Struct HashIndex 

pub struct HashIndex<K: Hash + Eq, V: Copy> { /* private fields */ }

A thread-safe hash index for O(1) key lookups.

Backed by DashMap (sharded concurrent hash map) for lock-free reads. Each read operation only locks one of ~16 internal shards, enabling high concurrent throughput without global lock contention.

Best for exact-match queries on unique keys.

Performance

• Concurrent reads: ~6x faster than RwLock under contention
• Point lookups: O(1) average case
• No lock acquisition for reads in common case

Example

use grafeo_core::index::HashIndex;
use grafeo_common::types::NodeId;

let index: HashIndex<String, NodeId> = HashIndex::new();
index.insert("alix".to_string(), NodeId::new(1));
index.insert("gus".to_string(), NodeId::new(2));

assert_eq!(index.get(&"alix".to_string()), Some(NodeId::new(1)));

Implementations

impl<K: Hash + Eq, V: Copy> HashIndex<K, V>

pub fn new() -> Self

Creates a new empty hash index.

pub fn with_capacity(capacity: usize) -> Self

Creates a new hash index with the given capacity.

pub fn insert(&self, key: K, value: V) -> Option<V>

Inserts a key-value pair into the index.

Returns the previous value if the key was already present.

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

Gets the value for a key.

This is a lock-free read operation that only briefly locks one of the internal shards.

pub fn remove(&self, key: &K) -> Option<V>

Removes a key from the index.

Returns the value if the key was present.

pub fn contains(&self, key: &K) -> bool

Checks if a key exists in the index.

pub fn len(&self) -> usize

Returns the number of entries in the index.

pub fn is_empty(&self) -> bool

Returns true if the index is empty.

pub fn clear(&self)

Clears all entries from the index.

Trait Implementations

impl<K: Hash + Eq, V: Copy> Default for HashIndex<K, V>

fn default() -> Self

Returns the “default value” for a type.