Delay set cache after response, make cache static

Uses `tokio::spawn` to delay updating the cache while the server responds to the request.

Because `tokio::spawn` can run on another thread, references need to be static, so I initialized the cache in `lazy_static`.

Cargo.lock

@@ -142,6 +142,7 @@ dependencies = [
  "http-api-problem",
  "hyper",
  "ipnetwork",
+ "lazy_static",
  "listenfd",
  "lru",
  "seahash",

Cargo.toml

@@ -12,6 +12,7 @@ chrono = { version = "0.4", features = ["serde"] }
 dotenv = "0.15"
 http-api-problem = { version = "0.17", features = ["with-warp"] }
 hyper = "0.13"
+lazy_static = "1.4"
 listenfd = "0.3"
 tokio = { version = "0.2", features = ["macros", "rt-threaded", "sync"] }
 sqlx = { version = "0.3", default-features = false, features = [ "runtime-tokio", "macros", "postgres", "chrono", "uuid", "ipnetwork", "json" ] }

src/caches/cache.rs

@@ -24,8 +24,8 @@ where
 
 impl<K, V> Cache<K, V>
 where
-    K: Eq + Hash + Debug,
-    V: Clone,
+    K: Eq + Hash + Debug + Send,
+    V: Clone + Send,
 {
     pub fn new(name: &str, capacity: usize) -> Self {
         Cache {
@@ -48,7 +48,7 @@ where
         }
     }
 
-    pub async fn get<G, F>(&self, key: K, getter: G) -> Result<V>
+    pub async fn get<G, F>(&'static self, key: K, getter: G) -> Result<V>
     where
         G: Fn() -> F,
         F: Future<Output = Result<V>>,
@@ -62,8 +62,13 @@ where
 
         self.log_with_key(&key, "get: miss");
         let value = getter().await?;
-        let mut guard = self.lru_mutex.lock().await;
-        guard.put(key, value.clone());
+
+        let to_cache = value.clone();
+        tokio::spawn(async move {
+            let mut guard = self.lru_mutex.lock().await;
+            self.log_with_key(&key, "get: update cache");
+            guard.put(key, to_cache);
+        });
 
         Ok(value)
     }
@@ -85,10 +90,10 @@ where
 
 impl<K> Cache<K, CachedResponse>
 where
-    K: Eq + Hash + Debug,
+    K: Eq + Hash + Debug + Send,
 {
     pub async fn get_response<G, F, R>(
-        &self,
+        &'static self,
         key: K,
         getter: G,
     ) -> Result<CachedResponse, Rejection>
@@ -111,8 +116,12 @@ where
                 let cached_response = CachedResponse::from_reply(reply)
                     .await
                     .map_err(reject_anyhow)?;
-                let mut guard = self.lru_mutex.lock().await;
-                guard.put(key, cached_response.clone());
+                let to_cache = cached_response.clone();
+                tokio::spawn(async move {
+                    let mut guard = self.lru_mutex.lock().await;
+                    self.log_with_key(&key, "get_response: update cache");
+                    guard.put(key, to_cache);
+                });
                 cached_response
             }
             Err(rejection) => {

src/caches/mod.rs

@@ -9,6 +9,10 @@ mod cached_response;
 pub use cache::Cache;
 pub use cached_response::CachedResponse;
 
+lazy_static! {
+    pub static ref CACHES: Caches = Caches::initialize();
+}
+
 #[derive(Debug, Clone)]
 pub struct Caches {
     pub owner_ids_by_api_key: Cache<Uuid, i32>,

src/handlers/interior_ref_list.rs

@@ -4,6 +4,7 @@ use uuid::Uuid;
 use warp::reply::{with_header, with_status};
 use warp::{Rejection, Reply};
 
