code_analyze_mcp/
metrics.rs

1//! Metrics collection and daily-rotating JSONL emission.
2//!
3//! Provides a channel-based pipeline: callers emit [`MetricEvent`] values via [`MetricsSender`],
4//! and [`MetricsWriter`] drains the channel and appends events to a daily-rotated JSONL file
5//! under the XDG data directory (`~/.local/share/code-analyze-mcp/metrics-YYYY-MM-DD.jsonl`).
6//! Files older than 30 days are deleted on startup.
7
8use serde::{Deserialize, Serialize};
9use std::path::{Path, PathBuf};
10use std::time::{SystemTime, UNIX_EPOCH};
11use tokio::io::AsyncWriteExt;
12use tokio::sync::mpsc;
13
14/// A single metric event emitted by a tool invocation.
15#[derive(Debug, Clone, Serialize, Deserialize)]
16pub struct MetricEvent {
17    pub ts: u64,
18    pub tool: &'static str,
19    pub duration_ms: u64,
20    pub output_chars: usize,
21    pub param_path_depth: usize,
22    pub max_depth: Option<u32>,
23    pub result: &'static str,
24    pub error_type: Option<String>,
25    #[serde(default)]
26    pub session_id: Option<String>,
27    #[serde(default)]
28    pub seq: Option<u32>,
29}
30
31/// Sender half of the metrics channel; cloned and passed to tools for event emission.
32#[derive(Clone)]
33pub struct MetricsSender(pub tokio::sync::mpsc::UnboundedSender<MetricEvent>);
34
35impl MetricsSender {
36    pub fn send(&self, event: MetricEvent) {
37        let _ = self.0.send(event);
38    }
39}
40
41/// Receiver half of the metrics channel; drains events and writes them to daily-rotated JSONL files.
42pub struct MetricsWriter {
43    rx: tokio::sync::mpsc::UnboundedReceiver<MetricEvent>,
44    base_dir: PathBuf,
45}
46
47impl MetricsWriter {
48    pub fn new(
49        rx: tokio::sync::mpsc::UnboundedReceiver<MetricEvent>,
50        base_dir: Option<PathBuf>,
51    ) -> Self {
52        let dir = base_dir.unwrap_or_else(xdg_metrics_dir);
53        Self { rx, base_dir: dir }
54    }
55
56    pub async fn run(mut self) {
57        cleanup_old_files(&self.base_dir).await;
58        let mut current_date = current_date_str();
59        let mut current_file: Option<PathBuf> = None;
60
61        loop {
62            let mut batch = Vec::new();
63            if let Some(event) = self.rx.recv().await {
64                batch.push(event);
65                for _ in 0..99 {
66                    match self.rx.try_recv() {
67                        Ok(e) => batch.push(e),
68                        Err(
69                            mpsc::error::TryRecvError::Empty
70                            | mpsc::error::TryRecvError::Disconnected,
71                        ) => break,
72                    }
73                }
74            } else {
75                break;
76            }
77
78            let new_date = current_date_str();
79            if new_date != current_date {
80                current_date = new_date;
81                current_file = None;
82            }
83
84            if current_file.is_none() {
85                current_file = Some(rotate_path(&self.base_dir, &current_date));
86            }
87
88            let path = current_file.as_ref().unwrap();
89
90            // Create directory once per batch
91            if let Some(parent) = path.parent()
92                && !parent.as_os_str().is_empty()
93            {
94                tokio::fs::create_dir_all(parent).await.ok();
95            }
96
97            // Open file once per batch
98            let file = tokio::fs::OpenOptions::new()
99                .create(true)
100                .append(true)
101                .open(path)
102                .await;
103
104            if let Ok(mut file) = file {
105                for event in batch {
106                    if let Ok(mut json) = serde_json::to_string(&event) {
107                        json.push('\n');
108                        let _ = file.write_all(json.as_bytes()).await;
109                    }
110                }
111                let _ = file.flush().await;
112            }
113        }
114    }
115}
116
117/// Returns the current UNIX timestamp in milliseconds.
118#[must_use]
119pub fn unix_ms() -> u64 {
120    SystemTime::now()
121        .duration_since(UNIX_EPOCH)
122        .unwrap_or_default()
123        .as_millis()
124        .try_into()
125        .unwrap_or(u64::MAX)
126}
127
128/// Counts the number of path segments in a file path.
