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/*
* Copyright (C) 2024 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
use crossbeam_queue::ArrayQueue;
/// A thread-safe storage that allows non-blocking attempts to store and visit elements.
pub struct Storage<T, const N: usize> {
insertion_buffer: ArrayQueue<T>,
}
impl<T, const N: usize> Storage<T, N> {
/// Creates a new Storage with the specified size.
pub fn new() -> Self {
Self { insertion_buffer: ArrayQueue::new(N) }
}
/// Inserts a value into the storage, returning an error if the lock cannot be acquired.
pub fn insert(&self, value: T) {
self.insertion_buffer.force_push(value);
}
/// Folds over the elements in the storage using the provided function.
pub fn fold<U, F>(&self, init: U, mut func: F) -> U
where
F: FnMut(U, &T) -> U,
{
let mut acc = init;
while let Some(value) = self.insertion_buffer.pop() {
acc = func(acc, &value);
}
acc
}
/// Returns the number of elements that have been inserted into the storage.
pub fn len(&self) -> usize {
self.insertion_buffer.len()
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_insert_and_retrieve() {
let storage = Storage::<i32, 10>::new();
storage.insert(7);
let sum = storage.fold(0, |acc, &x| acc + x);
assert_eq!(sum, 7, "The sum of the elements should be equal to the inserted value.");
}
#[test]
fn test_fold_functionality() {
let storage = Storage::<i32, 5>::new();
storage.insert(1);
storage.insert(2);
storage.insert(3);
let sum = storage.fold(0, |acc, &x| acc + x);
assert_eq!(
sum, 6,
"The sum of the elements should be equal to the sum of inserted values."
);
}
#[test]
fn test_insert_and_retrieve_multiple_values() {
let storage = Storage::<i32, 10>::new();
storage.insert(1);
storage.insert(2);
storage.insert(5);
let first_sum = storage.fold(0, |acc, &x| acc + x);
assert_eq!(first_sum, 8, "The sum of the elements should be equal to the inserted values.");
storage.insert(30);
storage.insert(22);
let second_sum = storage.fold(0, |acc, &x| acc + x);
assert_eq!(
second_sum, 52,
"The sum of the elements should be equal to the inserted values."
);
}
#[test]
fn test_storage_limit() {
let storage = Storage::<i32, 1>::new();
storage.insert(1);
// This value should overwrite the previously inserted value (1).
storage.insert(4);
let sum = storage.fold(0, |acc, &x| acc + x);
assert_eq!(sum, 4, "The sum of the elements should be equal to the inserted values.");
}
#[test]
fn test_concurrent_insertions() {
use std::sync::Arc;
use std::thread;
let storage = Arc::new(Storage::<i32, 100>::new());
let threads: Vec<_> = (0..10)
.map(|_| {
let storage_clone = Arc::clone(&storage);
thread::spawn(move || {
for i in 0..10 {
storage_clone.insert(i);
}
})
})
.collect();
for thread in threads {
thread.join().expect("Thread should finish without panicking");
}
let count = storage.fold(0, |acc, _| acc + 1);
assert_eq!(count, 100, "Storage should be filled to its limit with concurrent insertions.");
}
}
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