+use crate::caches::CACHES;
 use crate::models::{InteriorRefList, ListParams};
 use crate::problem::reject_anyhow;
 use crate::Environment;
@@ -11,8 +12,7 @@ use crate::Environment;
 use super::{authenticate, check_etag, JsonWithETag};
 
 pub async fn get(id: i32, etag: Option<String>, env: Environment) -> Result<impl Reply, Rejection> {
-    let response = env
-        .caches
+    let response = CACHES
         .interior_ref_list
         .get_response(id, || async {
             let interior_ref_list = InteriorRefList::get(&env.db, id).await?;
@@ -29,8 +29,7 @@ pub async fn get_by_shop_id(
     etag: Option<String>,
     env: Environment,
 ) -> Result<impl Reply, Rejection> {
-    let response = env
-        .caches
+    let response = CACHES
         .interior_ref_list_by_shop_id
         .get_response(shop_id, || async {
             let interior_ref_list = InteriorRefList::get_by_shop_id(&env.db, shop_id).await?;
@@ -47,8 +46,7 @@ pub async fn list(
     etag: Option<String>,
     env: Environment,
 ) -> Result<impl Reply, Rejection> {
-    let response = env
-        .caches
+    let response = CACHES
         .list_interior_ref_lists
         .get_response(list_params.clone(), || async {
             let interior_ref_lists = InteriorRefList::list(&env.db, &list_params).await?;
@@ -80,11 +78,13 @@ pub async fn create(
     let reply = JsonWithETag::from_serializable(&saved_interior_ref_list).map_err(reject_anyhow)?;
     let reply = with_header(reply, "Location", url.as_str());
     let reply = with_status(reply, StatusCode::CREATED);
-    env.caches.list_interior_ref_lists.clear().await;
-    env.caches
-        .interior_ref_list_by_shop_id
-        .delete_response(saved_interior_ref_list.shop_id)
-        .await;
+    tokio::spawn(async move {
+        CACHES.list_interior_ref_lists.clear().await;
+        CACHES
+            .interior_ref_list_by_shop_id
+            .delete_response(saved_interior_ref_list.shop_id)
+            .await;
+    });
     Ok(reply)
 }
 
@@ -118,12 +118,14 @@ pub async fn update(
         JsonWithETag::from_serializable(&updated_interior_ref_list).map_err(reject_anyhow)?;
     let reply = with_header(reply, "Location", url.as_str());
     let reply = with_status(reply, StatusCode::CREATED);
-    env.caches.interior_ref_list.delete_response(id).await;
-    env.caches
-        .interior_ref_list_by_shop_id
-        .delete_response(updated_interior_ref_list.shop_id)
-        .await;
-    env.caches.list_interior_ref_lists.clear().await;
+    tokio::spawn(async move {
+        CACHES.interior_ref_list.delete_response(id).await;
+        CACHES
+            .interior_ref_list_by_shop_id
+            .delete_response(updated_interior_ref_list.shop_id)
+            .await;
+        CACHES.list_interior_ref_lists.clear().await;
+    });
     Ok(reply)
 }
 
@@ -149,19 +151,21 @@ pub async fn update_by_shop_id(
         JsonWithETag::from_serializable(&updated_interior_ref_list).map_err(reject_anyhow)?;
     let reply = with_header(reply, "Location", url.as_str());
     let reply = with_status(reply, StatusCode::CREATED);
-    env.caches
-        .interior_ref_list
-        .delete_response(
-            updated_interior_ref_list
-                .id
-                .expect("saved interior_ref_list has no id"),
-        )
-        .await;
-    env.caches
-        .interior_ref_list_by_shop_id
-        .delete_response(updated_interior_ref_list.shop_id)
-        .await;
-    env.caches.list_interior_ref_lists.clear().await;
+    tokio::spawn(async move {
+        CACHES
+            .interior_ref_list
+            .delete_response(
+                updated_interior_ref_list
+                    .id
+                    .expect("saved interior_ref_list has no id"),
+            )
+            .await;
+        CACHES
+            .interior_ref_list_by_shop_id
+            .delete_response(updated_interior_ref_list.shop_id)
+            .await;
+        CACHES.list_interior_ref_lists.clear().await;
+    });
     Ok(reply)
 }
 
