#message-queue #posix #queue #mq #mqueue


An idiomatic library for using posix message queues, with optional mio integration

4 releases (1 stable)

1.0.0 Feb 2, 2021
0.2.0 Jul 8, 2019
0.1.1 Apr 5, 2019
0.1.0 Mar 25, 2019

#246 in Unix APIs

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Apache-2.0 / MIT

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A Rust library for using posix message queues.

crates.io Build Status License Documentation

let mq = posixmq::PosixMq::open("/queue").expect("cannot open /queue");
let mut buf = vec![0; mq.attributes().unwrap_or_default().max_msg_len];
loop {
    let (priority, len) = mq.recv(&mut buf).expect("recv() failed");
    let msg = std::str::from_utf8(&buf[..len]).expect("not UTF-8");
    println!("priority: {:3}, message: {}", priority, msg);

Supported Operating Systems

posixmq has been tested to work on Linux, FreeBSD, NetBSD, DragonFly BSD and OmniOSce, but not all features are available everywhere. See rustdoc for details.
*macOS, OpenBSD, Android and Windows doesn't have posix message queues, and this crate will fail to compile there.

Optional mio Integration

On Linux, FreeBSD and DragonFly BSD, posix message queues can be registered with epoll / kqueue, and therefore used with mio. Both mio version 0.6 and 0.7 are supported, through the opt-in crate features mio_06 and mio_07. Enable the feature for the mio version you use in Cargo.toml with for example:

mio = {version="0.7", features=["os-poll"]} # you probably need os-poll
posixmq = {version="1.0", features=["mio_07"]}

Also remember to open the message queues in nonblocking mode.

Minimum supported Rust version

The minimum Rust version for 1.0.* releases is 1.39.0 if the mio_07 feature is enabled, and 1.31.1 otherwise.
Later 1.*.0 releases might increase this. Until rustup has builds for DragonFly and Illumos, the minimum version will not be increased past what is available in repositories for these operating systems.
New optional features might require newer Rust versions. To lock to a minor release, use posixmq = "1.0.*" in Cargo.toml, or copy posixmq.rs into your project and remove feature gates as necessary.


Licensed under either of

at your option.


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.

Release History

Version 1.0.0 (2021-02-02)

  • Return errors from .attributes(), .is_nonblocking() and .is_cloexec(). For consistency with std and to make it easier to catch bugs.
  • Rename .receive() to .recv() for consistency with std. (.receive_deadline() and .receive_timeout() are also renamed to .recv_deadline() and .recv_timeout())
  • Rename unlink() to remove_queue() for consistency with std. (unlink_c() is also renamed to remove_queue_c())
  • Make Attributes partially opaque for future extensibility, and implement Default for it.
  • Remove name_from_bytes().
  • Rename mio feature for integrating with Mio 0.6 to mio_06.
  • Add mio_07 feature for integrating with Mio 0.7.
  • Implement Clone for the borrowing iterator posixmq::Iter.
  • Avoid allocating for queue names shorter than 47 bytes.
  • Disable non-standard features on unknown operating systems.

Version 0.2.0 (2019-07-08)

  • Change PosixMq::open() to open in read-write mode instead of read-only.
  • Rename OpenOptions.permissions() to .mode() for consistency with std.
  • Remove OpenOptions.not_cloexec().
  • Add .send_timeout(), .send_deadline(), .receive_timeout() and .receive_deadline().
  • Add Iter and IntoIter receiving iterator types.

Version 0.1.1 (2019-04-05)

  • Add .try_clone().
  • Add PosixMq::from_raw_mqd(), .as_raw_mqd() and .into_raw_mqd().
  • Implement Sync on FreeBSD.
  • Support DragonFly BSD, NetBSD and Illumos.
  • Support ARM targets and linux-x86_64-unknown-gnux32.

Version 0.1.0 (2019-03-25)

  • (initial release).
  • Support Linux and FreeBSD.