Struct WriteHandle

Source

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

Expand description

A write handle to the underlying map.

This type allows for the creation of WriteGuards which allow for mutation of the underlying map.

Implementations§

Source §

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

Source

pub fn synchronize(&self)

Blocks the calling thread until all readers see the same version of the map.

If all readers already see the same version of the map (or if there are no active readers) then this function is a no-op.

This function is meant for advanced use only. See Leaked::into_inner for an example use-case.

Source

pub fn guard(&mut self) -> View<WriteGuard<'_, K, V, S>>

Creates a new WriteGuard wrapped in a View, allowing for safe read and write access to the map.

§Examples

let (mut write, read) = flashmap::new::<String, String>();

let mut guard = write.guard();

// Insert a few values
guard.insert("apple".to_owned(), "red".to_owned());
guard.insert("banana".to_owned(), "yellow".to_owned());

// Remove a value
assert_eq!(&*guard.remove("apple".to_owned()).unwrap(), "red");

// Publishing makes all previous changes visible to new readers. Dropping the
// guard has the same effect.
guard.publish();

Unlike a read guard, when reading through a write guard, all changes will be immediately visible.

let (mut write, read) = flashmap::new::<String, String>();

let mut guard = write.guard();

// Our insert is immediately visible to us
guard.insert("apple".to_owned(), "red".to_owned());
assert_eq!(guard.get("apple").unwrap(), "red");
assert!(!guard.contains_key("banana"));

guard.insert("banana".to_owned(), "yellow".to_owned());
assert_eq!(guard.get("banana").unwrap(), "yellow");

// Likewise, removes (and all other operations) are immediately visible
assert_eq!(&*guard.remove("apple".to_owned()).unwrap(), "red");
assert!(!guard.contains_key("apple"));

Source

pub fn reclaim_one(&self, leaked: Leaked<V>) -> V

Reclaims a leaked value, providing ownership of the underlying value.

§Panics

Panics if the leaked value provided came from a different map then the one this handle is associated with.

§Examples

use flashmap::{self, Evicted};

let (mut write, read) = flashmap::new::<String, String>();

write.guard().insert("ferris".to_owned(), "crab".to_owned());

// ~~ stuff happens ~~

let leaked = write.guard().remove("ferris".to_owned())
    .map(Evicted::leak)
    .unwrap();

let value = write.reclaim_one(leaked);
assert_eq!(value, "crab");

Source

pub fn reclaimer(&self) -> impl Fn(Leaked<V>) -> V + '_

Returns a function which can safely reclaim leaked values. This is useful for reclaiming multiple leaked values while only performign the necessary synchronization once.

§Panics

The returned function will panic if given a leaked value not from the map this handle is associated with. This function itself will not panic.

§Examples

use flashmap::{self, Evicted};

let (mut write, read) = flashmap::new::<u32, String>();

let mut guard = write.guard();
guard.insert(0xFF0000, "red".to_owned());
guard.insert(0x00FF00, "green".to_owned());
guard.insert(0x0000FF, "blue".to_owned());
guard.publish();

// ~~ stuff happens ~~

let mut guard = write.guard();
let colors = [0xFF0000, 0x00FF00, 0x0000FF].map(|hex| {
    guard.remove(hex).map(Evicted::leak).unwrap()
});
guard.publish();

let [red, green, blue] = colors.map(write.reclaimer());

assert_eq!(red, "red");
assert_eq!(green, "green");
assert_eq!(blue, "blue");