Cache blocks and transactions in the chain statistics genserver

lib/explorer/chain.ex

@@ -7,7 +7,8 @@ defmodule Explorer.Chain do
 
   alias Ecto.Adapters.SQL
   alias Explorer.Block
-  alias Explorer.Repo
+  alias Explorer.Transaction
+  alias Explorer.Repo, as: Repo
   alias Timex.Duration
 
   defstruct [
@@ -18,7 +19,9 @@ defmodule Explorer.Chain do
     transaction_count: 0,
     skipped_blocks: 0,
     block_velocity: 0,
-    transaction_velocity: 0
+    transaction_velocity: 0,
+    blocks: [],
+    transactions: []
   ]
 
   @average_time_query """
@@ -68,6 +71,17 @@ defmodule Explorer.Chain do
   """
 
   def fetch do
+    blocks = from block in Block,
+      order_by: [desc: block.number],
+      preload: :transactions,
+      limit: 5
+
+    transactions = from transaction in Transaction,
+      join: block in assoc(transaction, :block),
+      order_by: [desc: block.number],
+      preload: [block: block],
+      limit: 5
+
     last_block = Block |> Block.latest() |> limit(1) |> Repo.one()
     latest_block = last_block || Block.null
     %Explorer.Chain{
@@ -78,7 +92,9 @@ defmodule Explorer.Chain do
       skipped_blocks: query_value(@skipped_blocks_query, [latest_block.number]),
       lag: query_duration(@lag_query),
       block_velocity: query_value(@block_velocity_query),
-      transaction_velocity: query_value(@transaction_velocity_query)
+      transaction_velocity: query_value(@transaction_velocity_query),
+      blocks: Repo.all(blocks),
+      transactions: Repo.all(transactions)
     }
   end
 

lib/explorer/servers/chain_statistics.ex

@@ -10,17 +10,16 @@ defmodule Explorer.Servers.ChainStatistics do
   def fetch do
     case GenServer.whereis(__MODULE__) do
       nil -> Chain.fetch()
-      pid -> GenServer.call(pid, :fetch)
+      _ -> GenServer.call(__MODULE__, :fetch)
     end
   end
-  def start_link, do: start_link(%Chain{})
-  def start_link(%Chain{} = chain) do
-    GenServer.start_link(__MODULE__, chain, name: __MODULE__)
-  end
 
-  def init(chain) do
+  def start_link, do: start_link(nil)
+  def start_link(_), do: GenServer.start_link(__MODULE__, nil, name: __MODULE__)
+
+  def init(_) do
     refresh()
-    {:ok, chain}
+    {:ok, %Chain{}}
   end
 
   def refresh, do: refresh(@interval)

lib/explorer_web/controllers/chain_controller.ex

@@ -1,32 +1,9 @@
 defmodule ExplorerWeb.ChainController do
   use ExplorerWeb, :controller
 
-  import Ecto.Query
-
-  alias Explorer.Block
-  alias Explorer.BlockForm
   alias Explorer.Servers.ChainStatistics
-  alias Explorer.Repo.NewRelic, as: Repo
-  alias Explorer.Transaction
 
   def show(conn, _params) do
-    blocks = from block in Block,
+    render(conn, "show.html", chain: ChainStatistics.fetch())
-      order_by: [desc: block.number],
-      preload: :transactions,
-      limit: 5
-
-    transactions = from transaction in Transaction,
-      join: block in assoc(transaction, :block),
-      order_by: [desc: block.number],
-      preload: [block: block],
-      limit: 5
-
-    render(
-      conn,
-      "show.html",
-      blocks: blocks |> Repo.all() |> Enum.map(&BlockForm.build/1),
-      transactions: transactions |> Repo.all(),
-      chain: ChainStatistics.fetch()
-    )
   end
 end

lib/explorer_web/templates/chain/show.html.eex

@@ -64,7 +64,7 @@
             </tr>
           </thead>
           <tbody>
-            <%= for block <- @blocks do %>
+            <%= for block <- @chain.blocks do %>
               <tr class="blocks__row">
                 <td class="blocks__column blocks__column--height"><%= link(block.number, to: block_path(@conn, :show, @conn.assigns.locale, block.number), class: "blocks__link") %></td>
                 <td class="blocks__column blocks__column--age"><%= block.timestamp |> Timex.from_now %></td>
@@ -91,7 +91,7 @@
             </tr>
           </thead>
           <tbody>
-            <%= for transaction <- @transactions do %>
+            <%= for transaction <- @chain.transactions do %>
               <tr class="transactions__row">
                 <td class="transactions__column transactions__column--hash">
                   <div class="transactions__hash-container" title="<%= transaction.hash %>">

test/explorer/chain_test.exs

@@ -80,5 +80,21 @@ defmodule Explorer.ChainTest do
       chain = Chain.fetch()
       assert chain.transaction_velocity == 1
     end
+
+    test "returns the last five blocks" do
+      insert_list(6, :block)
+      chain = Chain.fetch()
+      assert chain.blocks |> Enum.count() == 5
+    end
+
+    test "returns the last five transactions with blocks" do
+      block = insert(:block)
+      insert_list(6, :transaction)
+      |> Enum.map(fn (transaction) ->
+        insert(:block_transaction, block: block, transaction: transaction)
+      end)
+      chain = Chain.fetch()
+      assert chain.transactions |> Enum.count() == 5
+    end
   end
 end

test/explorer_web/controllers/chain_controller_test.exs

@@ -22,7 +22,7 @@ defmodule ExplorerWeb.ChainControllerTest do
       insert(:block, %{number: 23})
       conn = get conn, "/en"
 
-      assert(List.first(conn.assigns.blocks).number == 23)
+      assert(List.first(conn.assigns.chain.blocks).number == 23)
     end
 
     test "excludes all but the most recent five blocks", %{conn: conn} do
@@ -30,7 +30,7 @@ defmodule ExplorerWeb.ChainControllerTest do
       insert_list(5, :block)
       conn = get conn, "/en"
 
-      refute(Enum.member?(conn.assigns.blocks, old_block))
+      refute(Enum.member?(conn.assigns.chain.blocks, old_block))
     end
 
     test "only returns transactions with an associated block", %{conn: conn} do
@@ -38,7 +38,8 @@ defmodule ExplorerWeb.ChainControllerTest do
       insert(:transaction, id: 10, hash: "0xDECAFBAD") |> with_block(block) |> with_addresses(%{to: "0xsleepypuppy", from: "0xilovefrogs"})
       insert(:transaction, id: 30)
       conn = get conn, "/en"
-      transaction_ids = conn.assigns.transactions |> Enum.map(fn (transaction) -> transaction.id end)
+      transaction_ids = conn.assigns.chain.transactions
+      |> Enum.map(fn (transaction) -> transaction.id end)
 
       assert(Enum.member?(transaction_ids, 10))
       refute(Enum.member?(transaction_ids, 30))
@@ -49,7 +50,7 @@ defmodule ExplorerWeb.ChainControllerTest do
       insert(:transaction, hash: "0xDECAFBAD") |> with_block(block) |> with_addresses(%{to: "0xsleepypuppy", from: "0xilovefrogs"})
       conn = get conn, "/en"
 
-      assert(List.first(conn.assigns.transactions).hash == "0xDECAFBAD")
+      assert(List.first(conn.assigns.chain.transactions).hash == "0xDECAFBAD")
     end
   end
 end