moka/future/entry_selector.rs
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use crate::{ops::compute, Entry};
use super::Cache;
use std::{
borrow::Borrow,
future::Future,
hash::{BuildHasher, Hash},
sync::Arc,
};
/// Provides advanced methods to select or insert an entry of the cache.
///
/// Many methods here return an [`Entry`], a snapshot of a single key-value pair in
/// the cache, carrying additional information like `is_fresh`.
///
/// `OwnedKeyEntrySelector` is constructed from the [`entry`][entry-method] method on
/// the cache.
///
/// [`Entry`]: ../struct.Entry.html
/// [entry-method]: ./struct.Cache.html#method.entry
pub struct OwnedKeyEntrySelector<'a, K, V, S> {
owned_key: K,
hash: u64,
cache: &'a Cache<K, V, S>,
}
impl<'a, K, V, S> OwnedKeyEntrySelector<'a, K, V, S>
where
K: Hash + Eq + Send + Sync + 'static,
V: Clone + Send + Sync + 'static,
S: BuildHasher + Clone + Send + Sync + 'static,
{
pub(crate) fn new(owned_key: K, hash: u64, cache: &'a Cache<K, V, S>) -> Self {
Self {
owned_key,
hash,
cache,
}
}
/// Performs a compute operation on a cached entry by using the given closure
/// `f`. A compute operation is either put, remove or no-operation (nop).
///
/// The closure `f` should take the current entry of `Option<Entry<K, V>>` for
/// the key, and return a `Future` that resolves to an `ops::compute::Op<V>`
/// enum.
///
/// This method works as the followings:
///
/// 1. Apply the closure `f` to the current cached `Entry`, and get a `Future`.
/// 2. Resolve the `Future`, and get an `ops::compute::Op<V>`.
/// 3. Execute the op on the cache:
/// - `Op::Put(V)`: Put the new value `V` to the cache.
/// - `Op::Remove`: Remove the current cached entry.
/// - `Op::Nop`: Do nothing.
/// 4. Return an `ops::compute::CompResult<K, V>` as the followings:
///
/// | [`Op<V>`] | [`Entry<K, V>`] already exists? | [`CompResult<K, V>`] | Notes |
/// |:--------- |:--- |:--------------------------- |:------------------------------- |
/// | `Put(V)` | no | `Inserted(Entry<K, V>)` | The new entry is returned. |
/// | `Put(V)` | yes | `ReplacedWith(Entry<K, V>)` | The new entry is returned. |
/// | `Remove` | no | `StillNone(Arc<K>)` | |
/// | `Remove` | yes | `Removed(Entry<K, V>)` | The removed entry is returned. |
/// | `Nop` | no | `StillNone(Arc<K>)` | |
/// | `Nop` | yes | `Unchanged(Entry<K, V>)` | The existing entry is returned. |
///
/// # See Also
///
/// - If you want the `Future` resolve to `Result<Op<V>>` instead of `Op<V>`, and
/// modify entry only when resolved to `Ok(V)`, use the
/// [`and_try_compute_with`] method.
/// - If you only want to update or insert, use the [`and_upsert_with`] method.
///
/// [`Entry<K, V>`]: ../struct.Entry.html
/// [`Op<V>`]: ../ops/compute/enum.Op.html
/// [`CompResult<K, V>`]: ../ops/compute/enum.CompResult.html
/// [`and_upsert_with`]: #method.and_upsert_with
/// [`and_try_compute_with`]: #method.and_try_compute_with
///
/// # Example
///
/// ```rust
/// // Cargo.toml
/// //
/// // [dependencies]
/// // moka = { version = "0.12.8", features = ["future"] }
/// // tokio = { version = "1", features = ["rt-multi-thread", "macros" ] }
///
/// use moka::{
/// future::Cache,
/// ops::compute::{CompResult, Op},
/// };
///
/// #[tokio::main]
/// async fn main() {
/// let cache: Cache<String, u64> = Cache::new(100);
/// let key = "key1".to_string();
///
/// /// Increment a cached `u64` counter. If the counter is greater than or
/// /// equal to 2, remove it.
/// async fn inclement_or_remove_counter(
/// cache: &Cache<String, u64>,
/// key: &str,
/// ) -> CompResult<String, u64> {
/// cache
/// .entry(key.to_string())
/// .and_compute_with(|maybe_entry| {
/// let op = if let Some(entry) = maybe_entry {
/// let counter = entry.into_value();
/// if counter < 2 {
/// Op::Put(counter.saturating_add(1)) // Update
/// } else {
/// Op::Remove
/// }
/// } else {
/// Op::Put(1) // Insert
/// };
/// // Return a Future that is resolved to `op` immediately.
/// std::future::ready(op)
/// })
/// .await
/// }
///
/// // This should insert a new counter value 1 to the cache, and return the
/// // value with the kind of the operation performed.
/// let result = inclement_or_remove_counter(&cache, &key).await;
/// let CompResult::Inserted(entry) = result else {
/// panic!("`Inserted` should be returned: {result:?}");
/// };
/// assert_eq!(entry.into_value(), 1);
///
/// // This should increment the cached counter value by 1.
/// let result = inclement_or_remove_counter(&cache, &key).await;
/// let CompResult::ReplacedWith(entry) = result else {
/// panic!("`ReplacedWith` should be returned: {result:?}");
/// };
/// assert_eq!(entry.into_value(), 2);
///
/// // This should remove the cached counter from the cache, and returns the
/// // _removed_ value.
/// let result = inclement_or_remove_counter(&cache, &key).await;
/// let CompResult::Removed(entry) = result else {
/// panic!("`Removed` should be returned: {result:?}");
/// };
/// assert_eq!(entry.into_value(), 2);
///
/// // The key should not exist.
/// assert!(!cache.contains_key(&key));
///
/// // This should start over; insert a new counter value 1 to the cache.
