open up ttl backing for nested backings (#13)

cache-loader-async-macros/src/lib.rs

@@ -101,7 +101,7 @@ pub fn test_with_features(item: proc_macro::TokenStream) -> proc_macro::TokenStr
         #[cfg(feature = "ttl-cache")]
         #[tokio::test]
         async fn #fn_ident_ttl() {
-            let #ident: LoadingCache<#key_type, #value_type, #error_type, TtlCacheBacking<_, _>> = LoadingCache::with_backing(TtlCacheBacking::new(Duration::from_secs(3)), move |key: #key_type| {
+            let #ident: LoadingCache<#key_type, #value_type, #error_type, TtlCacheBacking<_, _, _>> = LoadingCache::with_backing(TtlCacheBacking::new(Duration::from_secs(3)), move |key: #key_type| {
                async move #loader
             });
 

src/backing.rs

@@ -5,6 +5,7 @@ use lru::LruCache;
 #[cfg(feature = "ttl-cache")]
 use std::collections::VecDeque;
 use std::fmt::Debug;
+use std::marker::PhantomData;
 use thiserror::Error;
 #[cfg(feature = "ttl-cache")]
 use std::ops::Add;
@@ -20,8 +21,8 @@ pub trait CacheBacking<K, V>
     fn get(&mut self, key: &K) -> Result<Option<&V>, BackingError>;
     fn set(&mut self, key: K, value: V, meta: Option<Self::Meta>) -> Result<Option<V>, BackingError>;
     fn remove(&mut self, key: &K) -> Result<Option<V>, BackingError>;
-    fn contains_key(&self, key: &K) -> Result<bool, BackingError>;
-    fn remove_if(&mut self, predicate: Box<dyn Fn((&K, &V)) -> bool + Send + 'static>) -> Result<(), BackingError>;
+    fn contains_key(&mut self, key: &K) -> Result<bool, BackingError>;
+    fn remove_if(&mut self, predicate: Box<dyn Fn((&K, &V)) -> bool + Send + Sync + 'static>) -> Result<Vec<(K, V)>, BackingError>;
     fn clear(&mut self) -> Result<(), BackingError>;
 }
 
@@ -62,11 +63,12 @@ impl<
         Ok(self.lru.pop(key))
     }
 
-    fn contains_key(&self, key: &K) -> Result<bool, BackingError> {
+    fn contains_key(&mut self, key: &K) -> Result<bool, BackingError> {
         Ok(self.lru.contains(&key.clone()))
     }
 
-    fn remove_if(&mut self, predicate: Box<dyn Fn((&K, &V)) -> bool + Send>) -> Result<(), BackingError> {
+    fn remove_if(&mut self, predicate: Box<dyn Fn((&K, &V)) -> bool + Send + Sync>) -> Result<Vec<(K, V)>, BackingError> {
+        let mut removed = Vec::new();
         let keys = self.lru.iter()
             .filter_map(|(key, value)| {
                 if predicate((key, value)) {
@@ -78,9 +80,10 @@ impl<
             .cloned()
             .collect::<Vec<K>>();
         for key in keys.into_iter() {
-            self.lru.pop(&key);
+            let val = self.lru.pop(&key);
+            removed.push((key, val.expect("LRU value is empty")))
         }
-        Ok(())
+        Ok(removed)
     }
 
     fn clear(&mut self) -> Result<(), BackingError> {
@@ -108,10 +111,15 @@ impl<
 }
 
 #[cfg(feature = "ttl-cache")]
-pub struct TtlCacheBacking<K, V> {
+pub struct TtlCacheBacking<
+    K: Clone + Eq + Hash + Send,
+    V: Clone + Sized + Send,
+    B: CacheBacking<K, (V, Instant)>
+> {
+    phantom: PhantomData<V>,
     ttl: Duration,
     expiry_queue: VecDeque<TTlEntry<K>>,
-    map: HashMap<K, (V, Instant)>,
+    map: B,
 }
 
 #[cfg(feature = "ttl-cache")]
@@ -154,25 +162,26 @@ impl From<Duration> for TtlMeta {
 
