特性 blake3-hash

通过启用blake3-hash存储库功能，可以提供使用BLAKE3加密哈希函数作为实现的Hasher，该函数在blake3存储库中实现，并可通过BLAKE3访问。

有关更多信息，请参阅Blake3Hasher类型的文档。

功能blake2b-hash

通过启用blake2b-hash存储库功能，可以获得基于BLAKE2b加密哈希函数和blake2b_simd存储库的Hasher实现。

有关更多信息，请参阅Blake2bHasher类型的文档。

两种主要操作类型

环形上支持的所有操作可以分为两大类：“读取”和“写入”。

• 读取操作需要访问存储在环形中的信息，但不会对环形本身进行更改。此类操作的最常见示例是根据一致性哈希算法查找键应分配到的位置（例如，参见HashRing::nodes_for_key）。另一个示例是通过迭代器遍历一致性哈希环形中包含的所有虚拟节点（例如，参见HashRing::iter和Iter）。
• 写入操作被认为是对环形本身进行有效更改的操作。常见示例是HashRing::insert和HashRing::remove方法，它们分别向一致性哈希环形插入新节点或删除现有节点。

示例

以下是一个基本的单线程示例，展示了其用法。

use std::sync::Arc;
use hex_literal::hex;
use lfchring::{HashRing, Node, VirtualNode, Vnid};

const VIRTUAL_NODES_PER_NODE: Vnid = 2;
const REPLICATION_FACTOR: u8 = 3;

// Create an empty ring (see the docs for further options on constructing a ring).
let ring = HashRing::new(VIRTUAL_NODES_PER_NODE, REPLICATION_FACTOR).unwrap();

// Insert three new Nodes.
let nodes: Vec<Arc<str>> = vec![Arc::from("Node1"), Arc::from("Node2"), Arc::from("Node3")];
ring.insert(&nodes).expect("hash collision when inserting 3 new Nodes");

assert_eq!(ring.len_nodes(), 3);
assert_eq!(ring.len_virtual_nodes(), 3 * VIRTUAL_NODES_PER_NODE as usize);

// Look up a key in the ring.
let key = hex!("232a8a941ee901c1");
let virtual_node_clone = ring.virtual_node_for_key(&key).unwrap();

// The Nodes that should own a replica for the particular key can also be found via:
let replica_owning_nodes = ring.nodes_for_key(&key).unwrap();
assert_eq!(replica_owning_nodes, virtual_node_clone.replica_owners());

// In this example, since the ring is populated with 3 Nodes and the replication factor is also
// equal to 3, all Nodes should be assigned with a replica of the key.
// However, the following assertion would fail, because of the order in which the replica
// owning Nodes are reported: they are reported according to the order in which their virtual
// nodes have been placed on the ring, rather than the order of the Nodes were inserted.
assert_ne!(nodes, replica_owning_nodes); // `ne` due to the order in which Nodes are reported!

实现说明

Arc

请注意，在多线程上下文中，使用HashRing<N, H>的用户应显式将其包装在Arc中，以便在线程之间共享。单线程上下文可以选择不这样做，以避免原子引用计数的开销；然而，整个存储库内部都在使用Arc。

$ RUST_LOG=debug cargo t --all-features -- --nocapture

$ cargo doc --all-features --no-deps