/// let result = inclement_or_remove_counter(&cache, &key).await;
/// let CompResult::Inserted(entry) = result else {
/// panic!("`Inserted` should be returned: {result:?}");
/// };
/// assert_eq!(entry.into_value(), 1);
/// }
/// ```
///
/// # Concurrent calls on the same key
///
/// This method guarantees that concurrent calls on the same key are executed
/// serially. That is, `and_compute_with` calls on the same key never run
/// concurrently. The calls are serialized by the order of their invocation. It
/// uses a key-level lock to achieve this.
pub async fn and_compute_with<F, Fut>(self, f: F) -> compute::CompResult<K, V>
where
F: FnOnce(Option<Entry<K, V>>) -> Fut,
Fut: Future<Output = compute::Op<V>>,
{
let key = Arc::new(self.owned_key);
self.cache
.compute_with_hash_and_fun(key, self.hash, f)
.await
}
/// Performs a compute operation on a cached entry by using the given closure
/// `f`. A compute operation is either put, remove or no-operation (nop).
///
/// The closure `f` should take the current entry of `Option<Entry<K, V>>` for
/// the key, and return a `Future` that resolves to a
/// `Result<ops::compute::Op<V>, E>`.
///
/// This method works as the followings:
///
/// 1. Apply the closure `f` to the current cached `Entry`, and get a `Future`.
/// 2. Resolve the `Future`, and get a `Result<ops::compute::Op<V>, E>`.
/// 3. If resolved to `Err(E)`, return it.
/// 4. Else, execute the op on the cache:
/// - `Ok(Op::Put(V))`: Put the new value `V` to the cache.
/// - `Ok(Op::Remove)`: Remove the current cached entry.
/// - `Ok(Op::Nop)`: Do nothing.
/// 5. Return an `Ok(ops::compute::CompResult<K, V>)` as the followings:
///
/// | [`Op<V>`] | [`Entry<K, V>`] already exists? | [`CompResult<K, V>`] | Notes |
/// |:--------- |:--- |:--------------------------- |:------------------------------- |
/// | `Put(V)` | no | `Inserted(Entry<K, V>)` | The new entry is returned. |
/// | `Put(V)` | yes | `ReplacedWith(Entry<K, V>)` | The new entry is returned. |
/// | `Remove` | no | `StillNone(Arc<K>)` | |
/// | `Remove` | yes | `Removed(Entry<K, V>)` | The removed entry is returned. |
/// | `Nop` | no | `StillNone(Arc<K>)` | |
/// | `Nop` | yes | `Unchanged(Entry<K, V>)` | The existing entry is returned. |
///
/// # See Also
///
/// - If you want the `Future` resolve to `Op<V>` instead of `Result<Op<V>>`, use
/// the [`and_compute_with`] method.
/// - If you only want to update or insert, use the [`and_upsert_with`] method.
///
/// [`Entry<K, V>`]: ../struct.Entry.html
/// [`Op<V>`]: ../ops/compute/enum.Op.html
/// [`CompResult<K, V>`]: ../ops/compute/enum.CompResult.html
/// [`and_upsert_with`]: #method.and_upsert_with
/// [`and_compute_with`]: #method.and_compute_with
///
/// # Example
///
/// See [`try_append_value_async.rs`] in the `examples` directory.
///
/// [`try_append_value_async.rs`]:
/// https://github.com/moka-rs/moka/tree/main/examples/try_append_value_async.rs
///
/// # Concurrent calls on the same key
///
/// This method guarantees that concurrent calls on the same key are executed
/// serially. That is, `and_try_compute_with` calls on the same key never run
/// concurrently. The calls are serialized by the order of their invocation. It
/// uses a key-level lock to achieve this.
pub async fn and_try_compute_with<F, Fut, E>(self, f: F) -> Result<compute::CompResult<K, V>, E>
where
F: FnOnce(Option<Entry<K, V>>) -> Fut,
Fut: Future<Output = Result<compute::Op<V>, E>>,
E: Send + Sync + 'static,
{
let key = Arc::new(self.owned_key);
self.cache
.try_compute_with_hash_and_fun(key, self.hash, f)
.await
}
/// Performs an upsert of an [`Entry`] by using the given closure `f`. The word
/// "upsert" here means "update" or "insert".
///
/// The closure `f` should take the current entry of `Option<Entry<K, V>>` for
/// the key, and return a `Future` that resolves to a new value `V`.
///
/// This method works as the followings:
///
/// 1. Apply the closure `f` to the current cached `Entry`, and get a `Future`.
/// 2. Resolve the `Future`, and get a new value `V`.
/// 3. Upsert the new value to the cache.
/// 4. Return the `Entry` having the upserted value.
///
/// # See Also
///
/// - If you want to optionally upsert, that is to upsert only when certain
/// conditions meet, use the [`and_compute_with`] method.
/// - If you try to upsert, that is to make the `Future` resolve to `Result<V>`
/// instead of `V`, and upsert only when resolved to `Ok(V)`, use the
/// [`and_try_compute_with`] method.
///
/// [`Entry`]: ../struct.Entry.html
/// [`and_compute_with`]: #method.and_compute_with
/// [`and_try_compute_with`]: #method.and_try_compute_with
///
/// # Example
///
/// ```rust
/// // Cargo.toml
/// //
/// // [dependencies]
/// // moka = { version = "0.12.8", features = ["future"] }
/// // tokio = { version = "1", features = ["rt-multi-thread", "macros" ] }
///
/// use moka::future::Cache;
///
/// #[tokio::main]
/// async fn main() {
/// let cache: Cache<String, u64> = Cache::new(100);
/// let key = "key1".to_string();
///
/// let entry = cache
/// .entry(key.clone())
/// .and_upsert_with(|maybe_entry| {
/// let counter = if let Some(entry) = maybe_entry {
/// entry.into_value().saturating_add(1) // Update
/// } else {
/// 1 // Insert
/// };
/// // Return a Future that is resolved to `counter` immediately.
/// std::future::ready(counter)
/// })
/// .await;
/// // It was not an update.
