openethereum/crates/util/len-caching-lock/src/lib.rs
2021-01-14 15:30:57 +01:00

106 lines
2.8 KiB
Rust

// Copyright 2015-2020 Parity Technologies (UK) Ltd.
// This file is part of OpenEthereum.
// OpenEthereum is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
// OpenEthereum is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License
// along with OpenEthereum. If not, see <http://www.gnu.org/licenses/>.
//! This crate allows automatic caching of `T.len()` with an api that
//! allows drop in replacement for `parking_lot`
//! [`Mutex`](../lock_api/struct.Mutex.html)
//! and [`RwLock`](../lock_api/struct.RwLock.html) for most common use-cases.
//!
//! This crate implements `Len` for the following types:
//! `std::collections::{VecDeque, LinkedList, HashMap, BTreeMap, HashSet, BTreeSet, BinaryHeap}`
//!
//! ## Example
//!
//! ```rust
//! extern crate len_caching_lock;
//! use len_caching_lock::LenCachingMutex;
//!
//! fn main() {
//! let vec: Vec<i32> = Vec::new();
//! let len_caching_mutex = LenCachingMutex::new(vec);
//! assert_eq!(len_caching_mutex.lock().len(), len_caching_mutex.load_len());
//! len_caching_mutex.lock().push(0);
//! assert_eq!(1, len_caching_mutex.load_len());
//! }
//! ```
extern crate parking_lot;
use std::{
collections::{BTreeMap, BTreeSet, BinaryHeap, HashMap, HashSet, LinkedList, VecDeque},
hash::Hash,
};
pub mod mutex;
pub mod rwlock;
pub use mutex::LenCachingMutex;
pub use rwlock::LenCachingRwLock;
/// Implement to allow a type with a len() method to be used
/// with [`LenCachingMutex`](mutex/struct.LenCachingMutex.html)
/// or [`LenCachingRwLock`](rwlock/struct.LenCachingRwLock.html)
pub trait Len {
fn len(&self) -> usize;
}
impl<T> Len for Vec<T> {
fn len(&self) -> usize {
Vec::len(self)
}
}
impl<T> Len for VecDeque<T> {
fn len(&self) -> usize {
VecDeque::len(self)
}
}
impl<T> Len for LinkedList<T> {
fn len(&self) -> usize {
LinkedList::len(self)
}
}
impl<K: Eq + Hash, V> Len for HashMap<K, V> {
fn len(&self) -> usize {
HashMap::len(self)
}
}
impl<K, V> Len for BTreeMap<K, V> {
fn len(&self) -> usize {
BTreeMap::len(self)
}
}
impl<T: Eq + Hash> Len for HashSet<T> {
fn len(&self) -> usize {
HashSet::len(self)
}
}
impl<T> Len for BTreeSet<T> {
fn len(&self) -> usize {
BTreeSet::len(self)
}
}
impl<T: Ord> Len for BinaryHeap<T> {
fn len(&self) -> usize {
BinaryHeap::len(self)
}
}