From f50409948551875d9626e1aa14a092d3a2738bf8 Mon Sep 17 00:00:00 2001 From: "J. Nick Koston" Date: Tue, 21 Apr 2026 13:47:37 +0200 Subject: [PATCH] [api] Replace clients_ std::vector with compile-time std::array + uint8_t count (#15889) --- esphome/components/api/__init__.py | 11 +++-- esphome/components/api/api_server.cpp | 61 ++++++++++++++------------- esphome/components/api/api_server.h | 33 ++++++++++++--- esphome/core/defines.h | 1 + 4 files changed, 64 insertions(+), 42 deletions(-) diff --git a/esphome/components/api/__init__.py b/esphome/components/api/__init__.py index 84589d540d..ad778f20ad 100644 --- a/esphome/components/api/__init__.py +++ b/esphome/components/api/__init__.py @@ -291,12 +291,12 @@ CONFIG_SCHEMA = cv.All( cv.SplitDefault( CONF_MAX_CONNECTIONS, esp8266=4, # ~40KB free RAM, each connection uses ~500-1000 bytes - esp32=8, # 520KB RAM available + esp32=5, # 520KB RAM available rp2040=4, # 264KB RAM but LWIP constraints - bk72xx=8, # Moderate RAM - rtl87xx=8, # Moderate RAM + bk72xx=5, # Moderate RAM + rtl87xx=5, # Moderate RAM host=8, # Abundant resources - ln882x=8, # Moderate RAM + ln882x=5, # Moderate RAM ): cv.int_range(min=1, max=20), # Maximum queued send buffers per connection before dropping connection # Each buffer uses ~8-12 bytes overhead plus actual message size @@ -336,8 +336,7 @@ async def to_code(config: ConfigType) -> None: cg.add(var.set_batch_delay(config[CONF_BATCH_DELAY])) if CONF_LISTEN_BACKLOG in config: cg.add(var.set_listen_backlog(config[CONF_LISTEN_BACKLOG])) - if CONF_MAX_CONNECTIONS in config: - cg.add(var.set_max_connections(config[CONF_MAX_CONNECTIONS])) + cg.add_define("MAX_API_CONNECTIONS", config[CONF_MAX_CONNECTIONS]) cg.add_define("API_MAX_SEND_QUEUE", config[CONF_MAX_SEND_QUEUE]) # Set USE_API_USER_DEFINED_ACTIONS if any services are enabled diff --git a/esphome/components/api/api_server.cpp b/esphome/components/api/api_server.cpp index d9c3cc6846..4559168ece 100644 --- a/esphome/components/api/api_server.cpp +++ b/esphome/components/api/api_server.cpp @@ -118,7 +118,7 @@ void APIServer::loop() { this->accept_new_connections_(); } - if (this->clients_.empty()) { + if (this->api_connection_count_ == 0) { // Check reboot timeout - done in loop to avoid scheduler heap churn // (cancelled scheduler items sit in heap memory until their scheduled time) if (this->reboot_timeout_ != 0) { @@ -135,15 +135,15 @@ void APIServer::loop() { // Check network connectivity once for all clients if (!network::is_connected()) { // Network is down - disconnect all clients - for (auto &client : this->clients_) { + for (auto &client : this->active_clients()) { client->on_fatal_error(); client->log_client_(ESPHOME_LOG_LEVEL_WARN, LOG_STR("Network down; disconnect")); } // Continue to process and clean up the clients below } - size_t client_index = 0; - while (client_index < this->clients_.size()) { + uint8_t client_index = 0; + while (client_index < this->api_connection_count_) { auto &client = this->clients_[client_index]; // Common case: process active client @@ -161,7 +161,7 @@ void APIServer::loop() { } } -void APIServer::remove_client_(size_t client_index) { +void APIServer::remove_client_(uint8_t client_index) { auto &client = this->clients_[client_index]; #ifdef USE_API_USER_DEFINED_ACTION_RESPONSES @@ -179,14 +179,17 @@ void APIServer::remove_client_(size_t client_index) { // Close socket now (was deferred from on_fatal_error to allow getpeername) client->helper_->close(); - // Swap with the last element and pop (avoids expensive vector shifts) - if (client_index < this->clients_.size() - 