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pub use anyhow::Result as AnyResult; pub use futures::{Future, FutureExt, TryFutureExt, TryStreamExt}; pub use nats::{Message as NatsMessage, Options as NatsOptions}; use blocking::unblock; use bytes::Bytes; use log::{debug, error}; use std::sync::atomic::{AtomicBool, Ordering}; use std::sync::Arc; use std::time::Duration; pub trait NatsMessageHandler: Sync + Send { fn handle_message(&mut self, message: &NatsMessage) -> AnyResult<ProcessResult>; } pub enum ProcessResult { Success(Bytes), Failure(Bytes), } pub struct CGLoop { pub url: String, pub source_topic: String, pub success_topic: String, pub failure_topic: String, pub group: String, pub unsub_on_exit: bool, pub timeout: Duration, } impl CGLoop { pub fn new( url: &str, source_topic: &str, success_topic: &str, failure_topic: &str, group: &str, unsub_on_exit: bool, timeout: Option<Duration>, ) -> Self { let timeout = if let Some(timeout_value) = timeout { timeout_value } else { Duration::from_millis(500) }; Self { url: url.into(), source_topic: source_topic.into(), success_topic: success_topic.into(), failure_topic: failure_topic.into(), group: group.into(), unsub_on_exit, timeout, } } pub async fn run( self, options: NatsOptions, shutdown_flag: Arc<AtomicBool>, on_message: Box<dyn NatsMessageHandler>, ) -> AnyResult<()> { let mut on_message = on_message; let _ = unblock(move || { let connection; if let Ok(new_connection) = options.connect(&self.url) { connection = new_connection; } else { error!("Unable to connect to {}", &self.url); panic!(); } if connection.flush_timeout(self.timeout).is_err() { error!("Unable to set flush timeout to {:#?}", self.timeout); panic!(); } let subscription; if let Ok(queue_subscription) = connection.queue_subscribe(&self.source_topic, &self.group) { subscription = queue_subscription; } else { error!( "Unable to do queue subscription to subject {} queue {}", &self.source_topic, &self.group ); panic!(); } while !shutdown_flag.load(Ordering::Relaxed) { if let Ok(received_message) = subscription.next_timeout(self.timeout) { match on_message.handle_message(&received_message) { Err(error) => { error!("{}", error); } Ok(process_result) => match process_result { ProcessResult::Failure(failure_message) => { let message_len = failure_message.len(); if let Err(error) = connection.publish(&self.failure_topic, &failure_message) { error!("{}", error); } else { debug!( "Failure message sent to topic {} with size {} bytes", &self.failure_topic, message_len ); } } ProcessResult::Success(success_message) => { let message_len = success_message.len(); if let Err(error) = connection.publish(&self.success_topic, &success_message) { error!("{}", error); } else { debug!( "Success message sent to topic {} with size {} bytes", &self.success_topic, message_len ); } } }, } } } debug!("Exiting..."); if self.unsub_on_exit { subscription.unsubscribe().unwrap(); } }) .await; Ok(()) } }