/// assert!(!entry.is_old_value_replaced());
/// assert_eq!(entry.key(), &key);
/// assert_eq!(entry.into_value(), 1);
///
/// let entry = cache
/// .entry(key.clone())
/// .and_upsert_with(|maybe_entry| {
/// let counter = if let Some(entry) = maybe_entry {
/// entry.into_value().saturating_add(1)
/// } else {
/// 1
/// };
/// std::future::ready(counter)
/// })
/// .await;
/// // It was an update.
/// assert!(entry.is_old_value_replaced());
/// assert_eq!(entry.key(), &key);
/// assert_eq!(entry.into_value(), 2);
/// }
/// ```
///
/// # Concurrent calls on the same key
///
/// This method guarantees that concurrent calls on the same key are executed
/// serially. That is, `and_upsert_with` calls on the same key never run
/// concurrently. The calls are serialized by the order of their invocation. It
/// uses a key-level lock to achieve this.
pub async fn and_upsert_with<F, Fut>(self, f: F) -> Entry<K, V>
where
F: FnOnce(Option<Entry<K, V>>) -> Fut,
Fut: Future<Output = V>,
{
let key = Arc::new(self.owned_key);
self.cache.upsert_with_hash_and_fun(key, self.hash, f).await
}
/// Returns the corresponding [`Entry`] for the key given when this entry
/// selector was constructed. If the entry does not exist, inserts one by calling
/// the [`default`][std-default-function] function of the value type `V`.
///
/// [`Entry`]: ../struct.Entry.html
/// [std-default-function]: https://doc.rust-lang.org/stable/std/default/trait.Default.html#tymethod.default
///
/// # Example
///
/// ```rust
/// // Cargo.toml
/// //
/// // [dependencies]
/// // moka = { version = "0.12", features = ["future"] }
/// // tokio = { version = "1", features = ["rt-multi-thread", "macros" ] }
///
/// use moka::future::Cache;
///
/// #[tokio::main]
/// async fn main() {
/// let cache: Cache<String, Option<u32>> = Cache::new(100);
/// let key = "key1".to_string();
///
/// let entry = cache.entry(key.clone()).or_default().await;
/// assert!(entry.is_fresh());
/// assert_eq!(entry.key(), &key);
/// assert_eq!(entry.into_value(), None);
///
/// let entry = cache.entry(key).or_default().await;
/// // Not fresh because the value was already in the cache.
/// assert!(!entry.is_fresh());
/// }
/// ```
pub async fn or_default(self) -> Entry<K, V>
where
V: Default,
{
let key = Arc::new(self.owned_key);
self.cache
.get_or_insert_with_hash(key, self.hash, Default::default)
.await
}
/// Returns the corresponding [`Entry`] for the key given when this entry
/// selector was constructed. If the entry does not exist, inserts one by using
/// the the given `default` value for `V`.
///
/// [`Entry`]: ../struct.Entry.html
///
/// # Example
///
/// ```rust
/// // Cargo.toml
/// //
/// // [dependencies]
/// // moka = { version = "0.12", features = ["future"] }
/// // tokio = { version = "1", features = ["rt-multi-thread", "macros" ] }
///
/// use moka::future::Cache;
///
/// #[tokio::main]
/// async fn main() {
/// let cache: Cache<String, u32> = Cache::new(100);
/// let key = "key1".to_string();
///
/// let entry = cache.entry(key.clone()).or_insert(3).await;
/// assert!(entry.is_fresh());
/// assert_eq!(entry.key(), &key);
/// assert_eq!(entry.into_value(), 3);
///
/// let entry = cache.entry(key).or_insert(6).await;
/// // Not fresh because the value was already in the cache.
/// assert!(!entry.is_fresh());
/// assert_eq!(entry.into_value(), 3);
/// }
/// ```
pub async fn or_insert(self, default: V) -> Entry<K, V> {
let key = Arc::new(self.owned_key);
let init = || default;
self.cache
.get_or_insert_with_hash(key, self.hash, init)
.await
}
/// Returns the corresponding [`Entry`] for the key given when this entry
/// selector was constructed. If the entry does not exist, resolves the `init`
/// future and inserts the output.
///
/// [`Entry`]: ../struct.Entry.html
///
/// # Example
///
/// ```rust
/// // Cargo.toml
/// //
/// // [dependencies]
/// // moka = { version = "0.12", features = ["future"] }
/// // tokio = { version = "1", features = ["rt-multi-thread", "macros" ] }
///
/// use moka::future::Cache;
///
/// #[tokio::main]
/// async fn main() {
/// let cache: Cache<String, String> = Cache::new(100);
/// let key = "key1".to_string();
///
/// let entry = cache
/// .entry(key.clone())
/// .or_insert_with(async { "value1".to_string() })
/// .await;
/// assert!(entry.is_fresh());
/// assert_eq!(entry.key(), &key);
/// assert_eq!(entry.into_value(), "value1");
///
/// let entry = cache
/// .entry(key)
/// .or_insert_with(async { "value2".to_string() })
/// .await;
/// // Not fresh because the value was already in the cache.
/// assert!(!entry.is_fresh());
/// assert_eq!(entry.into_value(), "value1");
/// }
/// ```
///
/// # Concurrent calls on the same key
///
/// This method guarantees that concurrent calls on the same not-existing entry
/// are coalesced into one evaluation of the `init` future. Only one of the calls
/// evaluates its future (thus returned entry's `is_fresh` method returns
/// `true`), and other calls wait for that future to resolve (and their
/// `is_fresh` return `false`).
///
/// For more detail about the coalescing behavior, see
/// [`Cache::get_with`][get-with-method].
///
/// [get-with-method]: ./struct.Cache.html#method.get_with
pub async fn or_insert_with(self, init: impl Future<Output = V>) -> Entry<K, V> {
futures_util::pin_mut!(init);
let key = Arc::new(self.owned_key);
let replace_if = None as Option<fn(&V) -> bool>;
self.cache
.get_or_insert_with_hash_and_fun(key, self.hash, init, replace_if, true)
.await
}
/// Works like [`or_insert_with`](#method.or_insert_with), but takes an additional
/// `replace_if` closure.
