_token_balances: 1,
+      async_import_token_instances: 1,
       async_import_uncles: 1,
       fetch_and_import_range: 2,
       async_import_staking_pools: 0
@@ -358,6 +359,7 @@ defmodule Indexer.Block.Realtime.Fetcher do
     async_import_internal_transactions(imported, Keyword.get(json_rpc_named_arguments, :variant))
     async_import_tokens(imported)
     async_import_token_balances(imported)
+    async_import_token_instances(imported)
     async_import_uncles(imported)
     async_import_replaced_transactions(imported)
     async_import_staking_pools()
diff --git a/apps/indexer/lib/indexer/fetcher/token_instance.ex b/apps/indexer/lib/indexer/fetcher/token_instance.ex
index 32d9ac0064..7fb924f057 100644
--- a/apps/indexer/lib/indexer/fetcher/token_instance.ex
+++ b/apps/indexer/lib/indexer/fetcher/token_instance.ex
@@ -69,6 +69,12 @@ defmodule Indexer.Fetcher.TokenInstance do
   @doc """
   Fetches token instance data asynchronously.
   """
+  def async_fetch(token_transfers) when is_list(token_transfers) do
+    data = Chain.token_transfers_without_instances(token_transfers)
+
+    BufferedTask.buffer(__MODULE__, data)
+  end
+
   def async_fetch(data) do
     BufferedTask.buffer(__MODULE__, data)
   end

From 5e185349d646fe8a41407480d4d706467380910e Mon Sep 17 00:00:00 2001
From: Ayrat Badykov <ayratin555@gmail.com>
Date: Mon, 7 Oct 2019 15:23:29 +0300
Subject: [PATCH 10/30] add CHANGELOG entry

---
 CHANGELOG.md | 1 +
 1 file changed, 1 insertion(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 21543cfb98..e6f3d3ca75 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -13,6 +13,7 @@
 - [#2665](https://github.com/poanetwork/blockscout/pull/2665) - new menu layout for mobile devices
 - [#2663](https://github.com/poanetwork/blockscout/pull/2663) - Fetch address counters in parallel
 - [#2642](https://github.com/poanetwork/blockscout/pull/2642) - add ERC721 coin instance page
+- [#2762](https://github.com/poanetwork/blockscout/pull/2762) - on-fly fetching of token instances
 
 ### Fixes
 - [#2750](https://github.com/poanetwork/blockscout/pull/2750) - fixed contract buttons color for NFT token instance on each theme

From 851e17d2183a61dc52b05aea18b26ef4e964c0b1 Mon Sep 17 00:00:00 2001
From: Ayrat Badykov <ayratin555@gmail.com>
Date: Tue, 8 Oct 2019 12:39:26 +0300
Subject: [PATCH 11/30] fix logging

---
 apps/explorer/lib/explorer/token/instance_metadata_retriever.ex | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/apps/explorer/lib/explorer/token/instance_metadata_retriever.ex b/apps/explorer/lib/explorer/token/instance_metadata_retriever.ex
index 9210bd0857..b12920b975 100644
--- a/apps/explorer/lib/explorer/token/instance_metadata_retriever.ex
+++ b/apps/explorer/lib/explorer/token/instance_metadata_retriever.ex
@@ -68,7 +68,7 @@ defmodule Explorer.Token.InstanceMetadataRetriever do
   end
 
   defp fetch_json(result) do
-    Logger.error(fn -> ["Unknown metadata format #{result}."] end)
+    Logger.error(fn -> ["Unknown metadata format #{inspect(result)}."] end)
 
     {:error, result}
   end

From a73082a5fcac883841f04aca5a7eda08b587663a Mon Sep 17 00:00:00 2001
From: Ayrat Badykov <ayratin555@gmail.com>
Date: Tue, 8 Oct 2019 13:11:14 +0300
Subject: [PATCH 12/30] add error logging

---
 apps/indexer/lib/indexer/fetcher/token_instance.ex | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/apps/indexer/lib/indexer/fetcher/token_instance.ex b/apps/indexer/lib/indexer/fetcher/token_instance.ex
index 32d9ac0064..a47fe11280 100644
--- a/apps/indexer/lib/indexer/fetcher/token_instance.ex
+++ b/apps/indexer/lib/indexer/fetcher/token_instance.ex
@@ -6,6 +6,8 @@ defmodule Indexer.Fetcher.TokenInstance do
   use Indexer.Fetcher
   use Spandex.Decorators
 
+  require Logger
+
   alias Explorer.Chain
   alias Explorer.Token.InstanceMetadataRetriever
   alias Indexer.BufferedTask
@@ -59,7 +61,16 @@ defmodule Indexer.Fetcher.TokenInstance do
 
         {:ok, _result} = Chain.upsert_token_instance(params)
 
-      _other ->
+      result ->
+        Logger.error(fn ->
+          [
+            "failed to fetch token instance metadata for #{
+              inspect({to_string(token_contract_address_hash), Decimal.to_integer(token_id)})
+            }: ",
+            inspect(result)
+          ]
+        end)
+
         :ok
     end
 

From cc894096358ee9e7b0b88be5250a9c6ba8896b25 Mon Sep 17 00:00:00 2001
From: YegorSan <egorgolovan89@gmail.com>
Date: Tue, 8 Oct 2019 13:54:25 +0300
Subject: [PATCH 13/30] fixed broken mobile view for cards on transaction
 details page

---
 apps/block_scout_web/assets/css/components/_card.scss  | 10 +++++++++-
 .../templates/transaction/overview.html.eex            |  2 +-
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/apps/block_scout_web/assets/css/components/_card.scss b/apps/block_scout_web/assets/css/components/_card.scss
index 8fff120deb..fee262ebd4 100644
--- a/apps/block_scout_web/assets/css/components/_card.scss
+++ b/apps/block_scout_web/assets/css/components/_card.scss
@@ -34,7 +34,9 @@ $card-tab-icon-color-active: #fff !default;
 .card-background-1 {
   background-color: $card-background-1;
   color: $card-background-1-text-color;
-
+  @include media-breakpoint-down(sm) {
+    margin-left: 15px;
+  }
   a:not(.dropdown-item),
   a:not(.dropdown-item):hover {
     color: $card-background-1-text-color;
@@ -249,3 +251,9 @@ $card-tab-icon-color-active: #fff !default;
     }
   }
 }
+
+.mob-transaction {
+  @include media-breakpoint-down(sm) {
+    margin-left: 15px!important;
+  } 
+}
\ No newline at end of file
diff --git a/apps/block_scout_web/lib/block_scout_web/templates/transaction/overview.html.eex b/apps/block_scout_web/lib/block_scout_web/templates/transaction/overview.html.eex
index 0f3095f4c4..b52a41c8c4 100644
--- a/apps/block_scout_web/lib/block_scout_web/templates/transaction/overview.html.eex
+++ b/apps/block_scout_web/lib/block_scout_web/templates/transaction/overview.html.eex
@@ -227,7 +227,7 @@
       </div>
     <% end %>
       <!-- Gas -->
-      <div class="card flex-grow-1 ml-0 ml-md-5 ml-lg-0">
+      <div class="card flex-grow-1 ml-0 ml-md-5 ml-lg-0 mob-transaction">
         <div class="card-body card-body-flex-column-space-between">
           <h2 class="card-title balance-card-title"> <%= gettext "Gas" %> </h2>
           <div class="text-right">

