add cache

src/cache.rs

@@ -0,0 +1,116 @@
+use std::collections::HashMap;
+
+use rocket::tokio::sync::RwLock;
+
+#[macro_export]
+macro_rules! use_api_cache {
+    ($route:literal, $id:ident, $cache:ident) => {
+        if let Some(ret) = $cache.get_only($route, $id).await {
+            return Ok(serde_json::from_str(&ret).unwrap());
+        }
+    };
+}
+
+pub struct RouteCache {
+    inner: RwLock<HashMap<String, HashMap<String, Option<String>>>>,
+}
+
+impl RouteCache {
+    pub fn new() -> Self {
+        Self {
+            inner: RwLock::new(HashMap::new()),
+        }
+    }
+
+    pub async fn get<F, Fut>(&self, route: &str, id: &str, generator: F) -> String
+    where
+        F: FnOnce() -> Fut,
+        Fut: std::future::Future<Output = String>,
+    {
+        {
+            // Try to get a read lock first.
+            let lock = self.inner.read().await;
+            if let Some(inner_map) = lock.get(route) {
+                if let Some(cached_value) = inner_map.get(id) {
+                    log::trace!("Using cached value for {route} / {id}");
+                    return cached_value.clone().unwrap();
+                }
+            }
+        }
+
+        // If the value was not found, acquire a write lock to insert the computed value.
+        let mut lock = self.inner.write().await;
+
+        log::trace!("Computing value for {route} / {id}");
+        let computed = generator().await;
+
+        lock.entry(route.to_string())
+            .or_insert_with(HashMap::new)
+            .insert(id.to_string(), Some(computed.clone()));
+
+        computed
+    }
+
+    pub async fn get_only(&self, route: &str, id: &str) -> Option<String> {
+        let lock = self.inner.read().await;
+        if let Some(inner_map) = lock.get(route) {
+            if let Some(cached_value) = inner_map.get(id) {
+                log::trace!("Using cached value for {route} / {id}");
+                return cached_value.clone();
+            }
+        }
+
+        None
+    }
+
+    pub async fn get_option<F, Fut>(&self, route: &str, id: &str, generator: F) -> Option<String>
+    where
+        F: FnOnce() -> Fut,
+        Fut: std::future::Future<Output = Option<String>>,
+    {
+        {
+            // Try to get a read lock first.
+            let lock = self.inner.read().await;
+            if let Some(inner_map) = lock.get(route) {
+                if let Some(cached_value) = inner_map.get(id) {
+                    log::trace!("Using cached value for {route} / {id}");
+                    return cached_value.clone();
+                }
+            }
+        }
+
+        // If the value was not found, acquire a write lock to insert the computed value.
+        let mut lock = self.inner.write().await;
+
+        log::trace!("Computing value for {route} / {id}");
+        let computed = generator().await;
+
+        lock.entry(route.to_string())
+            .or_insert_with(HashMap::new)
+            .insert(id.to_string(), computed.clone());
+
+        computed
+    }
+
+    pub async fn insert(&self, route: &str, id: &str, value: String) {
+        let mut lock = self.inner.write().await;
+
+        log::trace!("Inserting value for {route} / {id}");
+
+        lock.entry(route.to_string())
+            .or_insert_with(HashMap::new)
+            .insert(id.to_string(), Some(value));
+    }
+
+    pub async fn invalidate(&self, route: &str, id: &str) {
+        let mut lock = self.inner.write().await;
+        if let Some(inner_map) = lock.get_mut(route) {
+            inner_map.remove(id);
+
+            // If the inner map is empty, remove the route entry as well.
+            if inner_map.is_empty() {
+                lock.remove(route);
+            }
+        }
+    }
+}

src/main.rs

@@ -1,5 +1,6 @@
 use library::Libary;
 
+mod cache;
 mod library;
 mod route;
 
@@ -30,6 +31,8 @@ async fn rocket() -> _ {
 
     User::create("admin", "admin", UserRole::Admin).await;
 
+    let cache = cache::RouteCache::new();
+
     rocket::build()
         .mount(
             "/",
@@ -49,5 +52,6 @@ async fn rocket() -> _ {
             ],
         )
         .manage(lib)
+        .manage(cache)
         .attach(cors)
 }

src/route/album.rs

@@ -9,9 +9,11 @@ use rocket::fs::NamedFile;
 use rocket::*;
 use serde_json::json;
 
+use crate::cache::RouteCache;
 use crate::library::album::Album;
 use crate::library::Libary;
 use crate::route::to_api;
+use crate::use_api_cache;
 
 #[get("/artist/<artist_id>/albums")]
 pub async fn albums_route(artist_id: &str, lib: &State<Libary>) -> FallibleApiResponse {
@@ -37,13 +39,31 @@ fn sort_by_tracknumber(a: &serde_json::Value, b: &serde_json::Value) -> Ordering
 }
 
 #[get("/album/<album_id>/cover")]
-pub async fn album_cover_route(album_id: &str, lib: &State<Libary>) -> Option<NamedFile> {
-    let album = lib.get_album_by_id(album_id).await?;
-    NamedFile::open(album.get_cover().await?).await.ok()
+pub async fn album_cover_route(
+    album_id: &str,
+    lib: &State<Libary>,
+    cache: &State<RouteCache>,
+) -> Option<NamedFile> {
+    NamedFile::open(
+        cache
+            .get_option("album_cover_route", album_id, || async {
+                let album = lib.get_album_by_id(album_id).await?;
+                album.get_cover().await
+            })
+            .await?,
+    )
+    .await
+    .ok()
 }
 
 #[get("/album/<album_id>")]
-pub async fn album_route(album_id: &str, lib: &State<Libary>) -> FallibleApiResponse {
+pub async fn album_route(
+    album_id: &str,
+    lib: &State<Libary>,
+    cache: &State<RouteCache>,
+) -> FallibleApiResponse {
+    use_api_cache!("album_route", album_id, cache);
+
     let album = lib
         .get_album_by_id(album_id)
         .await
@@ -69,5 +89,13 @@ pub async fn album_route(album_id: &str, lib: &State<Libary>) -> FallibleApiResp
         .unwrap()
         .insert("tracks".into(), tracks.into());
 
+    cache
+        .insert(
+            "album_route",
+            album_id,
+            serde_json::to_string(&album).unwrap(),
+        )
+        .await;
+
     Ok(album)
 }

src/route/artist.rs

@@ -7,6 +7,7 @@ use mongod::Model;
 use mongodb::bson::doc;
 use rocket::*;
 
+use crate::cache::RouteCache;
 use crate::library::artist::Artist;
 use crate::library::Libary;
 
@@ -18,9 +19,14 @@ pub async fn artists_route(lib: &State<Libary>) -> FallibleApiResponse {
 }
 
 #[get("/artist/<id>/image")]
-pub async fn artist_image_route(id: &str) -> Option<NamedFile> {
-    let image = Artist::get_image_of(id).await?;
-    NamedFile::open(image).await.ok()
+pub async fn artist_image_route(id: &str, cache: &State<RouteCache>) -> Option<NamedFile> {
+    let image = cache
+        .get_option("artist_image_route", id, || async {
+            Artist::get_image_of(id).await
+        })
+        .await;
+
+    NamedFile::open(image?).await.ok()
 }
 
 #[get("/artist/<id>")]