///
/// This method will resolve the `init` future and insert the output to the
/// cache when:
///
/// - The key does not exist.
/// - Or, `replace_if` closure returns `true`.
pub async fn or_insert_with_if(
self,
init: impl Future<Output = V>,
replace_if: impl FnMut(&V) -> bool + Send,
) -> Entry<K, V> {
futures_util::pin_mut!(init);
let key = Arc::new(self.owned_key);
self.cache
.get_or_insert_with_hash_and_fun(key, self.hash, init, Some(replace_if), true)
.await
}
/// Returns the corresponding [`Entry`] for the key given when this entry
/// selector was constructed. If the entry does not exist, resolves the `init`
/// future, and inserts an entry if `Some(value)` was returned. If `None` was
/// returned from the future, this method does not insert an entry and returns
/// `None`.
///
/// [`Entry`]: ../struct.Entry.html
///
/// # Example
///
/// ```rust
/// // Cargo.toml
/// //
/// // [dependencies]
/// // moka = { version = "0.12", features = ["future"] }
/// // tokio = { version = "1", features = ["rt-multi-thread", "macros" ] }
///
/// use moka::future::Cache;
///
/// #[tokio::main]
/// async fn main() {
/// let cache: Cache<String, u32> = Cache::new(100);
/// let key = "key1".to_string();
///
/// let none_entry = cache
/// .entry(key.clone())
/// .or_optionally_insert_with(async { None })
/// .await;
/// assert!(none_entry.is_none());
///
/// let some_entry = cache
/// .entry(key.clone())
/// .or_optionally_insert_with(async { Some(3) })
/// .await;
/// assert!(some_entry.is_some());
/// let entry = some_entry.unwrap();
/// assert!(entry.is_fresh());
/// assert_eq!(entry.key(), &key);
/// assert_eq!(entry.into_value(), 3);
///
/// let some_entry = cache
/// .entry(key)
/// .or_optionally_insert_with(async { Some(6) })
/// .await;
/// let entry = some_entry.unwrap();
/// // Not fresh because the value was already in the cache.
/// assert!(!entry.is_fresh());
/// assert_eq!(entry.into_value(), 3);
/// }
/// ```
///
/// # Concurrent calls on the same key
///
/// This method guarantees that concurrent calls on the same not-existing entry
/// are coalesced into one evaluation of the `init` future. Only one of the calls
/// evaluates its future (thus returned entry's `is_fresh` method returns
/// `true`), and other calls wait for that future to resolve (and their
/// `is_fresh` return `false`).
///
/// For more detail about the coalescing behavior, see
/// [`Cache::optionally_get_with`][opt-get-with-method].
///
/// [opt-get-with-method]: ./struct.Cache.html#method.optionally_get_with
pub async fn or_optionally_insert_with(
self,
init: impl Future<Output = Option<V>>,
) -> Option<Entry<K, V>> {
futures_util::pin_mut!(init);
let key = Arc::new(self.owned_key);
self.cache
.get_or_optionally_insert_with_hash_and_fun(key, self.hash, init, true)
.await
}
/// Returns the corresponding [`Entry`] for the key given when this entry
/// selector was constructed. If the entry does not exist, resolves the `init`
/// future, and inserts an entry if `Ok(value)` was returned. If `Err(_)` was
/// returned from the future, this method does not insert an entry and returns
/// the `Err` wrapped by [`std::sync::Arc`][std-arc].
///
/// [`Entry`]: ../struct.Entry.html
/// [std-arc]: https://doc.rust-lang.org/stable/std/sync/struct.Arc.html
///
/// # Example
///
/// ```rust
/// // Cargo.toml
/// //
/// // [dependencies]
/// // moka = { version = "0.12", features = ["future"] }
/// // tokio = { version = "1", features = ["rt-multi-thread", "macros" ] }
///
/// use moka::future::Cache;
///
/// #[tokio::main]
/// async fn main() {
/// let cache: Cache<String, u32> = Cache::new(100);
/// let key = "key1".to_string();
///
/// let error_entry = cache
/// .entry(key.clone())
/// .or_try_insert_with(async { Err("error") })
/// .await;
/// assert!(error_entry.is_err());
///
/// let ok_entry = cache
/// .entry(key.clone())
/// .or_try_insert_with(async { Ok::<u32, &str>(3) })
/// .await;
/// assert!(ok_entry.is_ok());
/// let entry = ok_entry.unwrap();
/// assert!(entry.is_fresh());
/// assert_eq!(entry.key(), &key);
/// assert_eq!(entry.into_value(), 3);
///
/// let ok_entry = cache
/// .entry(key)
/// .or_try_insert_with(async { Ok::<u32, &str>(6) })
/// .await;
/// let entry = ok_entry.unwrap();
/// // Not fresh because the value was already in the cache.
/// assert!(!entry.is_fresh());
/// assert_eq!(entry.into_value(), 3);
/// }
/// ```
///
/// # Concurrent calls on the same key
///
/// This method guarantees that concurrent calls on the same not-existing entry
/// are coalesced into one evaluation of the `init` future (as long as these
/// futures return the same error type). Only one of the calls evaluates its
/// future (thus returned entry's `is_fresh` method returns `true`), and other
/// calls wait for that future to resolve (and their `is_fresh` return `false`).
///
/// For more detail about the coalescing behavior, see
/// [`Cache::try_get_with`][try-get-with-method].
///
/// [try-get-with-method]: ./struct.Cache.html#method.try_get_with
pub async fn or_try_insert_with<F, E>(self, init: F) -> Result<Entry<K, V>, Arc<E>>
where
F: Future<Output = Result<V, E>>,
E: Send + Sync + 'static,
{
futures_util::pin_mut!(init);
let key = Arc::new(self.owned_key);
self.cache
.get_or_try_insert_with_hash_and_fun(key, self.hash, init, true)
.await
}
}
/// Provides advanced methods to select or insert an entry of the cache.
