Optimize LLMQs sending of sig shares

src/llmq/quorums_signing_shares.cpp

@@ -896,6 +896,8 @@ void CSigSharesManager::SendMessages()
         CollectSigSharesToAnnounce(sigSharesToAnnounce);
     }
 
+    bool didSend = false;
+
     g_connman->ForEachNode([&](CNode* pnode) {
         CNetMsgMaker msgMaker(pnode->GetSendVersion());
 
@@ -905,7 +907,8 @@ void CSigSharesManager::SendMessages()
                 assert(p.second.CountSet() != 0);
                 LogPrint("llmq", "CSigSharesManager::SendMessages -- QGETSIGSHARES inv={%s}, node=%d\n",
                          p.second.ToString(), pnode->id);
-                g_connman->PushMessage(pnode, msgMaker.Make(NetMsgType::QGETSIGSHARES, p.second));
+                g_connman->PushMessage(pnode, msgMaker.Make(NetMsgType::QGETSIGSHARES, p.second), false);
+                didSend = true;
             }
         }
 
@@ -915,7 +918,8 @@ void CSigSharesManager::SendMessages()
                 assert(!p.second.sigShares.empty());
                 LogPrint("llmq", "CSigSharesManager::SendMessages -- QBSIGSHARES inv={%s}, node=%d\n",
                          p.second.ToInv().ToString(), pnode->id);
-                g_connman->PushMessage(pnode, msgMaker.Make(NetMsgType::QBSIGSHARES, p.second));
+                g_connman->PushMessage(pnode, msgMaker.Make(NetMsgType::QBSIGSHARES, p.second), false);
+                didSend = true;
             }
         }
 
@@ -925,12 +929,17 @@ void CSigSharesManager::SendMessages()
                 assert(p.second.CountSet() != 0);
                 LogPrint("llmq", "CSigSharesManager::SendMessages -- QSIGSHARESINV inv={%s}, node=%d\n",
                          p.second.ToString(), pnode->id);
-                g_connman->PushMessage(pnode, msgMaker.Make(NetMsgType::QSIGSHARESINV, p.second));
+                g_connman->PushMessage(pnode, msgMaker.Make(NetMsgType::QSIGSHARESINV, p.second), false);
+                didSend = true;
             }
         }
 
         return true;
     });
+
+    if (didSend) {
+        g_connman->WakeSelect();
+    }
 }
 
 void CSigSharesManager::Cleanup()

src/net.cpp

@@ -1210,6 +1210,18 @@ void CConnman::ThreadSocketHandler()
         SOCKET hSocketMax = 0;
         bool have_fds = false;
 
+#ifndef WIN32
+        // We add a pipe to the read set so that the select() call can be woken up from the outside
+        // This is done when data is available for sending and at the same time optimistic sending was disabled
+        // when pushing the data.
+        // This is currently only implemented for POSIX compliant systems. This means that Windows will fall back to
+        // timing out after 50ms and then trying to send. This is ok as we assume that heavy-load daemons are usually
+        // run on Linux and friends.
+        FD_SET(wakeupPipe[0], &fdsetRecv);
+        hSocketMax = std::max(hSocketMax, (SOCKET)wakeupPipe[0]);
+        have_fds = true;
+#endif
+
         BOOST_FOREACH(const ListenSocket& hListenSocket, vhListenSocket) {
             FD_SET(hListenSocket.socket, &fdsetRecv);
             hSocketMax = std::max(hSocketMax, hListenSocket.socket);
@@ -1276,6 +1288,20 @@ void CConnman::ThreadSocketHandler()
                 return;
         }
 
+#ifndef WIN32
+        // drain the wakeup pipe
+        if (FD_ISSET(wakeupPipe[0], &fdsetRecv)) {
+            LogPrint("net", "woke up select()\n");
+            char buf[128];
+            while (true) {
+                int r = read(wakeupPipe[0], buf, sizeof(buf));
+                if (r <= 0) {
+                    break;
+                }
+            }
+        }
+#endif
+
         //
         // Accept new connections
         //
@@ -1426,6 +1452,21 @@ void CConnman::WakeMessageHandler()
     condMsgProc.notify_one();
 }
 
