例如，对 Recyclable 的实现为 Vec<T> 分配了一个零容量的向量，但您可能想要给向量一个初始容量。在这种情况下，您可以这样做，例如

use swimmer::Pool;
let pool: Pool<Vec<u32>> = swimmer::builder()
    .with_supplier(|| Vec::with_capacity(128))
    .build();

let vec = pool.get();
assert_eq!(vec.capacity(), 128);

请注意，然而，供应商函数仅在对象首次初始化时被调用：它不会被用于回收对象。这意味着目前没有实现自定义回收功能的方法。

软件包功能

• hashbrown-impls：为 hashbrown::HashMap 和 hashbrown::HashSet 实现 Recyclable。
• smallvec-impls：为 SmallVec 实现 Recyclable。

示例

基本用法

use swimmer::Pool;

// Initialize a new pool, allocating
// 10 empty values to start
let pool: Pool<String> = swimmer::builder()
    .with_starting_size(10)
    .build();

assert_eq!(pool.size(), 10);

let mut string = pool.get();
assert_eq!(*string, ""); // Note that you need to dereference the string, since it is stored in a special smart pointer
string.push_str("test"); // Mutate the string

// One object was taken from the pool,
// so its size is now 9
assert_eq!(pool.size(), 9);

// Now, the string is returned to the pool
drop(string);

assert_eq!(pool.size(), 10);

// Get another string from the pool. This string
// could be the same one retrieved above, but
// since the string is cleared before returning
// into the pool, it is now empty. However, it
// retains any capacity which was allocated,
// which prevents additional allocations
// from occurring.
let another_string = pool.get();
assert_eq!(*another_string, "");

在您的对象上实现 Recyclable

use swimmer::{Pool, Recyclable};

struct Person {
    name: String,
    age: u32,
}

impl Recyclable for Person {
    fn new() -> Self {
        Self {
            name: String::new(),
            age: 0,
        }
    }

    fn recycle(&mut self) {
        // You are responsible for ensuring
        // that modified `Person`s get reset
        // before being returned to the pool.
        // Otherwise, the object could be put
        // back into the pool with its old state
        // still intact; this could cause weird behavior!
        self.name.clear();
        self.age = 0;
     }
}

let pool: Pool<Person> = Pool::new();
let mut josh = pool.get();
josh.name.push_str("Josh"); // Since `recycle` empties the string, this will effectively set `name` to `Josh`
josh.age = 47;

drop(josh); // Josh is returned to the pool and his name and age are reset

// Now get a new person
let another_person = pool.get();

在 lazy_static 变量中使用 Pool 对象，使其可以在全局范围内使用

use lazy_static::lazy_static;
use swimmer::Pool;

lazy_static! {
    static ref POOL: Pool<String> = {
        Pool::new()
    };
}

let value = POOL.get();