Struct ArcSwapMap 

pub struct ArcSwapMap<K, V, S = DefaultHashBuilder> { /* private fields */ }

A concurrent HashMap backed by an ArcSwap, offering lock-free reads and copy-on-write writes.

Reads load the current snapshot without blocking writers. Writes clone the whole map, apply their change, and atomically publish the new version, so a reader always observes a consistent snapshot and writers never block readers.

This is the shared building block behind the session-scoped registries (the plugin registries as well as the optimizer-kernel and aggregate-function registries) and the VortexSession type-map itself. Because every write clones the entire map, it is intended for maps that are written rarely (typically only while a session is being configured) and read often.

The map is held behind an Arc so that Clone shares the same underlying cell: a registry mutated through one clone is observed by all others. Session variables rely on this so that encodings registered after a session is built remain visible to clones of that session.

Implementations

impl<K, V, S> ArcSwapMap<K, V, S>

pub fn snapshot(&self) -> Arc<HashMap<K, V, S>>

Return the currently published map snapshot.

pub fn read<R>(&self, f: impl FnOnce(&HashMap<K, V, S>) -> R) -> R

Read the current snapshot, passing it to f.

Every lookup inside f observes the same snapshot, which matters when a single logical read consults more than one key.

impl<K: Eq + Hash, V, S: BuildHasher> ArcSwapMap<K, V, S>

pub fn get<Q>(&self, key: &Q) -> Option<V>

where K: Borrow<Q>, Q: Eq + Hash + ?Sized, V: Clone,

Return a clone of the value stored under key, if present.

pub fn contains_key<Q>(&self, key: &Q) -> bool

where K: Borrow<Q>, Q: Eq + Hash + ?Sized,

Returns whether a value is stored under key.

pub fn insert(&self, key: K, value: V)

where K: Clone, V: Clone, S: Clone,

pub fn insert_if_absent(&self, key: K, value: V)

where K: Clone, V: Clone, S: Clone,

Insert value under key only if no value is stored there yet.

If a concurrent writer publishes a value under key first, that value is kept and value is dropped. value is constructed by the caller before this call, so no user code runs while the map is being updated.

impl<K: Eq + Hash + Clone, T: Clone, S: BuildHasher + Clone> ArcSwapMap<K, Arc<[T]>, S>

pub fn extend(&self, key: K, values: &[T])

Append values to the list stored under key, creating it if absent.

Each key maps to an immutable Arc<[T]>; appending rebuilds that slice copy-on-write so existing readers keep their previous snapshot.

pub fn push(&self, key: K, value: T)

Append a single value to the list stored under key, creating it if absent.

Trait Implementations

impl<K, V, S> Clone for ArcSwapMap<K, V, S>

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<K: Debug, V: Debug, S> Debug for ArcSwapMap<K, V, S>

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

Formats the value using the given formatter.

impl<K, V, S: Default> Default for ArcSwapMap<K, V, S>

fn default() -> Self

Returns the “default value” for a type.