implement dynamic cache sizeing for recursor

With this commit, the number of (packet)cache entries can be changed at runtime, although the effect may not be immediate in case of shrinking the cache.

diff --git a/pdns/pdns_recursor.cc b/pdns/pdns_recursor.cc
index f733f81e9d05777c01837f5a99beb2bd06d33580..e863614f12c715b88c3d534ea1629787471309c2 100644 (file)
--- a/pdns/pdns_recursor.cc
+++ b/pdns/pdns_recursor.cc
@@ -156,6 +156,7 @@ static bool g_useOneSocketPerThread;
 static bool g_gettagNeedsEDNSOptions{false};
 static time_t g_statisticsInterval;
 static bool g_useIncomingECS;
+std::atomic<uint32_t> g_maxCacheEntries, g_maxPacketCacheEntries;
 
 RecursorControlChannel s_rcc; // only active in thread 0
 RecursorStats g_stats;
@@ -2080,10 +2081,10 @@ static void houseKeeping(void *)
     if(now.tv_sec - last_prune > (time_t)(5 + t_id)) {
       DTime dt;
       dt.setTimeval(now);
-      t_RC->doPrune(); // this function is local to a thread, so fine anyhow
-      t_packetCache->doPruneTo(::arg().asNum("max-packetcache-entries") / g_numWorkerThreads);
+      t_RC->doPrune(g_maxCacheEntries / g_numThreads); // this function is local to a thread, so fine anyhow
+      t_packetCache->doPruneTo(g_maxPacketCacheEntries / g_numWorkerThreads);
 
-      SyncRes::pruneNegCache(::arg().asNum("max-cache-entries") / (g_numWorkerThreads * 10));
+      SyncRes::pruneNegCache(g_maxCacheEntries / (g_numWorkerThreads * 10));
 
       if(!((cleanCounter++)%40)) {  // this is a full scan!
        time_t limit=now.tv_sec-300;
@@ -2817,6 +2818,9 @@ static int serviceMain(int argc, char*argv[])
   g_dnssecLogBogus = ::arg().mustDo("dnssec-log-bogus");
   g_maxNSEC3Iterations = ::arg().asNum("nsec3-max-iterations");
 
+  g_maxCacheEntries = ::arg().asNum("max-cache-entries");
+  g_maxPacketCacheEntries = ::arg().asNum("max-packetcache-entries");
+  
   try {
     loadRecursorLuaConfig(::arg()["lua-config-file"], ::arg().mustDo("daemon"));
   }

diff --git a/pdns/rec_channel_rec.cc b/pdns/rec_channel_rec.cc
index 269dbe649e743808ce9507507cc70984ba711aea..e722f202dd3e2c7327660a17e46545ac7b9eb56c 100644 (file)
--- a/pdns/rec_channel_rec.cc
+++ b/pdns/rec_channel_rec.cc
@@ -612,6 +612,24 @@ string setMinimumTTL(T begin, T end)
   return "New minimum TTL: " + std::to_string(SyncRes::s_minimumTTL) + "\n";
 }
 
+template<typename T>
+string setMaxCacheEntries(T begin, T end)
+{
+  if(end-begin != 1) 
+    return "Need to supply new cache size\n";
+  g_maxCacheEntries = pdns_stou(*begin);
+  return "New minimum TTL: " + std::to_string(g_maxCacheEntries) + "\n";
+}
+
+template<typename T>
+string setMaxPacketCacheEntries(T begin, T end)
+{
+  if(end-begin != 1) 
+    return "Need to supply new packet cache size\n";
+  g_maxPacketCacheEntries = pdns_stou(*begin);
+  return "New minimum TTL: " + std::to_string(g_maxPacketCacheEntries) + "\n";
+}
+
 
 static uint64_t getSysTimeMsec()
 {
@@ -1205,6 +1223,8 @@ string RecursorControlParser::getAnswer(const string& question, RecursorControlP
 "reload-lua-script [filename]     (re)load Lua script\n"
 "reload-lua-config [filename]     (re)load Lua configuration file\n"
 "reload-zones                     reload all auth and forward zones\n"
+"set-max-cache-entries value      set new maximum cache size"
+"set-max-packetcache-entries val  set new maximum packet cache size"      
 "set-minimum-ttl value            set minimum-ttl-override\n"
 "set-carbon-server                set a carbon server for telemetry\n"
 "set-dnssec-log-bogus SETTING     enable (SETTING=yes) or disable (SETTING=no) logging of DNSSEC validation failures\n"
@@ -1352,6 +1372,13 @@ string RecursorControlParser::getAnswer(const string& question, RecursorControlP
     return reloadAuthAndForwards();
   }
 
