From 7f53737000258d0e5e88d3acdfc3d676461a3991 Mon Sep 17 00:00:00 2001
From: Michael Vines <mvines@gmail.com>
Date: Fri, 4 Oct 2019 14:18:07 -0700
Subject: [PATCH] Periodically pull from the entrypoint if it's no longer in
 Crdt (#6240)

---
 core/src/cluster_info.rs | 79 ++++++++++++++++++++++++++++++++++++----
 1 file changed, 71 insertions(+), 8 deletions(-)

diff --git a/core/src/cluster_info.rs b/core/src/cluster_info.rs
index cb8a93dfda..264ab6f585 100644
--- a/core/src/cluster_info.rs
+++ b/core/src/cluster_info.rs
@@ -826,23 +826,47 @@ impl ClusterInfo {
     }
     // If the network entrypoint hasn't been discovered yet, add it to the crds table
     fn add_entrypoint(&mut self, pulls: &mut Vec<(Pubkey, CrdsFilter, SocketAddr, CrdsValue)>) {
-        match &self.entrypoint {
-            Some(entrypoint) => {
+        let pull_from_entrypoint = if let Some(entrypoint) = &mut self.entrypoint {
+            if pulls.is_empty() {
+                // Nobody else to pull from, try the entrypoint
+                true
+            } else {
+                let now = timestamp();
+                // Only consider pulling from the entrypoint periodically to avoid spamming it
+                if timestamp() - entrypoint.wallclock <= CRDS_GOSSIP_PULL_CRDS_TIMEOUT_MS / 2 {
+                    false
+                } else {
+                    entrypoint.wallclock = now;
+                    let found_entrypoint = self.gossip.crds.table.iter().any(|(_, v)| {
+                        v.value
+                            .contact_info()
+                            .map(|ci| ci.gossip == entrypoint.gossip)
+                            .unwrap_or(false)
+                    });
+                    !found_entrypoint
+                }
+            }
+        } else {
+            false
+        };
+
+        if pull_from_entrypoint {
+            if let Some(entrypoint) = &self.entrypoint {
                 let self_info = self
                     .gossip
                     .crds
                     .lookup(&CrdsValueLabel::ContactInfo(self.id()))
                     .unwrap_or_else(|| panic!("self_id invalid {}", self.id()));
 
-                self.gossip
+                return self
+                    .gossip
                     .pull
                     .build_crds_filters(&self.gossip.crds, Self::max_bloom_size())
                     .into_iter()
                     .for_each(|filter| {
                         pulls.push((entrypoint.id, filter, entrypoint.gossip, self_info.clone()))
-                    })
+                    });
             }
-            None => (),
         }
     }
 
@@ -910,9 +934,7 @@ impl ClusterInfo {
             })
             .flatten()
             .collect();
-        if pulls.is_empty() {
-            self.add_entrypoint(&mut pulls);
-        }
+        self.add_entrypoint(&mut pulls);
         pulls
             .into_iter()
             .map(|(peer, filter, gossip, self_info)| {
@@ -2430,4 +2452,45 @@ mod tests {
         assert_eq!(peers_and_stakes[0].0, 10);
         assert_eq!(peers_and_stakes[1].0, 1);
     }
+
+    #[test]
+    fn test_pull_from_entrypoint_if_not_present() {
+        let node_keypair = Arc::new(Keypair::new());
+        let mut cluster_info = ClusterInfo::new(
+            ContactInfo::new_localhost(&node_keypair.pubkey(), timestamp()),
+            node_keypair,
+        );
+        let entrypoint_pubkey = Pubkey::new_rand();
+        let mut entrypoint = ContactInfo::new_localhost(&entrypoint_pubkey, timestamp());
+        entrypoint.gossip = socketaddr!("127.0.0.2:1234");
+        cluster_info.set_entrypoint(entrypoint.clone());
+
+        let mut stakes = HashMap::new();
+
+        let other_node_pubkey = Pubkey::new_rand();
+        let other_node = ContactInfo::new_localhost(&other_node_pubkey, timestamp());
+        assert_ne!(other_node.gossip, entrypoint.gossip);
+        cluster_info.insert_info(other_node.clone());
+        stakes.insert(other_node_pubkey, 10);
+
+        // Pull request 1:  `other_node` is present but `entrypoint` was just added (so it has a
+        // fresh timestamp).  There should only be one pull request to `other_node`
+        let pulls = cluster_info.new_pull_requests(&stakes);
+        assert_eq!(1, pulls.len() as u64);
+        assert_eq!(pulls.get(0).unwrap().0, other_node.gossip);
+
+        // Pull request 2: pretend it's been a while since we've pulled from `entrypoint`.  There should
+        // now be two pull requests
+        cluster_info.entrypoint.as_mut().unwrap().wallclock = 0;
+        let pulls = cluster_info.new_pull_requests(&stakes);
+        assert_eq!(2, pulls.len() as u64);
+        assert_eq!(pulls.get(0).unwrap().0, other_node.gossip);
+        assert_eq!(pulls.get(1).unwrap().0, entrypoint.gossip);
+
+        // Pull request 3:  `other_node` is present and `entrypoint` was just pulled from.  There should
+        // only be one pull request to `other_node`
+        let pulls = cluster_info.new_pull_requests(&stakes);
+        assert_eq!(1, pulls.len() as u64);
+        assert_eq!(pulls.get(0).unwrap().0, other_node.gossip);
+    }
 }