@@ -177,11 +181,13 @@ pub async fn delete(
     InteriorRefList::delete(&env.db, owner_id, id)
         .await
         .map_err(reject_anyhow)?;
-    env.caches.interior_ref_list.delete_response(id).await;
-    env.caches.list_interior_ref_lists.clear().await;
-    env.caches
-        .interior_ref_list_by_shop_id
-        .delete_response(interior_ref_list.shop_id)
-        .await;
+    tokio::spawn(async move {
+        CACHES.interior_ref_list.delete_response(id).await;
+        CACHES.list_interior_ref_lists.clear().await;
+        CACHES
+            .interior_ref_list_by_shop_id
+            .delete_response(interior_ref_list.shop_id)
+            .await;
+    });
     Ok(StatusCode::NO_CONTENT)
 }

src/handlers/merchandise_list.rs

@@ -4,6 +4,7 @@ use uuid::Uuid;
 use warp::reply::{with_header, with_status};
 use warp::{Rejection, Reply};
 
+use crate::caches::CACHES;
 use crate::models::{ListParams, MerchandiseList};
 use crate::problem::reject_anyhow;
 use crate::Environment;
@@ -11,8 +12,7 @@ use crate::Environment;
 use super::{authenticate, check_etag, JsonWithETag};
 
 pub async fn get(id: i32, etag: Option<String>, env: Environment) -> Result<impl Reply, Rejection> {
-    let response = env
-        .caches
+    let response = CACHES
         .merchandise_list
         .get_response(id, || async {
             let merchandise_list = MerchandiseList::get(&env.db, id).await?;
@@ -29,8 +29,7 @@ pub async fn get_by_shop_id(
     etag: Option<String>,
     env: Environment,
 ) -> Result<impl Reply, Rejection> {
-    let response = env
-        .caches
+    let response = CACHES
         .merchandise_list_by_shop_id
         .get_response(shop_id, || async {
             let merchandise_list = MerchandiseList::get_by_shop_id(&env.db, shop_id).await?;
@@ -47,8 +46,7 @@ pub async fn list(
     etag: Option<String>,
     env: Environment,
 ) -> Result<impl Reply, Rejection> {
-    let response = env
-        .caches
+    let response = CACHES
         .list_merchandise_lists
         .get_response(list_params.clone(), || async {
             let merchandise_lists = MerchandiseList::list(&env.db, &list_params).await?;
@@ -80,11 +78,13 @@ pub async fn create(
     let reply = JsonWithETag::from_serializable(&saved_merchandise_list).map_err(reject_anyhow)?;
     let reply = with_header(reply, "Location", url.as_str());
     let reply = with_status(reply, StatusCode::CREATED);
-    env.caches.list_merchandise_lists.clear().await;
-    env.caches
-        .merchandise_list_by_shop_id
-        .delete_response(saved_merchandise_list.shop_id)
-        .await;
+    tokio::spawn(async move {
+        CACHES.list_merchandise_lists.clear().await;
+        CACHES
+            .merchandise_list_by_shop_id
+            .delete_response(saved_merchandise_list.shop_id)
+            .await;
+    });
     Ok(reply)
 }
 
@@ -118,12 +118,14 @@ pub async fn update(
         JsonWithETag::from_serializable(&updated_merchandise_list).map_err(reject_anyhow)?;
     let reply = with_header(reply, "Location", url.as_str());
     let reply = with_status(reply, StatusCode::CREATED);
-    env.caches.merchandise_list.delete_response(id).await;
-    env.caches
-        .merchandise_list_by_shop_id
-        .delete_response(updated_merchandise_list.shop_id)
-        .await;
-    env.caches.list_merchandise_lists.clear().await;
+    tokio::spawn(async move {
+        CACHES.merchandise_list.delete_response(id).await;
+        CACHES
+            .merchandise_list_by_shop_id
+            .delete_response(updated_merchandise_list.shop_id)
+            .await;
+        CACHES.list_merchandise_lists.clear().await;
+    });
     Ok(reply)
 }
 
