net: add a flag to indicate when a node's process queue is full

Messages are dumped very quickly from the socket handler to the processor, so
it's the depth of the processing queue that's interesting.

The socket handler checks the process queue's size during the brief message
hand-off and pauses if necessary, and the processor possibly unpauses each time
a message is popped off of its queue.

3 files changed, 11 insertions, 12 deletions

diff --git a/src/net.cpp b/src/net.cpp
index df2109e3f7..70c04d7a0e 100644
--- a/src/net.cpp
+++ b/src/net.cpp
@@ -1165,9 +1165,7 @@ void CConnman::ThreadSocketHandler()
                 }
                 {
                     TRY_LOCK(pnode->cs_vRecvMsg, lockRecv);
-                    if (lockRecv && (
-                        pnode->vRecvMsg.empty() || !pnode->vRecvMsg.front().complete() ||
-                        pnode->GetTotalRecvSize() <= GetReceiveFloodSize()))
+                    if (lockRecv && !pnode->fPauseRecv)
                         FD_SET(pnode->hSocket, &fdsetRecv);
                 }
             }
@@ -1240,14 +1238,18 @@ void CConnman::ThreadSocketHandler()
                                 pnode->CloseSocketDisconnect();
                             RecordBytesRecv(nBytes);
                             if (notify) {
+                                size_t nSizeAdded = 0;
                                 auto it(pnode->vRecvMsg.begin());
                                 for (; it != pnode->vRecvMsg.end(); ++it) {
                                     if (!it->complete())
                                         break;
+                                    nSizeAdded += it->vRecv.size() + CMessageHeader::HEADER_SIZE;
                                 }
                                 {
                                     LOCK(pnode->cs_vProcessMsg);
                                     pnode->vProcessMsg.splice(pnode->vProcessMsg.end(), pnode->vRecvMsg, pnode->vRecvMsg.begin(), it);
+                                    pnode->nProcessQueueSize += nSizeAdded;
+                                    pnode->fPauseRecv = pnode->nProcessQueueSize > nReceiveFloodSize;
                                 }
                                 WakeMessageHandler();
                             }
@@ -2592,6 +2594,8 @@ CNode::CNode(NodeId idIn, ServiceFlags nLocalServicesIn, int nMyStartingHeightIn
     minFeeFilter = 0;
     lastSentFeeFilter = 0;
     nextSendTimeFeeFilter = 0;
+    fPauseRecv = false;
+    nProcessQueueSize = 0;
 
     BOOST_FOREACH(const std::string &msg, getAllNetMessageTypes())
         mapRecvBytesPerMsgCmd[msg] = 0;
diff --git a/src/net.h b/src/net.h
index 21864e73d1..0eb430a8bf 100644
--- a/src/net.h
+++ b/src/net.h
@@ -610,6 +610,7 @@ public:
 
     CCriticalSection cs_vProcessMsg;
     std::list<CNetMessage> vProcessMsg;
+    size_t nProcessQueueSize;
 
     std::deque<CInv> vRecvGetData;
     std::list<CNetMessage> vRecvMsg;
@@ -650,6 +651,7 @@ public:
     const NodeId id;
 
     const uint64_t nKeyedNetGroup;
+    std::atomic_bool fPauseRecv;
 protected:
 
     mapMsgCmdSize mapSendBytesPerMsgCmd;
@@ -744,15 +746,6 @@ public:
     }
 
     // requires LOCK(cs_vRecvMsg)
-    unsigned int GetTotalRecvSize()
-    {
-        unsigned int total = 0;
-        BOOST_FOREACH(const CNetMessage &msg, vRecvMsg)
-            total += msg.vRecv.size() + 24;
-        return total;
-    }
-
-    // requires LOCK(cs_vRecvMsg)
     bool ReceiveMsgBytes(const char *pch, unsigned int nBytes, bool& complete);
 
     void SetRecvVersion(int nVersionIn)
diff --git a/src/net_processing.cpp b/src/net_processing.cpp
index 9963a872e8..93b6e2ec01 100644
--- a/src/net_processing.cpp
+++ b/src/net_processing.cpp
@@ -2475,6 +2475,8 @@ bool ProcessMessages(CNode* pfrom, CConnman& connman, std::atomic<bool>& interru
                 return false;
             // Just take one message
             msgs.splice(msgs.begin(), pfrom->vProcessMsg, pfrom->vProcessMsg.begin());
+            pfrom->nProcessQueueSize -= msgs.front().vRecv.size() + CMessageHeader::HEADER_SIZE;
+            pfrom->fPauseRecv = pfrom->nProcessQueueSize > connman.GetReceiveFloodSize();
             fMoreWork = !pfrom->vProcessMsg.empty();
         }
         CNetMessage& msg(msgs.front());