///
/// Many methods here return an [`Entry`], a snapshot of a single key-value pair in
/// the cache, carrying additional information like `is_fresh`.
///
/// `RefKeyEntrySelector` is constructed from the
/// [`entry_by_ref`][entry-by-ref-method] method on the cache.
///
/// [`Entry`]: ../struct.Entry.html
/// [entry-by-ref-method]: ./struct.Cache.html#method.entry_by_ref
pub struct RefKeyEntrySelector<'a, K, Q, V, S>
where
Q: ?Sized,
{
ref_key: &'a Q,
hash: u64,
cache: &'a Cache<K, V, S>,
}
impl<'a, K, Q, V, S> RefKeyEntrySelector<'a, K, Q, V, S>
where
K: Borrow<Q> + Hash + Eq + Send + Sync + 'static,
Q: ToOwned<Owned = K> + Hash + Eq + ?Sized,
V: Clone + Send + Sync + 'static,
S: BuildHasher + Clone + Send + Sync + 'static,
{
pub(crate) fn new(ref_key: &'a Q, hash: u64, cache: &'a Cache<K, V, S>) -> Self {
Self {
ref_key,
hash,
cache,
}
}
/// Performs a compute operation on a cached entry by using the given closure
/// `f`. A compute operation is either put, remove or no-operation (nop).
///
/// The closure `f` should take the current entry of `Option<Entry<K, V>>` for
/// the key, and return a `Future` that resolves to an `ops::compute::Op<V>`
/// enum.
///
/// This method works as the followings:
///
/// 1. Apply the closure `f` to the current cached `Entry`, and get a `Future`.
/// 2. Resolve the `Future`, and get an `ops::compute::Op<V>`.
/// 3. Execute the op on the cache:
/// - `Op::Put(V)`: Put the new value `V` to the cache.
/// - `Op::Remove`: Remove the current cached entry.
/// - `Op::Nop`: Do nothing.
/// 4. Return an `ops::compute::CompResult<K, V>` as the followings:
///
/// | [`Op<V>`] | [`Entry<K, V>`] already exists? | [`CompResult<K, V>`] | Notes |
/// |:--------- |:--- |:--------------------------- |:------------------------------- |
/// | `Put(V)` | no | `Inserted(Entry<K, V>)` | The new entry is returned. |
/// | `Put(V)` | yes | `ReplacedWith(Entry<K, V>)` | The new entry is returned. |
/// | `Remove` | no | `StillNone(Arc<K>)` | |
/// | `Remove` | yes | `Removed(Entry<K, V>)` | The removed entry is returned. |
/// | `Nop` | no | `StillNone(Arc<K>)` | |
/// | `Nop` | yes | `Unchanged(Entry<K, V>)` | The existing entry is returned. |
///
/// # See Also
///
/// - If you want the `Future` resolve to `Result<Op<V>>` instead of `Op<V>`, and
/// modify entry only when resolved to `Ok(V)`, use the
/// [`and_try_compute_with`] method.
/// - If you only want to update or insert, use the [`and_upsert_with`] method.
///
/// [`Entry<K, V>`]: ../struct.Entry.html
/// [`Op<V>`]: ../ops/compute/enum.Op.html
/// [`CompResult<K, V>`]: ../ops/compute/enum.CompResult.html
/// [`and_upsert_with`]: #method.and_upsert_with
/// [`and_try_compute_with`]: #method.and_try_compute_with
///
/// # Example
///
/// ```rust
/// // Cargo.toml
/// //
/// // [dependencies]
/// // moka = { version = "0.12.8", features = ["future"] }
/// // tokio = { version = "1", features = ["rt-multi-thread", "macros" ] }
///
/// use moka::{
/// future::Cache,
/// ops::compute::{CompResult, Op},
/// };
///
/// #[tokio::main]
/// async fn main() {
/// let cache: Cache<String, u64> = Cache::new(100);
/// let key = "key1";
///
/// /// Increment a cached `u64` counter. If the counter is greater than or
/// /// equal to 2, remove it.
/// async fn inclement_or_remove_counter(
/// cache: &Cache<String, u64>,
/// key: &str,
/// ) -> CompResult<String, u64> {
/// cache
/// .entry_by_ref(key)
/// .and_compute_with(|maybe_entry| {
/// let op = if let Some(entry) = maybe_entry {
/// let counter = entry.into_value();
/// if counter < 2 {
/// Op::Put(counter.saturating_add(1)) // Update
/// } else {
/// Op::Remove
/// }
/// } else {
/// Op::Put(1) // Insert
/// };
/// // Return a Future that is resolved to `op` immediately.
/// std::future::ready(op)
/// })
/// .await
/// }
///
/// // This should insert a now counter value 1 to the cache, and return the
/// // value with the kind of the operation performed.
/// let result = inclement_or_remove_counter(&cache, &key).await;
/// let CompResult::Inserted(entry) = result else {
/// panic!("`Inserted` should be returned: {result:?}");
/// };
/// assert_eq!(entry.into_value(), 1);
///
/// // This should increment the cached counter value by 1.
/// let result = inclement_or_remove_counter(&cache, &key).await;
/// let CompResult::ReplacedWith(entry) = result else {
/// panic!("`ReplacedWith` should be returned: {result:?}");
/// };
/// assert_eq!(entry.into_value(), 2);
///
/// // This should remove the cached counter from the cache, and returns the
/// // _removed_ value.
/// let result = inclement_or_remove_counter(&cache, &key).await;
/// let CompResult::Removed(entry) = result else {
/// panic!("`Removed` should be returned: {result:?}");
/// };
/// assert_eq!(entry.into_value(), 2);
///
/// // The key should no longer exist.
/// assert!(!cache.contains_key(key));
///
/// // This should start over; insert a new counter value 1 to the cache.