@@ -149,19 +151,21 @@ pub async fn update_by_shop_id(
         JsonWithETag::from_serializable(&updated_merchandise_list).map_err(reject_anyhow)?;
     let reply = with_header(reply, "Location", url.as_str());
     let reply = with_status(reply, StatusCode::CREATED);
-    env.caches
-        .merchandise_list
-        .delete_response(
-            updated_merchandise_list
-                .id
-                .expect("saved merchandise_list has no id"),
-        )
-        .await;
-    env.caches
-        .merchandise_list_by_shop_id
-        .delete_response(updated_merchandise_list.shop_id)
-        .await;
-    env.caches.list_merchandise_lists.clear().await;
+    tokio::spawn(async move {
+        CACHES
+            .merchandise_list
+            .delete_response(
+                updated_merchandise_list
+                    .id
+                    .expect("saved merchandise_list has no id"),
+            )
+            .await;
+        CACHES
+            .merchandise_list_by_shop_id
+            .delete_response(updated_merchandise_list.shop_id)
+            .await;
+        CACHES.list_merchandise_lists.clear().await;
+    });
     Ok(reply)
 }
 
@@ -177,11 +181,13 @@ pub async fn delete(
     MerchandiseList::delete(&env.db, owner_id, id)
         .await
         .map_err(reject_anyhow)?;
-    env.caches.merchandise_list.delete_response(id).await;
-    env.caches
-        .merchandise_list_by_shop_id
-        .delete_response(merchandise_list.shop_id)
-        .await;
-    env.caches.list_merchandise_lists.clear().await;
+    tokio::spawn(async move {
+        CACHES.merchandise_list.delete_response(id).await;
+        CACHES
+            .merchandise_list_by_shop_id
+            .delete_response(merchandise_list.shop_id)
+            .await;
+        CACHES.list_merchandise_lists.clear().await;
+    });
     Ok(StatusCode::NO_CONTENT)
 }

src/handlers/mod.rs

@@ -15,14 +15,14 @@ pub mod owner;
 pub mod shop;
 pub mod transaction;
 
-use super::caches::CachedResponse;
+use super::caches::{CachedResponse, CACHES};
 use super::problem::{unauthorized_no_api_key, unauthorized_no_owner};
 use super::Environment;
 
 #[instrument(level = "debug", skip(env, api_key))]
 pub async fn authenticate(env: &Environment, api_key: Option<Uuid>) -> Result<i32> {
     if let Some(api_key) = api_key {
-        env.caches
+        CACHES
             .owner_ids_by_api_key
             .get(api_key, || async {
                 Ok(

src/handlers/owner.rs

@@ -6,6 +6,7 @@ use uuid::Uuid;
 use warp::reply::{with_header, with_status};
 use warp::{Rejection, Reply};
 
+use crate::caches::CACHES;
 use crate::models::{ListParams, Owner};
 use crate::problem::{reject_anyhow, unauthorized_no_api_key};
 use crate::Environment;
@@ -13,8 +14,7 @@ use crate::Environment;
 use super::{authenticate, check_etag, JsonWithETag};
 
 pub async fn get(id: i32, etag: Option<String>, env: Environment) -> Result<impl Reply, Rejection> {
-    let response = env
-        .caches
+    let response = CACHES
         .owner
         .get_response(id, || async {
             let owner = Owner::get(&env.db, id).await?;
@@ -31,8 +31,7 @@ pub async fn list(
     etag: Option<String>,
     env: Environment,
 ) -> Result<impl Reply, Rejection> {
-    let response = env
-        .caches
+    let response = CACHES
         .list_owners
         .get_response(list_params.clone(), || async {
             let owners = Owner::list(&env.db, &list_params).await?;
@@ -72,7 +71,9 @@ pub async fn create(
         let reply = JsonWithETag::from_serializable(&saved_owner).map_err(reject_anyhow)?;
         let reply = with_header(reply, "Location", url.as_str());
         let reply = with_status(reply, StatusCode::CREATED);
-        env.caches.list_owners.clear().await;
+        tokio::spawn(async move {
+            CACHES.list_owners.clear().await;
+        });
         Ok(reply)
     } else {
         Err(reject_anyhow(unauthorized_no_api_key()))
@@ -98,8 +99,10 @@ pub async fn update(
     let reply = JsonWithETag::from_serializable(&updated_owner).map_err(reject_anyhow)?;
     let reply = with_header(reply, "Location", url.as_str());
     let reply = with_status(reply, StatusCode::CREATED);
-    env.caches.owner.delete_response(id).await;
-    env.caches.list_owners.clear().await;
+    tokio::spawn(async move {
+        CACHES.owner.delete_response(id).await;
+        CACHES.list_owners.clear().await;
+    });
     Ok(reply)
 }
 
