From 122b740e2d4c17fd0fc93cf331eedd56e78fe22b Mon Sep 17 00:00:00 2001
From: Alexander Block <ablock84@gmail.com>
Date: Tue, 7 Apr 2020 06:55:09 +0200
Subject: [PATCH] Optimize deletion of vNodes entries

Iterate through the vectors with iterators and use them for .erase().
This avoids an expensive lookup when erasing.
---
 src/net.cpp | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/src/net.cpp b/src/net.cpp
index fc09517470..ba514b3ba7 100644
--- a/src/net.cpp
+++ b/src/net.cpp
@@ -1239,9 +1239,9 @@ void CConnman::ThreadSocketHandler()
         {
             LOCK(cs_vNodes);
             // Disconnect unused nodes
-            std::vector<CNode*> vNodesCopy = vNodes;
-            for (CNode* pnode : vNodesCopy)
+            for (auto it = vNodes.begin(); it != vNodes.end(); )
             {
+                CNode* pnode = *it;
                 if (pnode->fDisconnect)
                 {
                     if (fLogIPs) {
@@ -1253,7 +1253,7 @@ void CConnman::ThreadSocketHandler()
                     }
 
                     // remove from vNodes
-                    vNodes.erase(remove(vNodes.begin(), vNodes.end(), pnode), vNodes.end());
+                    it = vNodes.erase(it);
 
                     // release outbound grant (if any)
                     pnode->grantOutbound.Release();
@@ -1265,17 +1265,20 @@ void CConnman::ThreadSocketHandler()
                     // hold in disconnected pool until all refs are released
                     pnode->Release();
                     vNodesDisconnected.push_back(pnode);
+                } else {
+                    ++it;
                 }
             }
         }
         {
             // Delete disconnected nodes
             std::list<CNode*> vNodesDisconnectedCopy = vNodesDisconnected;
-            for (CNode* pnode : vNodesDisconnectedCopy)
+            for (auto it = vNodesDisconnected.begin(); it != vNodesDisconnected.end(); )
             {
+                CNode* pnode = *it;
                 // wait until threads are done using it
+                bool fDelete = false;
                 if (pnode->GetRefCount() <= 0) {
-                    bool fDelete = false;
                     {
                         TRY_LOCK(pnode->cs_inventory, lockInv);
                         if (lockInv) {
@@ -1286,10 +1289,13 @@ void CConnman::ThreadSocketHandler()
                         }
                     }
                     if (fDelete) {
-                        vNodesDisconnected.remove(pnode);
+                        it = vNodesDisconnected.erase(it);
                         DeleteNode(pnode);
                     }
                 }
+                if (!fDelete) {
+                    ++it;
+                }
             }
         }
         size_t vNodesSize;