From ca18dfb8f8f442808add71464f893c9da40afc56 Mon Sep 17 00:00:00 2001
From: Lee Salzman <lsalzman@gmail.com>
Date: Sat, 4 Feb 2023 22:48:18 -0500
Subject: [PATCH] avoid revisiting peers when continuing to send

---
 include/enet/enet.h |  6 +++---
 protocol.c          | 29 ++++++++++++++++-------------
 2 files changed, 19 insertions(+), 16 deletions(-)

diff --git a/include/enet/enet.h b/include/enet/enet.h
index 0dd7589..b52a629 100644
--- a/include/enet/enet.h
+++ b/include/enet/enet.h
@@ -254,7 +254,8 @@ typedef struct _ENetChannel
 
 typedef enum _ENetPeerFlag
 {
-   ENET_PEER_FLAG_NEEDS_DISPATCH = (1 << 0)
+   ENET_PEER_FLAG_NEEDS_DISPATCH   = (1 << 0),
+   ENET_PEER_FLAG_CONTINUE_SENDING = (1 << 1)
 } ENetPeerFlag;
 
 /**
@@ -378,7 +379,7 @@ typedef struct _ENetHost
    size_t               channelLimit;                /**< maximum number of channels allowed for connected peers */
    enet_uint32          serviceTime;
    ENetList             dispatchQueue;
-   int                  continueSending;
+   enet_uint32          totalQueued;
    size_t               packetSize;
    enet_uint16          headerFlags;
    ENetProtocol         commands [ENET_PROTOCOL_MAXIMUM_PACKET_COMMANDS];
@@ -401,7 +402,6 @@ typedef struct _ENetHost
    size_t               duplicatePeers;              /**< optional number of allowed peers from duplicate IPs, defaults to ENET_PROTOCOL_MAXIMUM_PEER_ID */
    size_t               maximumPacketSize;           /**< the maximum allowable packet size that may be sent or received on a peer */
    size_t               maximumWaitingData;          /**< the maximum aggregate amount of buffer space a peer may use waiting for packets to be delivered */
-   enet_uint32          totalQueued;
 } ENetHost;
 
 /**
diff --git a/protocol.c b/protocol.c
index 2a6a5c6..3602af7 100644
--- a/protocol.c
+++ b/protocol.c
@@ -1304,7 +1304,7 @@ enet_protocol_send_acknowledgements (ENetHost * host, ENetPeer * peer)
            buffer >= & host -> buffers [sizeof (host -> buffers) / sizeof (ENetBuffer)] ||
            peer -> mtu - host -> packetSize < sizeof (ENetProtocolAcknowledge))
        {
-          host -> continueSending = 1;
+          peer -> flags |= ENET_PEER_FLAG_CONTINUE_SENDING;
 
           break;
        }
@@ -1479,8 +1479,8 @@ enet_protocol_check_outgoing_commands (ENetHost * host, ENetPeer * peer)
            (outgoingCommand -> packet != NULL && 
              (enet_uint16) (peer -> mtu - host -> packetSize) < (enet_uint16) (commandSize + outgoingCommand -> fragmentLength)))
        {
-          host -> continueSending = 1;
-          
+          peer -> flags |= ENET_PEER_FLAG_CONTINUE_SENDING;
+
           break;
        }
 
@@ -1596,22 +1596,21 @@ enet_protocol_send_outgoing_commands (ENetHost * host, ENetEvent * event, int ch
 {
     enet_uint8 headerData [sizeof (ENetProtocolHeader) + sizeof (enet_uint32)];
     ENetProtocolHeader * header = (ENetProtocolHeader *) headerData;
-    ENetPeer * currentPeer;
-    int sentLength;
+    int continueSending = 0, sentLength = 0;
     size_t shouldCompress = 0;
- 
-    host -> continueSending = 1;
 
-    while (host -> continueSending)
-    for (host -> continueSending = 0,
-           currentPeer = host -> peers;
+    for (int sendPass = 0; sendPass <= continueSending; ++ sendPass)
+    for (ENetPeer * currentPeer = host -> peers;
          currentPeer < & host -> peers [host -> peerCount];
          ++ currentPeer)
     {
         if (currentPeer -> state == ENET_PEER_STATE_DISCONNECTED ||
-            currentPeer -> state == ENET_PEER_STATE_ZOMBIE)
+            currentPeer -> state == ENET_PEER_STATE_ZOMBIE ||
+            (sendPass > 0 && ! (currentPeer -> flags & ENET_PEER_FLAG_CONTINUE_SENDING)))
           continue;
 
+        currentPeer -> flags &= ~ ENET_PEER_FLAG_CONTINUE_SENDING;
+
         host -> headerFlags = 0;
         host -> commandCount = 0;
         host -> bufferCount = 1;
@@ -1628,7 +1627,7 @@ enet_protocol_send_outgoing_commands (ENetHost * host, ENetEvent * event, int ch
             if (event != NULL && event -> type != ENET_EVENT_TYPE_NONE)
               return 1;
             else
-              continue;
+              goto nextPeer;
         }
 
         if (((enet_list_empty (& currentPeer -> outgoingCommands) &&
@@ -1643,7 +1642,7 @@ enet_protocol_send_outgoing_commands (ENetHost * host, ENetEvent * event, int ch
         }
 
         if (host -> commandCount == 0)
-          continue;
+          goto nextPeer;
 
         if (currentPeer -> packetLossEpoch == 0)
           currentPeer -> packetLossEpoch = host -> serviceTime;
@@ -1723,6 +1722,10 @@ enet_protocol_send_outgoing_commands (ENetHost * host, ENetEvent * event, int ch
 
         host -> totalSentData += sentLength;
         host -> totalSentPackets ++;
+
+    nextPeer:
+        if (currentPeer -> flags & ENET_PEER_FLAG_CONTINUE_SENDING)
+          continueSending = sendPass + 1;
     }
    
     return 0;