permit::Permit 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.
• Implements Future. You can await a permit and return when it is revoked.
• Similar to Golang's context
• Depends only on std.
• forbid(unsafe_code)
• 100% test coverage

Limitations

• Does not hold data values
• Allocates. Uses alloc::sync::Arc.

Alternatives

• async_ctx
  • Good API
  • Async only
• stopper
  • Async only
• io-context
  • Holds Any values
  • Unmaintained
• ctx
  • Holds an Any value
  • API is a direct copy of Golang's 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:

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 and wait for them to
// finish and drop their permits.
top_permit
    .revoke()
    .wait_subs_timeout(Duration::from_secs(3))
    .unwrap();

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 0.2.1

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

Changelog

• v0.2.1 - Fix bug where sleep and sleep_until would sometimes not return early.
• v0.2.0
  • Rename try_wait_for to wait_subs_timeout
  • Rename try_wait_until to wait_subs_deadline
  • Replace spinlock with Condvar in wait* methods
  • Remove wait
  • Add sleep and sleep_until
• v0.1.5 - Implement Debug
• v0.1.4 - Fix bug where revoke() and then wait() would not wait.
• v0.1.3
  • Don't keep or wake stale std::task::Waker structs.
  • Eliminate race that causes unnecessary wake.
• v0.1.2 - Implement Future
• v0.1.1 - Make revoke return &Self
• v0.1.0 - Initial version

License: Apache-2.0