From e1f89f363e0a8e8309b2bda6d0003da8d26bc7c5 Mon Sep 17 00:00:00 2001
From: YegorSan <egorgolovan89@gmail.com>
Date: Tue, 8 Oct 2019 14:03:58 +0300
Subject: [PATCH 14/30] Updated Changelog

---
 CHANGELOG.md | 1 +
 1 file changed, 1 insertion(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 21543cfb98..57a3da8f5c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -15,6 +15,7 @@
 - [#2642](https://github.com/poanetwork/blockscout/pull/2642) - add ERC721 coin instance page
 
 ### Fixes
+- [#2765](https://github.com/poanetwork/blockscout/pull/2765) - fixed width issue for cards in mobile view for Transaction Details page
 - [#2750](https://github.com/poanetwork/blockscout/pull/2750) - fixed contract buttons color for NFT token instance on each theme
 - [#2746](https://github.com/poanetwork/blockscout/pull/2746) - fixed wrong alignment in logs decoded view
 - [#2745](https://github.com/poanetwork/blockscout/pull/2745) - optimize addresses page

From 971a8831c85f03ae2502f24cf3aeaa183f5bb2df Mon Sep 17 00:00:00 2001
From: Ayrat Badykov <ayratin555@gmail.com>
Date: Tue, 8 Oct 2019 14:04:05 +0300
Subject: [PATCH 15/30] fix token instances query

---
 apps/explorer/lib/explorer/chain.ex | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/apps/explorer/lib/explorer/chain.ex b/apps/explorer/lib/explorer/chain.ex
index d7b031cd51..19d286c61e 100644
--- a/apps/explorer/lib/explorer/chain.ex
+++ b/apps/explorer/lib/explorer/chain.ex
@@ -2945,7 +2945,7 @@ defmodule Explorer.Chain do
         inner_join: token in Token,
         on: token.contract_address_hash == token_transfer.token_contract_address_hash,
         left_join: instance in Instance,
-        on: token_transfer.token_id == instance.token_id,
+        on: token_transfer.token_id == instance.token_id and token_transfer.token_contract_address_hash == instance.token_contract_address_hash,
         where: token.type == ^"ERC-721" and is_nil(instance.token_id) and not is_nil(token_transfer.token_id),
         distinct: [token_transfer.token_contract_address_hash, token_transfer.token_id],
         select: %{contract_address_hash: token_transfer.token_contract_address_hash, token_id: token_transfer.token_id}

From 017b053be6b6324922f97249b2ac1a0c36d25494 Mon Sep 17 00:00:00 2001
From: Ayrat Badykov <ayratin555@gmail.com>
Date: Tue, 8 Oct 2019 14:07:08 +0300
Subject: [PATCH 16/30] fix query

---
 apps/explorer/lib/explorer/chain.ex | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/apps/explorer/lib/explorer/chain.ex b/apps/explorer/lib/explorer/chain.ex
index 468c969399..e9f8f92761 100644
--- a/apps/explorer/lib/explorer/chain.ex
+++ b/apps/explorer/lib/explorer/chain.ex
@@ -2966,9 +2966,11 @@ defmodule Explorer.Chain do
         inner_join: token in Token,
         on: token.contract_address_hash == token_transfer.token_contract_address_hash,
         left_join: instance in Instance,
-        on: token_transfer.token_id == instance.token_id,
+        on:
+          token_transfer.token_id == instance.token_id and
+            token_transfer.token_contract_address_hash == instance.token_contract_address_hash,
         where:
-          token.type == ^"ERC-721" and is_nil(instance.token_id) and
+          token.type == ^"ERC-721" and is_nil(instance.token_id) and not is_nil(token_transfer.token_id) and
             token_transfer.token_contract_address_hash in ^token_contract_address_hashes,
         distinct: [token_transfer.token_contract_address_hash, token_transfer.token_id],
         select: %{contract_address_hash: token_transfer.token_contract_address_hash, token_id: token_transfer.token_id}

From 1bb57dd524fc2b3f1030fc5805d0b920659b9348 Mon Sep 17 00:00:00 2001
From: Ayrat Badykov <ayratin555@gmail.com>
Date: Tue, 8 Oct 2019 14:08:20 +0300
Subject: [PATCH 17/30] mix format

---
 apps/explorer/lib/explorer/chain.ex | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/apps/explorer/lib/explorer/chain.ex b/apps/explorer/lib/explorer/chain.ex
index 19d286c61e..7b56fee605 100644
--- a/apps/explorer/lib/explorer/chain.ex
+++ b/apps/explorer/lib/explorer/chain.ex
@@ -2945,7 +2945,9 @@ defmodule Explorer.Chain do
         inner_join: token in Token,
         on: token.contract_address_hash == token_transfer.token_contract_address_hash,
         left_join: instance in Instance,
-        on: token_transfer.token_id == instance.token_id and token_transfer.token_contract_address_hash == instance.token_contract_address_hash,
+        on:
+          token_transfer.token_id == instance.token_id and
+            token_transfer.token_contract_address_hash == instance.token_contract_address_hash,
         where: token.type == ^"ERC-721" and is_nil(instance.token_id) and not is_nil(token_transfer.token_id),
         distinct: [token_transfer.token_contract_address_hash, token_transfer.token_id],
         select: %{contract_address_hash: token_transfer.token_contract_address_hash, token_id: token_transfer.token_id}

From e644949b8dd24e176a481c850c518a79a811b80f Mon Sep 17 00:00:00 2001
From: Ayrat Badykov <ayratin555@gmail.com>
Date: Tue, 8 Oct 2019 15:47:45 +0300
Subject: [PATCH 18/30] do not make heavy db request

---
 apps/explorer/lib/explorer/chain.ex           | 25 -------------------
 .../lib/indexer/fetcher/token_instance.ex     |  8 +++++-
 2 files changed, 7 insertions(+), 26 deletions(-)

diff --git a/apps/explorer/lib/explorer/chain.ex b/apps/explorer/lib/explorer/chain.ex
index e9f8f92761..b83b3fe3e3 100644
--- a/apps/explorer/lib/explorer/chain.ex
+++ b/apps/explorer/lib/explorer/chain.ex
@@ -2954,31 +2954,6 @@ defmodule Explorer.Chain do
     Repo.stream_reduce(query, initial, reducer)
   end
 