+void CConnman::WakeSelect()
+{
+#ifndef WIN32
+    if (wakeupPipe[1] == -1) {
+        return;
+    }
+
+    LogPrint("net", "waking up select()\n");
+
+    char buf[1];
+    if (write(wakeupPipe[1], buf, 1) != 1) {
+        LogPrint("net", "write to wakeupPipe failed\n");
+    }
+#endif
+}
 
 
 
@@ -2387,6 +2428,22 @@ bool CConnman::Start(CScheduler& scheduler, std::string& strNodeError, Options c
         fMsgProcWake = false;
     }
 
+#ifndef WIN32
+    if (pipe(wakeupPipe) != 0) {
+        wakeupPipe[0] = wakeupPipe[1] = -1;
+        LogPrint("net", "pipe() for wakeupPipe failed\n");
+    } else {
+        int fFlags = fcntl(wakeupPipe[0], F_GETFL, 0);
+        if (fcntl(wakeupPipe[0], F_SETFL, fFlags | O_NONBLOCK) == -1) {
+            LogPrint("net", "fcntl for O_NONBLOCK on wakeupPipe failed\n");
+        }
+        fFlags = fcntl(wakeupPipe[1], F_GETFL, 0);
+        if (fcntl(wakeupPipe[1], F_SETFL, fFlags | O_NONBLOCK) == -1) {
+            LogPrint("net", "fcntl for O_NONBLOCK on wakeupPipe failed\n");
+        }
+    }
+#endif
+
     // Send and receive from sockets, accept connections
     threadSocketHandler = std::thread(&TraceThread<std::function<void()> >, "net", std::function<void()>(std::bind(&CConnman::ThreadSocketHandler, this)));
 
@@ -2512,6 +2569,12 @@ void CConnman::Stop()
     semAddnode = NULL;
     delete semMasternodeOutbound;
     semMasternodeOutbound = NULL;
+
+#ifndef WIN32
+    if (wakeupPipe[0] != -1) close(wakeupPipe[0]);
+    if (wakeupPipe[1] != -1) close(wakeupPipe[1]);
+    wakeupPipe[0] = wakeupPipe[1] = -1;
+#endif
 }
 
 void CConnman::DeleteNode(CNode* pnode)
@@ -3054,7 +3117,7 @@ bool CConnman::NodeFullyConnected(const CNode* pnode)
     return pnode && pnode->fSuccessfullyConnected && !pnode->fDisconnect;
 }
 
-void CConnman::PushMessage(CNode* pnode, CSerializedNetMsg&& msg)
+void CConnman::PushMessage(CNode* pnode, CSerializedNetMsg&& msg, bool allowOptimisticSend)
 {
     size_t nMessageSize = msg.data.size();
     size_t nTotalSize = nMessageSize + CMessageHeader::HEADER_SIZE;
@@ -3071,7 +3134,7 @@ void CConnman::PushMessage(CNode* pnode, CSerializedNetMsg&& msg)
     size_t nBytesSent = 0;
     {
         LOCK(pnode->cs_vSend);
-        bool optimisticSend(pnode->vSendMsg.empty());
+        bool optimisticSend(allowOptimisticSend && pnode->vSendMsg.empty());
 
         //log total amount of bytes per command
         pnode->mapSendBytesPerMsgCmd[msg.command] += nTotalSize;

src/net.h

@@ -201,7 +201,7 @@ class CConnman
 
     bool IsMasternodeOrDisconnectRequested(const CService& addr);
 
-    void PushMessage(CNode* pnode, CSerializedNetMsg&& msg);
+    void PushMessage(CNode* pnode, CSerializedNetMsg&& msg, bool allowOptimisticSend = true);
 
     template<typename Condition, typename Callable>
     bool ForEachNodeContinueIf(const Condition& cond, Callable&& func)
@@ -408,6 +408,8 @@ class CConnman
     unsigned int GetReceiveFloodSize() const;
 
     void WakeMessageHandler();
+    void WakeSelect();
+
 private:
     struct ListenSocket {
         SOCKET socket;
@@ -525,6 +527,11 @@ class CConnman
 
     CThreadInterrupt interruptNet;
 
+#ifndef WIN32
+    /** a pipe which is added to select() calls to wakeup before the timeout */
+    int wakeupPipe[2]{-1,-1};
+#endif
+
     std::thread threadDNSAddressSeed;
     std::thread threadSocketHandler;
     std::thread threadOpenAddedConnections;