rskit-messaging 0.1.0-alpha.2

Message broker abstractions, registry, middleware, and in-memory adapter
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131

//! Handler-level metrics instrumentation middleware.

use std::sync::Arc;
use std::time::Instant;

use async_trait::async_trait;
use rskit_errors::AppResult;

use crate::handler::{HandlerMiddleware, MessageHandler};
use crate::message::Message;
use crate::metrics::MetricsCollector;

/// Create a middleware that records handler processing metrics.
///
/// Each handler invocation is timed and reported to the supplied
/// [`MetricsCollector`] via `record_consume`.
pub fn instrument<T: Send + Sync + 'static>(
    metrics: Arc<dyn MetricsCollector>,
    topic: String,
) -> impl HandlerMiddleware<T> {
    InstrumentMiddleware { metrics, topic }
}

struct InstrumentMiddleware {
    metrics: Arc<dyn MetricsCollector>,
    topic: String,
}

impl<T: Send + Sync + 'static> HandlerMiddleware<T> for InstrumentMiddleware {
    fn wrap(&self, next: Arc<dyn MessageHandler<T>>) -> Arc<dyn MessageHandler<T>> {
        Arc::new(InstrumentHandler {
            metrics: self.metrics.clone(),
            topic: self.topic.clone(),
            next,
        })
    }
}

struct InstrumentHandler<T: Send + Sync + 'static> {
    metrics: Arc<dyn MetricsCollector>,
    topic: String,
    next: Arc<dyn MessageHandler<T>>,
}

#[async_trait]
impl<T: Send + Sync + 'static> MessageHandler<T> for InstrumentHandler<T> {
    async fn handle(&self, msg: Message<T>) -> AppResult<()> {
        let start = Instant::now();
        let result = self.next.handle(msg).await;
        self.metrics
            .record_consume(&self.topic, start.elapsed(), result.is_ok());
        result
    }
}

#[cfg(test)]
mod tests {
    use std::time::Duration;

    use super::*;
    use crate::handler::{FnHandler, chain_handlers};
    use rskit_errors::{AppError, ErrorCode};

    struct RecordingMetrics {
        calls: Arc<parking_lot::Mutex<Vec<(String, Duration, bool)>>>,
    }

    impl MetricsCollector for RecordingMetrics {
        fn record_publish(&self, _topic: &str, _duration: Duration, _success: bool) {}

        fn record_consume(&self, topic: &str, duration: Duration, success: bool) {
            self.calls
                .lock()
                .push((topic.to_string(), duration, success));
        }
    }

    #[tokio::test]
    async fn records_success_metric() {
        let calls = Arc::new(parking_lot::Mutex::new(Vec::new()));
        let metrics: Arc<dyn MetricsCollector> = Arc::new(RecordingMetrics {
            calls: calls.clone(),
        });

        let base: Arc<dyn MessageHandler<String>> =
            Arc::new(FnHandler::new(|_msg: Message<String>| async { Ok(()) }));

        let mw: Arc<dyn HandlerMiddleware<String>> = Arc::new(InstrumentMiddleware {
            metrics,
            topic: "test".to_string(),
        });
        let handler = chain_handlers(base, &[mw]);

        handler
            .handle(Message::new("test", "ok".to_string()))
            .await
            .unwrap();

        let recorded = calls.lock();
        assert_eq!(recorded.len(), 1);
        assert_eq!(recorded[0].0, "test");
        assert!(recorded[0].2); // success = true
    }

    #[tokio::test]
    async fn records_failure_metric() {
        let calls = Arc::new(parking_lot::Mutex::new(Vec::new()));
        let metrics: Arc<dyn MetricsCollector> = Arc::new(RecordingMetrics {
            calls: calls.clone(),
        });

        let base: Arc<dyn MessageHandler<String>> =
            Arc::new(FnHandler::new(|_msg: Message<String>| async {
                Err(AppError::new(ErrorCode::Internal, "fail"))
            }));

        let mw: Arc<dyn HandlerMiddleware<String>> = Arc::new(InstrumentMiddleware {
            metrics,
            topic: "test".to_string(),
        });
        let handler = chain_handlers(base, &[mw]);

        let _ = handler
            .handle(Message::new("test", "fail".to_string()))
            .await;

        let recorded = calls.lock();
        assert_eq!(recorded.len(), 1);
        assert!(!recorded[0].2); // success = false
    }
}