From eb7fae646a6080fe1e1a913b65f5c01d619d373f Mon Sep 17 00:00:00 2001
From: Otto Moerbeek <otto.moerbeek@open-xchange.com>
Date: Fri, 12 Jun 2020 12:24:26 +0200
Subject: [PATCH] Fix three shared cache issues:

- Only prime share cache once on startup

- Cache pruning could go into an infinite loop if not enough expired
entries could be pruned.

- Handler thread isn't run very often, but now the record cache
pruning is done by it, so increase frequency of the housekeeping
call for the handler thread.
---
 pdns/cachecleaner.hh  |  5 +++--
 pdns/pdns_recursor.cc | 10 +++++++---
 2 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/pdns/cachecleaner.hh b/pdns/cachecleaner.hh
index 18e5ea1474..7d42274bff 100644
--- a/pdns/cachecleaner.hh
+++ b/pdns/cachecleaner.hh
@@ -190,7 +190,7 @@ template <typename S, typename C, typename T> uint64_t pruneMutexCollectionsVect
 
   toTrim -= totErased;
 
-  while (toTrim > 0) {
+    while (true) {
     size_t pershard = toTrim / maps_size + 1;
     for (auto& mc : maps) {
       const typename C::lock l(mc);
@@ -204,11 +204,12 @@ template <typename S, typename C, typename T> uint64_t pruneMutexCollectionsVect
         totErased++;
         toTrim--;
         if (toTrim == 0) {
-          break;
+          return totErased;
         }
       }
     }
   }
+  // Not reached
   return totErased;
 }
 
diff --git a/pdns/pdns_recursor.cc b/pdns/pdns_recursor.cc
index 8e51e26350..f99dd5af58 100644
--- a/pdns/pdns_recursor.cc
+++ b/pdns/pdns_recursor.cc
@@ -4662,11 +4662,13 @@ try
   t_allowFrom = g_initialAllowFrom;
   t_udpclientsocks = std::unique_ptr<UDPClientSocks>(new UDPClientSocks());
   t_tcpClientCounts = std::unique_ptr<tcpClientCounts_t>(new tcpClientCounts_t());
-  primeHints();
+  if (threadInfo.isHandler) {
+    primeHints();
+    g_log<<Logger::Warning<<"Done priming cache with root hints"<<endl;
+  }
 
   t_packetCache = std::unique_ptr<RecursorPacketCache>(new RecursorPacketCache());
 
-  g_log<<Logger::Warning<<"Done priming cache with root hints"<<endl;
 
 #ifdef NOD_ENABLED
   if (threadInfo.isWorker)
@@ -4784,7 +4786,9 @@ try
   while (!RecursorControlChannel::stop) {
     while(MT->schedule(&g_now)); // MTasker letting the mthreads do their thing
 
-    if(!(counter%500)) {
+    // Use primes, it avoid not being scheduled in cases where the counter has a regular pattern.
+    // We want to call handler thread often, it gets scheduled about 2 times per second
+    if ((threadInfo.isHandler && counter % 11 == 0) || counter % 499 == 0) {
       MT->makeThread(houseKeeping, 0);
     }
 
-- 
2.47.2