Send 'mempool' P2P command at the start of each P2P session

to query remote node mempool contents.

src/main.cpp

@@ -2404,6 +2404,14 @@ bool static AlreadyHave(CTxDB& txdb, const CInv& inv)
 
 
 
+static bool NodeRecentlyStarted()
+{
+    extern int64 nTimeNodeStart;
+    int64 timediff = GetTime() - nTimeNodeStart;
+
+    return (timediff < (2 * 60 * 60));
+}
+
 
 // The message start string is designed to be unlikely to occur in normal data.
 // The characters are rarely used upper ASCII, not valid as UTF-8, and produce
@@ -2510,6 +2518,12 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv)
             }
         }
 
+        // Trigger download of remote node's memory pool
+        if (!IsInitialBlockDownload() && !pfrom->fInbound &&
+            !pfrom->fClient && NodeRecentlyStarted() &&
+            pfrom->nVersion >= MEMPOOL_GD_VERSION)
+            pfrom->PushMessage("mempool");
+
         // Ask the first connected node for block updates
         static int nAskedForBlocks = 0;
         if (!pfrom->fClient && !pfrom->fOneShot &&