-  def token_transfers_without_instances(token_transfers) do
-    token_contract_address_hashes =
-      token_transfers
-      |> Enum.map(fn token_transfer -> token_transfer.token_contract_address_hash end)
-      |> Enum.uniq()
-
-    query =
-      from(
-        token_transfer in TokenTransfer,
-        inner_join: token in Token,
-        on: token.contract_address_hash == token_transfer.token_contract_address_hash,
-        left_join: instance in Instance,
-        on:
-          token_transfer.token_id == instance.token_id and
-            token_transfer.token_contract_address_hash == instance.token_contract_address_hash,
-        where:
-          token.type == ^"ERC-721" and is_nil(instance.token_id) and not is_nil(token_transfer.token_id) and
-            token_transfer.token_contract_address_hash in ^token_contract_address_hashes,
-        distinct: [token_transfer.token_contract_address_hash, token_transfer.token_id],
-        select: %{contract_address_hash: token_transfer.token_contract_address_hash, token_id: token_transfer.token_id}
-      )
-
-    Repo.all(query)
-  end
-
   @doc """
   Streams a list of token contract addresses that have been cataloged.
   """
diff --git a/apps/indexer/lib/indexer/fetcher/token_instance.ex b/apps/indexer/lib/indexer/fetcher/token_instance.ex
index 7fb924f057..2312761446 100644
--- a/apps/indexer/lib/indexer/fetcher/token_instance.ex
+++ b/apps/indexer/lib/indexer/fetcher/token_instance.ex
@@ -70,7 +70,13 @@ defmodule Indexer.Fetcher.TokenInstance do
   Fetches token instance data asynchronously.
   """
   def async_fetch(token_transfers) when is_list(token_transfers) do
-    data = Chain.token_transfers_without_instances(token_transfers)
+    data =
+      token_transfers
+      |> Enum.reject(fn token_transfer -> is_nil(token_transfer.token_id) end)
+      |> Enum.map(fn token_transfer ->
+        %{contract_address_hash: token_transfer.token_contract_address_hash, token_id: token_transfer.token_id}
+      end)
+      |> Enum.uniq()
 
     BufferedTask.buffer(__MODULE__, data)
   end

From 00529d922e99ec9a525575fc025f32ea1f643bed Mon Sep 17 00:00:00 2001
From: Ayrat Badykov <ayratin555@gmail.com>
Date: Wed, 9 Oct 2019 10:39:18 +0300
Subject: [PATCH 19/30] fix websocket subscriptions with token instances

---
 .../lib/block_scout_web/templates/transaction/_tile.html.eex  | 4 ++--
 .../templates/transaction/_token_transfer.html.eex            | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/apps/block_scout_web/lib/block_scout_web/templates/transaction/_tile.html.eex b/apps/block_scout_web/lib/block_scout_web/templates/transaction/_tile.html.eex
index 85711ca136..91a7d9973a 100644
--- a/apps/block_scout_web/lib/block_scout_web/templates/transaction/_tile.html.eex
+++ b/apps/block_scout_web/lib/block_scout_web/templates/transaction/_tile.html.eex
@@ -38,11 +38,11 @@
         <div class="d-flex flex-column mt-2">
           <% [first_token_transfer | remaining_token_transfers] = @transaction.token_transfers %>
 
-          <%= render "_token_transfer.html", address: assigns[:current_address], token_transfer: first_token_transfer, conn: @conn %>
+          <%= render "_token_transfer.html", address: assigns[:current_address], token_transfer: first_token_transfer %>
 
           <div class="collapse token-transfer-toggle" id="transaction-<%= @transaction.hash %>">
             <%= for token_transfer <- remaining_token_transfers do %>
-              <%= render "_token_transfer.html", address: assigns[:current_address], token_transfer: token_transfer, conn: @conn %>
+              <%= render "_token_transfer.html", address: assigns[:current_address], token_transfer: token_transfer %>
             <% end %>
           </div>
         </div>
diff --git a/apps/block_scout_web/lib/block_scout_web/templates/transaction/_token_transfer.html.eex b/apps/block_scout_web/lib/block_scout_web/templates/transaction/_token_transfer.html.eex
index 4926406a12..1a5024d14d 100644
--- a/apps/block_scout_web/lib/block_scout_web/templates/transaction/_token_transfer.html.eex
+++ b/apps/block_scout_web/lib/block_scout_web/templates/transaction/_token_transfer.html.eex
@@ -22,7 +22,7 @@
   <span class="col-xs-12 col-lg-4 ml-3 ml-sm-0 text-truncate">
     <%= case token_transfer_amount(@token_transfer) do %>
       <% {:ok, :erc721_instance} -> %>
-        <%= "TokenID ["%><%= link(@token_transfer.token_id, to: token_instance_path(@conn, :show,  @token_transfer.token.contract_address_hash, to_string(@token_transfer.token_id))) %><%= "] " %>
+        <%= "TokenID ["%><%= link(@token_transfer.token_id, to: token_instance_path(BlockScoutWeb.Endpoint, :show,  @token_transfer.token.contract_address_hash, to_string(@token_transfer.token_id))) %><%= "] " %>
       <% {:ok, value} -> %>
         <%= "#{value} " %>
     <% end %>

From ca309afaa74e180ce9a1f6ff74b1c30085a55f71 Mon Sep 17 00:00:00 2001
From: Ayrat Badykov <ayratin555@gmail.com>
Date: Thu, 10 Oct 2019 11:09:05 +0300
Subject: [PATCH 20/30] add error field to token instances

---
 apps/explorer/lib/explorer/chain/token/instance.ex    |  7 +++++--
 .../20191010075740_add_error_to_token_instances.exs   | 11 +++++++++++
 2 files changed, 16 insertions(+), 2 deletions(-)
 create mode 100644 apps/explorer/priv/repo/migrations/20191010075740_add_error_to_token_instances.exs

diff --git a/apps/explorer/lib/explorer/chain/token/instance.ex b/apps/explorer/lib/explorer/chain/token/instance.ex
index 0e704650a0..a986f974bc 100644
--- a/apps/explorer/lib/explorer/chain/token/instance.ex
+++ b/apps/explorer/lib/explorer/chain/token/instance.ex
@@ -12,18 +12,21 @@ defmodule Explorer.Chain.Token.Instance do
   * `token_id` - ID of the token
   * `token_contract_address_hash` - Address hash foreign key
   * `metadata` - Token instance metadata
+  * `error` - error fetching token instance
   """
 
   @type t :: %Instance{
           token_id: non_neg_integer(),
           token_contract_address_hash: Hash.Address.t(),
-          metadata: Map.t()
+          metadata: Map.t(),
+          error: String.t()
         }
 
   @primary_key false
   schema "token_instances" do
     field(:token_id, :decimal, primary_key: true)
     field(:metadata, :map)
+    field(:error, :string)
 
     belongs_to(
       :token,
@@ -39,7 +42,7 @@ defmodule Explorer.Chain.Token.Instance do
 
   def changeset(%Instance{} = instance, params \\ %{}) do
     instance
-    |> cast(params, [:token_id, :metadata, :token_contract_address_hash])
+    |> cast(params, [:token_id, :metadata, :token_contract_address_hash, :error])
     |> validate_required([:token_id, :token_contract_address_hash])
     |> foreign_key_constraint(:token_contract_address_hash)
   end
diff --git a/apps/explorer/priv/repo/migrations/20191010075740_add_error_to_token_instances.exs b/apps/explorer/priv/repo/migrations/20191010075740_add_error_to_token_instances.exs
new file mode 100644
index 0000000000..a2a9e6a8a5
--- /dev/null
+++ b/apps/explorer/priv/repo/migrations/20191010075740_add_error_to_token_instances.exs
@@ -0,0 +1,11 @@
+defmodule Explorer.Repo.Migrations.AddErrorToTokenInstances do
+  use Ecto.Migration
+
+  def change do
+    alter table(:token_instances) do
+      add(:error, :string)
+    end
+
+    create(index(:token_instances, [:error]))
+  end
+end