/// let result = inclement_or_remove_counter(&cache, &key).await;
/// let CompResult::Inserted(entry) = result else {
/// panic!("`Inserted` should be returned: {result:?}");
/// };
/// assert_eq!(entry.into_value(), 1);
/// }
/// ```
///
/// # Concurrent calls on the same key
///
/// This method guarantees that concurrent calls on the same key are executed
/// serially. That is, `and_compute_with` calls on the same key never run
/// concurrently. The calls are serialized by the order of their invocation. It
/// uses a key-level lock to achieve this.
pub async fn and_compute_with<F, Fut>(self, f: F) -> compute::CompResult<K, V>
where
F: FnOnce(Option<Entry<K, V>>) -> Fut,
Fut: Future<Output = compute::Op<V>>,
{
let key = Arc::new(self.ref_key.to_owned());
self.cache
.compute_with_hash_and_fun(key, self.hash, f)
.await
}
/// Performs a compute operation on a cached entry by using the given closure
/// `f`. A compute operation is either put, remove or no-operation (nop).
///
/// The closure `f` should take the current entry of `Option<Entry<K, V>>` for
/// the key, and return a `Future` that resolves to a
/// `Result<ops::compute::Op<V>, E>`.
///
/// This method works as the followings:
///
/// 1. Apply the closure `f` to the current cached `Entry`, and get a `Future`.
/// 2. Resolve the `Future`, and get a `Result<ops::compute::Op<V>, E>`.
/// 3. If resolved to `Err(E)`, return it.
/// 4. Else, execute the op on the cache:
/// - `Ok(Op::Put(V))`: Put the new value `V` to the cache.
/// - `Ok(Op::Remove)`: Remove the current cached entry.
/// - `Ok(Op::Nop)`: Do nothing.
/// 5. Return an `Ok(ops::compute::CompResult<K, V>)` as the followings:
///
/// | [`Op<V>`] | [`Entry<K, V>`] already exists? | [`CompResult<K, V>`] | Notes |
/// |:--------- |:--- |:--------------------------- |:------------------------------- |
/// | `Put(V)` | no | `Inserted(Entry<K, V>)` | The new entry is returned. |
/// | `Put(V)` | yes | `ReplacedWith(Entry<K, V>)` | The new entry is returned. |
/// | `Remove` | no | `StillNone(Arc<K>)` | |
/// | `Remove` | yes | `Removed(Entry<K, V>)` | The removed entry is returned. |
/// | `Nop` | no | `StillNone(Arc<K>)` | |
/// | `Nop` | yes | `Unchanged(Entry<K, V>)` | The existing entry is returned. |
///
/// # See Also
///
/// - If you want the `Future` resolve to `Op<V>` instead of `Result<Op<V>>`, use
/// the [`and_compute_with`] method.
/// - If you only want to update or insert, use the [`and_upsert_with`] method.
///
/// [`Entry<K, V>`]: ../struct.Entry.html
/// [`Op<V>`]: ../ops/compute/enum.Op.html
/// [`CompResult<K, V>`]: ../ops/compute/enum.CompResult.html
/// [`and_upsert_with`]: #method.and_upsert_with
/// [`and_compute_with`]: #method.and_compute_with
///
/// # Example
///
/// See [`try_append_value_async.rs`] in the `examples` directory.
///
/// [`try_append_value_async.rs`]:
/// https://github.com/moka-rs/moka/tree/main/examples/try_append_value_async.rs
///
/// # Concurrent calls on the same key
///
/// This method guarantees that concurrent calls on the same key are executed
/// serially. That is, `and_try_compute_with` calls on the same key never run
/// concurrently. The calls are serialized by the order of their invocation. It
/// uses a key-level lock to achieve this.
pub async fn and_try_compute_with<F, Fut, E>(self, f: F) -> Result<compute::CompResult<K, V>, E>
where
F: FnOnce(Option<Entry<K, V>>) -> Fut,
Fut: Future<Output = Result<compute::Op<V>, E>>,
E: Send + Sync + 'static,
{
let key = Arc::new(self.ref_key.to_owned());
self.cache
.try_compute_with_hash_and_fun(key, self.hash, f)
.await
}
/// Performs an upsert of an [`Entry`] by using the given closure `f`. The word
/// "upsert" here means "update" or "insert".
///
/// The closure `f` should take the current entry of `Option<Entry<K, V>>` for
/// the key, and return a `Future` that resolves to a new value `V`.
///
/// This method works as the followings:
///
/// 1. Apply the closure `f` to the current cached `Entry`, and get a `Future`.
/// 2. Resolve the `Future`, and get a new value `V`.
/// 3. Upsert the new value to the cache.
/// 4. Return the `Entry` having the upserted value.
///
/// # See Also
///
/// - If you want to optionally upsert, that is to upsert only when certain
/// conditions meet, use the [`and_compute_with`] method.
/// - If you try to upsert, that is to make the `Future` resolve to `Result<V>`
/// instead of `V`, and upsert only when resolved to `Ok(V)`, use the
/// [`and_try_compute_with`] method.
///
/// [`Entry`]: ../struct.Entry.html
/// [`and_compute_with`]: #method.and_compute_with
/// [`and_try_compute_with`]: #method.and_try_compute_with
///
/// # Example
///
/// ```rust
/// // Cargo.toml
/// //
/// // [dependencies]
/// // moka = { version = "0.12.8", features = ["future"] }
/// // tokio = { version = "1", features = ["rt-multi-thread", "macros" ] }
///
/// use moka::future::Cache;
///
/// #[tokio::main]
/// async fn main() {
/// let cache: Cache<String, u64> = Cache::new(100);
/// let key = "key1";
///
/// let entry = cache
/// .entry_by_ref(key)
/// .and_upsert_with(|maybe_entry| {
/// let counter = if let Some(entry) = maybe_entry {
/// entry.into_value().saturating_add(1) // Update
/// } else {
/// 1 // Insert
/// };
/// // Return a Future that is resolved to `counter` immediately.
/// std::future::ready(counter)
/// })
/// .await;
/// // It was not an update.