129#[must_use]
130pub fn path_component_count(path: &str) -> usize {
131    Path::new(path).components().count()
132}
133
134/// Maps an MCP error code to a short string representation for metrics.
135#[must_use]
136pub fn error_code_to_type(code: rmcp::model::ErrorCode) -> &'static str {
137    match code {
138        rmcp::model::ErrorCode::PARSE_ERROR => "parse",
139        rmcp::model::ErrorCode::INVALID_PARAMS => "invalid_params",
140        _ => "unknown",
141    }
142}
143
144fn xdg_metrics_dir() -> PathBuf {
145    if let Ok(xdg_data_home) = std::env::var("XDG_DATA_HOME")
146        && !xdg_data_home.is_empty()
147    {
148        return PathBuf::from(xdg_data_home).join("code-analyze-mcp");
149    }
150
151    if let Ok(home) = std::env::var("HOME") {
152        PathBuf::from(home)
153            .join(".local")
154            .join("share")
155            .join("code-analyze-mcp")
156    } else {
157        PathBuf::from(".")
158    }
159}
160
161fn rotate_path(base_dir: &Path, date_str: &str) -> PathBuf {
162    base_dir.join(format!("metrics-{date_str}.jsonl"))
163}
164
165async fn cleanup_old_files(base_dir: &Path) {
166    let now_days = u32::try_from(unix_ms() / 86_400_000).unwrap_or(u32::MAX);
167
168    let Ok(mut entries) = tokio::fs::read_dir(base_dir).await else {
169        return;
170    };
171
172    loop {
173        match entries.next_entry().await {
174            Ok(Some(entry)) => {
175                let path = entry.path();
176                let file_name = match path.file_name() {
177                    Some(n) => n.to_string_lossy().into_owned(),
178                    None => continue,
179                };
180
181                // Expected format: metrics-YYYY-MM-DD.jsonl
182                if !file_name.starts_with("metrics-")
183                    || std::path::Path::new(&*file_name)
184                        .extension()
185                        .is_none_or(|e| !e.eq_ignore_ascii_case("jsonl"))
186                {
187                    continue;
188                }
189                let date_part = &file_name[8..file_name.len() - 6];
190                if date_part.len() != 10
191                    || date_part.as_bytes().get(4) != Some(&b'-')
192                    || date_part.as_bytes().get(7) != Some(&b'-')
193                {
194                    continue;
195                }
196                let Ok(year) = date_part[0..4].parse::<u32>() else {
197                    continue;
198                };
199                let Ok(month) = date_part[5..7].parse::<u32>() else {
200                    continue;
201                };
202                let Ok(day) = date_part[8..10].parse::<u32>() else {
203                    continue;
204                };
205                if month == 0 || month > 12 || day == 0 || day > 31 {
206                    continue;
207                }
208
209                let file_days = date_to_days_since_epoch(year, month, day);
210                if now_days > file_days && (now_days - file_days) > 30 {
211                    let _ = tokio::fs::remove_file(&path).await;
212                }
213            }
214            Ok(None) => break,
215            Err(e) => {
216                tracing::warn!("error reading metrics directory entry: {e}");
217            }
218        }
219    }
220}
221
222fn date_to_days_since_epoch(y: u32, m: u32, d: u32) -> u32 {
223    // Shift year so March is month 0
224    let (y, m) = if m <= 2 { (y - 1, m + 9) } else { (y, m - 3) };
225    let era = y / 400;
226    let yoe = y - era * 400;
227    let doy = (153 * m + 2) / 5 + d - 1;
228    let doe = yoe * 365 + yoe / 4 - yoe / 100 + doy;
229    // Compute the proleptic Gregorian day number, then subtract the Unix epoch offset.
230    // The subtraction must wrap the full expression; applying .saturating_sub to `doe`
231    // alone would underflow for recent dates where doe < 719_468.
232    (era * 146_097 + doe).saturating_sub(719_468)
233}
234
235/// Returns the current UTC date as a string in YYYY-MM-DD format.