From 483beaa10d9c3f0630f6d53a63bc9821ac725495 Mon Sep 17 00:00:00 2001
From: Ayrat Badykov <ayratin555@gmail.com>
Date: Thu, 10 Oct 2019 11:25:04 +0300
Subject: [PATCH 21/30] do not fetch token instances with errors

---
 apps/explorer/lib/explorer/chain.ex           |  4 ++-
 apps/explorer/test/explorer/chain_test.exs    | 36 +++++++++++++++++++
 apps/explorer/test/support/factory.ex         |  3 +-
 .../lib/indexer/fetcher/token_instance.ex     |  3 +-
 4 files changed, 43 insertions(+), 3 deletions(-)

diff --git a/apps/explorer/lib/explorer/chain.ex b/apps/explorer/lib/explorer/chain.ex
index b83b3fe3e3..cb6b1363cb 100644
--- a/apps/explorer/lib/explorer/chain.ex
+++ b/apps/explorer/lib/explorer/chain.ex
@@ -3208,7 +3208,9 @@ defmodule Explorer.Chain do
       from(tt in TokenTransfer,
         left_join: instance in Instance,
         on: tt.token_contract_address_hash == instance.token_contract_address_hash and tt.token_id == instance.token_id,
-        where: tt.token_contract_address_hash == ^token_contract_address and tt.token_id == ^token_id,
+        where:
+          tt.token_contract_address_hash == ^token_contract_address and tt.token_id == ^token_id and
+            is_nil(instance.error),
         limit: 1,
         select: %{tt | instance: instance}
       )
diff --git a/apps/explorer/test/explorer/chain_test.exs b/apps/explorer/test/explorer/chain_test.exs
index c623ea2d4c..85a08e7312 100644
--- a/apps/explorer/test/explorer/chain_test.exs
+++ b/apps/explorer/test/explorer/chain_test.exs
@@ -173,6 +173,42 @@ defmodule Explorer.ChainTest do
          valid?: false
        }} = Chain.upsert_token_instance(params)
     end
+
+    test "inserts just an error without metadata" do
+      token = insert(:token)
+      error = "no uri"
+
+      params = %{
+        token_id: 1,
+        token_contract_address_hash: token.contract_address_hash,
+        error: error
+      }
+
+      {:ok, result} = Chain.upsert_token_instance(params)
+
+      assert result.error == error
+    end
+
+    test "nillifies error" do
+      token = insert(:token)
+
+      insert(:token_instance,
+        token_id: 1,
+        token_contract_address_hash: token.contract_address_hash,
+        error: "no uri"
+      )
+
+      params = %{
+        token_id: 1,
+        token_contract_address_hash: token.contract_address_hash,
+        metadata: %{uri: "http://example1.com"}
+      }
+
+      {:ok, result} = Chain.upsert_token_instance(params)
+
+      assert is_nil(result.error)
+      assert result.metadata == params.metadata
+    end
   end
 
   describe "address_to_logs/2" do
diff --git a/apps/explorer/test/support/factory.ex b/apps/explorer/test/support/factory.ex
index edad876a8b..b2a1feeac6 100644
--- a/apps/explorer/test/support/factory.ex
+++ b/apps/explorer/test/support/factory.ex
@@ -547,7 +547,8 @@ defmodule Explorer.Factory do
     %Instance{
       token_contract_address_hash: build(:address),
       token_id: 5,
-      metadata: %{key: "value"}
+      metadata: %{key: "value"},
+      error: nil
     }
   end
 
diff --git a/apps/indexer/lib/indexer/fetcher/token_instance.ex b/apps/indexer/lib/indexer/fetcher/token_instance.ex
index 32d9ac0064..84e987aefa 100644
--- a/apps/indexer/lib/indexer/fetcher/token_instance.ex
+++ b/apps/indexer/lib/indexer/fetcher/token_instance.ex
@@ -54,7 +54,8 @@ defmodule Indexer.Fetcher.TokenInstance do
         params = %{
           token_id: token_id,
           token_contract_address_hash: token_contract_address_hash,
-          metadata: metadata
+          metadata: metadata,
+          error: nil
         }
 
         {:ok, _result} = Chain.upsert_token_instance(params)

From 1fefec100f04a3f2bf05e12c3d8102b395feebd4 Mon Sep 17 00:00:00 2001
From: Ayrat Badykov <ayratin555@gmail.com>
Date: Thu, 10 Oct 2019 12:28:59 +0300
Subject: [PATCH 22/30] save no uri error to instance

---
 .../lib/explorer/token/instance_metadata_retriever.ex | 10 ++++++++--
 apps/indexer/lib/indexer/fetcher/token_instance.ex    | 11 ++++++++++-
 2 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/apps/explorer/lib/explorer/token/instance_metadata_retriever.ex b/apps/explorer/lib/explorer/token/instance_metadata_retriever.ex
index a4cf460e74..1080b932d1 100644
--- a/apps/explorer/lib/explorer/token/instance_metadata_retriever.ex
+++ b/apps/explorer/lib/explorer/token/instance_metadata_retriever.ex
@@ -29,6 +29,8 @@ defmodule Explorer.Token.InstanceMetadataRetriever do
 
   @cryptokitties_address_hash "0x06012c8cf97bead5deae237070f9587f8e7a266d"
 
+  @no_uri_error "no uri"
+
   def fetch_metadata(unquote(@cryptokitties_address_hash), token_id) do
     %{"tokenURI" => {:ok, ["https://api.cryptokitties.co/kitties/#{token_id}"]}}
     |> fetch_json()
@@ -47,13 +49,17 @@ defmodule Explorer.Token.InstanceMetadataRetriever do
   end
 
   defp fetch_json(%{"tokenURI" => {:ok, [""]}}) do
-    {:error, :no_uri}
+    {:ok, %{error: @no_uri_error}}
+  end
+
+  defp fetch_json(%{"tokenURI" => {:error, "(-32015) VM execution error."}}) do
+    {:ok, %{error: @no_uri_error}}
   end
 
   defp fetch_json(%{"tokenURI" => {:ok, [token_uri]}}) do
     case HTTPoison.get(token_uri) do
       {:ok, %Response{body: body, status_code: 200}} ->
-        Jason.decode(body)
+        %{metadata: Jason.decode(body)}
 
       {:ok, %Response{body: body}} ->
         {:error, body}
diff --git a/apps/indexer/lib/indexer/fetcher/token_instance.ex b/apps/indexer/lib/indexer/fetcher/token_instance.ex
index 84e987aefa..35bb589d1c 100644
--- a/apps/indexer/lib/indexer/fetcher/token_instance.ex
+++ b/apps/indexer/lib/indexer/fetcher/token_instance.ex
@@ -50,7 +50,7 @@ defmodule Indexer.Fetcher.TokenInstance do
   @impl BufferedTask
   def run([%{contract_address_hash: token_contract_address_hash, token_id: token_id}], _json_rpc_named_arguments) do
     case InstanceMetadataRetriever.fetch_metadata(to_string(token_contract_address_hash), Decimal.to_integer(token_id)) do
-      {:ok, metadata} ->
+      {:ok, %{metadata: metadata}} ->
         params = %{
           token_id: token_id,
           token_contract_address_hash: token_contract_address_hash,
@@ -60,6 +60,15 @@ defmodule Indexer.Fetcher.TokenInstance do
 
