Allow setting maxOustanding and maxTCPClientThreads in configuration

This commit adds the setMaxTCPClientThreads() and
setMaxUDPOutstanding() directives.
These controls, respectively, the maximum number of TCP threads
handling client connections and the maximum number of oustanding
UDP queries to a given backend server.
setMaxUDPOutstanding() is only usable at configuration-time, and
not at runtime.

diff --git a/pdns/README-dnsdist.md b/pdns/README-dnsdist.md
index 0bf1b8b52bf1ca7c47bb02a4e6d36a004e6ae0fb..b5366c397ab878b0f4196a2175a1b1cf185ab882 100644 (file)
--- a/pdns/README-dnsdist.md
+++ b/pdns/README-dnsdist.md
@@ -671,6 +671,11 @@ instantiate a server with additional parameters
      * newSuffixMatchNode(): returns a new SuffixMatchNode
      * member `check(DNSName)`: returns true if DNSName is matched by this group
      * member `add(DNSName)`: add this DNSName to the node
+ * Tuning related:
+   * setTCPRecvTimeout(n): set the read timeout on TCP connections from the client, in seconds.
+   * setTCPSendTimeout(n): set the write timeout on TCP connections from the client, in seconds.
+   * setMaxTCPClientThreads(n): set the maximum of TCP client threads, handling TCP connections.
+   * setMaxUDPOutstanding(n): set the maximum number of outstanding UDP queries to a given backend server. This can only be set at configuration time.
 
 All hooks
 ---------

diff --git a/pdns/dnsdist-lua.cc b/pdns/dnsdist-lua.cc
index 0b99313424547f7122bccd0768587cec35b5eec2..edc1ea216f6dfae816e242129641c47419a9a677 100644 (file)
--- a/pdns/dnsdist-lua.cc
+++ b/pdns/dnsdist-lua.cc
@@ -897,6 +897,16 @@ vector<std::function<void(void)>> setupLua(bool client, const std::string& confi
 
   g_lua.writeFunction("setTCPSendTimeout", [](int timeout) { g_tcpSendTimeout=timeout; });
 
+  g_lua.writeFunction("setMaxUDPOutstanding", [](uint16_t max) {
+      if (!g_configurationDone) {
+        g_maxOutstanding = max;
+      } else {
+        g_outputBuffer="Max UDP outstanding cannot be altered at runtime!\n";
+      }
+    });
+
+  g_lua.writeFunction("setMaxTCPClientThreads", [](uint64_t max) { g_maxTCPClientThreads = max; });
+
   g_lua.writeFunction("dumpStats", [] {
       vector<string> leftcolumn, rightcolumn;
 

diff --git a/pdns/dnsdist.cc b/pdns/dnsdist.cc
index e19035d631926e0b47e8af4ac289ee39d15715bc..4dd205a59d3316408b009ea7d5709db4cbaf6d7d 100644 (file)
--- a/pdns/dnsdist.cc
+++ b/pdns/dnsdist.cc
@@ -654,6 +654,8 @@ catch(...)
   return false;
 }
 
+std::atomic<uint64_t> g_maxTCPClientThreads{10};
+
 void* maintThread()
 {
   int interval = 1;
@@ -661,7 +663,7 @@ void* maintThread()
   for(;;) {
     sleep(interval);
 
-    if(g_tcpclientthreads.d_queued > 1 && g_tcpclientthreads.d_numthreads < 10)
+    if(g_tcpclientthreads.d_queued > 1 && g_tcpclientthreads.d_numthreads < g_maxTCPClientThreads)
       g_tcpclientthreads.addTCPClientThread();
 
     for(auto& dss : g_dstates.getCopy()) { // this points to the actual shared_ptrs!
@@ -1053,7 +1055,8 @@ char* my_generator(const char* text, int state)
   vector<string> words{"showRules()", "shutdown()", "rmRule(", "mvRule(", "addACL(", "addLocal(", "setServerPolicy(", "setServerPolicyLua(",
       "newServer(", "rmServer(", "showServers()", "show(", "newDNSName(", "newSuffixMatchNode(", "controlSocket(", "topClients(", "showResponseLatency()", 
       "newQPSLimiter(", "makeKey()", "setKey(", "testCrypto()", "addAnyTCRule()", "showServerPolicy()", "setACL(", "showACL()", "addDomainBlock(", 
-      "addPoolRule(", "addQPSLimit(", "topResponses(", "topQueries(", "topRule()", "setDNSSECPool(", "addDelay("};
+      "addPoolRule(", "addQPSLimit(", "topResponses(", "topQueries(", "topRule()", "setDNSSECPool(", "addDelay(",
+      "setMaxUDPOutstanding(", "setMaxTCPClientThreads("};
   static int s_counter=0;
   int counter=0;
   if(!state)
@@ -1096,6 +1099,7 @@ struct
   string gid;
 } g_cmdLine;
 
+std::atomic<bool> g_configurationDone{false};
 
 int main(int argc, char** argv)
 try
@@ -1244,6 +1248,8 @@ try
     g_locals.push_back({ComboAddress("127.0.0.1", 53), true});
   
 
+  g_configurationDone = true;
+
   vector<ClientState*> toLaunch;
   for(const auto& local : g_locals) {
     ClientState* cs = new ClientState;

diff --git a/pdns/dnsdist.hh b/pdns/dnsdist.hh
index 54e56e64fc994c0853213a2a3ff47c8268e8f8eb..537d34ed6225196410ce1879baccb495dfda578f 100644 (file)
--- a/pdns/dnsdist.hh
+++ b/pdns/dnsdist.hh
@@ -361,6 +361,9 @@ extern std::string g_key; // in theory needs locking
 extern bool g_truncateTC;
 extern int g_tcpRecvTimeout;
 extern int g_tcpSendTimeout;
+extern uint16_t g_maxOutstanding;
+extern std::atomic<bool> g_configurationDone;
+extern std::atomic<uint64_t> g_maxTCPClientThreads;
 struct dnsheader;
 
 void controlThread(int fd, ComboAddress local);