From 0ba58442420eb172e64ea88ddd78d02be98017be Mon Sep 17 00:00:00 2001
From: Chrysostomos Nanakos <chris@include.gr>
Date: Wed, 29 Apr 2026 17:24:14 +0300
Subject: [PATCH] fix: re-seed DHT routing table when empty

Part of https://github.com/logos-storage/logos-storage-nim/issues/1427

Signed-off-by: Chrysostomos Nanakos <chris@include.gr>
---
 storage/blockexchange/engine/discovery.nim | 33 ++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/storage/blockexchange/engine/discovery.nim b/storage/blockexchange/engine/discovery.nim
index 2d672102..ef045214 100644
--- a/storage/blockexchange/engine/discovery.nim
+++ b/storage/blockexchange/engine/discovery.nim
@@ -30,6 +30,7 @@ declareGauge(storage_inflight_discovery, "inflight discovery requests")
 const
   DefaultConcurrentDiscRequests = 10
   DefaultDiscoveryTimeout = 1.minutes
+  RoutingTableHealthInterval = 30.seconds
 
 type DiscoveryEngine* = ref object of RootObj
   localStore*: BlockStore # Local block store for this instance
@@ -79,6 +80,33 @@ proc discoveryTaskLoop(b: DiscoveryEngine) {.async: (raises: []).} =
 
   info "Exiting discovery task runner"
 
+proc routingTableHealthLoop(b: DiscoveryEngine) {.async: (raises: []).} =
+  ## Re-seed the DHT routing table from the configured bootstrap records when
+  ## it goes empty.
+  try:
+    while b.discEngineRunning:
+      await sleepAsync(RoutingTableHealthInterval)
+
+      if b.discovery.protocol.nodesDiscovered() != 0:
+        continue
+
+      warn "Routing table empty, re-seeding from bootstrap records",
+        bootstrap = b.discovery.protocol.bootstrapRecords.len
+
+      b.discovery.protocol.seedTable()
+
+      try:
+        await b.discovery.protocol.populateTable()
+        debug "Routing table re-populated",
+          total = b.discovery.protocol.nodesDiscovered()
+      except CancelledError:
+        return
+      except CatchableError as exc:
+        warn "Failed to re-populate routing table", exc = exc.msg
+  except CancelledError:
+    trace "Routing table health loop cancelled"
+    return
+
 proc queueFindBlocksReq*(b: DiscoveryEngine, cids: seq[Cid]) =
   for cid in cids:
     if cid notin b.discoveryQueue:
@@ -102,6 +130,11 @@ proc start*(b: DiscoveryEngine) {.async: (raises: []).} =
     let fut = b.discoveryTaskLoop()
     b.trackedFutures.track(fut)
 
+  if not b.discovery.protocol.isNil and b.discovery.protocol.bootstrapRecords.len > 0:
+    b.trackedFutures.track(b.routingTableHealthLoop())
+  else:
+    trace "No bootstrap records configured, routing table health watchdog disabled"
+
   trace "Discovery engine started"
 
 proc stop*(b: DiscoveryEngine) {.async: (raises: []).} =