+  if(cmd=="set-max-cache-entries") {
+    return setMaxCacheEntries(begin, end);
+  }
+  if(cmd=="set-max-packetcache-entries") {
+    return setMaxPacketCacheEntries(begin, end);
+  }
+  
   if(cmd=="set-minimum-ttl") {
     return setMinimumTTL(begin, end);
   }

diff --git a/pdns/recursor_cache.cc b/pdns/recursor_cache.cc
index 2b6e9010b52fbf8772f1bb6d57455952d4ac902d..d3245420fb1d81014a0278fa25a6998fe1862714 100644 (file)
--- a/pdns/recursor_cache.cc
+++ b/pdns/recursor_cache.cc
@@ -484,8 +484,3 @@ void MemRecursorCache::doPrune(unsigned int keep)
   pruneCollection(*this, d_cache, keep);
 }
 
-void MemRecursorCache::doPrune(void)
-{
-  unsigned int maxCached=::arg().asNum("max-cache-entries") / g_numThreads;
-  doPrune(maxCached);
-}

diff --git a/pdns/recursor_cache.hh b/pdns/recursor_cache.hh
index ca9cf4a982c3469e8d48269f8a4c108a4cb0186f..9f53ca5724c91a432980d28f4232f1017076189d 100644 (file)
--- a/pdns/recursor_cache.hh
+++ b/pdns/recursor_cache.hh
@@ -61,7 +61,6 @@ public:
 
   void replace(time_t, const DNSName &qname, const QType& qt,  const vector<DNSRecord>& content, const vector<shared_ptr<RRSIGRecordContent>>& signatures, const std::vector<std::shared_ptr<DNSRecord>>& authorityRecs, bool auth, boost::optional<Netmask> ednsmask=boost::none, vState state=Indeterminate);
 
-  void doPrune(void);
   void doPrune(unsigned int keep);
   uint64_t doDump(int fd);
 

diff --git a/pdns/recursordist/docs/manpages/rec_control.rst b/pdns/recursordist/docs/manpages/rec_control.rst
index 352b5d577c2fae1d96ca9822bba45e162840662e..0db7b10c85f9af5e9ac84598092c987114827422 100644 (file)
--- a/pdns/recursordist/docs/manpages/rec_control.rst
+++ b/pdns/recursordist/docs/manpages/rec_control.rst
@@ -150,6 +150,16 @@ set-dnssec-log-bogus *SETTING*
     DNSSEC validation failures and to 'no' or 'off' to disable logging these
     failures.
 
+set-max-cache-entries *NUM*
+    Change the maximum number of entries in the DNS cache.  If reduced, the
+    cache size will start shrinking to this number as part of the normal
+    cache purging process, which might take a while.
+
+set-max-packetcache-entries *NUM*
+    Change the maximum number of entries in the packet cache.  If reduced, the
+    cache size will start shrinking to this number as part of the normal
+    cache purging process, which might take a while.
+
 set-minimum-ttl *NUM*
     Set minimum-ttl-override to *NUM*.
 

diff --git a/pdns/syncres.hh b/pdns/syncres.hh
index 980650f6d31d306b49ebb27da6392523564a8e63..fddfb9721a2420f09243053ed2557a23e49f5a13 100644 (file)
--- a/pdns/syncres.hh
+++ b/pdns/syncres.hh
@@ -949,6 +949,7 @@ void parseACLs();
 extern RecursorStats g_stats;
 extern unsigned int g_numThreads;
 extern uint16_t g_outgoingEDNSBufsize;
+extern std::atomic<uint32_t> g_maxCacheEntries, g_maxPacketCacheEntries;
 
 
 std::string reloadAuthAndForwards();