Fix locking when downloading RIS dump files (#1177) (#1179)

This PR does not lock the 'seen' announcements while downloading new RIR dump
files. This prevented read access to the announcement during download. This
change postpones getting the write lock until after the download is
completed, so it only keeps it for the shortest possible time.

src/commons/bgp/analyser.rs

@@ -43,27 +43,36 @@ impl BgpAnalyser {
     }
 
     pub async fn update(&self) -> Result<bool, BgpAnalyserError> {
-        if let Some(loader) = &self.dump_loader {
-            let mut seen = self.seen.write().await;
-            if let Some(last_time) = seen.last_checked() {
-                if (last_time + Duration::minutes(BGP_RIS_REFRESH_MINUTES)) > Time::now() {
-                    trace!("Will not check BGP Ris Dumps until the refresh interval has passed");
-                    return Ok(false); // no need to update yet
-                }
-            }
-            let announcements = loader.download_updates().await?;
-            if seen.equivalent(&announcements) {
-                debug!("BGP Ris Dumps unchanged");
-                seen.update_checked();
-                Ok(false)
-            } else {
-                info!("Updated announcements ({}) based on BGP Ris Dumps", announcements.len());
-                seen.update(announcements);
-                Ok(true)
+        let loader = match self.dump_loader.as_ref() {
+            Some(loader) => loader,
+            None => return Ok(false)
+        };
+        if let Some(last_time) = self.seen.read().await.last_checked() {
+            if (last_time + Duration::minutes(BGP_RIS_REFRESH_MINUTES))
+                > Time::now()
+            {
+                trace!(
+                    "Will not check BGP RIS dumps until the \
+                    refresh interval has passed"
+                );
+                return Ok(false); // no need to update yet
             }
-        } else {
+        }
+        let announcements = loader.download_updates().await?;
+        let mut seen = self.seen.write().await;
+        if seen.equivalent(&announcements) {
+            debug!("BGP Ris Dumps unchanged");
+            seen.update_checked();
             Ok(false)
         }
+        else {
+            info!(
+                "Updated announcements ({}) based on BGP Ris Dumps",
+                announcements.len()
+            );
+            seen.update(announcements);
+            Ok(true)
+        }
     }
 
     pub async fn analyse(
@@ -349,10 +358,11 @@ mod tests {
     #[tokio::test]
     #[ignore]
     async fn download_ris_dumps() {
-        let bgp_ris_dump_v4_uri = "http://www.ris.ripe.net/dumps/riswhoisdump.IPv4.gz";
-        let bgp_ris_dump_v6_uri = "http://www.ris.ripe.net/dumps/riswhoisdump.IPv6.gz";
-
-        let analyser = BgpAnalyser::new(true, bgp_ris_dump_v4_uri, bgp_ris_dump_v6_uri);
+        let analyser = BgpAnalyser::new(
+            true,
+            "http://www.ris.ripe.net/dumps/riswhoisdump.IPv4.gz",
+            "http://www.ris.ripe.net/dumps/riswhoisdump.IPv6.gz",
+        );
 
         assert!(analyser.seen.read().await.is_empty());
         assert!(analyser.seen.read().await.last_checked().is_none());