 #[cfg(feature = "ttl-cache")]
 impl<
-    K: Eq + Hash + Sized + Clone + Send,
-    V: Sized + Clone + Send
-> CacheBacking<K, V> for TtlCacheBacking<K, V> {
+    K: Clone + Eq + Hash + Send + 'static,
+    V: Clone + Sized + Send + 'static,
+    B: CacheBacking<K, (V, Instant)>
+> CacheBacking<K, V> for TtlCacheBacking<K, V, B> {
     type Meta = TtlMeta;
 
     fn get_mut(&mut self, key: &K) -> Result<Option<&mut V>, BackingError> {
-        self.remove_old();
-        Ok(self.map.get_mut(key)
+        self.remove_old()?;
+        Ok(self.map.get_mut(key)?
             .map(|(value, _)| value))
     }
 
     fn get(&mut self, key: &K) -> Result<Option<&V>, BackingError> {
-        self.remove_old();
-        Ok(self.map.get(key)
+        self.remove_old()?;
+        Ok(self.map.get(key)?
             .map(|(value, _)| value))
     }
 
     fn set(&mut self, key: K, value: V, meta: Option<Self::Meta>) -> Result<Option<V>, BackingError> {
-        self.remove_old();
+        self.remove_old()?;
         let ttl = if let Some(meta) = meta {
             meta.ttl
         } else {
@@ -184,66 +193,77 @@ impl<
     }
 
     fn remove(&mut self, key: &K) -> Result<Option<V>, BackingError> {
-        self.remove_old();
+        self.remove_old()?;
         Ok(self.remove_key(key)?)
     }
 
-    fn contains_key(&self, key: &K) -> Result<bool, BackingError> {
-        // we cant clean old keys on this, since the self ref is not mutable :(
-        Ok(self.map.get(key)
-            .filter(|(_, expiry)| Instant::now().lt(expiry))
-            .is_some())
+    fn contains_key(&mut self, key: &K) -> Result<bool, BackingError> {
+        self.remove_old()?;
+        Ok(self.map.get(key)?.is_some())
     }
 
-    fn remove_if(&mut self, predicate: Box<dyn Fn((&K, &V)) -> bool + Send>) -> Result<(), BackingError> {
-        let keys = self.map.iter()
-            .filter_map(|(key, (value, _))| {
-                if predicate((key, value)) {
-                    Some(key)
-                } else {
-                    None
-                }
-            })
-            .cloned()
-            .collect::<Vec<K>>();
-        for key in keys.into_iter() {
-            self.map.remove(&key);
+    fn remove_if(&mut self, predicate: Box<dyn Fn((&K, &V)) -> bool + Send + Sync>) -> Result<Vec<(K, V)>, BackingError> {
+        let values = self.map.remove_if(Box::new(move |(key, (value, _))| predicate((key, value))))?;
+        let mut mapped = Vec::with_capacity(values.len());
+        for (key, (value, _)) in values {
             // optimize looping through expiry_queue multiple times?
-            self.expiry_queue.retain(|entry| entry.key.ne(&key))
+            self.expiry_queue.retain(|entry| entry.key.ne(&key));
+            mapped.push((key, value));
         }
-        Ok(())
+        Ok(mapped)
     }
 
     fn clear(&mut self) -> Result<(), BackingError> {
         self.expiry_queue.clear();
-        self.map.clear();
+        self.map.clear()?;
         Ok(())
     }
 }
 
 #[cfg(feature = "ttl-cache")]
-impl<K: Eq + Hash + Sized + Clone + Send, V: Sized + Clone + Send> TtlCacheBacking<K, V> {
-    pub fn new(ttl: Duration) -> TtlCacheBacking<K, V> {
+impl<
+    K: Eq + Hash + Sized + Clone + Send,
+    V: Sized + Clone + Send,
+> TtlCacheBacking<K, V, HashMapBacking<K, (V, Instant)>> {
+    pub fn new(ttl: Duration) -> TtlCacheBacking<K, V, HashMapBacking<K, (V, Instant)>> {
+        TtlCacheBacking {
+            phantom: Default::default(),
+            ttl,
+            map: HashMapBacking::new(),
+            expiry_queue: VecDeque::new(),
+        }
+    }
+}
+
+#[cfg(feature = "ttl-cache")]
+impl<
+    K: Eq + Hash + Sized + Clone + Send,
+    V: Sized + Clone + Send,
+    B: CacheBacking<K, (V, Instant)>
+> TtlCacheBacking<K, V, B> {
+    pub fn with_backing(ttl: Duration, backing: B) -> TtlCacheBacking<K, V, B> {
         TtlCacheBacking {
+            phantom: Default::default(),
             ttl,
-            map: HashMap::new(),
+            map: backing,
             expiry_queue: VecDeque::new(),
         }
     }
 
-    fn remove_old(&mut self) {
+    fn remove_old(&mut self) -> Result<(), BackingError> {
         let now = Instant::now();
         while let Some(entry) = self.expiry_queue.pop_front() {
             if now.lt(&entry.expiry) {
                 self.expiry_queue.push_front(entry);
                 break;
             }
-            self.map.remove(&entry.key);
+            self.map.remove(&entry.key)?;
         }
+        Ok(())
     }
 
