Crate permit[−][src]

permit

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.
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
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

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 an drop their permits.
top_permit.revoke().try_wait_for(
    core::time::Duration::from_secs(3));

Cargo Geiger Safety Report

Changelog

v0.1.1 - Make revoke return &Self
v0.1.0 - Initial version

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Structs

DeadlineExceeded
Permit	A struct for cancelling operations.