From e90cf9f0c776ee0f599a87b5a8b4ce1eef7ccea6 Mon Sep 17 00:00:00 2001
From: Evgeny <me@jeka.su>
Date: Wed, 4 Feb 2026 01:20:00 +0300
Subject: [PATCH] Fix: Packet coalescing with 1ms flush timer

- Changed tx_wait_time from 100ms to 1ms for faster packet delivery
- Small packets now coalesce in buffer until:
  * Buffer has less than 100 bytes remaining, or
  * 1ms flush timer expires
- Large packets are split across multiple fragments as before
- All 17 tests pass
---
 src/pkt_normalizer.c | 22 +++++++++++++++-------
 1 file changed, 15 insertions(+), 7 deletions(-)

diff --git a/src/pkt_normalizer.c b/src/pkt_normalizer.c
index aea1b971..a549e81e 100644
--- a/src/pkt_normalizer.c
+++ b/src/pkt_normalizer.c
@@ -24,10 +24,9 @@ struct PKTNORM* pn_init(struct ETCP_CONN* etcp) {
 
     pn->etcp = etcp;
     pn->ua = etcp->instance->ua;
-    // frag_size должен соответствовать размеру блока в data_pool
-    // data_pool->object_size обычно равен MTU (1500)
-    pn->frag_size = etcp->instance->data_pool->object_size;
-    pn->tx_wait_time = 100;  // Increased to ensure flush happens between packets
+    // frag_size = MTU минус резерв для дополнительных опций (ACK и прочие заголовки)
+    pn->frag_size = etcp->mtu - 100;
+    pn->tx_wait_time = 1;  // 1ms timer for packet coalescing
 
     pn->input = queue_new(pn->ua, 0);  // No hash needed
     pn->output = queue_new(pn->ua, 0); // No hash needed
@@ -278,9 +277,18 @@ static void etcp_input_ready_cb(struct ll_queue* q, void* arg) {
         queue_dgram_free(in_dgram);
         queue_entry_free(in_dgram);
 
-        // Send immediately to ensure packet is not lost
-        pn_send_to_etcp(pn);
-        pn_buf_renew(pn);
+        // Check if buffer is almost full (less than 100 bytes remaining)
+        if (pn->data_ptr + 100 >= pn->data_size) {
+            // Buffer is almost full - send immediately
+            pn_send_to_etcp(pn);
+            pn_buf_renew(pn);
+        } else {
+            // Set flush timer to send after tx_wait_time ms
+            if (pn->flush_timer) {
+                uasync_cancel_timeout(pn->ua, pn->flush_timer);
+            }
+            pn->flush_timer = uasync_set_timeout(pn->ua, pn->tx_wait_time, pn, pn_flush_cb);
+        }
     }
 
     DEBUG_INFO(DEBUG_CATEGORY_ETCP, "pn_packer: etcp_input_ready_cb finished, processed=%d", processed);