From 253861ebd39f309f19fe3e3bcd41f3b7120a8814 Mon Sep 17 00:00:00 2001
From: Arceliar <Arceliar@users.noreply.github.com>
Date: Sun, 21 Oct 2018 18:15:04 -0500
Subject: [PATCH] reverse dht ownership order from predecessor to successor,
 this plays nicer with the default 0 bits in unknown node IDs

---
 src/yggdrasil/dht.go    | 41 ++++++++---------------------------------
 src/yggdrasil/search.go |  5 +++--
 2 files changed, 11 insertions(+), 35 deletions(-)

diff --git a/src/yggdrasil/dht.go b/src/yggdrasil/dht.go
index bbf08ca8..398cdb74 100644
--- a/src/yggdrasil/dht.go
+++ b/src/yggdrasil/dht.go
@@ -11,7 +11,7 @@ import (
 	"time"
 )
 
-const dht_lookup_size = 4
+const dht_lookup_size = 16
 
 // dhtInfo represents everything we know about a node in the DHT.
 // This includes its key, a cache of it's NodeID, coords, and timing/ping related info for deciding who/when to ping nodes for maintenance.
@@ -75,43 +75,16 @@ func (t *dht) reset() {
 }
 
 // Does a DHT lookup and returns up to dht_lookup_size results
-// If allowWorse = true, begins with best know predecessor for ID and works backwards, even if these nodes are worse predecessors than we are, to be used when intializing searches
-// If allowWorse = false, begins with the best known successor for ID and works backwards (next is predecessor, etc, inclusive of the ID if it's a known node)
 func (t *dht) lookup(nodeID *NodeID, everything bool) []*dhtInfo {
 	results := make([]*dhtInfo, 0, len(t.table))
 	for _, info := range t.table {
 		results = append(results, info)
 	}
 	sort.SliceStable(results, func(i, j int) bool {
-		return dht_ordered(results[j].getNodeID(), results[i].getNodeID(), nodeID)
+		return dht_ordered(nodeID, results[i].getNodeID(), results[j].getNodeID())
 	})
 	if len(results) > dht_lookup_size {
-		//results = results[:dht_lookup_size] //FIXME debug
-	}
-	return results
-}
-
-func (t *dht) old_lookup(nodeID *NodeID, allowWorse bool) []*dhtInfo {
-	var results []*dhtInfo
-	var successor *dhtInfo
-	sTarget := t.nodeID.next()
-	for infoID, info := range t.table {
-		if true || allowWorse || dht_ordered(&t.nodeID, &infoID, nodeID) {
-			results = append(results, info)
-		} else {
-			if successor == nil || dht_ordered(&sTarget, &infoID, successor.getNodeID()) {
-				successor = info
-			}
-		}
-	}
-	sort.SliceStable(results, func(i, j int) bool {
-		return dht_ordered(results[j].getNodeID(), results[i].getNodeID(), nodeID)
-	})
-	if successor != nil {
-		results = append([]*dhtInfo{successor}, results...)
-	}
-	if len(results) > dht_lookup_size {
-		//results = results[:dht_lookup_size] //FIXME debug
+		results = results[:dht_lookup_size]
 	}
 	return results
 }
@@ -350,8 +323,9 @@ func (t *dht) getImportant() []*dhtInfo {
 	}
 	// Sort them by increasing order in distance along the ring
 	sort.SliceStable(infos, func(i, j int) bool {
-		// Sort in order of successors
-		return dht_ordered(&t.nodeID, infos[i].getNodeID(), infos[j].getNodeID())
+		// Sort in order of predecessors (!), reverse from chord normal, becuase it plays nicer with zero bits for unknown parts of target addresses
+		return dht_ordered(infos[j].getNodeID(), infos[i].getNodeID(), &t.nodeID)
+		//return dht_ordered(&t.nodeID, infos[i].getNodeID(), infos[j].getNodeID())
 	})
 	// Keep the ones that are no further than the closest seen so far
 	minDist := ^uint64(0)
@@ -377,7 +351,8 @@ func (t *dht) isImportant(ninfo *dhtInfo, important []*dhtInfo) bool {
 		if dist < minDist {
 			minDist = dist
 		}
-		if dht_ordered(&t.nodeID, ninfo.getNodeID(), info.getNodeID()) && ndist <= minDist {
+		//if dht_ordered(&t.nodeID, ninfo.getNodeID(), info.getNodeID()) && ndist <= minDist {
+		if dht_ordered(info.getNodeID(), ninfo.getNodeID(), &t.nodeID) && ndist <= minDist {
 			// This node is at least as close in both key space and tree space
 			return true
 		}
diff --git a/src/yggdrasil/search.go b/src/yggdrasil/search.go
index d27b8c5a..b4bbb123 100644
--- a/src/yggdrasil/search.go
+++ b/src/yggdrasil/search.go
@@ -113,11 +113,12 @@ func (s *searches) addToSearch(sinfo *searchInfo, res *dhtRes) {
 	sort.SliceStable(sinfo.toVisit, func(i, j int) bool {
 		// Should return true if i is closer to the destination than j
 		// FIXME for some reason it works better backwards, why?!
-		return dht_ordered(sinfo.toVisit[j].getNodeID(), sinfo.toVisit[i].getNodeID(), &res.Dest)
+		//return dht_ordered(sinfo.toVisit[j].getNodeID(), sinfo.toVisit[i].getNodeID(), &res.Dest)
+		return dht_ordered(&res.Dest, sinfo.toVisit[i].getNodeID(), sinfo.toVisit[j].getNodeID())
 	})
 	// Truncate to some maximum size
 	if len(sinfo.toVisit) > search_MAX_SEARCH_SIZE {
-		//sinfo.toVisit = sinfo.toVisit[:search_MAX_SEARCH_SIZE]
+		sinfo.toVisit = sinfo.toVisit[:search_MAX_SEARCH_SIZE]
 	}
 }