Struct evmap::ReadHandle

pub struct ReadHandle<K, V, M = (), S = RandomState>where
    K: Eq + Hash,
    S: BuildHasher,{ /* private fields */ }

A handle that may be used to read from the eventually consistent map.

Note that any changes made to the map will not be made visible until the writer calls refresh(). In other words, all operations performed on a ReadHandle will only see writes to the map that preceeded the last call to refresh().

Implementations

impl<K, V, M, S> ReadHandle<K, V, M, S>where
    K: Eq + Hash,
    S: BuildHasher,
    M: Clone,

pub fn len(&self) -> usize

Returns the number of non-empty keys present in the map.

pub fn is_empty(&self) -> bool

Returns true if the map contains no elements.

pub fn meta(&self) -> Option<M>

Get the current meta value.

pub fn get_and<Q: ?Sized, F, T>(&self, key: &Q, then: F) -> Option<T>where
    F: FnOnce(&[V]) -> T,
    K: Borrow<Q>,
    Q: Hash + Eq,

Applies a function to the values corresponding to the key, and returns the result.

The key may be any borrowed form of the map’s key type, but Hash and Eq on the borrowed form must match those for the key type.

Note that not all writes will be included with this read – only those that have been refreshed by the writer. If no refresh has happened, this function returns None.

If no values exist for the given key, no refresh has happened, or the map has been destroyed, then will not be called, and None will be returned.

pub fn meta_get_and<Q: ?Sized, F, T>(
    &self,
    key: &Q,
    then: F
) -> Option<(Option<T>, M)>where
    F: FnOnce(&[V]) -> T,
    K: Borrow<Q>,
    Q: Hash + Eq,

Applies a function to the values corresponding to the key, and returns the result alongside the meta information.

The key may be any borrowed form of the map’s key type, but Hash and Eq on the borrowed form must match those for the key type.

Note that not all writes will be included with this read – only those that have been refreshed by the writer. If no refresh has happened, or if the map has been closed by the writer, this function returns None.

If no values exist for the given key, then will not be called, and Some(None, _) is returned.

pub fn is_destroyed(&self) -> bool

If the writer has destroyed this map, this method will return true.

See WriteHandle::destroy.

pub fn contains_key<Q: ?Sized>(&self, key: &Q) -> boolwhere
    K: Borrow<Q>,
    Q: Hash + Eq,

Returns true if the map contains any values for the specified key.

The key may be any borrowed form of the map’s key type, but Hash and Eq on the borrowed form must match those for the key type.

pub fn for_each<F>(&self, f: F)where
    F: FnMut(&K, &[V]),

Read all values in the map, and transform them into a new collection.

Be careful with this function! While the iteration is ongoing, any writer that tries to refresh will block waiting on this reader to finish.

pub fn map_into<Map, Collector, Target>(&self, f: Map) -> Collectorwhere
    Map: FnMut(&K, &[V]) -> Target,
    Collector: FromIterator<Target>,

Read all values in the map, and transform them into a new collection.

Trait Implementations

impl<K, V, M, S> Clone for ReadHandle<K, V, M, S>where
    K: Eq + Hash,
    S: BuildHasher,
    M: Clone,

fn clone(&self) -> Self

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.