@@ -112,11 +115,13 @@ pub async fn delete(
     Owner::delete(&env.db, owner_id, id)
         .await
         .map_err(reject_anyhow)?;
-    env.caches.owner.delete_response(id).await;
-    env.caches
-        .owner_ids_by_api_key
-        .delete(api_key.expect("api-key has been validated during authenticate"))
-        .await;
-    env.caches.list_owners.clear().await;
+    tokio::spawn(async move {
+        CACHES.owner.delete_response(id).await;
+        CACHES
+            .owner_ids_by_api_key
+            .delete(api_key.expect("api-key has been validated during authenticate"))
+            .await;
+        CACHES.list_owners.clear().await;
+    });
     Ok(StatusCode::NO_CONTENT)
 }

src/handlers/shop.rs

@@ -5,6 +5,7 @@ use uuid::Uuid;
 use warp::reply::{with_header, with_status};
 use warp::{Rejection, Reply};
 
+use crate::caches::CACHES;
 use crate::models::{InteriorRefList, ListParams, MerchandiseList, Shop};
 use crate::problem::reject_anyhow;
 use crate::Environment;
@@ -12,8 +13,7 @@ use crate::Environment;
 use super::{authenticate, check_etag, JsonWithETag};
 
 pub async fn get(id: i32, etag: Option<String>, env: Environment) -> Result<impl Reply, Rejection> {
-    let response = env
-        .caches
+    let response = CACHES
         .shop
         .get_response(id, || async {
             let shop = Shop::get(&env.db, id).await?;
@@ -30,8 +30,7 @@ pub async fn list(
     etag: Option<String>,
     env: Environment,
 ) -> Result<impl Reply, Rejection> {
-    let response = env
-        .caches
+    let response = CACHES
         .list_shops
         .get_response(list_params.clone(), || async {
             let shops = Shop::list(&env.db, &list_params).await?;
@@ -90,7 +89,9 @@ pub async fn create(
     let reply = JsonWithETag::from_serializable(&saved_shop).map_err(reject_anyhow)?;
     let reply = with_header(reply, "Location", url.as_str());
     let reply = with_status(reply, StatusCode::CREATED);
-    env.caches.list_shops.clear().await;
+    tokio::spawn(async move {
+        CACHES.list_shops.clear().await;
+    });
     Ok(reply)
 }
 
@@ -122,8 +123,10 @@ pub async fn update(
     let reply = JsonWithETag::from_serializable(&updated_shop).map_err(reject_anyhow)?;
     let reply = with_header(reply, "Location", url.as_str());
     let reply = with_status(reply, StatusCode::CREATED);
-    env.caches.shop.delete_response(id).await;
-    env.caches.list_shops.clear().await;
+    tokio::spawn(async move {
+        CACHES.shop.delete_response(id).await;
+        CACHES.list_shops.clear().await;
+    });
     Ok(reply)
 }
 
@@ -136,15 +139,14 @@ pub async fn delete(
     Shop::delete(&env.db, owner_id, id)
         .await
         .map_err(reject_anyhow)?;
-    env.caches.shop.delete_response(id).await;
-    env.caches.list_shops.clear().await;
-    env.caches
-        .interior_ref_list_by_shop_id
-        .delete_response(id)
-        .await;
-    env.caches
-        .merchandise_list_by_shop_id
-        .delete_response(id)
-        .await;
+    tokio::spawn(async move {
+        CACHES.shop.delete_response(id).await;
+        CACHES.list_shops.clear().await;
+        CACHES
+            .interior_ref_list_by_shop_id
+            .delete_response(id)
+            .await;
+        CACHES.merchandise_list_by_shop_id.delete_response(id).await;
+    });
     Ok(StatusCode::NO_CONTENT)
 }

src/handlers/transaction.rs

@@ -4,6 +4,7 @@ use uuid::Uuid;
 use warp::reply::{with_header, with_status};
 use warp::{Rejection, Reply};
 
