udp: add statistics latencies flag, only calculate when set

TODO.md

@@ -5,7 +5,6 @@
 latency histogram
   * use SyncHistogram?
   * avoid reporting zero (send more often?)
-  * add config flag, don't calculate when turned off
   * cleaning
 
 ## Medium priority

aquatic_udp/src/common.rs

@@ -17,6 +17,12 @@ pub const MAX_PACKET_SIZE: usize = 8192;
 #[derive(Clone, Copy, Debug)]
 pub struct RequestTag(pub usize);
 
+impl RequestTag {
+    pub fn placeholder() -> Self {
+        Self(0)
+    }
+}
+
 #[derive(Debug)]
 pub struct PendingScrapeRequest {
     pub slab_key: usize,

aquatic_udp/src/config.rs

@@ -141,6 +141,8 @@ pub struct StatisticsConfig {
     pub write_html_to_file: bool,
     /// Path to save HTML file to
     pub html_file_path: PathBuf,
+    /// Report response latencies
+    pub latencies: bool,
 }
 
 impl StatisticsConfig {
@@ -156,6 +158,7 @@ impl Default for StatisticsConfig {
             print_to_stdout: false,
             write_html_to_file: false,
             html_file_path: "tmp/statistics.html".into(),
+            latencies: true,
         }
     }
 }

aquatic_udp/src/workers/socket.rs

@@ -308,7 +308,9 @@ pub fn run_socket_worker(
 
                 last_pending_scrape_cleaning = now;
             }
-            if now > last_histogram_sending + statistics_update_interval {
+            if config.statistics.latencies
+                & (now > last_histogram_sending + statistics_update_interval)
+            {
                 if let Err(err) = histogram_sender.try_send(latency_recorder.extract_histogram()) {
                     ::log::error!("Couldn't send latency data to statistics worker: {:#}", err);
                 }
@@ -345,7 +347,11 @@ fn read_requests(
     loop {
         match socket.recv_from(&mut buffer[..]) {
             Ok((amt, src)) => {
-                let request_tag = latency_recorder.request_received();
+                let request_tag = if config.statistics.latencies {
+                    latency_recorder.request_received()
+                } else {
+                    RequestTag::placeholder()
+                };
 
                 let res_request =
                     Request::from_bytes(&buffer[..amt], config.protocol.max_scrape_torrents);
@@ -580,7 +586,9 @@ fn send_response(
 
             match socket.send_to(&cursor.get_ref()[..amt], addr) {
                 Ok(amt) if config.statistics.active() => {
-                    latency_recorder.response_sent(tag);
+                    if config.statistics.latencies {
+                        latency_recorder.response_sent(tag);
+                    }
 
                     let stats = if canonical_addr_is_ipv4 {
                         &state.statistics_ipv4

aquatic_udp/src/workers/statistics.rs

@@ -171,7 +171,8 @@ struct TemplateData {
     ipv6_active: bool,
     ipv4: FormattedStatistics,
     ipv6: FormattedStatistics,
-    latency: LatencyData,
+    latencies_active: bool,
+    latencies: LatencyData,
     last_updated: String,
     peer_update_interval: String,
 }
@@ -201,7 +202,7 @@ pub fn run_statistics_worker(
     loop {
         ::std::thread::sleep(Duration::from_secs(config.statistics.interval));
 
-        let latency_data: LatencyData = histogram_receivers
+        let latency_data = histogram_receivers
             .iter()
             .filter_map(|receiver| receiver.try_recv().ok())
             .sum::<Histogram<u64>>()
@@ -215,7 +216,10 @@ pub fn run_statistics_worker(
         if config.statistics.print_to_stdout {
             println!("General:");
             println!("  access list entries: {}", state.access_list.load().len());
-            println!("  {}", latency_data);
+
+            if config.statistics.latencies {
+                println!("  {}", latency_data);
+            }
 
             if config.network.ipv4_active() {
                 println!("IPv4:");
@@ -236,7 +240,8 @@ pub fn run_statistics_worker(
                 ipv6_active: config.network.ipv6_active(),
                 ipv4: statistics_ipv4,
                 ipv6: statistics_ipv6,
-                latency: latency_data,
+                latencies_active: config.statistics.latencies,
+                latencies: latency_data,
                 last_updated: OffsetDateTime::now_utc()
                     .format(&Rfc2822)
                     .unwrap_or("(formatting error)".into()),

aquatic_udp/templates/statistics.html

@@ -20,31 +20,35 @@
         <strong>Updated:</strong> { last_updated } (UTC)
     </p>
 
+    {{ if latencies_active }}
+
     <h2>Response latencies</h2>
 
     <table>
         <tr>
             <th scope="row">Mean</th>
-            <td>{ latency.mean } ms</td>
+            <td>{ latencies.mean } ms</td>
         </tr>
         <tr>
             <th scope="row">Standard deviation</th>
-            <td>{ latency.stdev } ms</td>
+            <td>{ latencies.stdev } ms</td>
         </tr>
         <tr>
             <th scope="row">95:th percentile</th>
-            <td>{ latency.p95 } ms</td>
+            <td>{ latencies.p95 } ms</td>
         </tr>
         <tr>
             <th scope="row">99:th percentile</th>
-            <td>{ latency.p99 } ms</td>
+            <td>{ latencies.p99 } ms</td>
         </tr>
         <tr>
             <th scope="row">99.9:th percentile</th>
-            <td>{ latency.p999 } ms</td>
+            <td>{ latencies.p999 } ms</td>
         </tr>
     </table>
 
+    {{ endif }}
+
     {{ if ipv4_active }}
 
     <h2>IPv4</h2>