Use place holders when receiving out of order blocks realtime

apps/block_scout_web/assets/__tests__/pages/block.js

@@ -1,13 +1,59 @@
 import { reducer, initialState } from '../../js/pages/block'
 
-test('RECEIVED_NEW_BLOCK', () => {
+
+test('CHANNEL_DISCONNECTED', () => {
+  const state = initialState
+  const action = {
+    type: 'CHANNEL_DISCONNECTED'
+  }
+  const output = reducer(state, action)
+
+  expect(output.channelDisconnected).toBe(true)
+})
+
+describe('RECEIVED_NEW_BLOCK', () => {
+  test('receives new block', () => {
     const action = {
       type: 'RECEIVED_NEW_BLOCK',
       msg: {
-      blockHtml: "test"
+        blockHtml: 'test',
+        blockNumber: 1
       }
     }
     const output = reducer(initialState, action)
 
-  expect(output.newBlock).toBe("test")
+    expect(output.newBlock).toBe('test')
+    expect(output.currentBlockNumber).toBe(1)
+  })
+  test('on page 2+', () => {
+    const state = Object.assign({}, initialState, {
+      beyondPageOne: true
+    })
+    const action = {
+      type: 'RECEIVED_NEW_BLOCK',
+      msgs: [{
+        blockHtml: 'test'
+      }]
+    }
+    const output = reducer(state, action)
+
+    expect(output.newBlock).toBe(null)
+  })
+  test('inserts place holders if block received out of order', () => {
+    const state = Object.assign({}, initialState, {
+      currentBlockNumber: 2
+    })
+    const action = {
+      type: 'RECEIVED_NEW_BLOCK',
+      msg: {
+        blockHtml: 'test5',
+        blockNumber: 5
+      }
+    }
+    const output = reducer(state, action)
+
+    expect(output.newBlock).toBe('test5')
+    expect(output.currentBlockNumber).toBe(5)
+    expect(output.skippedBlockNumbers).toEqual([3, 4])
+  })
 })

apps/block_scout_web/assets/__tests__/pages/transaction.js

@@ -1,5 +1,16 @@
 import { reducer, initialState } from '../../js/pages/transaction'
 
+test('CHANNEL_DISCONNECTED', () => {
+  const state = initialState
+  const action = {
+    type: 'CHANNEL_DISCONNECTED'
+  }
+  const output = reducer(state, action)
+
+  expect(output.channelDisconnected).toBe(true)
+  expect(output.batchCountAccumulator).toBe(0)
+})
+
 test('RECEIVED_NEW_BLOCK', () => {
   const state = { ...initialState, blockNumber: 1 }
   const action = {

apps/block_scout_web/assets/js/pages/block.js

@@ -1,4 +1,5 @@
 import $ from 'jquery'
+import _ from 'lodash'
 import URI from 'urijs'
 import humps from 'humps'
 import socket from '../socket'
@@ -8,14 +9,22 @@ import { initRedux, prependWithClingBottom } from '../utils'
 export const initialState = {
   beyondPageOne: null,
   channelDisconnected: false,
-  newBlock: null
+  currentBlockNumber: null,
+  newBlock: null,
+  replaceBlock: null,
+  skippedBlockNumbers: []
 }
 
 export function reducer (state = initialState, action) {
   switch (action.type) {
     case 'PAGE_LOAD': {
+      let blockNumber = parseInt(state.currentBlockNumber)
+      if (!action.beyondPageOne) {
+        blockNumber = parseInt(action.highestBlockNumber)
+      }
       return Object.assign({}, state, {
-        beyondPageOne: action.beyondPageOne
+        beyondPageOne: action.beyondPageOne,
+        currentBlockNumber: blockNumber
       })
     }
     case 'CHANNEL_DISCONNECTED': {
@@ -24,10 +33,24 @@ export function reducer (state = initialState, action) {
       })
     }
     case 'RECEIVED_NEW_BLOCK': {
-      if (state.channelDisconnected) return state
+      if (state.channelDisconnected || state.beyondPageOne) return state
 
+      let skippedBlockNumbers = state.skippedBlockNumbers.slice(0)
+      let replaceBlock = null
+      const blockNumber = parseInt(action.msg.blockNumber)
+      if (blockNumber > state.currentBlockNumber + 1) {
+        for (let i = state.currentBlockNumber + 1; i < action.msg.blockNumber; i++) {
+          skippedBlockNumbers.push(i)
+        }
+      } else if (_.indexOf(skippedBlockNumbers, blockNumber) != -1) {
+        skippedBlockNumbers = _.without(skippedBlockNumbers, blockNumber)
+        replaceBlock = blockNumber
+      }
       return Object.assign({}, state, {
-        newBlock: action.msg.blockHtml
+        currentBlockNumber: blockNumber > state.currentBlockNumber ? blockNumber : state.currentBlockNumber,
+        newBlock: action.msg.blockHtml,
+        replaceBlock,
+        skippedBlockNumbers
       })
     }
     default:
@@ -41,7 +64,8 @@ if ($blockListPage.length) {
     main (store) {
       const state = store.dispatch({
         type: 'PAGE_LOAD',
-        beyondPageOne: !!humps.camelizeKeys(URI(window.location).query(true)).blockNumber
+        beyondPageOne: !!humps.camelizeKeys(URI(window.location).query(true)).blockNumber,
+        highestBlockNumber: $('[data-selector="block-number"]').filter(':first').text()
       })
       if (!state.beyondPageOne) {
         const blocksChannel = socket.channel(`blocks:new_block`, {})
@@ -58,9 +82,42 @@ if ($blockListPage.length) {
 
