1 files changed, 28 insertions, 10 deletions

diff --git a/src/api/dashboard/mod.rs b/src/api/dashboard/mod.rs
index dd454ec..f0cbbfd 100644
--- a/src/api/dashboard/mod.rs
+++ b/src/api/dashboard/mod.rs
@@ -10,8 +10,9 @@
 //! themselves: they alone changing is no change, and the page counts them on.
 //!
 //! The map: the graph the member list makes (`topology::intended_graph`, as this node
-//! sees it), and the links every member measures, asked for with LINKS every
-//! `LINKS_EVERY` while anyone looks (`swarm::links`), the same answers for all clients.
+//! sees it), and the links every member measures: subscribed to with LINKS while anyone
+//! looks (renewed every `LINKS_EVERY`, ended when nobody does; `swarm::links`), so a
+//! member tells of a change as it happens; the same answers for all clients.
 
 use std::collections::{BTreeMap, BTreeSet};
 use std::convert::Infallible;
@@ -34,10 +35,14 @@ use crate::transport::Link;
 
 /// How often the snapshot is built and compared, while anyone looks.
 const TICK: Duration = Duration::from_secs(2);
-/// How often members are asked for their links, and the graph recomputed.
-const LINKS_EVERY: Duration = Duration::from_secs(10);
+/// How often the subscriptions to the members' links are renewed (each renewal is
+/// answered: a reply at least this often), and the graph recomputed; changes come in
+/// between, as they happen (`swarm::links`).
+const LINKS_EVERY: Duration = Duration::from_secs(30);
+/// How long a subscription lasts unless renewed: a node that is gone stops it.
+const LINKS_LEASE: Duration = Duration::from_secs(90);
 /// A member's links older than this are left out (it didn't answer since).
-const LINKS_KEPT_FOR: Duration = Duration::from_secs(30);
+const LINKS_KEPT_FOR: Duration = Duration::from_secs(90);
 /// The producer runs on this long after the last request for the state.
 const LINGER: Duration = Duration::from_secs(60);
 /// Members asked for their links at most, each round.
@@ -164,14 +169,27 @@ impl Hub {
             if let Some(changed) = document_changes(&mut changes) {
                 let _ = self.documents.send(Arc::new(changed.to_string()));
             }
-            {
+            let unwanted = || {
+                self.patches.receiver_count() == 0
+                    && Instant::now() >= self.control.lock_or_recover().wanted_until
+            };
+            if *self.closing.borrow() {
+                self.control.lock_or_recover().running = false;
+                return;
+            }
+            if unwanted() {
+                // Nobody looks: the members needn't tell us any more. Unless someone
+                // came meanwhile, then it goes on (and subscribes again).
+                for member in self.state.links.subscribed() {
+                    links::unsubscribe(&self.state, &member).await;
+                }
                 let mut control = self.control.lock_or_recover();
-                let unwanted =
-                    self.patches.receiver_count() == 0 && Instant::now() >= control.wanted_until;
-                if unwanted || *self.closing.borrow() {
+                if self.patches.receiver_count() == 0 && Instant::now() >= control.wanted_until {
                     control.running = false;
                     return;
                 }
+                drop(control);
+                graph_due = Instant::now();
             }
         }
     }
@@ -232,7 +250,7 @@ impl Graph {
             .take(MAX_ASKED)
         {
             let state = state.clone();
-            tokio::spawn(async move { links::ask(&state, &member).await });
+            tokio::spawn(async move { links::ask(&state, &member, LINKS_LEASE).await });
         }
     }
 }