11 releases
Uses old Rust 2015
0.3.1 | Jan 5, 2021 |
---|---|
0.3.0 | Jan 5, 2021 |
0.2.7 | Jan 3, 2021 |
0.2.5 | Dec 28, 2020 |
0.1.6 | Dec 26, 2020 |
#4 in #mosquitto
42 downloads per month
Used in cerk_port_mqtt_mosquitto
44KB
792 lines
A Rust interface to the Mosquitto MQTT broker client
Mosquitto is a popular MQTT broker implemented in C. Although there are pure Rust MQTT clients, it is still useful to have a binding to the Mosquitto client.
The basic story is that you connect to a broker, subscribing to topics that interest you and publishing messages on a particular topic. The messages may be any arbitrary bytes, but this implementation does require that the topics themselves be UTF-8. The C API is based on callbacks, which are mapped onto Rust closures.
The Mosquitto client is thread-safe, so you can publish from one thread and listen for the messages on another. This example demonstrates mosquitto-client usage:
extern crate mosquitto_client_wrapper as mosq;
use mosq::Mosquitto;
use std::{thread, time};
fn main() {
let m = Mosquitto::new("test");
m.connect("localhost",1883,5).expect("can't connect");
m.subscribe("bilbo/#",1).expect("can't subscribe to bonzo");
let mt = m.clone();
thread::spawn(move || {
let timeout = time::Duration::from_millis(500);
for _ in 0..5 {
mt.publish("bilbo/baggins","hello dolly".as_bytes(), 1, false).unwrap();
thread::sleep(timeout);
}
mt.disconnect().unwrap();
});
let mut mc = m.callbacks(0);
mc.on_message(|data,msg| {
println!("bilbo {:?}",msg);
*data += 1;
});
m.loop_until_disconnect(200).expect("broken loop");
println!("received {} messages",mc.data);
}
The Mosquitto
struct is a thin wrapper around the C pointer we get from the client.
It is Clone + Send + Sync
, so we can pass it to a thread which simply publishes some
bytes and waits; at the end of the thread we explicitly disconnect.
The Callbacks
handler struct is separate, to avoid antagonizing the borrow checker.
It is created by the callbacks
method and is generic over some data (accessed as the data
field)
Whenever an event occurs, the callback will be passed a mutable reference to that data, and
event-specific data - in this case a message struct.
loop_until_disconnect
is a relative of loop_forever
which ends without error if we
explicitly disconnect from the broker.
Features
bundled (on by default)
This feature will automatically download and build the mosquitto client library. By default, the master branch is taken. This could be overwritten with the following variables:
MOSQUITTO_GIT_URL
Url of the git repository; by default https://github.com/eclipse/mosquitto.gitMOSQUITTO_GIT_HASH
Git hash to checkout for the build; by default none
Cross compilation
The library could be cross-compiled. The following env parameters have to be set for that:
MOSQUITTO_CROSS_COMPILER
default none, e.g.arm-linux-gnueabihf-
MOSQUITTO_CC
defaultgcc
No runtime deps
~0–630KB