         {:ok, _result} = Chain.upsert_token_instance(params)
 
+      {:ok, %{error: error}} ->
+        params = %{
+          token_id: token_id,
+          token_contract_address_hash: token_contract_address_hash,
+          error: error
+        }
+
+        {:ok, _result} = Chain.upsert_token_instance(params)
+
       _other ->
         :ok
     end

From 2df6d0f85d454923f8f7a7f05c8eda4de001fdbc Mon Sep 17 00:00:00 2001
From: Ayrat Badykov <ayratin555@gmail.com>
Date: Thu, 10 Oct 2019 12:40:36 +0300
Subject: [PATCH 23/30] fix dialyzer

---
 .../lib/explorer/token/instance_metadata_retriever.ex         | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/apps/explorer/lib/explorer/token/instance_metadata_retriever.ex b/apps/explorer/lib/explorer/token/instance_metadata_retriever.ex
index 1080b932d1..8b09ca8521 100644
--- a/apps/explorer/lib/explorer/token/instance_metadata_retriever.ex
+++ b/apps/explorer/lib/explorer/token/instance_metadata_retriever.ex
@@ -59,7 +59,9 @@ defmodule Explorer.Token.InstanceMetadataRetriever do
   defp fetch_json(%{"tokenURI" => {:ok, [token_uri]}}) do
     case HTTPoison.get(token_uri) do
       {:ok, %Response{body: body, status_code: 200}} ->
-        %{metadata: Jason.decode(body)}
+        {:ok, json} = Jason.decode(body)
+
+        {:ok, %{metadata: json}}
 
       {:ok, %Response{body: body}} ->
         {:error, body}

From 054d38117ceb8a4cb1b203eee94fd4a8e470c3ee Mon Sep 17 00:00:00 2001
From: Ayrat Badykov <ayratin555@gmail.com>
Date: Thu, 10 Oct 2019 13:50:20 +0300
Subject: [PATCH 24/30] add CHANGELOG entry

---
 CHANGELOG.md | 1 +
 1 file changed, 1 insertion(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index b26ab858ad..b1cba5bdf7 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -15,6 +15,7 @@
 - [#2642](https://github.com/poanetwork/blockscout/pull/2642) - add ERC721 coin instance page
 
 ### Fixes
+- [#2770](https://github.com/poanetwork/blockscout/pull/2770) - do not re-fetch token instances without uris
 - [#2753](https://github.com/poanetwork/blockscout/pull/2753) - fix nft token instance images
 - [#2750](https://github.com/poanetwork/blockscout/pull/2750) - fixed contract buttons color for NFT token instance on each theme
 - [#2746](https://github.com/poanetwork/blockscout/pull/2746) - fixed wrong alignment in logs decoded view

From 47a44a50a9b944569b220f538b56225905f20b62 Mon Sep 17 00:00:00 2001
From: Ayrat Badykov <ayratin555@gmail.com>
Date: Fri, 11 Oct 2019 11:36:53 +0300
Subject: [PATCH 25/30] fix not found token instance

---
 apps/explorer/lib/explorer/chain.ex | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/apps/explorer/lib/explorer/chain.ex b/apps/explorer/lib/explorer/chain.ex
index cb6b1363cb..b83b3fe3e3 100644
--- a/apps/explorer/lib/explorer/chain.ex
+++ b/apps/explorer/lib/explorer/chain.ex
@@ -3208,9 +3208,7 @@ defmodule Explorer.Chain do
       from(tt in TokenTransfer,
         left_join: instance in Instance,
         on: tt.token_contract_address_hash == instance.token_contract_address_hash and tt.token_id == instance.token_id,
-        where:
-          tt.token_contract_address_hash == ^token_contract_address and tt.token_id == ^token_id and
-            is_nil(instance.error),
+        where: tt.token_contract_address_hash == ^token_contract_address and tt.token_id == ^token_id,
         limit: 1,
         select: %{tt | instance: instance}
       )

From de2681563228a7e40d303022adad90152942b382 Mon Sep 17 00:00:00 2001
From: Ayrat Badykov <ayratin555@gmail.com>
Date: Fri, 11 Oct 2019 13:47:08 +0300
Subject: [PATCH 26/30] add token instance images to inventory tab

---
 apps/block_scout_web/assets/css/app.scss               |  1 +
 .../_inventory_token_instance_image_container.scss     | 10 ++++++++++
 .../templates/tokens/inventory/_token.html.eex         |  7 +++++++
 .../lib/block_scout_web/views/tokens/inventory_view.ex |  2 ++
 apps/explorer/lib/explorer/chain/token_transfer.ex     |  6 ++++--
 5 files changed, 24 insertions(+), 2 deletions(-)
 create mode 100644 apps/block_scout_web/assets/css/components/_inventory_token_instance_image_container.scss

diff --git a/apps/block_scout_web/assets/css/app.scss b/apps/block_scout_web/assets/css/app.scss
index a6c5e40c01..a67984dc44 100644
--- a/apps/block_scout_web/assets/css/app.scss
+++ b/apps/block_scout_web/assets/css/app.scss
@@ -116,6 +116,7 @@ $fa-font-path: "~@fortawesome/fontawesome-free/webfonts";
 @import "components/btn_no_border";
 @import "components/custom_tooltips_block_details";
 @import "components/_erc721_token_image_container";
+@import "components/_inventory_token_instance_image_container";
 
 @import "theme/dark-theme";
 
diff --git a/apps/block_scout_web/assets/css/components/_inventory_token_instance_image_container.scss b/apps/block_scout_web/assets/css/components/_inventory_token_instance_image_container.scss
new file mode 100644
index 0000000000..b895a0e4cf
--- /dev/null
+++ b/apps/block_scout_web/assets/css/components/_inventory_token_instance_image_container.scss
@@ -0,0 +1,10 @@
+/* ERC721 image block */
+.inventory-erc721-image {
+    display: flex;
+    justify-content: center;
+}
+
+ .inventory-erc721-image img {
+    height: 50px;
+}
+/* ERC721 image block end */
diff --git a/apps/block_scout_web/lib/block_scout_web/templates/tokens/inventory/_token.html.eex b/apps/block_scout_web/lib/block_scout_web/templates/tokens/inventory/_token.html.eex
index c3fea04269..b99b082468 100644
--- a/apps/block_scout_web/lib/block_scout_web/templates/tokens/inventory/_token.html.eex
+++ b/apps/block_scout_web/lib/block_scout_web/templates/tokens/inventory/_token.html.eex
@@ -24,5 +24,12 @@
         </span>
       </span>
     </div>
+
+    <div class="pl-5 col-md-2 d-flex flex-column align-items-left justify-content-start justify-content-lg-center">
+      <!-- substitute the span with <img class="tile-image" /> to token with images -->
+      <div class="inventory-erc721-image" >
+        <img src=<%=image_src(@token_transfer.instance)%> />
+      </div>
+    </div>
   </div>
 </div>
diff --git a/apps/block_scout_web/lib/block_scout_web/views/tokens/inventory_view.ex b/apps/block_scout_web/lib/block_scout_web/views/tokens/inventory_view.ex
index 6c3f3a6845..ca7b6de94a 100644
--- a/apps/block_scout_web/lib/block_scout_web/views/tokens/inventory_view.ex
+++ b/apps/block_scout_web/lib/block_scout_web/views/tokens/inventory_view.ex
@@ -1,5 +1,7 @@
 defmodule BlockScoutWeb.Tokens.InventoryView do
   use BlockScoutWeb, :view
 
