Struct Cache 

pub struct Cache<K, V> {
    data: DashMap<K, Arc<SetOnce<V>>>,
    pub num_hits: AtomicUsize,
    pub num_misses: AtomicUsize,
}

Cache for asynchronous operations. Each operation is associated with a key, and operations are cached, deduplicated and mutually exclusive with other operations on the same key, including in-progress operations.

Fields

data: DashMap<K, Arc<SetOnce<V>>>

Internal map of keys to set-once values.

num_hits: AtomicUsize

Number of cache hits (including hits to in-progress values).

num_misses: AtomicUsize

Number of cache misses.

Implementations

impl<K, V> Cache<K, V>

where K: Hash + Eq,

pub fn new() -> Self

Constructs a new empty Cache.

pub fn lock_entry(&self, key: &K) -> Result<CacheSetter<V>, CacheFut<V>>

where K: Clone,

Locks the cache entry with the given key, adding it to the cache if it does not already exist. This function returns values which can be used to write into or read from the cache.

If this is the first task to lock this entry, Ok of CacheSetter is returned so the call can compute and store the value. If the value is already cached or another task is currently computing the value, Err of CacheFut is returned which can be used to wait and retrieve the value from the cache.

The given key will only be cloned if the cache does not currently have an entry for this key.

Errors

An Err means the cache key is already completed or in-progress, as described above.

pub fn into_completed_entries(self) -> impl Iterator<Item = (K, V)>

Consumes the cache and returns an iterator over the completed key and value pairs.

Panics

This function will panic if there are leftover CacheFut or CacheSetter references pointing to the current cache.

Trait Implementations

impl<K, V> Debug for Cache<K, V>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<K, V> Default for Cache<K, V>

where K: Hash + Eq,

fn default() -> Self

Returns the “default value” for a type.

impl<K, V> FromIterator<(K, V)> for Cache<K, V>

where K: Hash + Eq,

fn from_iter<It: IntoIterator<Item = (K, V)>>(iter: It) -> Self

Creates a value from an iterator.