-    fn replace(&mut self, key: K, value: V, expiry: Instant) -> Result<Option<V>, TtlError> {
-        let entry = self.map.insert(key.clone(), (value, expiry));
+    fn replace(&mut self, key: K, value: V, expiry: Instant) -> Result<Option<V>, BackingError> {
+        let entry = self.map.set(key.clone(), (value, expiry), None)?;
         let res = self.cleanup_expiry(entry, &key);
         match self.expiry_queue.binary_search_by_key(&expiry, |entry| entry.expiry) {
             Ok(found) => {
@@ -256,24 +276,24 @@ impl<K: Eq + Hash + Sized + Clone + Send, V: Sized + Clone + Send> TtlCacheBacki
         res
     }
 
-    fn remove_key(&mut self, key: &K) -> Result<Option<V>, TtlError> {
-        let entry = self.map.remove(key);
+    fn remove_key(&mut self, key: &K) -> Result<Option<V>, BackingError> {
+        let entry = self.map.remove(key)?;
         self.cleanup_expiry(entry, key)
     }
 
-    fn cleanup_expiry(&mut self, entry: Option<(V, Instant)>, key: &K) -> Result<Option<V>, TtlError> {
+    fn cleanup_expiry(&mut self, entry: Option<(V, Instant)>, key: &K) -> Result<Option<V>, BackingError> {
         if let Some((value, old_expiry)) = entry {
             match self.expiry_queue.binary_search_by_key(&old_expiry, |entry| entry.expiry) {
                 Ok(found) => {
                     let index = self.expiry_index_on_key_eq(found, &old_expiry, key);
                     if let Some(index) = index {
                         self.expiry_queue.remove(index);
                     } else {
-                        return Err(TtlError::ExpiryKeyNotFound);
+                        return Err(TtlError::ExpiryKeyNotFound.into());
                     }
                 }
                 Err(_) => {
-                    return Err(TtlError::ExpiryNotFound);
+                    return Err(TtlError::ExpiryNotFound.into());
                 }
             }
             Ok(Some(value))
@@ -340,13 +360,20 @@ impl<
         Ok(self.map.remove(key))
     }
 
-    fn contains_key(&self, key: &K) -> Result<bool, BackingError> {
+    fn contains_key(&mut self, key: &K) -> Result<bool, BackingError> {
         Ok(self.map.contains_key(key))
     }
 
-    fn remove_if(&mut self, predicate: Box<dyn Fn((&K, &V)) -> bool + Send>) -> Result<(), BackingError> {
-        self.map.retain(|k, v| !predicate((k, v)));
-        Ok(())
+    fn remove_if(&mut self, predicate: Box<dyn Fn((&K, &V)) -> bool + Send + Sync>) -> Result<Vec<(K, V)>, BackingError> {
+        let removed = self.map.iter()
+            .filter(|(k, v)| predicate((k, v)))
+            .map(|(k, v)| (k.clone(), v.clone()))
+            .collect::<Vec<(K, V)>>();
+
+        for (k, _) in removed.iter() {
+            self.map.remove(k);
+        }
+        Ok(removed)
     }
 
     fn clear(&mut self) -> Result<(), BackingError> {

src/test.rs

@@ -396,4 +396,29 @@ async fn test_ttl_backing() {
     tokio::time::sleep(Duration::from_secs(2)).await;
 
     assert_eq!(cache.exists("key1".to_owned()).await.unwrap(), false);
+}
+
+#[cfg(all(feature = "ttl-cache", feature = "lru-cache"))]
+#[tokio::test]
+async fn test_ttl_lru_backing() {
+    let cache: LoadingCache<String, _, u8, _> = LoadingCache::with_meta_loader(TtlCacheBacking::with_backing(Duration::from_secs(1), LruCacheBacking::new(2)), move |key: String| {
+       async move {
+           if key.len() < 3 {
+               Ok(key.to_lowercase())
+                   .with_meta(Some(TtlMeta::from(Duration::from_secs(15))))
+           } else {
+               Ok(key.to_lowercase())
+                   .with_meta(None)
+           }
+       }
+    });
+    assert_eq!(cache.get("a".to_owned()).await.unwrap(), "a");
+    assert_eq!(cache.get("bbbbb".to_owned()).await.unwrap(), "bbbbb");
+    tokio::time::sleep(Duration::from_secs(2)).await;
+    assert!(cache.exists("a".to_owned()).await.unwrap());
+    assert!(!cache.exists("bbbbb".to_owned()).await.unwrap());
+    assert_eq!(cache.get("bbbbb".to_owned()).await.unwrap(), "bbbbb");
+    assert_eq!(cache.get("ccccc".to_owned()).await.unwrap(), "ccccc");
+    assert_eq!(cache.get("ddddd".to_owned()).await.unwrap(), "ddddd");
+    assert!(!cache.exists("a".to_owned()).await.unwrap());
 }