From e923c8772423e660a9db6f69f9c35f2def2def2a Mon Sep 17 00:00:00 2001
From: Felix Ableitner <me@nutomic.com>
Date: Thu, 21 Nov 2024 23:20:44 +0100
Subject: [PATCH] Better caching of api calls

---
 crates/api_crud/src/site/read.rs | 77 ++++++++++++++++++--------------
 1 file changed, 43 insertions(+), 34 deletions(-)

diff --git a/crates/api_crud/src/site/read.rs b/crates/api_crud/src/site/read.rs
index 47fd1f154..30e74837f 100644
--- a/crates/api_crud/src/site/read.rs
+++ b/crates/api_crud/src/site/read.rs
@@ -16,54 +16,37 @@ use lemmy_db_schema::source::{
 use lemmy_db_views::structs::{LocalUserView, SiteView};
 use lemmy_db_views_actor::structs::{CommunityFollowerView, CommunityModeratorView, PersonView};
 use lemmy_utils::{
-  error::{LemmyError, LemmyErrorExt, LemmyErrorType, LemmyResult},
+  error::{LemmyErrorExt, LemmyErrorType, LemmyResult},
   CACHE_DURATION_API,
   VERSION,
 };
 use moka::future::Cache;
 use std::sync::LazyLock;
 
+fn build_cache<K, V>() -> Cache<K, V>
+where
+  K: std::fmt::Debug + Eq + std::hash::Hash + Send + Sync + 'static,
+  V: std::fmt::Debug + Clone + Send + Sync + 'static,
+{
+  Cache::<K, V>::builder()
+    .max_capacity(1)
+    .time_to_live(CACHE_DURATION_API)
+    .build()
+}
+
+type CacheLock<T> = LazyLock<Cache<(), T>>;
+
 #[tracing::instrument(skip(context))]
 pub async fn get_site(
   local_user_view: Option<LocalUserView>,
   context: Data<LemmyContext>,
 ) -> LemmyResult<Json<GetSiteResponse>> {
-  static CACHE: LazyLock<Cache<(), GetSiteResponse>> = LazyLock::new(|| {
-    Cache::builder()
-      .max_capacity(1)
-      .time_to_live(CACHE_DURATION_API)
-      .build()
-  });
-
   // This data is independent from the user account so we can cache it across requests
+  static CACHE: CacheLock<GetSiteResponse> = LazyLock::new(build_cache);
   let mut site_response = CACHE
-    .try_get_with::<_, LemmyError>((), async {
-      let site_view = SiteView::read_local(&mut context.pool()).await?;
-      let admins = PersonView::admins(&mut context.pool()).await?;
-      let all_languages = Language::read_all(&mut context.pool()).await?;
-      let discussion_languages = SiteLanguage::read_local_raw(&mut context.pool()).await?;
-      let blocked_urls = LocalSiteUrlBlocklist::get_all(&mut context.pool()).await?;
-      let tagline = Tagline::get_random(&mut context.pool()).await.ok();
-      let admin_oauth_providers = OAuthProvider::get_all(&mut context.pool()).await?;
-      let oauth_providers =
-        OAuthProvider::convert_providers_to_public(admin_oauth_providers.clone());
-
-      Ok(GetSiteResponse {
-        site_view,
-        admins,
-        version: VERSION.to_string(),
-        my_user: None,
-        all_languages,
-        discussion_languages,
-        blocked_urls,
-        tagline,
-        oauth_providers: Some(oauth_providers),
-        admin_oauth_providers: Some(admin_oauth_providers),
-        taglines: vec![],
-        custom_emojis: vec![],
-      })
-    })
+    .try_get_with((), read_site(&context))
     .await
+    // TODO: we should never call anyhow like this, add lemmyerror instead
     .map_err(|e| anyhow::anyhow!("Failed to construct site response: {e}"))?;
 
   // Build the local user with parallel queries and add it to site response
@@ -112,3 +95,29 @@ pub async fn get_site(
 
   Ok(Json(site_response))
 }
+
+async fn read_site(context: &LemmyContext) -> LemmyResult<GetSiteResponse> {
+  let site_view = SiteView::read_local(&mut context.pool()).await?;
+  let admins = PersonView::admins(&mut context.pool()).await?;
+  let all_languages = Language::read_all(&mut context.pool()).await?;
+  let discussion_languages = SiteLanguage::read_local_raw(&mut context.pool()).await?;
+  let blocked_urls = LocalSiteUrlBlocklist::get_all(&mut context.pool()).await?;
+  let tagline = Tagline::get_random(&mut context.pool()).await.ok();
+  let admin_oauth_providers = OAuthProvider::get_all(&mut context.pool()).await?;
+  let oauth_providers = OAuthProvider::convert_providers_to_public(admin_oauth_providers.clone());
+
+  Ok(GetSiteResponse {
+    site_view,
+    admins,
+    version: VERSION.to_string(),
+    my_user: None,
+    all_languages,
+    discussion_languages,
+    blocked_urls,
+    tagline,
+    oauth_providers: Some(oauth_providers),
+    admin_oauth_providers: Some(admin_oauth_providers),
+    taglines: vec![],
+    custom_emojis: vec![],
+  })
+}