+  import BlockScoutWeb.Tokens.Instance.OverviewView, only: [image_src: 1]
+
   alias BlockScoutWeb.Tokens.OverviewView
 end
diff --git a/apps/explorer/lib/explorer/chain/token_transfer.ex b/apps/explorer/lib/explorer/chain/token_transfer.ex
index 216a01daf0..ef0cb4e876 100644
--- a/apps/explorer/lib/explorer/chain/token_transfer.ex
+++ b/apps/explorer/lib/explorer/chain/token_transfer.ex
@@ -278,11 +278,13 @@ defmodule Explorer.Chain.TokenTransfer do
   def address_to_unique_tokens(contract_address_hash) do
     from(
       tt in TokenTransfer,
-      where: tt.token_contract_address_hash == ^contract_address_hash,
+      left_join: instance in Instance,
+      on: tt.token_contract_address_hash == instance.token_contract_address_hash and tt.token_id == instance.token_id,
+      where: tt.token_contract_address_hash == ^contract_address_hash and tt.token_id == tt.token_id,
       order_by: [desc: tt.block_number],
       distinct: tt.token_id,
       preload: [:to_address],
-      select: tt
+      select: %{tt | instance: instance}
     )
   end
 end

From 3cdda22ab71787acef021399bca8e1e9c9abc93d Mon Sep 17 00:00:00 2001
From: Ayrat Badykov <ayratin555@gmail.com>
Date: Fri, 11 Oct 2019 13:52:49 +0300
Subject: [PATCH 27/30] add CHANGELOG entry

---
 CHANGELOG.md | 1 +
 1 file changed, 1 insertion(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 88b8f36ae7..71b5412749 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,7 @@
 ## Current
 
 ### Features
+- [#2772](https://github.com/poanetwork/blockscout/pull/2772) - add token instance images to the token inventory tab
 - [#2733](https://github.com/poanetwork/blockscout/pull/2733) - Add cache for first page of uncles
 - [#2735](https://github.com/poanetwork/blockscout/pull/2735) - Add pending transactions cache
 - [#2726](https://github.com/poanetwork/blockscout/pull/2726) - Remove internal_transaction block_number setting from blocks runner

From e8c2fa554ea18e42f8a9b2458f35382fa824d3f7 Mon Sep 17 00:00:00 2001
From: pasqu4le <pasqu4le@gmail.com>
Date: Tue, 30 Jul 2019 14:07:16 +0200
Subject: [PATCH 28/30] Allow Realtime Fetcher to wait for small skips

Problem: Sometimes the realtime fetcher's `newHeads` websocket subscription skips a small amount of block numbers, just to be followed by those very same numbers that were skipped, without repeating the number that caused the skipping.
This may be cause by out-of-order events or be a legitimate reorg, but in any case this causes close-in-time refetching which in turn leads to async insertions problems.

Solution: allow the Realtime fetcher to keep track of a small (settable) skip and wait for the block number inside the skip to arrive before fetching the whole window.
Obviously if it gets notified of the blocks following the skip (or it is forced into polling) the whole window gets fetched and inserted.
---
 CHANGELOG.md                                  |  1 +
 apps/indexer/config/config.exs                |  9 ++-
 .../lib/indexer/block/catchup/fetcher.ex      | 30 +++++----
 .../lib/indexer/block/realtime/fetcher.ex     | 64 +++++++++++++------
 .../bound_interval_supervisor_test.exs        |  5 ++
 .../indexer/block/catchup/fetcher_test.exs    |  5 ++
 .../indexer/block/realtime/fetcher_test.exs   | 52 +++++++++++++++
 docs/env-variables.md                         |  1 +
 8 files changed, 133 insertions(+), 34 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 88b8f36ae7..01d62268b2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,7 @@
 ## Current
 
 ### Features
+- [#2470](https://github.com/poanetwork/blockscout/pull/2470) - Allow Realtime Fetcher to wait for small skips
 - [#2733](https://github.com/poanetwork/blockscout/pull/2733) - Add cache for first page of uncles
 - [#2735](https://github.com/poanetwork/blockscout/pull/2735) - Add pending transactions cache
 - [#2726](https://github.com/poanetwork/blockscout/pull/2726) - Remove internal_transaction block_number setting from blocks runner
diff --git a/apps/indexer/config/config.exs b/apps/indexer/config/config.exs
index 071f741a74..1eb4d1a16f 100644
--- a/apps/indexer/config/config.exs
+++ b/apps/indexer/config/config.exs
@@ -28,6 +28,12 @@ block_transformer =
       transformer
   end
 
+max_skipping_distance =
+  case Integer.parse(System.get_env("MAX_SKIPPING_DISTANCE", "")) do
+    {num, ""} -> num
+    _ -> 5
+  end
+
 config :indexer,
   block_transformer: block_transformer,
   ecto_repos: [Explorer.Repo],
@@ -36,7 +42,8 @@ config :indexer,
   # bytes
   memory_limit: 1 <<< 30,
   first_block: System.get_env("FIRST_BLOCK") || "0",
-  last_block: System.get_env("LAST_BLOCK") || ""
+  last_block: System.get_env("LAST_BLOCK") || "",
+  max_skipping_distance: max_skipping_distance
 
 # config :indexer, Indexer.Fetcher.ReplacedTransaction.Supervisor, disabled?: true
 # config :indexer, Indexer.Fetcher.BlockReward.Supervisor, disabled?: true
diff --git a/apps/indexer/lib/indexer/block/catchup/fetcher.ex b/apps/indexer/lib/indexer/block/catchup/fetcher.ex
index f228551a37..f9f201caba 100644
--- a/apps/indexer/lib/indexer/block/catchup/fetcher.ex
+++ b/apps/indexer/lib/indexer/block/catchup/fetcher.ex
@@ -72,21 +72,12 @@ defmodule Indexer.Block.Catchup.Fetcher do
       ) do
     Logger.metadata(fetcher: :block_catchup)
 
-    {:ok, latest_block_number} =
-      case latest_block() do
-        nil ->
-          EthereumJSONRPC.fetch_block_number_by_tag("latest", json_rpc_named_arguments)
-
-        number ->
-          {:ok, number}
-      end
-
-    case latest_block_number do
+    case latest_block(json_rpc_named_arguments) do
       # let realtime indexer get the genesis block
       0 ->
         %{first_block_number: 0, missing_block_count: 0, shrunk: false}
 
-      _ ->
+      latest_block_number ->
         # realtime indexer gets the current latest block
         first = latest_block_number - 1
         last = last_block()
@@ -345,12 +336,23 @@ defmodule Indexer.Block.Catchup.Fetcher do
     end
   end
 