236#[must_use]
237pub fn current_date_str() -> String {
238    let days = u32::try_from(unix_ms() / 86_400_000).unwrap_or(u32::MAX);
239    let z = days + 719_468;
240    let era = z / 146_097;
241    let doe = z - era * 146_097;
242    let yoe = (doe - doe / 1460 + doe / 36524 - doe / 146_096) / 365;
243    let y = yoe + era * 400;
244    let doy = doe - (365 * yoe + yoe / 4 - yoe / 100);
245    let mp = (5 * doy + 2) / 153;
246    let d = doy - (153 * mp + 2) / 5 + 1;
247    let m = if mp < 10 { mp + 3 } else { mp - 9 };
248    let y = if m <= 2 { y + 1 } else { y };
249    format!("{y:04}-{m:02}-{d:02}")
250}
251
252#[cfg(test)]
253mod tests {
254    use super::*;
255
256    // --- date math tests ---
257
258    #[test]
259    fn test_date_to_days_since_epoch_known_dates() {
260        // Unix epoch: 1970-01-01 = day 0
261        assert_eq!(date_to_days_since_epoch(1970, 1, 1), 0);
262        // 2020-01-01: known value 18262 (50 years, accounting for leap years)
263        assert_eq!(date_to_days_since_epoch(2020, 1, 1), 18_262);
264        // Leap day 2000-02-29: 2000-02-29 is day 11_016
265        assert_eq!(date_to_days_since_epoch(2000, 2, 29), 11_016);
266    }
267
268    #[test]
269    fn test_current_date_str_format() {
270        let s = current_date_str();
271        assert_eq!(s.len(), 10, "date string must be 10 chars: {s}");
272        assert_eq!(s.as_bytes()[4], b'-', "char at index 4 must be '-': {s}");
273        assert_eq!(s.as_bytes()[7], b'-', "char at index 7 must be '-': {s}");
274        // Sanity: year must parse and be in reasonable range
275        let year: u32 = s[0..4].parse().expect("year must be numeric");
276        assert!(year >= 2020 && year <= 2100, "unexpected year {year}");
277    }
278
279    #[tokio::test]
280    async fn test_metrics_writer_batching() {
281        use tempfile::TempDir;
282
283        let dir = TempDir::new().unwrap();
284        let (tx, rx) = tokio::sync::mpsc::unbounded_channel::<MetricEvent>();
285        let writer = MetricsWriter::new(rx, Some(dir.path().to_path_buf()));
286
287        let make_event = || MetricEvent {
288            ts: unix_ms(),
289            tool: "analyze_directory",
290            duration_ms: 1,
291            output_chars: 10,
292            param_path_depth: 1,
293            max_depth: None,
294            result: "ok",
295            error_type: None,
296            session_id: None,
297            seq: None,
298        };
299
300        tx.send(make_event()).unwrap();
301        tx.send(make_event()).unwrap();
302        tx.send(make_event()).unwrap();
303        // Drop sender so run() exits after draining
304        drop(tx);
305
306        writer.run().await;
307
308        // Exactly 1 .jsonl file must exist with exactly 3 lines
309        let entries: Vec<_> = std::fs::read_dir(dir.path())
310            .unwrap()
311            .filter_map(|e| e.ok())
312            .filter(|e| {
313                e.path()
314                    .extension()
315                    .and_then(|x| x.to_str())
316                    .map(|x| x.eq_ignore_ascii_case("jsonl"))
317                    .unwrap_or(false)
318            })
319            .collect();
320        assert_eq!(entries.len(), 1, "expected exactly 1 .jsonl file");
321        let content = std::fs::read_to_string(entries[0].path()).unwrap();
322        let lines: Vec<&str> = content.lines().collect();
323        assert_eq!(lines.len(), 3, "expected exactly 3 lines; got: {content}");
324    }
325
326    #[tokio::test]
327    async fn test_cleanup_old_files_deletes_old_keeps_recent() {
328        use tempfile::TempDir;
329
330        // Today = 2026-03-28 (hard-coded to match plan; adjust if re-run later)
331        // 31 days ago = 2026-02-25; 29 days ago = 2026-02-27
332        let dir = TempDir::new().unwrap();
333        let old_file = dir.path().join("metrics-2026-02-25.jsonl");
334        let recent_file = dir.path().join("metrics-2026-02-27.jsonl");
335        std::fs::write(&old_file, "old\n").unwrap();
336        std::fs::write(&recent_file, "recent\n").unwrap();
337
338        cleanup_old_files(dir.path()).await;
339
340        assert!(
