blocking
Block on async code or await blocking code.
To convert async to blocking, block on async code with block_on()
, block_on!
, or
BlockOn
.
To convert blocking to async, unblock blocking code with unblock()
, unblock!
, or
Unblock
.
Thread pool
Sometimes there's no way to avoid blocking I/O in async programs. Consider files or stdin, which have weak async support on modern operating systems. While IOCP, AIO, and io_uring are possible solutions, they're not always available or ideal.
Since blocking is not allowed inside futures, we must move blocking I/O onto a special thread pool provided by this crate. The pool dynamically spawns and stops threads depending on the current number of running I/O jobs.
Note that there is a limit on the number of active threads. Once that limit is hit, a running job has to finish before others get a chance to run. When a thread is idle, it waits for the next job or shuts down after a certain timeout.
Examples
Await a blocking file read with unblock!
:
use ;
use ;
block_on;
Read a file and pipe its contents to stdout:
use ;
use File;
use ;
block_on;
Iterate over the contents of a directory:
use ;
use *;
use ;
block_on;
Convert a stream into an iterator:
use BlockOn;
use stream;
let stream = once;
let mut iter = new;
assert_eq!;
assert_eq!;
License
Licensed under either of
- Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
- MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)
at your option.
Contribution
Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.