1) { - std::swap(this->clients_[client_index], this->clients_.back()); + // Swap-and-reset: move the removed client to the trailing slot and null it out so slots + // [api_connection_count_, N) remain nullptr. + const uint8_t last_index = this->api_connection_count_ - 1; + if (client_index < last_index) { + std::swap(this->clients_[client_index], this->clients_[last_index]); } - this->clients_.pop_back(); + this->clients_[last_index].reset(); + this->api_connection_count_--; // Last client disconnected - set warning and start tracking for reboot timeout - if (this->clients_.empty() && this->reboot_timeout_ != 0) { + if (this->api_connection_count_ == 0 && this->reboot_timeout_ != 0) { this->status_set_warning(LOG_STR("waiting for client connection")); this->last_connected_ = App.get_loop_component_start_time(); } @@ -210,8 +213,8 @@ void __attribute__((flatten)) APIServer::accept_new_connections_() { sock->getpeername_to(peername); // Check if we're at the connection limit - if (this->clients_.size() >= this->max_connections_) { - ESP_LOGW(TAG, "Max connections (%d), rejecting %s", this->max_connections_, peername); + if (this->api_connection_count_ >= MAX_API_CONNECTIONS) { + ESP_LOGW(TAG, "Max connections (%d), rejecting %s", MAX_API_CONNECTIONS, peername); // Immediately close - socket destructor will handle cleanup sock.reset(); continue; @@ -220,11 +223,11 @@ void __attribute__((flatten)) APIServer::accept_new_connections_() { ESP_LOGD(TAG, "Accept %s", peername); auto *conn = new APIConnection(std::move(sock), this); - this->clients_.emplace_back(conn); + this->clients_[this->api_connection_count_++].reset(conn); conn->start(); // First client connected - clear warning and update timestamp - if (this->clients_.size() == 1 && this->reboot_timeout_ != 0) { + if (this->api_connection_count_ == 1 && this->reboot_timeout_ != 0) { this->status_clear_warning(); this->last_connected_ = App.get_loop_component_start_time(); } @@ -237,7 +240,7 @@ void APIServer::dump_config() { " Address: %s:%u\n" " Listen backlog: %u\n" " Max connections: %u", - network::get_use_address(), this->port_, this->listen_backlog_, this->max_connections_); + network::get_use_address(), this->port_, this->listen_backlog_, MAX_API_CONNECTIONS); #ifdef USE_API_NOISE ESP_LOGCONFIG(TAG, " Noise encryption: %s", YESNO(this->noise_ctx_.has_psk())); if (!this->noise_ctx_.has_psk()) { @@ -255,7 +258,7 @@ void APIServer::handle_disconnect(APIConnection *conn) {} void APIServer::on_##entity_name##_update(entity_type *obj) { /* NOLINT(bugprone-macro-parentheses) */ \ if (obj->is_internal()) \ return; \ - for (auto &c : this->clients_) { \ + for (auto &c : this->active_clients()) { \ if (c->flags_.state_subscription) \ c->send_##entity_name##_state(obj); \ } \ @@ -337,7 +340,7 @@ API_DISPATCH_UPDATE(water_heater::WaterHeater, water_heater) void APIServer::on_event(event::Event *obj) { if (obj->is_internal()) return; - for (auto &c : this->clients_) { + for (auto &c : this->active_clients()) { if (c->flags_.state_subscription) c->send_event(obj); } @@ -349,7 +352,7 @@ void APIServer::on_event(event::Event *obj) { void APIServer::on_update(update::UpdateEntity *obj) { if (obj->is_internal()) return; - for (auto &c : this->clients_) { + for (auto &c : this->active_clients()) { if (c->flags_.state_subscription) c->send_update_state(obj); } @@ -360,7 +363,7 @@ void APIServer::on_update(update::UpdateEntity *obj) { void APIServer::on_zwave_proxy_request(const ZWaveProxyRequest &msg) { // We could add code to manage a second subscription type, but, since this message type is // very infrequent and small, we simply send it