-  defp latest_block do
+  defp latest_block(json_rpc_named_arguments) do
     string_value = Application.get_env(:indexer, :last_block)
 
     case Integer.parse(string_value) do
-      {integer, ""} -> integer
-      _ -> nil
+      {integer, ""} ->
+        integer
+
+      _ ->
+        {:ok, number} = EthereumJSONRPC.fetch_block_number_by_tag("latest", json_rpc_named_arguments)
+        # leave to realtime indexer the blocks in the skipping window
+        skipping_distance = Application.get_env(:indexer, :max_skipping_distance)
+
+        if number > skipping_distance do
+          number - skipping_distance
+        else
+          0
+        end
     end
   end
 end
diff --git a/apps/indexer/lib/indexer/block/realtime/fetcher.ex b/apps/indexer/lib/indexer/block/realtime/fetcher.ex
index 897eab2cff..4ba725cc77 100644
--- a/apps/indexer/lib/indexer/block/realtime/fetcher.ex
+++ b/apps/indexer/lib/indexer/block/realtime/fetcher.ex
@@ -87,9 +87,16 @@ defmodule Indexer.Block.Realtime.Fetcher do
     number = quantity_to_integer(quantity)
     # Subscriptions don't support getting all the blocks and transactions data,
     # so we need to go back and get the full block
-    start_fetch_and_import(number, block_fetcher, previous_number, max_number_seen)
+    {new_previous_number, new_max_number} =
+      case start_fetch_and_import(number, block_fetcher, previous_number, max_number_seen) do
+        # The number may have not been inserted if it was part of a small skip
+        :skip ->
+          Logger.debug(["#{inspect(number)} was skipped"])
+          {previous_number, max_number_seen}
 
-    new_max_number = new_max_number(number, max_number_seen)
+        _ ->
+          {number, new_max_number(number, max_number_seen)}
+      end
 
     Process.cancel_timer(timer)
     new_timer = schedule_polling()
@@ -97,7 +104,7 @@ defmodule Indexer.Block.Realtime.Fetcher do
     {:noreply,
      %{
        state
-       | previous_number: number,
+       | previous_number: new_previous_number,
          max_number_seen: new_max_number,
          timer: new_timer
      }}
@@ -115,7 +122,14 @@ defmodule Indexer.Block.Realtime.Fetcher do
     {number, new_max_number} =
       case EthereumJSONRPC.fetch_block_number_by_tag("latest", json_rpc_named_arguments) do
         {:ok, number} when is_nil(max_number_seen) or number > max_number_seen ->
-          start_fetch_and_import(number, block_fetcher, previous_number, number)
+          # in case of polling the realtime fetcher should take care of all the
+          # blocks in the skipping window, because the cathup fetcher wont
+          max_skipping_distance = Application.get_env(:indexer, :max_skipping_distance)
+
+          last_catchup_number = max(0, 10 - max_skipping_distance - 1)
+          starting_number = max(previous_number, last_catchup_number) || last_catchup_number
+
+          start_fetch_and_import(number, block_fetcher, starting_number, nil)
 
           {max_number_seen, number}
 
@@ -211,27 +225,31 @@ defmodule Indexer.Block.Realtime.Fetcher do
   end
 
   defp start_fetch_and_import(number, block_fetcher, previous_number, max_number_seen) do
-    start_at = determine_start_at(number, previous_number, max_number_seen)
+    fetching_action = determine_fetching_action(number, previous_number, max_number_seen)
 
-    for block_number_to_fetch <- start_at..number do
-      args = [block_number_to_fetch, block_fetcher, reorg?(number, max_number_seen)]
-      Task.Supervisor.start_child(TaskSupervisor, __MODULE__, :fetch_and_import_block, args)
+    if fetching_action != :skip do
+      for block_number_to_fetch <- fetching_action do
+        args = [block_number_to_fetch, block_fetcher, reorg?(number, max_number_seen)]
+        Task.Supervisor.start_child(TaskSupervisor, __MODULE__, :fetch_and_import_block, args)
+      end
     end
+
+    fetching_action
   end
 
-  defp determine_start_at(number, nil, nil), do: number
+  def determine_fetching_action(number, previous_number, max_number_seen) do
+    cond do
+      reorg?(number, max_number_seen) ->
+        [number]
 
-  defp determine_start_at(number, nil, max_number_seen) do
-    determine_start_at(number, number - 1, max_number_seen)
-  end
+      can_be_skipped?(number, max_number_seen) ->
+        :skip
 
-  defp determine_start_at(number, previous_number, max_number_seen) do
-    if reorg?(number, max_number_seen) do
-      # set start_at to NOT fill in skipped numbers
-      number
-    else
-      # set start_at to fill in skipped numbers, if any
-      previous_number + 1
+      is_nil(previous_number) ->
+        [number]
+
+      true ->
+        (previous_number + 1)..number
     end
   end
 
@@ -241,6 +259,14 @@ defmodule Indexer.Block.Realtime.Fetcher do
 
   defp reorg?(_, _), do: false
 
+  defp can_be_skipped?(number, max_number_seen) when is_integer(max_number_seen) and number > max_number_seen + 1 do
+    max_skipping_distance = Application.get_env(:indexer, :max_skipping_distance)
+
+    max_skipping_distance > 1 and number <= max_number_seen + max_skipping_distance
+  end
+
+  defp can_be_skipped?(_, _), do: false
+
   @reorg_delay 5_000
 
   @decorate trace(name: "fetch", resource: "Indexer.Block.Realtime.Fetcher.fetch_and_import_block/3", tracer: Tracer)
diff --git a/apps/indexer/test/indexer/block/catchup/bound_interval_supervisor_test.exs b/apps/indexer/test/indexer/block/catchup/bound_interval_supervisor_test.exs
index 556abf69bd..73134306a6 100644
--- a/apps/indexer/test/indexer/block/catchup/bound_interval_supervisor_test.exs
+++ b/apps/indexer/test/indexer/block/catchup/bound_interval_supervisor_test.exs
@@ -28,6 +28,11 @@ defmodule Indexer.Block.Catchup.BoundIntervalSupervisorTest do
 
   setup :verify_on_exit!
 
+  # run the tests without the skipping window
+  setup do
+    Application.put_env(:indexer, :max_skipping_distance, 0)
+  end
+
   describe "start_link/1" do
     # See https://github.com/poanetwork/blockscout/issues/597
     @tag :no_geth
diff --git a/apps/indexer/test/indexer/block/catchup/fetcher_test.exs b/apps/indexer/test/indexer/block/catchup/fetcher_test.exs
index 6230552c3f..c2bcc9dd3b 100644
--- a/apps/indexer/test/indexer/block/catchup/fetcher_test.exs
+++ b/apps/indexer/test/indexer/block/catchup/fetcher_test.exs
@@ -32,6 +32,11 @@ defmodule Indexer.Block.Catchup.FetcherTest do
     }
   end
 
+  setup do
+    # run the tests without the skipping window
+    Application.put_env(:indexer, :max_skipping_distance, 0)
+  end
+
   describe "import/1" do
     test "fetches uncles asynchronously", %{json_rpc_named_arguments: json_rpc_named_arguments} do
       CoinBalance.Supervisor.Case.start_supervised!(json_rpc_named_arguments: json_rpc_named_arguments)
diff --git a/apps/indexer/test/indexer/block/realtime/fetcher_test.exs b/apps/indexer/test/indexer/block/realtime/fetcher_test.exs
index f222805d26..50dfb52ecf 100644
--- a/apps/indexer/test/indexer/block/realtime/fetcher_test.exs
+++ b/apps/indexer/test/indexer/block/realtime/fetcher_test.exs
@@ -40,6 +40,11 @@ defmodule Indexer.Block.Realtime.FetcherTest do
     %{block_fetcher: block_fetcher, json_rpc_named_arguments: core_json_rpc_named_arguments}
   end
 