/// assert!(!entry.is_old_value_replaced());
/// assert_eq!(entry.key(), &key);
/// assert_eq!(entry.into_value(), 1);
///
/// let entry = cache
/// .entry_by_ref(key)
/// .and_upsert_with(|maybe_entry| {
/// let counter = if let Some(entry) = maybe_entry {
/// entry.into_value().saturating_add(1)
/// } else {
/// 1
/// };
/// std::future::ready(counter)
/// })
/// .await;
/// // It was an update.
/// assert!(entry.is_old_value_replaced());
/// assert_eq!(entry.key(), &key);
/// assert_eq!(entry.into_value(), 2);
/// }
/// ```
///
/// # Concurrent calls on the same key
///
/// This method guarantees that concurrent calls on the same key are executed
/// serially. That is, `and_upsert_with` calls on the same key never run
/// concurrently. The calls are serialized by the order of their invocation. It
/// uses a key-level lock to achieve this.
pub async fn and_upsert_with<F, Fut>(self, f: F) -> Entry<K, V>
where
F: FnOnce(Option<Entry<K, V>>) -> Fut,
Fut: Future<Output = V>,
{
let key = Arc::new(self.ref_key.to_owned());
self.cache.upsert_with_hash_and_fun(key, self.hash, f).await
}
/// Returns the corresponding [`Entry`] for the reference of the key given when
/// this entry selector was constructed. If the entry does not exist, inserts one
/// by cloning the key and calling the [`default`][std-default-function] function
/// of the value type `V`.
///
/// [`Entry`]: ../struct.Entry.html
/// [std-default-function]: https://doc.rust-lang.org/stable/std/default/trait.Default.html#tymethod.default
///
/// # Example
///
/// ```rust
/// // Cargo.toml
/// //
/// // [dependencies]
/// // moka = { version = "0.12", features = ["future"] }
/// // tokio = { version = "1", features = ["rt-multi-thread", "macros" ] }
///
/// use moka::future::Cache;
///
/// #[tokio::main]
/// async fn main() {
/// let cache: Cache<String, Option<u32>> = Cache::new(100);
/// let key = "key1".to_string();
///
/// let entry = cache.entry_by_ref(&key).or_default().await;
/// assert!(entry.is_fresh());
/// assert_eq!(entry.key(), &key);
/// assert_eq!(entry.into_value(), None);
///
/// let entry = cache.entry_by_ref(&key).or_default().await;
/// // Not fresh because the value was already in the cache.
/// assert!(!entry.is_fresh());
/// }
/// ```
pub async fn or_default(self) -> Entry<K, V>
where
V: Default,
{
self.cache
.get_or_insert_with_hash_by_ref(self.ref_key, self.hash, Default::default)
.await
}
/// Returns the corresponding [`Entry`] for the reference of the key given when
/// this entry selector was constructed. If the entry does not exist, inserts one
/// by cloning the key and using the given `default` value for `V`.
///
/// [`Entry`]: ../struct.Entry.html
///
/// # Example
///
/// ```rust
/// // Cargo.toml
/// //
/// // [dependencies]
/// // moka = { version = "0.12", features = ["future"] }
/// // tokio = { version = "1", features = ["rt-multi-thread", "macros" ] }
///
/// use moka::future::Cache;
///
/// #[tokio::main]
/// async fn main() {
/// let cache: Cache<String, u32> = Cache::new(100);
/// let key = "key1".to_string();
///
/// let entry = cache.entry_by_ref(&key).or_insert(3).await;
/// assert!(entry.is_fresh());
/// assert_eq!(entry.key(), &key);
/// assert_eq!(entry.into_value(), 3);
///
/// let entry = cache.entry_by_ref(&key).or_insert(6).await;
/// // Not fresh because the value was already in the cache.
/// assert!(!entry.is_fresh());
/// assert_eq!(entry.into_value(), 3);
/// }
/// ```
pub async fn or_insert(self, default: V) -> Entry<K, V> {
let init = || default;
self.cache
.get_or_insert_with_hash_by_ref(self.ref_key, self.hash, init)
.await
}
/// Returns the corresponding [`Entry`] for the reference of the key given when
/// this entry selector was constructed. If the entry does not exist, inserts one
/// by cloning the key and resolving the `init` future for the value.
///
/// [`Entry`]: ../struct.Entry.html
///
/// # Example
///
/// ```rust
/// // Cargo.toml
/// //
/// // [dependencies]
/// // moka = { version = "0.12", features = ["future"] }
/// // tokio = { version = "1", features = ["rt-multi-thread", "macros" ] }
///
/// use moka::future::Cache;
///
/// #[tokio::main]
/// async fn main() {
/// let cache: Cache<String, String> = Cache::new(100);
/// let key = "key1".to_string();
///
/// let entry = cache
/// .entry_by_ref(&key)
/// .or_insert_with(async { "value1".to_string() })
/// .await;
/// assert!(entry.is_fresh());
/// assert_eq!(entry.key(), &key);
/// assert_eq!(entry.into_value(), "value1");
///
/// let entry = cache
/// .entry_by_ref(&key)
/// .or_insert_with(async { "value2".to_string() })
/// .await;
/// // Not fresh because the value was already in the cache.
/// assert!(!entry.is_fresh());
/// assert_eq!(entry.into_value(), "value1");
/// }
/// ```
///
/// # Concurrent calls on the same key
///
/// This method guarantees that concurrent calls on the same not-existing entry
/// are coalesced into one evaluation of the `init` future. Only one of the calls
/// evaluates its future (thus returned entry's `is_fresh` method returns
/// `true`), and other calls wait for that future to resolve (and their
/// `is_fresh` return `false`).
///
/// For more detail about the coalescing behavior, see
/// [`Cache::get_with`][get-with-method].
///
/// [get-with-method]: ./struct.Cache.html#method.get_with
pub async fn or_insert_with(self, init: impl Future<Output = V>) -> Entry<K, V> {
futures_util::pin_mut!(init);
let replace_if = None as Option<fn(&V) -> bool>;
self.cache
.get_or_insert_with_hash_by_ref_and_fun(self.ref_key, self.hash, init, replace_if, true)
.await
}
/// Works like [`or_insert_with`](#method.or_insert_with), but takes an additional
/// `replace_if` closure.