       if (state.channelDisconnected) $channelDisconnected.show()
       if (oldState.newBlock !== state.newBlock) {
+        if (oldState.skippedBlockNumbers !== state.skippedBlockNumbers) {
+          const newSkippedBlockNumbers = _.difference(state.skippedBlockNumbers, oldState.skippedBlockNumbers)
+          if (state.replaceBlock) {
+            const $placeHolder = $(`[data-selector="place-holder"][data-block-number="${state.replaceBlock}"]`)
+            $placeHolder.addClass('shrink-out')
+            setTimeout(() => $placeHolder.slideUp({
+              complete: () => {
+                $placeHolder.replaceWith(state.newBlock)
+              }
+            }), 400)
+          } else {
+            _.map(newSkippedBlockNumbers, (skippedBlockNumber) => {
+              prependWithClingBottom($blocksList, placeHolderBlock(skippedBlockNumber))
+            })
             prependWithClingBottom($blocksList, state.newBlock)
+          }
+        } else {
+          prependWithClingBottom($blocksList, state.newBlock)
+        }
         updateAllAges()
       }
     }
   })
 }
+
+function placeHolderBlock(blockNumber) {
+  return `
+    <div class="tile tile-type-block fade-up" data-selector="place-holder" data-block-number="${blockNumber}">
+      <div class="row">
+        <div class="col-md-6">
+          <span>${blockNumber}</span>
+        <div>
+        <div class="col-md-6">
+          Block Mined, awaiting import...
+        <div>
+      </div>
+    </div>
+  `
+}

apps/block_scout_web/lib/block_scout_web/templates/block/_tile.html.eex

@@ -6,7 +6,7 @@
             @block,
             class: "tile-title",
             to: block_path(BlockScoutWeb.Endpoint, :show, @block),
-            "data-test": "block_number",
+            "data-selector": "block-number",
             "data-block-number": to_string(@block.number)
           ) %>
       <div>

apps/block_scout_web/test/block_scout_web/features/pages/block_list_page.ex

@@ -3,7 +3,7 @@ defmodule BlockScoutWeb.BlockListPage do
 
   use Wallaby.DSL
 
-  import Wallaby.Query, only: [css: 1]
+  import Wallaby.Query, only: [css: 1, css: 2]
 
   alias Explorer.Chain.Block
 
@@ -12,6 +12,10 @@ defmodule BlockScoutWeb.BlockListPage do
   end
 
   def block(%Block{number: block_number}) do
-    css("[data-test='block_number'][data-block-number='#{block_number}']")
+    css("[data-selector='block-number'][data-block-number='#{block_number}']")
+  end
+
+  def place_holder_blocks(count) do
+    css("[data-selector='place-holder']", count: count)
   end
 end

apps/block_scout_web/test/block_scout_web/features/viewing_blocks_test.exs

@@ -1,7 +1,7 @@
 defmodule BlockScoutWeb.ViewingBlocksTest do
   use BlockScoutWeb.FeatureCase, async: true
 
-  alias BlockScoutWeb.{BlockListPage, BlockPage}
+  alias BlockScoutWeb.{BlockListPage, BlockPage, Notifier}
 
   setup do
     timestamp = Timex.now() |> Timex.shift(hours: -1)
@@ -35,6 +35,35 @@ defmodule BlockScoutWeb.ViewingBlocksTest do
       |> assert_has(BlockPage.detail_number(block))
     end
 
+    test "inserts place holder blocks if out of order block received", %{session: session} do
+      BlockListPage.visit_page(session)
+
+      block = insert(:block, number: 315)
+      Notifier.handle_event({:chain_event, :blocks, [block]})
+
+      session
+      |> assert_has(BlockListPage.block(block))
+      |> assert_has(BlockListPage.place_holder_blocks(3))
+    end
+
+    test "replaces place holder block if skipped block received", %{session: session} do
+      BlockListPage.visit_page(session)
+
+      block = insert(:block, number: 315)
+      Notifier.handle_event({:chain_event, :blocks, [block]})
+
+      session
+      |> assert_has(BlockListPage.block(block))
+      |> assert_has(BlockListPage.place_holder_blocks(3))
+
+      skipped_block = insert(:block, number: 314)
+      Notifier.handle_event({:chain_event, :blocks, [skipped_block]})
+
+      session
+      |> assert_has(BlockListPage.block(skipped_block))
+      |> assert_has(BlockListPage.place_holder_blocks(2))
+    end
+
     test "block detail page has transactions", %{session: session} do
       block = insert(:block, number: 42)