+  setup do
+    # run the tests with a realistic skipping window
+    Application.put_env(:indexer, :max_skipping_distance, 3)
+  end
+
   describe "Indexer.Block.Fetcher.fetch_and_import_range/1" do
     @tag :no_geth
     test "in range with internal transactions", %{
@@ -424,4 +429,51 @@ defmodule Indexer.Block.Realtime.FetcherTest do
               }} = Indexer.Block.Fetcher.fetch_and_import_range(block_fetcher, 3_946_079..3_946_080)
     end
   end
+
+  describe "determine_fetching_action/4" do
+    test "when everything (except number) is nil results in fetching only the number" do
+      assert [14] == Realtime.Fetcher.determine_fetching_action(14, nil, nil)
+    end
+
+    test "when number is also max_number_seen results in fetching only the number" do
+      number = 23
+      assert [number] == Realtime.Fetcher.determine_fetching_action(number, nil, number)
+      assert [number] == Realtime.Fetcher.determine_fetching_action(number, 21, number)
+    end
+
+    test "when max_number_seen is nil, fetching will start from previous_number" do
+      # note: this is a way to force this behavior, used by `poll_latest_block_number`
+      number = 156
+      previous_number = 150
+      old_number = 94
+
+      assert (previous_number + 1)..number == Realtime.Fetcher.determine_fetching_action(number, previous_number, nil)
+      assert (old_number + 1)..number == Realtime.Fetcher.determine_fetching_action(number, old_number, nil)
+    end
+
+    test "when number immediately follows the previous_number it is fetched" do
+      max_number_seen = 26
+      number = 27
+
+      assert [number] == Realtime.Fetcher.determine_fetching_action(number, nil, max_number_seen)
+    end
+
+    test "when number is inside the allowed skipping window nothing is fetched" do
+      max_number_seen = 26
+
+      assert :skip == Realtime.Fetcher.determine_fetching_action(28, nil, max_number_seen)
+      assert :skip == Realtime.Fetcher.determine_fetching_action(29, nil, max_number_seen)
+    end
+
+    test "when number is over the allowed skipping window all the values since the previous_number will be fetched" do
+      max_number_seen = 390
+      previous_number = 381
+      max_skipping_distance = Application.get_env(:indexer, :max_skipping_distance)
+
+      number = max_number_seen + max_skipping_distance + 1
+
+      assert (previous_number + 1)..number ==
+               Realtime.Fetcher.determine_fetching_action(number, previous_number, max_number_seen)
+    end
+  end
 end
diff --git a/docs/env-variables.md b/docs/env-variables.md
index 88f4cfbc07..c055bed1c3 100644
--- a/docs/env-variables.md
+++ b/docs/env-variables.md
@@ -70,3 +70,4 @@ $ export NETWORK=POA
 | `EMISSION_FORMAT` | | Should be set to `POA` if you have block emission indentical to POA Network. This env var is used only if `CHAIN_SPEC_PATH` is set | `STANDARD` | v2.0.4+ | | |
 | `REWARDS_CONTRACT_ADDRESS` | | Emission rewards contract address. This env var is used only if `EMISSION_FORMAT` is set to `POA` | `0xeca443e8e1ab29971a45a9c57a6a9875701698a5` | v2.0.4+ | | |
 | `BLOCKSCOUT_PROTOCOL` | | Url scheme for blockscout | in prod env `https` is used, in dev env `http` is used | master | | |
+| `MAX_SKIPPING_DISTANCE` | | The maximum distance the indexer is allowed to wait for when notified of a number not following the lask known one. | 4 | master | |

From 1c99df345498c308b28ce45b2960cad07d25f7bd Mon Sep 17 00:00:00 2001
From: Victor Baranov <baranov.viktor.27@gmail.com>
Date: Sun, 13 Oct 2019 11:21:37 +0900
Subject: [PATCH 29/30] Update README.md

Athereum Testnet
---
 README.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/README.md b/README.md
index d8cb35d7a0..c5041a33ba 100644
--- a/README.md
+++ b/README.md
@@ -33,7 +33,7 @@ Currently available full-featured block explorers (Etherscan, Etherchain, Blockc
 | [Callisto](https://blockscout.com/callisto/mainnet) | [Goerli Testnet](https://blockscout.com/eth/goerli) | [ARTIS](https://explorer.sigma1.artis.network) | [Celo Testnet](https://alfajores-blockscout.celo-testnet.org/) |
 | [Ethereum Classic](https://blockscout.com/etc/mainnet) | [Kovan Testnet](https://blockscout.com/eth/kovan) | [Ether-1](https://blocks.ether1.wattpool.net/) | [Matic Testnet](https://explorer.testnet2.matic.network/) |
 | [Ethereum Mainnet](https://blockscout.com/eth/mainnet) | [LUKSO L14 Testnet](https://blockscout.com/lukso/l14) | [Kotti Testnet](https://kottiexplorer.ethernode.io/) | [Mordor Testnet](https://mordorexplorer.ethernode.io/) |
-| [POA Core Network](https://blockscout.com/poa/core) | [POA Sokol Testnet](https://blockscout.com/poa/sokol) | [Fuse Network](https://explorer.fuse.io/) |  |
+| [POA Core Network](https://blockscout.com/poa/core)| [POA Sokol Testnet](https://blockscout.com/poa/sokol) | [Fuse Network](https://explorer.fuse.io/)  | [Athereum Testnet](http://athexplorer.ava.network/) |
 | [RSK](https://blockscout.com/rsk/mainnet) | [Rinkeby Testnet](https://blockscout.com/eth/rinkeby) | [Oasis Labs](https://blockexplorer.oasiscloud.io/) |  |
 | [xDai Chain](https://blockscout.com/poa/dai) | [Ropsten Testnet](https://blockscout.com/eth/ropsten) | [Petrichor](https://explorer.petrachor.com/) |  |
 |  |  | [PIRL](http://pirl.es/) |  |

From b22cbc2f97daa5ecb175fd19a7a1d2b8b121fc1d Mon Sep 17 00:00:00 2001
From: Ayrat Badykov <ayratin555@gmail.com>
Date: Mon, 14 Oct 2019 10:05:44 +0300
Subject: [PATCH 30/30] add CHANGELOG entry

---
 CHANGELOG.md | 1 +
 1 file changed, 1 insertion(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 88b8f36ae7..92879618b0 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -15,6 +15,7 @@
 - [#2642](https://github.com/poanetwork/blockscout/pull/2642) - add ERC721 coin instance page
 
 ### Fixes
+- [#2767](https://github.com/poanetwork/blockscout/pull/2767) - fix websocket subscriptions with token instances
 - [#2765](https://github.com/poanetwork/blockscout/pull/2765) - fixed width issue for cards in mobile view for Transaction Details page
 - [#2753](https://github.com/poanetwork/blockscout/pull/2753) - fix nft token instance images
 - [#2750](https://github.com/poanetwork/blockscout/pull/2750) - fixed contract buttons color for NFT token instance on each theme