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use std::time::Duration;
use crate::converter::*;
use crate::error::*;
use mqtt_channel::{
Connection, Message, MqttError, SinkExt, StreamExt, TopicFilter, UnboundedReceiver,
UnboundedSender,
};
use tracing::{error, info, instrument};
const SYNC_WINDOW: Duration = Duration::from_secs(3);
pub async fn create_mapper<'a>(
app_name: &'a str,
mqtt_port: u16,
converter: Box<dyn Converter<Error = ConversionError>>,
) -> Result<Mapper, anyhow::Error> {
info!("{} starting", app_name);
let mapper_config = converter.get_mapper_config();
let mqtt_client = Connection::new(&mqtt_config(
app_name,
mqtt_port,
mapper_config.in_topic_filter.clone().into(),
)?)
.await?;
Mapper::subscribe_errors(mqtt_client.errors);
Ok(Mapper::new(
mqtt_client.received,
mqtt_client.published,
converter,
))
}
pub(crate) fn mqtt_config(
name: &str,
port: u16,
topics: TopicFilter,
) -> Result<mqtt_channel::Config, anyhow::Error> {
Ok(mqtt_channel::Config::default()
.with_port(port)
.with_session_name(name)
.with_subscriptions(topics)
.with_max_packet_size(10 * 1024 * 1024))
}
pub struct Mapper {
input: UnboundedReceiver<Message>,
output: UnboundedSender<Message>,
converter: Box<dyn Converter<Error = ConversionError>>,
}
impl Mapper {
pub fn new(
input: UnboundedReceiver<Message>,
output: UnboundedSender<Message>,
converter: Box<dyn Converter<Error = ConversionError>>,
) -> Self {
Self {
input,
output,
converter,
}
}
pub(crate) async fn run(&mut self) -> Result<(), MqttError> {
info!("Running");
self.process_messages().await?;
Ok(())
}
#[instrument(skip(errors), name = "errors")]
fn subscribe_errors(mut errors: UnboundedReceiver<MqttError>) {
tokio::spawn(async move {
while let Some(error) = errors.next().await {
error!("{}", error);
}
});
}
#[instrument(skip(self), name = "messages")]
async fn process_messages(&mut self) -> Result<(), MqttError> {
let init_messages = self.converter.init_messages();
for init_message in init_messages.into_iter() {
let _ = self.output.send(init_message).await;
}
// Start the sync phase here and process messages until the sync window times out
let _ = tokio::time::timeout(SYNC_WINDOW, async {
while let Some(message) = self.input.next().await {
self.process_message(message).await;
}
})
.await;
// Once the sync phase is complete, retrieve all sync messages from the converter and process them
let sync_messages = self.converter.sync_messages();
for message in sync_messages {
self.process_message(message).await;
}
// Continue processing messages after the sync period
while let Some(message) = self.input.next().await {
self.process_message(message).await;
}
Ok(())
}
async fn process_message(&mut self, message: Message) {
let converted_messages = self.converter.convert(&message);
for converted_message in converted_messages.into_iter() {
let _ = self.output.send(converted_message).await;
}
}
}
#[cfg(test)]
mod tests {
use super::*;
use mqtt_channel::{Message, Topic, TopicFilter};
use std::time::Duration;
use tokio::time::sleep;
#[tokio::test]
#[serial_test::serial]
async fn a_valid_input_leads_to_a_translated_output() -> Result<(), anyhow::Error> {
// Given an MQTT broker
let broker = mqtt_tests::test_mqtt_broker();
// Given a mapper
let name = "mapper_under_test";
let mqtt_config = mqtt_channel::Config::default()
.with_port(broker.port)
.with_session_name(name)
.with_subscriptions(TopicFilter::new_unchecked("in_topic"));
let mqtt_client = Connection::new(&mqtt_config).await?;
let mut mapper = Mapper {
input: mqtt_client.received,
output: mqtt_client.published,
converter: Box::new(UppercaseConverter::new()),
};
// Let's run the mapper in the background
tokio::spawn(async move {
let _ = mapper.run().await;
});
sleep(Duration::from_secs(1)).await;
// One can now send requests
let timeout = Duration::from_secs(1);
// Happy path
let input = "abcde";
let expected = Some("ABCDE".to_string());
let actual = broker
.wait_for_response_on_publish("in_topic", input, "out_topic", timeout)
.await;
assert_eq!(expected, actual);
// Ill-formed input
let input = "éèê";
let expected = Some(format!("{}", UppercaseConverter::conversion_error()));
let actual = broker
.wait_for_response_on_publish("in_topic", input, "err_topic", timeout)
.await;
assert_eq!(expected, actual);
Ok(())
}
struct UppercaseConverter {
mapper_config: MapperConfig,
}
impl UppercaseConverter {
pub fn new() -> UppercaseConverter {
let mapper_config = MapperConfig {
in_topic_filter: TopicFilter::new("in_topic").expect("invalid topic filter"),
out_topic: Topic::new_unchecked("out_topic"),
errors_topic: Topic::new_unchecked("err_topic"),
};
UppercaseConverter { mapper_config }
}
pub fn conversion_error() -> ConversionError {
// Just a stupid error that matches the expectations of the mapper
ConversionError::FromMapper(MapperError::HomeDirNotFound)
}
}
impl Converter for UppercaseConverter {
type Error = ConversionError;
fn get_mapper_config(&self) -> &MapperConfig {
&self.mapper_config
}
fn try_convert(&mut self, input: &Message) -> Result<Vec<Message>, Self::Error> {
let input = input.payload_str().expect("utf8");
if input.is_ascii() {
let msg = vec![Message::new(
&self.mapper_config.out_topic,
input.to_uppercase(),
)];
Ok(msg)
} else {
Err(UppercaseConverter::conversion_error())
}
}
}
}
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