From ee620ecbf11398277551ef603355a56a53690461 Mon Sep 17 00:00:00 2001
From: Ekaterina Vaartis <vaartis@cock.li>
Date: Mon, 12 Aug 2019 13:13:01 +0300
Subject: [PATCH] Add caching for emoji pack sharing

---
 config/config.exs                             |  3 +-
 docs/config.md                                |  2 +
 lib/pleroma/application.ex                    |  6 ++-
 .../web/emoji_api/emoji_api_controller.ex     | 42 ++++++++++++++++++-
 4 files changed, 50 insertions(+), 3 deletions(-)

diff --git a/config/config.exs b/config/config.exs
index c7e0cf09f..4c758d4a0 100644
--- a/config/config.exs
+++ b/config/config.exs
@@ -122,7 +122,8 @@ config :pleroma, :emoji,
     # Put groups that have higher priority than defaults here. Example in `docs/config/custom_emoji.md`
     Custom: ["/emoji/*.png", "/emoji/**/*.png"]
   ],
-  default_manifest: "https://git.pleroma.social/pleroma/emoji-index/raw/master/index.json"
+  default_manifest: "https://git.pleroma.social/pleroma/emoji-index/raw/master/index.json",
+  shared_pack_cache_seconds_per_file: 60
 
 config :pleroma, :uri_schemes,
   valid_schemes: [
diff --git a/docs/config.md b/docs/config.md
index 3f37fa561..1179def56 100644
--- a/docs/config.md
+++ b/docs/config.md
@@ -707,6 +707,8 @@ Configure OAuth 2 provider capabilities:
 * `pack_extensions`: A list of file extensions for emojis, when no emoji.txt for a pack is present. Example `[".png", ".gif"]`
 * `groups`: Emojis are ordered in groups (tags). This is an array of key-value pairs where the key is the groupname and the value the location or array of locations. `*` can be used as a wildcard. Example `[Custom: ["/emoji/*.png", "/emoji/custom/*.png"]]`
 * `default_manifest`: Location of the JSON-manifest. This manifest contains information about the emoji-packs you can download. Currently only one manifest can be added (no arrays).
+* `shared_pack_cache_seconds_per_file`: When an emoji pack is shared, the archive is created and cached in
+  memory for this amount of seconds multiplied by the number of files.
 
 ## Database options
 
diff --git a/lib/pleroma/application.ex b/lib/pleroma/application.ex
index dabce771d..a339e2c48 100644
--- a/lib/pleroma/application.ex
+++ b/lib/pleroma/application.ex
@@ -102,10 +102,14 @@ defmodule Pleroma.Application do
       build_cachex("rich_media", default_ttl: :timer.minutes(120), limit: 5000),
       build_cachex("scrubber", limit: 2500),
       build_cachex("idempotency", expiration: idempotency_expiration(), limit: 2500),
-      build_cachex("web_resp", limit: 2500)
+      build_cachex("web_resp", limit: 2500),
+      build_cachex("emoji_packs", expiration: emoji_packs_expiration(), limit: 10)
     ]
   end
 
+  defp emoji_packs_expiration,
+    do: expiration(default: :timer.seconds(5 * 60), interval: :timer.seconds(60))
+
   defp idempotency_expiration,
     do: expiration(default: :timer.seconds(6 * 60 * 60), interval: :timer.seconds(60))
 
diff --git a/lib/pleroma/web/emoji_api/emoji_api_controller.ex b/lib/pleroma/web/emoji_api/emoji_api_controller.ex
index 915059783..8219eaaa1 100644
--- a/lib/pleroma/web/emoji_api/emoji_api_controller.ex
+++ b/lib/pleroma/web/emoji_api/emoji_api_controller.ex
@@ -1,6 +1,8 @@
 defmodule Pleroma.Web.EmojiAPI.EmojiAPIController do
   use Pleroma.Web, :controller
 
+  require Logger
+
   def reload(conn, _params) do
     Pleroma.Emoji.reload()
 
@@ -12,6 +14,8 @@ defmodule Pleroma.Web.EmojiAPI.EmojiAPIController do
                     "emoji"
                   )
 
+  @cache_seconds_per_file Pleroma.Config.get!([:emoji, :shared_pack_cache_seconds_per_file])
+
   def list_packs(conn, _params) do
     pack_infos =
       case File.ls(@emoji_dir_path) do
@@ -66,13 +70,49 @@ defmodule Pleroma.Web.EmojiAPI.EmojiAPIController do
       end)
   end
 
-  defp make_archive(name, pack, pack_dir) do
+  defp create_archive_and_cache(name, pack, pack_dir, md5) do
     files =
       ['pack.yml'] ++
         (pack["files"] |> Enum.map(fn {_, path} -> to_charlist(path) end))
 
     {:ok, {_, zip_result}} = :zip.zip('#{name}.zip', files, [:memory, cwd: to_charlist(pack_dir)])
 
+    cache_ms = :timer.seconds(@cache_seconds_per_file * Enum.count(files))
+
+    Cachex.put!(
+      :emoji_packs_cache,
+      name,
+      # if pack.yml MD5 changes, the cache is not valid anymore
+      %{pack_yml_md5: md5, pack_data: zip_result},
+      # Add a minute to cache time for every file in the pack
+      ttl: cache_ms
+    )
+
+    Logger.debug("Create an archive for the '#{name}' shared emoji pack, \
+keeping it in cache for #{div(cache_ms, 1000)}s")
+
+    zip_result
+  end
+
+  defp make_archive(name, pack, pack_dir) do
+    # Having a different pack.yml md5 invalidates cache
+    pack_yml_md5 = :crypto.hash(:md5, File.read!(Path.join(pack_dir, "pack.yml")))
+
+    maybe_cached_pack = Cachex.get!(:emoji_packs_cache, name)
+
+    zip_result =
+      if is_nil(maybe_cached_pack) do
+        create_archive_and_cache(name, pack, pack_dir, pack_yml_md5)
+      else
+        if maybe_cached_pack[:pack_yml_md5] == pack_yml_md5 do
+          Logger.debug("Using cache for the '#{name}' shared emoji pack")
+
+          maybe_cached_pack[:pack_data]
+        else
+          create_archive_and_cache(name, pack, pack_dir, pack_yml_md5)
+        end
+      end
+
     zip_result
   end