///
/// This method will resolve the `init` future and insert the output to the
/// cache when:
///
/// - The key does not exist.
/// - Or, `replace_if` closure returns `true`.
pub async fn or_insert_with_if(
self,
init: impl Future<Output = V>,
replace_if: impl FnMut(&V) -> bool + Send,
) -> Entry<K, V> {
futures_util::pin_mut!(init);
self.cache
.get_or_insert_with_hash_by_ref_and_fun(
self.ref_key,
self.hash,
init,
Some(replace_if),
true,
)
.await
}
/// Returns the corresponding [`Entry`] for the reference of the key given when
/// this entry selector was constructed. If the entry does not exist, clones the
/// key and resolves the `init` future. If `Some(value)` was returned by the
/// future, inserts an entry with the value . If `None` was returned, this method
/// does not insert an entry and returns `None`.
///
/// [`Entry`]: ../struct.Entry.html
///
/// # Example
///
/// ```rust
/// // Cargo.toml
/// //
/// // [dependencies]
/// // moka = { version = "0.12", features = ["future"] }
/// // tokio = { version = "1", features = ["rt-multi-thread", "macros" ] }
///
/// use moka::future::Cache;
///
/// #[tokio::main]
/// async fn main() {
/// let cache: Cache<String, u32> = Cache::new(100);
/// let key = "key1".to_string();
///
/// let none_entry = cache
/// .entry_by_ref(&key)
/// .or_optionally_insert_with(async { None })
/// .await;
/// assert!(none_entry.is_none());
///
/// let some_entry = cache
/// .entry_by_ref(&key)
/// .or_optionally_insert_with(async { Some(3) })
/// .await;
/// assert!(some_entry.is_some());
/// let entry = some_entry.unwrap();
/// assert!(entry.is_fresh());
/// assert_eq!(entry.key(), &key);
/// assert_eq!(entry.into_value(), 3);
///
/// let some_entry = cache
/// .entry_by_ref(&key)
/// .or_optionally_insert_with(async { Some(6) })
/// .await;
/// let entry = some_entry.unwrap();
/// // Not fresh because the value was already in the cache.
/// assert!(!entry.is_fresh());
/// assert_eq!(entry.into_value(), 3);
/// }
/// ```
///
/// # Concurrent calls on the same key
/// This method guarantees that concurrent calls on the same not-existing entry
/// are coalesced into one evaluation of the `init` future. Only one of the calls
/// evaluates its future (thus returned entry's `is_fresh` method returns
/// `true`), and other calls wait for that future to resolve (and their
/// `is_fresh` return `false`).
///
/// For more detail about the coalescing behavior, see
/// [`Cache::optionally_get_with`][opt-get-with-method].
///
/// [opt-get-with-method]: ./struct.Cache.html#method.optionally_get_with
pub async fn or_optionally_insert_with(
self,
init: impl Future<Output = Option<V>>,
) -> Option<Entry<K, V>> {
futures_util::pin_mut!(init);
self.cache
.get_or_optionally_insert_with_hash_by_ref_and_fun(self.ref_key, self.hash, init, true)
.await
}
/// Returns the corresponding [`Entry`] for the reference of the key given when
/// this entry selector was constructed. If the entry does not exist, clones the
/// key and resolves the `init` future. If `Ok(value)` was returned from the
/// future, inserts an entry with the value. If `Err(_)` was returned, this
/// method does not insert an entry and returns the `Err` wrapped by
/// [`std::sync::Arc`][std-arc].
///
/// [`Entry`]: ../struct.Entry.html
/// [std-arc]: https://doc.rust-lang.org/stable/std/sync/struct.Arc.html
///
/// # Example
///
/// ```rust
/// // Cargo.toml
/// //
/// // [dependencies]
/// // moka = { version = "0.12", features = ["future"] }
/// // tokio = { version = "1", features = ["rt-multi-thread", "macros" ] }
///
/// use moka::future::Cache;
///
/// #[tokio::main]
/// async fn main() {
/// let cache: Cache<String, u32> = Cache::new(100);
/// let key = "key1".to_string();
///
/// let error_entry = cache
/// .entry_by_ref(&key)
/// .or_try_insert_with(async { Err("error") })
/// .await;
/// assert!(error_entry.is_err());
///
/// let ok_entry = cache
/// .entry_by_ref(&key)
/// .or_try_insert_with(async { Ok::<u32, &str>(3) })
/// .await;
/// assert!(ok_entry.is_ok());
/// let entry = ok_entry.unwrap();
/// assert!(entry.is_fresh());
/// assert_eq!(entry.key(), &key);
/// assert_eq!(entry.into_value(), 3);
///
/// let ok_entry = cache
/// .entry_by_ref(&key)
/// .or_try_insert_with(async { Ok::<u32, &str>(6) })
/// .await;
/// let entry = ok_entry.unwrap();
/// // Not fresh because the value was already in the cache.
/// assert!(!entry.is_fresh());
/// assert_eq!(entry.into_value(), 3);
/// }
/// ```
///
/// # Concurrent calls on the same key
///
/// This method guarantees that concurrent calls on the same not-existing entry
/// are coalesced into one evaluation of the `init` future (as long as these
/// futures return the same error type). Only one of the calls evaluates its
/// future (thus returned entry's `is_fresh` method returns `true`), and other
/// calls wait for that future to resolve (and their `is_fresh` return `false`).
///
/// For more detail about the coalescing behavior, see
/// [`Cache::try_get_with`][try-get-with-method].
///
/// [try-get-with-method]: ./struct.Cache.html#method.try_get_with
pub async fn or_try_insert_with<F, E>(self, init: F) -> Result<Entry<K, V>, Arc<E>>
where
F: Future<Output = Result<V, E>>,
E: Send + Sync + 'static,
{
futures_util::pin_mut!(init);
self.cache
.get_or_try_insert_with_hash_by_ref_and_fun(self.ref_key, self.hash, init, true)
.await
}
}