+use crate::caches::CACHES;
 use crate::models::{ListParams, MerchandiseList, Transaction};
 use crate::problem::reject_anyhow;
 use crate::Environment;
@@ -11,8 +12,7 @@ use crate::Environment;
 use super::{authenticate, check_etag, JsonWithETag};
 
 pub async fn get(id: i32, etag: Option<String>, env: Environment) -> Result<impl Reply, Rejection> {
-    let response = env
-        .caches
+    let response = CACHES
         .transaction
         .get_response(id, || async {
             let transaction = Transaction::get(&env.db, id).await?;
@@ -29,8 +29,7 @@ pub async fn list(
     etag: Option<String>,
     env: Environment,
 ) -> Result<impl Reply, Rejection> {
-    let response = env
-        .caches
+    let response = CACHES
         .list_transactions
         .get_response(list_params.clone(), || async {
             let transactions = Transaction::list(&env.db, &list_params).await?;
@@ -48,8 +47,7 @@ pub async fn list_by_shop_id(
     etag: Option<String>,
     env: Environment,
 ) -> Result<impl Reply, Rejection> {
-    let response = env
-        .caches
+    let response = CACHES
         .list_transactions_by_shop_id
         .get_response((shop_id, list_params.clone()), || async {
             let transactions = Transaction::list_by_shop_id(&env.db, shop_id, &list_params).await?;
@@ -104,22 +102,24 @@ pub async fn create(
     let reply = JsonWithETag::from_serializable(&saved_transaction).map_err(reject_anyhow)?;
     let reply = with_header(reply, "Location", url.as_str());
     let reply = with_status(reply, StatusCode::CREATED);
-    // TODO: will this make these caches effectively useless?
-    env.caches.list_transactions.clear().await;
-    env.caches.list_transactions_by_shop_id.clear().await;
-    env.caches
-        .merchandise_list
-        .delete_response(
-            updated_merchandise_list
-                .id
-                .expect("saved merchandise_list has no id"),
-        )
-        .await;
-    env.caches
-        .merchandise_list_by_shop_id
-        .delete_response(updated_merchandise_list.shop_id)
-        .await;
-    env.caches.list_merchandise_lists.clear().await;
+    tokio::spawn(async move {
+        // TODO: will this make these caches effectively useless?
+        CACHES.list_transactions.clear().await;
+        CACHES.list_transactions_by_shop_id.clear().await;
+        CACHES
+            .merchandise_list
+            .delete_response(
+                updated_merchandise_list
+                    .id
+                    .expect("saved merchandise_list has no id"),
+            )
+            .await;
+        CACHES
+            .merchandise_list_by_shop_id
+            .delete_response(updated_merchandise_list.shop_id)
+            .await;
+        CACHES.list_merchandise_lists.clear().await;
+    });
     Ok(reply)
 }
 
@@ -132,8 +132,10 @@ pub async fn delete(
     Transaction::delete(&env.db, owner_id, id)
         .await
         .map_err(reject_anyhow)?;
-    env.caches.transaction.delete_response(id).await;
-    env.caches.list_transactions.clear().await;
-    env.caches.list_transactions_by_shop_id.clear().await;
+    tokio::spawn(async move {
+        CACHES.transaction.delete_response(id).await;
+        CACHES.list_transactions.clear().await;
+        CACHES.list_transactions_by_shop_id.clear().await;
+    });
     Ok(StatusCode::NO_CONTENT)
 }

src/main.rs

@@ -1,3 +1,6 @@
+#[macro_use]
+extern crate lazy_static;
+
 use anyhow::Result;
 use dotenv::dotenv;
 use http::StatusCode;
@@ -18,13 +21,11 @@ mod macros;
 mod models;
 mod problem;
 
-use caches::Caches;
 use models::{InteriorRefList, ListParams, MerchandiseList, Owner, Shop, Transaction};
 
 #[derive(Debug, Clone)]
 pub struct Environment {
     pub db: PgPool,
-    pub caches: Caches,
     pub api_url: Url,
 }
 
@@ -35,7 +36,6 @@ impl Environment {
                 .max_size(5)
                 .build(&env::var("DATABASE_URL")?)
                 .await?,
-            caches: Caches::initialize(),
             api_url,
         })
     }