perf: hold database handle through all filters when querying

src/repo/sqlite.rs

@@ -350,6 +350,7 @@ impl NostrRepo for SqliteRepo {
             let slow_cutoff = Duration::from_millis(250);
             let mut filter_count = 0;
             // remove duplicates from the filter list.
+            if let Ok(mut conn) = self.read_pool.get() {
                 for filter in sub.filters.iter() {
                     let filter_start = Instant::now();
                     filter_count += 1;
@@ -364,10 +365,9 @@ impl NostrRepo for SqliteRepo {
                     let abort_cutoff = Duration::from_secs(5);
                     let mut slow_first_event;
                     let mut last_successful_send = Instant::now();
-                if let Ok(mut conn) = self.read_pool.get() {
                     // execute the query.
                     // make the actual SQL query (with parameters inserted) available
-                    conn.trace(Some(|x| {trace!("SQL trace: {:?}", x)}));
+                    conn.trace(Some(|x| {debug!("SQL trace: {:?}", x)}));
                     let mut stmt = conn.prepare_cached(&q)?;
                     let mut event_rows = stmt.query(rusqlite::params_from_iter(p))?;
 
@@ -445,9 +445,9 @@ impl NostrRepo for SqliteRepo {
                             .ok();
                         last_successful_send = Instant::now();
                     }
-                } else {
+                    metrics
-                    warn!("Could not get a database connection for querying");
+                        .query_db
-                }
+                        .observe(filter_start.elapsed().as_secs_f64());
                     // if the filter took too much db_time, print out the JSON.
                     if filter_start.elapsed() > slow_cutoff && client_id.starts_with('0') {
                         debug!(
@@ -457,6 +457,9 @@ impl NostrRepo for SqliteRepo {
                     }
 
                 }
+            } else {
+                warn!("Could not get a database connection for querying");
+            }
             drop(sem); // new query can begin
             debug!(
                 "query completed in {:?} (cid: {}, sub: {:?}, db_time: {:?}, rows: {})",

src/server.rs

@@ -232,6 +232,10 @@ fn create_metrics() -> (Registry, NostrMetrics) {
         "nostr_query_seconds",
         "Subscription response times",
     )).unwrap();
+    let query_db = Histogram::with_opts(HistogramOpts::new(
+        "nostr_filter_seconds",
+        "Filter SQL query times",
+    )).unwrap();
     let write_events = Histogram::with_opts(HistogramOpts::new(
         "nostr_events_write_seconds",
         "Event writing response times",
@@ -265,6 +269,7 @@ fn create_metrics() -> (Registry, NostrMetrics) {
         vec!["reason"].as_slice(),
         ).unwrap();
     registry.register(Box::new(query_sub.clone())).unwrap();
+    registry.register(Box::new(query_db.clone())).unwrap();
     registry.register(Box::new(write_events.clone())).unwrap();
     registry.register(Box::new(sent_events.clone())).unwrap();
     registry.register(Box::new(connections.clone())).unwrap();
@@ -275,6 +280,7 @@ fn create_metrics() -> (Registry, NostrMetrics) {
     registry.register(Box::new(disconnects.clone())).unwrap();
     let metrics = NostrMetrics {
         query_sub,
+        query_db,
         write_events,
         sent_events,
         connections,
@@ -830,6 +836,7 @@ async fn nostr_server(
 #[derive(Clone)]
 pub struct NostrMetrics {
     pub query_sub: Histogram, // response time of successful subscriptions
+    pub query_db: Histogram, // individual database query execution time
     pub write_events: Histogram, // response time of event writes
     pub sent_events: IntCounterVec, // count of events sent to clients
     pub connections: IntCounter, // count of websocket connections