From 70b2bb6eded5597bd768d7dc8754c2c994561aee Mon Sep 17 00:00:00 2001
From: rinpatch <rinpatch@sdf.org>
Date: Wed, 16 Jan 2019 10:26:01 +0300
Subject: [PATCH] add caching

---
 lib/pleroma/application.ex  | 11 +++++++++++
 lib/pleroma/web/metadata.ex | 10 ++++++++++
 lib/pleroma/web/router.ex   |  2 +-
 3 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/lib/pleroma/application.ex b/lib/pleroma/application.ex
index ad2797209..5f9518914 100644
--- a/lib/pleroma/application.ex
+++ b/lib/pleroma/application.ex
@@ -84,6 +84,17 @@ def start(_type, _args) do
           ],
           id: :cachex_scrubber
         ),
+        worker(
+          Cachex,
+          [
+            :metadata_cache,
+            [
+              limit: 2500,
+              default_ttl: :timer.minutes(15)
+            ]
+          ],
+          id: :cachex_metadata
+        ),
         worker(
           Cachex,
           [
diff --git a/lib/pleroma/web/metadata.ex b/lib/pleroma/web/metadata.ex
index cf2b86aaa..a5a706b8f 100644
--- a/lib/pleroma/web/metadata.ex
+++ b/lib/pleroma/web/metadata.ex
@@ -2,6 +2,16 @@ defmodule Pleroma.Web.Metadata do
   alias Phoenix.HTML
 
   @parsers Pleroma.Config.get([:metadata, :providers], [])
+
+  def get_cached_tags(params) do
+    # I am unsure how well ETS works with big keys
+    key = :erlang.term_to_binary(params)
+
+    Cachex.fetch!(:metadata_cache, key, fn _key ->
+      {:commit, build_tags(params)}
+    end)
+  end
+
   def build_tags(params) do
     Enum.reduce(@parsers, "", fn parser, acc ->
       rendered_html =
diff --git a/lib/pleroma/web/router.ex b/lib/pleroma/web/router.ex
index 25e866c48..1ecd4aee1 100644
--- a/lib/pleroma/web/router.ex
+++ b/lib/pleroma/web/router.ex
@@ -534,7 +534,7 @@ def redirector_with_meta(conn, %{"maybe_nickname_or_id" => maybe_nickname_or_id}
 
   def redirector_with_meta(conn, params) do
     {:ok, index_content} = File.read(index_file_path())
-    tags = Metadata.build_tags(params)
+    tags = Metadata.get_cached_tags(params)
     response = String.replace(index_content, "<!--server-generated-meta-->", tags)
 
     conn