add most recent crawl table

CHANGELOG.md

@@ -17,7 +17,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Fixed
 
-- Added missing indices on crawls and crawl_interactions tables.
+- Added missing indices on `crawls` and `crawl_interactions` tables.
+- Added table to store most recent crawl. This speeds up the instance view by a lot!
 
 ### Security
 

backend/lib/backend/crawler/crawler.ex

@@ -6,7 +6,7 @@ defmodule Backend.Crawler do
   alias __MODULE__
   alias Backend.Crawler.Crawlers.{GnuSocial, Mastodon, Misskey, Nodeinfo}
   alias Backend.Crawler.ApiCrawler
-  alias Backend.{Crawl, CrawlInteraction, Repo, Instance, InstancePeer}
+  alias Backend.{Crawl, CrawlInteraction, MostRecentCrawl, Repo, Instance, InstancePeer}
   import Ecto.Query
   import Backend.Util
   require Logger
@@ -167,10 +167,23 @@ defmodule Backend.Crawler do
       Repo.insert!(%Crawl{
         instance_domain: domain,
         interactions_seen:
-          result.interactions |> Map.values() |> Enum.reduce(0, fn count, acc -> count + acc end),
+          result.interactions
+          |> Map.values()
+          |> Enum.reduce(0, fn count, acc -> count + acc end),
         statuses_seen: result.statuses_seen
       })
 
+    Repo.insert!(
+      %MostRecentCrawl{
+        instance_domain: domain,
+        crawl_id: curr_crawl.id,
+        inserted_at: now,
+        updated_at: now
+      },
+      on_conflict: {:replace, [:crawl_id, :updated_at]},
+      conflict_target: :instance_domain
+    )
+
     # We get a list of peers from two places:
     # * the official peers endpoint (which may be disabled)
     # * the interactions

backend/lib/backend/crawler/crawlers/gnu_social.ex

@@ -49,11 +49,24 @@ defmodule Backend.Crawler.Crawlers.GnuSocial do
 
     {interactions, statuses_seen} = get_interactions(domain, min_timestamp)
 
+    if nodeinfo_result != nil do
       Map.merge(nodeinfo_result, %{
         interactions: interactions,
         statuses_seen: statuses_seen,
         peers: []
       })
+    else
+      %{
+        version: nil,
+        description: nil,
+        user_count: nil,
+        status_count: nil,
+        peers: [],
+        interactions: interactions,
+        statuses_seen: statuses_seen,
+        instance_type: :gnusocial
+      }
+    end
   end
 
   @spec get_interactions(

backend/lib/backend/most_recent_crawl.ex

@@ -0,0 +1,22 @@
+defmodule Backend.MostRecentCrawl do
+  use Ecto.Schema
+  import Ecto.Changeset
+
+  schema "most_recent_crawl" do
+    belongs_to :instance, Backend.Instance,
+      references: :domain,
+      type: :string,
+      foreign_key: :instance_domain
+
+    belongs_to :crawl, Backend.Crawl
+
+    timestamps()
+  end
+
+  @doc false
+  def changeset(edge, attrs) do
+    edge
+    |> cast(attrs, [:instance, :crawl])
+    |> validate_required([:instance, :crawl])
+  end
+end

backend/lib/backend/util.ex

@@ -1,7 +1,7 @@
 defmodule Backend.Util do
   import Ecto.Query
   require Logger
-  alias Backend.{Crawl, Repo}
+  alias Backend.{Crawl, MostRecentCrawl, Repo}
 
   @doc """
   Returns the given key from :backend, :crawler in the config.
@@ -78,11 +78,17 @@ defmodule Backend.Util do
 
   @spec get_last_crawl(String.t()) :: Crawl.t() | nil
   def get_last_crawl(domain) do
+    most_recent_crawl_subquery =
+      MostRecentCrawl
+      |> select([mrc], %{
+        most_recent_id: mrc.crawl_id
+      })
+      |> where([mrc], mrc.instance_domain == ^domain)
+
     Crawl
-    |> select([c], c)
-    |> where([c], c.instance_domain == ^domain)
-    |> order_by(desc: :id)
-    |> limit(1)
+    |> join(:inner, [c], mrc in subquery(most_recent_crawl_subquery),
+      on: c.id == mrc.most_recent_id
+    )
     |> Repo.one()
   end
 

backend/priv/repo/migrations/20190810125304_add_most_recent_crawl_table.exs

@@ -0,0 +1,32 @@
+defmodule Backend.Repo.Migrations.AddMostRecentCrawlTable do
+  use Ecto.Migration
+
+  def change do
+    create table(:most_recent_crawl) do
+      add :instance_domain, references(:instances, column: :domain, type: :string)
+      add :crawl_id, references(:crawls)
+
+      timestamps()
+    end
+
+    create unique_index(:most_recent_crawl, [:instance_domain])
+
+    flush()
+
+    execute(
+      "
+    INSERT INTO most_recent_crawl (instance_domain, crawl_id, updated_at, inserted_at)
+    SELECT
+      c.instance_domain,
+      MAX(c.id) AS crawl_id,
+      (SELECT NOW()) AS updated_at,
+      (SELECT NOW()) AS inserted_at
+    FROM
+      crawls c
+    GROUP BY
+      c.instance_domain
+    ",
+      "DELETE FROM most_recent_crawl"
+    )
+  end
+end