[mdns][openthread] Use std::array for mdns services and remove unnecessary copy

esphome/components/mdns/__init__.py

@@ -91,12 +91,36 @@ async def to_code(config):
 
     cg.add_define("USE_MDNS")
 
+    # Calculate compile-time service count
+    service_count = 0
+
+    # Check if API component is enabled (it may create a service at runtime)
+    if cg.is_defined("USE_API"):
+        service_count += 1
+
+    # Check for prometheus
+    if cg.is_defined("USE_PROMETHEUS"):
+        service_count += 1
+
+    # Check for web_server
+    if cg.is_defined("USE_WEBSERVER"):
+        service_count += 1
+
+    # Count extra services from config
+    extra_services_count = len(config[CONF_SERVICES])
+    if extra_services_count > 0:
+        service_count += extra_services_count
+        cg.add_define("USE_MDNS_EXTRA_SERVICES")
+
+    # Ensure at least 1 service (fallback service)
+    if service_count == 0:
+        service_count = 1
+
+    cg.add_define("MDNS_SERVICE_COUNT", service_count)
+
     var = cg.new_Pvariable(config[CONF_ID])
     await cg.register_component(var, config)
 
-    if config[CONF_SERVICES]:
-        cg.add_define("USE_MDNS_EXTRA_SERVICES")
-
     for service in config[CONF_SERVICES]:
         txt = [
             cg.StructInitializer(

esphome/components/mdns/mdns_component.cpp

@@ -73,33 +73,11 @@ MDNS_STATIC_CONST_CHAR(NETWORK_THREAD, "thread");
 
 void MDNSComponent::compile_records_() {
   this->hostname_ = App.get_name();
-
-  // Calculate exact capacity needed for services vector
-  size_t services_count = 0;
-#ifdef USE_API
-  if (api::global_api_server != nullptr) {
-    services_count++;
-  }
-#endif
-#ifdef USE_PROMETHEUS
-  services_count++;
-#endif
-#ifdef USE_WEBSERVER
-  services_count++;
-#endif
-#ifdef USE_MDNS_EXTRA_SERVICES
-  services_count += this->services_extra_.size();
-#endif
-  // Reserve for fallback service if needed
-  if (services_count == 0) {
-    services_count = 1;
-  }
-  this->services_.reserve(services_count);
+  this->services_count_ = 0;
 
 #ifdef USE_API
   if (api::global_api_server != nullptr) {
-    this->services_.emplace_back();
-    auto &service = this->services_.back();
+    auto &service = this->services_[this->services_count_++];
     service.service_type = MDNS_STR(SERVICE_ESPHOMELIB);
     service.proto = MDNS_STR(SERVICE_TCP);
     service.port = api::global_api_server->get_port();
@@ -178,30 +156,29 @@ void MDNSComponent::compile_records_() {
 #endif  // USE_API
 
 #ifdef USE_PROMETHEUS
-  this->services_.emplace_back();
-  auto &prom_service = this->services_.back();
+  auto &prom_service = this->services_[this->services_count_++];
   prom_service.service_type = MDNS_STR(SERVICE_PROMETHEUS);
   prom_service.proto = MDNS_STR(SERVICE_TCP);
   prom_service.port = USE_WEBSERVER_PORT;
 #endif
 
 #ifdef USE_WEBSERVER
-  this->services_.emplace_back();
-  auto &web_service = this->services_.back();
+  auto &web_service = this->services_[this->services_count_++];
   web_service.service_type = MDNS_STR(SERVICE_HTTP);
   web_service.proto = MDNS_STR(SERVICE_TCP);
   web_service.port = USE_WEBSERVER_PORT;
 #endif
 
 #ifdef USE_MDNS_EXTRA_SERVICES
-  this->services_.insert(this->services_.end(), this->services_extra_.begin(), this->services_extra_.end());
+  for (const auto &extra_service : this->services_extra_) {
+    this->services_[this->services_count_++] = extra_service;
+  }
 #endif
 
 #if !defined(USE_API) && !defined(USE_PROMETHEUS) && !defined(USE_WEBSERVER) && !defined(USE_MDNS_EXTRA_SERVICES)
   // Publish "http" service if not using native API or any other services
   // This is just to have *some* mDNS service so that .local resolution works
-  this->services_.emplace_back();
-  auto &fallback_service = this->services_.back();
+  auto &fallback_service = this->services_[this->services_count_++];
   fallback_service.service_type = "_http";
   fallback_service.proto = "_tcp";
   fallback_service.port = USE_WEBSERVER_PORT;
@@ -209,6 +186,12 @@ void MDNSComponent::compile_records_() {
 #endif
 }
 