to all clients - for (auto &c : this->clients_) + for (auto &c : this->active_clients()) c->send_message(msg); } #endif @@ -375,7 +378,7 @@ void APIServer::send_infrared_rf_receive_event([[maybe_unused]] uint32_t device_ resp.key = key; resp.timings = timings; - for (auto &c : this->clients_) + for (auto &c : this->active_clients()) c->send_infrared_rf_receive_event(resp); } #endif @@ -392,7 +395,7 @@ void APIServer::set_batch_delay(uint16_t batch_delay) { this->batch_delay_ = bat #ifdef USE_API_HOMEASSISTANT_SERVICES void APIServer::send_homeassistant_action(const HomeassistantActionRequest &call) { - for (auto &client : this->clients_) { + for (auto &client : this->active_clients()) { client->send_homeassistant_action(call); } } @@ -532,7 +535,7 @@ bool APIServer::update_noise_psk_(const SavedNoisePsk &new_psk, const LogString return; } ESP_LOGW(TAG, "Disconnecting all clients to reset PSK"); - for (auto &c : this->clients_) { + for (auto &c : this->active_clients()) { DisconnectRequest req; c->send_message(req); } @@ -583,7 +586,7 @@ bool APIServer::clear_noise_psk(bool make_active) { #ifdef USE_HOMEASSISTANT_TIME void APIServer::request_time() { - for (auto &client : this->clients_) { + for (auto &client : this->active_clients()) { if (!client->flags_.remove && client->is_authenticated()) { client->send_time_request(); return; // Only request from one client to avoid clock conflicts @@ -593,8 +596,8 @@ void APIServer::request_time() { #endif bool APIServer::is_connected_with_state_subscription() const { - for (const auto &client : this->clients_) { - if (client->flags_.state_subscription) { + for (uint8_t i = 0; i < this->api_connection_count_; i++) { + if (this->clients_[i]->flags_.state_subscription) { return true; } } @@ -609,7 +612,7 @@ void APIServer::on_log(uint8_t level, const char *tag, const char *message, size // we would be filling a buffer we are trying to clear return; } - for (auto &c : this->clients_) { + for (auto &c : this->active_clients()) { if (!c->flags_.remove && c->get_log_subscription_level() >= level) c->try_send_log_message(level, tag, message, message_len); } @@ -618,7 +621,7 @@ void APIServer::on_log(uint8_t level, const char *tag, const char *message, size #ifdef USE_CAMERA void APIServer::on_camera_image(const std::shared_ptr &image) { - for (auto &c : this->clients_) { + for (auto &c : this->active_clients()) { if (!c->flags_.remove) c->set_camera_state(image); } @@ -635,7 +638,7 @@ void APIServer::on_shutdown() { this->batch_delay_ = 5; // Send disconnect requests to all connected clients - for (auto &c : this->clients_) { + for (auto &c : this->active_clients()) { DisconnectRequest req; if (!c->send_message(req)) { // If we can't send the disconnect request directly (tx_buffer full), @@ -653,7 +656,7 @@ bool APIServer::teardown() { this->loop(); // Return true only when all clients have been torn down - return this->clients_.empty(); + return this->api_connection_count_ == 0; } #ifdef USE_API_USER_DEFINED_ACTION_RESPONSES diff --git a/esphome/components/api/api_server.h b/esphome/components/api/api_server.h index 65076879a2..d6ac1a6d5d 100644 --- a/esphome/components/api/api_server.h +++ b/esphome/components/api/api_server.h @@ -21,6 +21,8 @@ #include "esphome/components/camera/camera.h" #endif +#include +#include #include namespace esphome::api { @@ -63,7 +65,6 @@ class APIServer final : public Component, void set_batch_delay(uint16_t batch_delay); uint16_t get_batch_delay() const { return batch_delay_; } void set_listen_backlog(uint8_t listen_backlog) { this->listen_backlog_ = listen_backlog; } - void