From 9bf72ff05f28533f42020fcb6e71ae1c5239a19c 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 15014b7937..172e1040ad 100644
--- a/esphome/components/api/api_frame_helper.cpp
+++ b/esphome/components/api/api_frame_helper.cpp
@@ -126,6 +126,14 @@ 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));
 
@@ -721,6 +729,13 @@ 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 3c225aeb82..0fe608b62e 100644
--- a/esphome/components/socket/lwip_raw_tcp_impl.cpp
+++ b/esphome/components/socket/lwip_raw_tcp_impl.cpp
@@ -256,7 +256,7 @@ 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;
     }
@@ -285,11 +285,7 @@ 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;
     }
 
@@ -443,9 +439,11 @@ 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 {
@@ -465,9 +463,11 @@ 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 {
@@ -549,6 +549,9 @@ 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) {