txmap 1.1.0

A concurrent transactional hash map for Rust with fine-grained locking, internal mutability and composable transactions
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62

use crate::{
    indexed_key::IndexedKey, locks::lock_policy::LockPolicy, new_types::BitMask,
    ops::op_trait::OpTrait, shard::Shard, shard_count::ShardCount,
};
use intmap::IntMap;
use std::hash::Hash;

pub(crate) struct UpdateOp<K, V, P = ()>
where
    K: Hash + Eq,
{
    indexed_key: IndexedKey<K>,
    #[allow(clippy::type_complexity)]
    transform: Box<dyn Fn(&K, Option<&V>, &P) -> Option<V>>,
}

impl<K, V, P> UpdateOp<K, V, P>
where
    K: Hash + Eq,
{
    pub fn new_with_params<T>(shard_count: u8, key: K, transform: T) -> Self
    where
        T: Fn(&K, Option<&V>, &P) -> Option<V> + 'static,
    {
        Self {
            indexed_key: ShardCount::indexed_key(shard_count, key),
            transform: Box::new(transform),
        }
    }
}

impl<K, V> UpdateOp<K, V, ()>
where
    K: Hash + Eq,
{
    pub fn new<T>(shard_count: u8, key: K, transform: T) -> Self
    where
        T: Fn(&K, Option<&V>) -> Option<V> + 'static,
    {
        Self::new_with_params(shard_count, key, move |k, v, _| transform(k, v))
    }
}

impl<L, K, V, P> OpTrait<L, K, V, P> for UpdateOp<K, V, P>
where
    L: LockPolicy,
    K: Clone + Hash + Eq,
{
    fn guards_bitmask(&self) -> BitMask {
        self.indexed_key.2
    }
    fn apply(&self, mutex_guards: &mut IntMap<u8, L::WriteGuard<'_, Shard<K, V>>>, params: &P) {
        let value_ref = self.indexed_key.value_ref::<L, V>(mutex_guards);
        let new_value = (self.transform)(&self.indexed_key.3, value_ref, params);
        match new_value {
            Some(v) => self.indexed_key.insert::<L, V>(mutex_guards, v),
            None => {
                self.indexed_key.remove_entry::<L, V>(mutex_guards);
            }
        };
    }
}