From 97e76d64d60d2d46a4bd4a4b50d11c496d596138 Mon Sep 17 00:00:00 2001
From: Otto Winter <otto@otto-winter.com>
Date: Mon, 27 Sep 2021 11:40:28 +0200
Subject: [PATCH] Re-enable TCP nodelay for ESP32 (#2390)

---
 esphome/components/api/api_frame_helper.cpp   | 15 +++++++++++
 .../components/socket/lwip_raw_tcp_impl.cpp   | 27 ++++++++++---------
 2 files changed, 30 insertions(+), 12 deletions(-)

diff --git a/esphome/components/api/api_frame_helper.cpp b/esphome/components/api/api_frame_helper.cpp
index 00f28457ae..4971272f41 100644
--- a/esphome/components/api/api_frame_helper.cpp
+++ b/esphome/components/api/api_frame_helper.cpp
@@ -127,6 +127,14 @@ APIError APINoiseFrameHelper::init() {
     return APIError::TCP_NONBLOCKING_FAILED;
   }
 
+  int enable = 1;
+  err = socket_->setsockopt(IPPROTO_TCP, TCP_NODELAY, &enable, sizeof(int));
+  if (err != 0) {
+    state_ = State::FAILED;
+    HELPER_LOG("Setting nodelay failed with errno %d", errno);
+    return APIError::TCP_NODELAY_FAILED;
+  }
+
   // init prologue
   prologue_.insert(prologue_.end(), PROLOGUE_INIT, PROLOGUE_INIT + strlen(PROLOGUE_INIT));
 
@@ -722,6 +730,13 @@ APIError APIPlaintextFrameHelper::init() {
     HELPER_LOG("Setting nonblocking failed with errno %d", errno);
     return APIError::TCP_NONBLOCKING_FAILED;
   }
+  int enable = 1;
+  err = socket_->setsockopt(IPPROTO_TCP, TCP_NODELAY, &enable, sizeof(int));
+  if (err != 0) {
+    state_ = State::FAILED;
+    HELPER_LOG("Setting nodelay failed with errno %d", errno);
+    return APIError::TCP_NODELAY_FAILED;
+  }
 
   state_ = State::DATA;
   return APIError::OK;
diff --git a/esphome/components/socket/lwip_raw_tcp_impl.cpp b/esphome/components/socket/lwip_raw_tcp_impl.cpp
index 7521d1339f..54dfddac3f 100644
--- a/esphome/components/socket/lwip_raw_tcp_impl.cpp
+++ b/esphome/components/socket/lwip_raw_tcp_impl.cpp
@@ -257,7 +257,7 @@ class LWIPRawImpl : public Socket {
         errno = EINVAL;
         return -1;
       }
-      *reinterpret_cast<int *>(optval) = tcp_nagle_disabled(pcb_);
+      *reinterpret_cast<int *>(optval) = nodelay_;
       *optlen = 4;
       return 0;
     }
@@ -286,11 +286,7 @@ class LWIPRawImpl : public Socket {
         return -1;
       }
       int val = *reinterpret_cast<const int *>(optval);
-      if (val != 0) {
-        tcp_nagle_disable(pcb_);
-      } else {
-        tcp_nagle_enable(pcb_);
-      }
+      nodelay_ = val;
       return 0;
     }
 
@@ -444,9 +440,11 @@ class LWIPRawImpl : public Socket {
     if (written == 0)
       // no need to output if nothing written
       return 0;
-    int err = internal_output();
-    if (err == -1)
-      return -1;
+    if (nodelay_) {
+      int err = internal_output();
+      if (err == -1)
+        return -1;
+    }
     return written;
   }
   ssize_t writev(const struct iovec *iov, int iovcnt) override {
@@ -466,9 +464,11 @@ class LWIPRawImpl : public Socket {
     if (written == 0)
       // no need to output if nothing written
       return 0;
-    int err = internal_output();
-    if (err == -1)
-      return -1;
+    if (nodelay_) {
+      int err = internal_output();
+      if (err == -1)
+        return -1;
+    }
     return written;
   }
   int setblocking(bool blocking) override {
@@ -550,6 +550,9 @@ class LWIPRawImpl : public Socket {
   bool rx_closed_ = false;
   pbuf *rx_buf_ = nullptr;
   size_t rx_buf_offset_ = 0;
+  // don't use lwip nodelay flag, it sometimes causes reconnect
+  // instead use it for determining whether to call lwip_output
+  bool nodelay_ = false;
 };
 
 std::unique_ptr<Socket> socket(int domain, int type, int protocol) {