From: Remi Gacogne <remi.gacogne@powerdns.com>
Date: Fri, 17 Aug 2018 09:03:38 +0000 (+0200)
Subject: rec: Without reuseport, every listener thread watches all TCP sockets
X-Git-Tag: dnsdist-1.3.3~153^2
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=refs%2Fpull%2F6850%2Fhead;p=thirdparty%2Fpdns.git

rec: Without reuseport, every listener thread watches all TCP sockets

So we simply add all TCP sockets to the list watched by these threads
instead of using a separate variable, to make it easier to read later
on.
---

diff --git a/pdns/pdns_recursor.cc b/pdns/pdns_recursor.cc
index 0026d13abf..ed29b5f7b1 100644
--- a/pdns/pdns_recursor.cc
+++ b/pdns/pdns_recursor.cc
@@ -144,7 +144,7 @@ struct RecThreadInfo
   };
 
   /* FD corresponding to TCP sockets this thread is listening
-     on if reuseport is set. Otherwise g_tcpSockets is used instead.
+     on.
      These FDs are also in deferredAdds when we have one
      socket per listener, and in g_deferredAdds instead. */
   std::set<int> tcpSockets;
@@ -169,7 +169,6 @@ struct RecThreadInfo
 static std::vector<RecThreadInfo> s_threadInfos;
 /* without reuseport, all listeners share the same sockets */
 static deferredAdd_t g_deferredAdds;
-static std::set<int> g_tcpSockets;
 
 typedef vector<int> tcpListenSockets_t;
 typedef map<int, ComboAddress> listenSocketsAddresses_t; // is shared across all threads right now
@@ -3512,10 +3511,26 @@ static int serviceMain(int argc, char*argv[])
     }
   }
   else {
+    std::set<int> tcpSockets;
     /* we don't have reuseport so we can only open one socket per
        listening addr:port and everyone will listen on it */
     makeUDPServerSockets(g_deferredAdds);
-    makeTCPServerSockets(g_deferredAdds, g_tcpSockets);
+    makeTCPServerSockets(g_deferredAdds, tcpSockets);
+
+    /* every listener (so distributor if g_weDistributeQueries, workers otherwise)
+       needs to listen to the shared sockets */
+    if (g_weDistributeQueries) {
+      /* first thread is the handler, then distributors */
+      for (unsigned int threadId = 1; threadId <= g_numDistributorThreads; threadId++) {
+        s_threadInfos.at(threadId).tcpSockets = tcpSockets;
+      }
+    }
+    else {
+      /* first thread is the handler, there is no distributor here and workers are accepting queries */
+      for (unsigned int threadId = 1; threadId <= g_numWorkerThreads; threadId++) {
+        s_threadInfos.at(threadId).tcpSockets = tcpSockets;
+      }
+    }
   }
 
 #ifdef NOD_ENABLED
@@ -3859,37 +3874,20 @@ try
 
     if(threadInfo.isListener) {
       if(listenOnTCP) {
-	if(TCPConnection::getCurrentConnections() > maxTcpClients) {  // shutdown, too many connections
-
-          if (g_reusePort) {
-            for(const auto fd : threadInfo.tcpSockets) {
-              t_fdm->removeReadFD(fd);
-            }
+        if(TCPConnection::getCurrentConnections() > maxTcpClients) {  // shutdown, too many connections
+          for(const auto fd : threadInfo.tcpSockets) {
+            t_fdm->removeReadFD(fd);
           }
-          else {
-            for(const auto fd : g_tcpSockets) {
-              t_fdm->removeReadFD(fd);
-            }
-          }
-
-	  listenOnTCP=false;
-	}
+          listenOnTCP=false;
+        }
       }
       else {
-	if(TCPConnection::getCurrentConnections() <= maxTcpClients) {  // reenable
-          if (g_reusePort) {
-            for(const auto fd : threadInfo.tcpSockets) {
-              t_fdm->addReadFD(fd, handleNewTCPQuestion);
-            }
+        if(TCPConnection::getCurrentConnections() <= maxTcpClients) {  // reenable
+          for(const auto fd : threadInfo.tcpSockets) {
+            t_fdm->addReadFD(fd, handleNewTCPQuestion);
           }
-          else {
-            for(const auto fd : g_tcpSockets) {
-              t_fdm->addReadFD(fd, handleNewTCPQuestion);
-            }
-          }
-
-	  listenOnTCP=true;
-	}
+          listenOnTCP=true;
+        }
       }
     }
   }