341            !old_file.exists(),
342            "31-day-old file should have been deleted"
343        );
344        assert!(
345            recent_file.exists(),
346            "29-day-old file should have been kept"
347        );
348    }
349
350    #[test]
351    fn test_metric_event_serialization() {
352        let event = MetricEvent {
353            ts: 1_700_000_000_000,
354            tool: "analyze_directory",
355            duration_ms: 42,
356            output_chars: 100,
357            param_path_depth: 3,
358            max_depth: Some(2),
359            result: "ok",
360            error_type: None,
361            session_id: None,
362            seq: None,
363        };
364        let json = serde_json::to_string(&event).unwrap();
365        assert!(json.contains("analyze_directory"));
366        assert!(json.contains(r#""result":"ok""#));
367        assert!(json.contains(r#""output_chars":100"#));
368    }
369
370    #[test]
371    fn test_metric_event_serialization_error() {
372        let event = MetricEvent {
373            ts: 1_700_000_000_000,
374            tool: "analyze_directory",
375            duration_ms: 5,
376            output_chars: 0,
377            param_path_depth: 3,
378            max_depth: Some(3),
379            result: "error",
380            error_type: Some("invalid_params".to_string()),
381            session_id: None,
382            seq: None,
383        };
384        let json = serde_json::to_string(&event).unwrap();
385        assert!(json.contains(r#""result":"error""#));
386        assert!(json.contains(r#""error_type":"invalid_params""#));
387        assert!(json.contains(r#""output_chars":0"#));
388        assert!(json.contains(r#""max_depth":3"#));
389    }
390
391    #[test]
392    fn test_metric_event_new_fields_round_trip() {
393        let event = MetricEvent {
394            ts: 1_700_000_000_000,
395            tool: "analyze_file",
396            duration_ms: 100,
397            output_chars: 500,
398            param_path_depth: 2,
399            max_depth: Some(3),
400            result: "ok",
401            error_type: None,
402            session_id: Some("1742468880123-42".to_string()),
403            seq: Some(5),
404        };
405        let serialized = serde_json::to_string(&event).unwrap();
406        let json_str = r#"{"ts":1700000000000,"tool":"analyze_file","duration_ms":100,"output_chars":500,"param_path_depth":2,"max_depth":3,"result":"ok","error_type":null,"session_id":"1742468880123-42","seq":5}"#;
407        assert_eq!(serialized, json_str);
408        let parsed: MetricEvent = serde_json::from_str(json_str).unwrap();
409        assert_eq!(parsed.session_id, Some("1742468880123-42".to_string()));
410        assert_eq!(parsed.seq, Some(5));
411    }
412
413    #[test]
414    fn test_metric_event_backward_compat_parse() {
415        let old_jsonl = r#"{"ts":1700000000000,"tool":"analyze_directory","duration_ms":42,"output_chars":100,"param_path_depth":3,"max_depth":2,"result":"ok","error_type":null}"#;
416        let parsed: MetricEvent = serde_json::from_str(old_jsonl).unwrap();
417        assert_eq!(parsed.tool, "analyze_directory");
418        assert_eq!(parsed.session_id, None);
419        assert_eq!(parsed.seq, None);
420    }
421
422    #[test]
423    fn test_session_id_format() {
424        let event = MetricEvent {
425            ts: 1_700_000_000_000,
426            tool: "analyze_symbol",
427            duration_ms: 20,
428            output_chars: 50,
429            param_path_depth: 1,
430            max_depth: None,
431            result: "ok",
432            error_type: None,
433            session_id: Some("1742468880123-0".to_string()),
434            seq: Some(0),
435        };
436        let sid = event.session_id.unwrap();
437        assert!(sid.contains('-'), "session_id should contain a dash");
438        let parts: Vec<&str> = sid.split('-').collect();
439        assert_eq!(parts.len(), 2, "session_id should have exactly 2 parts");
440        assert!(parts[0].len() == 13, "millis part should be 13 digits");
441    }
442}
code_analyze_mcp/metrics.rs

code_analyze_mcp/
metrics.rs
