net: add a flag to indicate when a node's send buffer is full

Similar to the recv flag, but this one indicates whether or not the net's send
buffer is full.

The socket handler checks the send queue when a new message is added and pauses
if necessary, and possibly unpauses after each message is drained from its buffer.

1 files changed, 8 insertions, 3 deletions

diff --git a/src/net.cpp b/src/net.cpp
index 70c04d7a0..8ae2bebd3 100644
--- a/src/net.cpp
+++ b/src/net.cpp
@@ -761,7 +761,7 @@ const uint256& CNetMessage::GetMessageHash() const
 
 
 // requires LOCK(cs_vSend)
-size_t SocketSendData(CNode *pnode)
+size_t CConnman::SocketSendData(CNode *pnode)
 {
     auto it = pnode->vSendMsg.begin();
     size_t nSentSize = 0;
@@ -778,6 +778,7 @@ size_t SocketSendData(CNode *pnode)
             if (pnode->nSendOffset == data.size()) {
                 pnode->nSendOffset = 0;
                 pnode->nSendSize -= data.size();
+                pnode->fPauseSend = pnode->nSendSize > nSendBufferMaxSize;
                 it++;
             } else {
                 // could not send full message; stop sending more
@@ -1286,8 +1287,9 @@ void CConnman::ThreadSocketHandler()
                 TRY_LOCK(pnode->cs_vSend, lockSend);
                 if (lockSend) {
                     size_t nBytes = SocketSendData(pnode);
-                    if (nBytes)
+                    if (nBytes) {
                         RecordBytesSent(nBytes);
+                    }
                 }
             }
 
@@ -1868,7 +1870,7 @@ void CConnman::ThreadMessageHandler()
                 if (lockRecv)
                 {
                     bool fMoreNodeWork = GetNodeSignals().ProcessMessages(pnode, *this, flagInterruptMsgProc);
-                    fMoreWork |= (fMoreNodeWork && pnode->nSendSize < GetSendBufferSize());
+                    fMoreWork |= (fMoreNodeWork && !pnode->fPauseSend);
                 }
             }
             if (flagInterruptMsgProc)
@@ -2595,6 +2597,7 @@ CNode::CNode(NodeId idIn, ServiceFlags nLocalServicesIn, int nMyStartingHeightIn
     lastSentFeeFilter = 0;
     nextSendTimeFeeFilter = 0;
     fPauseRecv = false;
+    fPauseSend = false;
     nProcessQueueSize = 0;
 
     BOOST_FOREACH(const std::string &msg, getAllNetMessageTypes())
@@ -2675,6 +2678,8 @@ void CConnman::PushMessage(CNode* pnode, CSerializedNetMsg&& msg)
         pnode->mapSendBytesPerMsgCmd[msg.command] += nTotalSize;
         pnode->nSendSize += nTotalSize;
 
+        if (pnode->nSendSize > nSendBufferMaxSize)
+            pnode->fPauseSend = true;
         pnode->vSendMsg.push_back(std::move(serializedHeader));
         if (nMessageSize)
             pnode->vSendMsg.push_back(std::move(msg.data));