set_max_connections(uint8_t max_connections) { this->max_connections_ = max_connections; } // Get reference to shared buffer for API connections APIBuffer &get_shared_buffer_ref() { return shared_write_buffer_; } @@ -186,9 +187,26 @@ class APIServer final : public Component, void send_infrared_rf_receive_event(uint32_t device_id, uint32_t key, const std::vector *timings); #endif - bool is_connected() const { return !this->clients_.empty(); } + bool is_connected() const { return this->api_connection_count_ != 0; } bool is_connected_with_state_subscription() const; + // Range-for view over the populated slice [0, api_connection_count_). Read-only with respect + // to ownership — callers get `const unique_ptr&` so they can invoke non-const methods on the + // APIConnection but cannot reset/move the slot and break the count invariant. + using APIConnectionPtr = std::unique_ptr; + class ActiveClientsView { + const APIConnectionPtr *begin_; + const APIConnectionPtr *end_; + + public: + ActiveClientsView(const APIConnectionPtr *b, const APIConnectionPtr *e) : begin_(b), end_(e) {} + const APIConnectionPtr *begin() const { return this->begin_; } + const APIConnectionPtr *end() const { return this->end_; } + }; + ActiveClientsView active_clients() const { + return {this->clients_.data(), this->clients_.data() + this->api_connection_count_}; + } + #ifdef USE_API_HOMEASSISTANT_STATES struct HomeAssistantStateSubscription { const char *entity_id; // Pointer to flash (internal) or heap (external) @@ -234,8 +252,8 @@ class APIServer final : public Component, protected: // Accept incoming socket connections. Only called when socket has pending connections. void __attribute__((noinline)) accept_new_connections_(); - // Remove a disconnected client by index. Swaps with last element and pops. - void __attribute__((noinline)) remove_client_(size_t client_index); + // Remove a disconnected client by index. Swaps with the last populated slot and resets it. + void __attribute__((noinline)) remove_client_(uint8_t client_index); #ifdef USE_API_NOISE bool update_noise_psk_(const SavedNoisePsk &new_psk, const LogString *save_log_msg, const LogString *fail_log_msg, @@ -273,8 +291,9 @@ class APIServer final : public Component, uint32_t reboot_timeout_{300000}; uint32_t last_connected_{0}; + // Slots [0, api_connection_count_) are populated; trailing slots are always nullptr. + std::array, MAX_API_CONNECTIONS> clients_{}; // Vectors and strings (12 bytes each on 32-bit) - std::vector> clients_; // Shared proto write buffer for all connections. // Not pre-allocated: all send paths call prepare_first_message_buffer() which // reserves the exact needed size. Pre-allocating here would cause heap fragmentation @@ -309,10 +328,10 @@ class APIServer final : public Component, uint16_t port_{6053}; uint16_t batch_delay_{100}; // Connection limits - these defaults will be overridden by config values - // from cv.SplitDefault in __init__.py which sets platform-specific defaults + // from cv.SplitDefault in __init__.py which sets platform-specific defaults. uint8_t listen_backlog_{4}; - uint8_t max_connections_{8}; bool shutting_down_ = false; + uint8_t api_connection_count_{0}; // 7 bytes used, 1 byte padding #ifdef USE_API_NOISE diff --git a/esphome/core/defines.h b/esphome/core/defines.h index d8b4faced9..0fb7221571 100644 --- a/esphome/core/defines.h +++ b/esphome/core/defines.h @@ -177,6 +177,7 @@ #define USE_API_USER_DEFINED_ACTION_RESPONSES #define USE_API_USER_DEFINED_ACTION_RESPONSES_JSON #define API_MAX_SEND_QUEUE 8 +#define MAX_API_CONNECTIONS 6 #define USE_MD5 #define USE_SHA256 #define USE_MQTT