Refactor how we keep track of old nodes and add dedupe.

partitions.go

@@ -25,7 +25,7 @@ type partitions struct {
 	selected        map[int]bool
 	local           map[int]bool
 	remote          map[int][]string
-	old             []map[int][]string
+	old             map[int][]string
 	numMissing      int
 	ready           chan bool
 	readyClosed     bool
@@ -45,7 +45,7 @@ func watchPartitions(zkWatcher *zkWatcher, peers *peers, db, version string, num
 		replication:   replication,
 		local:         make(map[int]bool),
 		remote:        make(map[int][]string),
-		old:           make([]map[int][]string, 1024),
+		old:           make(map[int][]string, 1024),
 		ready:         make(chan bool),
 	}
 
@@ -132,11 +132,24 @@ func (p *partitions) updateRemotePartitions(nodes []string) {
 	}
 
 	// Keep track of old peers in case zookeeper goes away.
-	if len(p.old) >= 1024 {
-		p.old = p.old[:1024]
+	for partitionId, partition := range remote {
+		newPartition := make([]string, len(partition))
+		copy(newPartition, partition)
+
+		unDedupedPartition := append(newPartition, p.old[partitionId]...)
+		found := map[string]bool{}
+
+		// Shitty dedupe, iterate though the remote peers
+		for _, node := range unDedupedPartition {
+			if !found[node] {
+				found[node] = true
+				p.old[partitionId] = append([]string{node}, p.old[partitionId]...)
+			}
+		}
+		if len(p.old[partitionId]) >= 1024 {
+			p.old[partitionId] = p.old[partitionId][:1024]
+		}
 	}
-	oldRemote := []map[int][]string{remote}
-	p.old = append(oldRemote, p.old...)
 
 	p.remote = remote
 	p.updateMissing()
@@ -241,11 +254,11 @@ func (p *partitions) getPeers(partition int) []string {
 	peers := make([]string, len(p.remote[partition]))
 	copy(peers, p.remote[partition])
 
+	oldPeers := make([]string, 1024)
+	copy(oldPeers, p.old[partition])
 	// Append old peers to peer list, in case of Zookeeper issues.
-	for _, oldPeer := range p.old {
-		peers = append(peers, oldPeer[partition]...)
-	}
-
+	peers = append(peers, oldPeers...)
+
 	return peers
 }