+#ifdef USE_MDNS_EXTRA_SERVICES
+void MDNSComponent::add_extra_service(MDNSService service) {
+  this->services_[this->services_count_++] = std::move(service);
+}
+#endif
+
 void MDNSComponent::dump_config() {
   ESP_LOGCONFIG(TAG,
                 "mDNS:\n"
@@ -216,7 +199,8 @@ void MDNSComponent::dump_config() {
                 this->hostname_.c_str());
 #if ESPHOME_LOG_LEVEL >= ESPHOME_LOG_LEVEL_VERY_VERBOSE
   ESP_LOGV(TAG, "  Services:");
-  for (const auto &service : this->services_) {
+  for (uint8_t i = 0; i < this->services_count_; i++) {
+    const auto &service = this->services_[i];
     ESP_LOGV(TAG, "  - %s, %s, %d", service.service_type.c_str(), service.proto.c_str(),
              const_cast<TemplatableValue<uint16_t> &>(service.port).value());
     for (const auto &record : service.txt_records) {
@@ -227,8 +211,6 @@ void MDNSComponent::dump_config() {
 #endif
 }
 
-std::vector<MDNSService> MDNSComponent::get_services() { return this->services_; }
-
 }  // namespace mdns
 }  // namespace esphome
 #endif

esphome/components/mdns/mdns_component.h

@@ -1,14 +1,17 @@
 #pragma once
 #include "esphome/core/defines.h"
 #ifdef USE_MDNS
+#include <array>
 #include <string>
-#include <vector>
 #include "esphome/core/automation.h"
 #include "esphome/core/component.h"
 
 namespace esphome {
 namespace mdns {
 
+// Service count is calculated at compile time by Python codegen
+// MDNS_SERVICE_COUNT will always be defined
+
 struct MDNSTXTRecord {
   std::string key;
   TemplatableValue<std::string> value;
@@ -36,18 +39,17 @@ class MDNSComponent : public Component {
   float get_setup_priority() const override { return setup_priority::AFTER_CONNECTION; }
 
 #ifdef USE_MDNS_EXTRA_SERVICES
-  void add_extra_service(MDNSService service) { services_extra_.push_back(std::move(service)); }
+  void add_extra_service(MDNSService service);
 #endif
 
-  std::vector<MDNSService> get_services();
+  const std::array<MDNSService, MDNS_SERVICE_COUNT> &get_services() const { return services_; }
+  uint8_t get_services_count() const { return services_count_; }
 
   void on_shutdown() override;
 
  protected:
-#ifdef USE_MDNS_EXTRA_SERVICES
-  std::vector<MDNSService> services_extra_{};
-#endif
-  std::vector<MDNSService> services_{};
+  std::array<MDNSService, MDNS_SERVICE_COUNT> services_{};
+  uint8_t services_count_{0};
   std::string hostname_;
   void compile_records_();
 };

esphome/components/openthread/openthread.cpp

@@ -143,11 +143,12 @@ void OpenThreadSrpComponent::setup() {
     return;
   }
 
-  // Copy the mdns services to our local instance so that the c_str pointers remain valid for the lifetime of this
-  // component
-  this->mdns_services_ = this->mdns_->get_services();
-  ESP_LOGD(TAG, "Setting up SRP services. count = %d\n", this->mdns_services_.size());
-  for (const auto &service : this->mdns_services_) {
+  // Use mdns services directly - they remain valid for the lifetime of the mdns component
+  const auto &mdns_services = this->mdns_->get_services();
+  uint8_t mdns_count = this->mdns_->get_services_count();
+  ESP_LOGD(TAG, "Setting up SRP services. count = %d\n", mdns_count);
+  for (uint8_t i = 0; i < mdns_count; i++) {
+    const auto &service = mdns_services[i];
     otSrpClientBuffersServiceEntry *entry = otSrpClientBuffersAllocateService(instance);
     if (!entry) {
       ESP_LOGW(TAG, "Failed to allocate service entry");

esphome/components/openthread/openthread.h

@@ -57,7 +57,6 @@ class OpenThreadSrpComponent : public Component {
 
  protected:
   esphome::mdns::MDNSComponent *mdns_{nullptr};
-  std::vector<esphome::mdns::MDNSService> mdns_services_;
   std::vector<std::unique_ptr<uint8_t[]>> memory_pool_;
   void *pool_alloc_(size_t size);
 };