permit 0.1.0

A struct for cancelling operations.
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

[![crates.io version](https://img.shields.io/crates/v/permit.svg)](https://crates.io/crates/permit)
[![license: Apache 2.0](https://gitlab.com/leonhard-llc/ops/-/raw/main/license-apache-2.0.svg)](https://gitlab.com/leonhard-llc/ops/-/raw/main/permit/LICENSE)
[![unsafe forbidden](https://gitlab.com/leonhard-llc/ops/-/raw/main/unsafe-forbidden.svg)](https://github.com/rust-secure-code/safety-dance/)
[![pipeline status](https://gitlab.com/leonhard-llc/ops/badges/main/pipeline.svg)](https://gitlab.com/leonhard-llc/ops/-/pipelines)

# permit

[`permit::Permit`](https://docs.rs/permit/latest/permit/struct.Permit.html)
is a struct for cancelling operations.

## Use Cases
- Graceful server shutdown
- Cancel operations that take too long
- Stop in-flight operations when revoking authorization

## Features
- Subordinate permits.
  Revoking a permit also revokes its subordinates, recursively.
- Drop a permit to revoke its subordinates, recursively.
- Wait for all subordinate permits to drop.
- Similar to Golang's [`context`](https://golang.org/pkg/context/)
- Depends only on `std`.
- `forbid(unsafe_code)`
- 100% test coverage

## Limitations
- Does not hold data values
- Allocates.  Uses [`alloc::sync::Arc`](https://doc.rust-lang.org/alloc/sync/struct.Arc.html).

## Alternatives
- [`async_ctx`](https://crates.io/crates/async_ctx)
  - Good API
  - Async only
- [`io-context`](https://crates.io/crates/io-context)
  - Holds [Any](https://doc.rust-lang.org/core/any/trait.Any.html) values
  - Unmaintained
- [`ctx`](https://crates.io/crates/ctx)
  - Holds an [Any](https://doc.rust-lang.org/core/any/trait.Any.html) value
  - API is a direct copy of Golang's
    [`context`](https://golang.org/pkg/context/),
    even where that doesn't make sense for Rust.
    For example, to cancel, one must copy the context and call
    a returned `Box<Fn>`.
  - Unmaintained

## Related Crates

## Example

Graceful shutdown:
```rust
let top_permit = permit::Permit::new();
// Start some worker threads.
for _ in 0..5 {
    let permit = top_permit.new_sub();
    std::thread::spawn(move || {
        while !permit.is_revoked() {
            // ...
        }
    });
}
wait_for_shutdown_signal();
// Revoke all thread permits.
top_permit.revoke();
// Give the threads time to finish
// and drop their permits.
let _ = top_permit.try_wait_for(
    core::time::Duration::from_secs(3));
```

## Cargo Geiger Safety Report
```

Metric output format: x/y
    x = unsafe code used by the build
    y = total unsafe code found in the crate

Symbols: 
    🔒  = No `unsafe` usage found, declares #![forbid(unsafe_code)]
    ❓  = No `unsafe` usage found, missing #![forbid(unsafe_code)]
    ☢️  = `unsafe` usage found

Functions  Expressions  Impls  Traits  Methods  Dependency

0/0        0/0          0/0    0/0     0/0      🔒  permit 0.1.0

0/0        0/0          0/0    0/0     0/0    

```
## Changelog
- v0.1.0 - Initial version

## Happy Contributors 🙂
Fixing bugs and adding features is easy and fast.
Send us a pull request and we intend to:
- Always respond within 24 hours
- Provide clear & concrete feedback
- Immediately make a new release for your accepted change

License: Apache-2.0