piscina 0.2.1

A simple generic pool that supports both sync and async
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
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130

# piscina

A simple generic pool that supports both sync and async.

[![crate_version](https://img.shields.io/crates/v/piscina.svg?style=flat)](https://crates.io/crates/piscina)
[![docs_version](https://img.shields.io/badge/docs-latest-blue.svg?style=flat)](https://docs.rs/piscina/latest/piscina/)

Two types of pools are provided:

- [`Pool`]: A simple pool that supports both sync and async.
- [`PriorityPool`]: A pool of items with priorities and supports both sync and async.

This crate internally utilizes `futures_channel::oneshot` and is thus lock-free.

## Features

```toml
default = []
```

The features below are related to logging errors, which should be unreachable.

- `log`: Enables logging using the `log` crate.
- `tracing`: Enables logging using the `tracing` crate.

## Examples

Non-async [`Pool`] example:

```rust
use piscina::Pool;

let mut pool = Pool::new();
pool.put(1);
pool.put(2);

let item1 = pool.try_get();
assert!(item1.is_some());

let item2 = pool.blocking_get();

let none = pool.try_get();
assert!(none.is_none());

drop(item1); // Return the item to the pool by dropping it
let item3 = pool.try_get();
assert!(item3.is_some());
```

Async [`Pool`] example:

```rust
use piscina::Pool;

futures::executor::block_on(async {
    let mut pool = Pool::new();
    pool.put(1);
    pool.put(2);

    let item1 = pool.get().await;
    let item2 = pool.get().await;

    let none = pool.try_get();
    assert!(none.is_none());

    drop(item1); // Return the item to the pool by dropping it
    let item3 = pool.get().await;
});
```

Non-async [`PriorityPool`] example:

```rust
use piscina::PriorityPool;

let mut pool = PriorityPool::new();
pool.put("hello", 1);
pool.put("world", 2); // Larger value means higher priority.

// Get the highest priority item.
let item = pool.try_get();
assert!(item.is_some());
let item = item.unwrap();
assert_eq!(item.item(), &"world");

let another_item = pool.try_get();
assert!(another_item.is_some());
let another_item = another_item.unwrap();
assert_eq!(another_item.item(), &"hello");

// The pool is now empty.
let empty_item = pool.try_get();
assert!(empty_item.is_none());

drop(another_item); // Return the item back to the pool by dropping it.
let hello = pool.try_get();
assert!(hello.is_some());
assert_eq!(hello.unwrap().item(), &"hello");
```

Async [`PriorityPool`] example:

```rust
use piscina::PriorityPool;

let mut pool = PriorityPool::new();
pool.put("hello", 1);
pool.put("world", 2); // Larger value means higher priority.

futures::executor::block_on(async {
    // Get the highest priority item.
    let world = pool.get().await;
    assert_eq!(world.item(), &"world");

    let hello = pool.get().await;
    assert_eq!(hello.item(), &"hello");

    // The pool is now empty.
    drop(hello); // Return the item back to the pool by dropping it.
    let item = pool.get().await;
    assert_eq!(item.item(), &"hello");
});
```

## Safety

Instead of using an `Option`, this crate uses unsafe code `ManuallyDrop` in `PooledItem`.
And the only use of unsafe code `ManuallyDrop::take()` occurs when `PooledItem` is dropped.

License: MIT/Apache-2.0