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[api] Use union for iterators to reduce APIConnection size by ~16 bytes (#12563)

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This commit is contained in:
J. Nick Koston
2025-12-22 07:54:17 -10:00
committed by GitHub
parent 74b075d3cf
commit 1756fc31b0
2 changed files with 82 additions and 25 deletions
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75
esphome/components/api/api_connection.cpp
View File

@@ -13,6 +13,7 @@
#include <cinttypes>
#include <functional>
#include <limits>
#include <new>
#include <utility>
#ifdef USE_ESP8266
#include <pgmspace.h>
@@ -96,8 +97,7 @@ static const int CAMERA_STOP_STREAM = 5000;
return;
#endif // USE_DEVICES
APIConnection::APIConnection(std::unique_ptr<socket::Socket> sock, APIServer *parent)
: parent_(parent), initial_state_iterator_(this), list_entities_iterator_(this) {
APIConnection::APIConnection(std::unique_ptr<socket::Socket> sock, APIServer *parent) : parent_(parent) {
#if defined(USE_API_PLAINTEXT) && defined(USE_API_NOISE)
auto &noise_ctx = parent->get_noise_ctx();
if (noise_ctx.has_psk()) {
@@ -136,6 +136,7 @@ void APIConnection::start() {
}
APIConnection::~APIConnection() {
this->destroy_active_iterator_();
#ifdef USE_BLUETOOTH_PROXY
if (bluetooth_proxy::global_bluetooth_proxy->get_api_connection() == this) {
bluetooth_proxy::global_bluetooth_proxy->unsubscribe_api_connection(this);
@@ -148,6 +149,32 @@ APIConnection::~APIConnection() {
#endif
}
void APIConnection::destroy_active_iterator_() {
switch (this->active_iterator_) {
case ActiveIterator::LIST_ENTITIES:
this->iterator_storage_.list_entities.~ListEntitiesIterator();
break;
case ActiveIterator::INITIAL_STATE:
this->iterator_storage_.initial_state.~InitialStateIterator();
break;
case ActiveIterator::NONE:
break;
}
this->active_iterator_ = ActiveIterator::NONE;
}
void APIConnection::begin_iterator_(ActiveIterator type) {
this->destroy_active_iterator_();
this->active_iterator_ = type;
if (type == ActiveIterator::LIST_ENTITIES) {
new (&this->iterator_storage_.list_entities) ListEntitiesIterator(this);
this->iterator_storage_.list_entities.begin();
} else {
new (&this->iterator_storage_.initial_state) InitialStateIterator(this);
this->iterator_storage_.initial_state.begin();
}
}
void APIConnection::loop() {
if (this->flags_.next_close) {
// requested a disconnect
@@ -190,23 +217,35 @@ void APIConnection::loop() {
this->process_batch_();
}
if (!this->list_entities_iterator_.completed()) {
this->process_iterator_batch_(this->list_entities_iterator_);
} else if (!this->initial_state_iterator_.completed()) {
this->process_iterator_batch_(this->initial_state_iterator_);
// If we've completed initial states, process any remaining and clear the flag
if (this->initial_state_iterator_.completed()) {
// Process any remaining batched messages immediately
if (!this->deferred_batch_.empty()) {
this->process_batch_();
switch (this->active_iterator_) {
case ActiveIterator::LIST_ENTITIES:
if (this->iterator_storage_.list_entities.completed()) {
this->destroy_active_iterator_();
if (this->flags_.state_subscription) {
this->begin_iterator_(ActiveIterator::INITIAL_STATE);
}
} else {
this->process_iterator_batch_(this->iterator_storage_.list_entities);
}
// Now that everything is sent, enable immediate sending for future state changes
this->flags_.should_try_send_immediately = true;
// Release excess memory from buffers that grew during initial sync
this->deferred_batch_.release_buffer();
this->helper_->release_buffers();
}
break;
case ActiveIterator::INITIAL_STATE:
if (this->iterator_storage_.initial_state.completed()) {
this->destroy_active_iterator_();
// Process any remaining batched messages immediately
if (!this->deferred_batch_.empty()) {
this->process_batch_();
}
// Now that everything is sent, enable immediate sending for future state changes
this->flags_.should_try_send_immediately = true;
// Release excess memory from buffers that grew during initial sync
this->deferred_batch_.release_buffer();
this->helper_->release_buffers();
} else {
this->process_iterator_batch_(this->iterator_storage_.initial_state);
}
break;
case ActiveIterator::NONE:
break;
}
if (this->flags_.sent_ping) {

32
esphome/components/api/api_connection.h
View File

@@ -208,10 +208,14 @@ class APIConnection final : public APIServerConnection {
bool send_disconnect_response(const DisconnectRequest &msg) override;
bool send_ping_response(const PingRequest &msg) override;
bool send_device_info_response(const DeviceInfoRequest &msg) override;
void list_entities(const ListEntitiesRequest &msg) override { this->list_entities_iterator_.begin(); }
void list_entities(const ListEntitiesRequest &msg) override { this->begin_iterator_(ActiveIterator::LIST_ENTITIES); }
void subscribe_states(const SubscribeStatesRequest &msg) override {
this->flags_.state_subscription = true;
this->initial_state_iterator_.begin();
// Start initial state iterator only if no iterator is active
// If list_entities is running, we'll start initial_state when it completes
if (this->active_iterator_ == ActiveIterator::NONE) {
this->begin_iterator_(ActiveIterator::INITIAL_STATE);
}
}
void subscribe_logs(const SubscribeLogsRequest &msg) override {
this->flags_.log_subscription = msg.level;
@@ -501,10 +505,22 @@ class APIConnection final : public APIServerConnection {
std::unique_ptr<APIFrameHelper> helper_;
APIServer *parent_;
// Group 2: Larger objects (must be 4-byte aligned)
// These contain vectors/pointers internally, so putting them early ensures good alignment
InitialStateIterator initial_state_iterator_;
ListEntitiesIterator list_entities_iterator_;
// Group 2: Iterator union (saves ~16 bytes vs separate iterators)
// These iterators are never active simultaneously - list_entities runs to completion
// before initial_state begins, so we use a union with explicit construction/destruction.
enum class ActiveIterator : uint8_t { NONE, LIST_ENTITIES, INITIAL_STATE };
union IteratorUnion {
ListEntitiesIterator list_entities;
InitialStateIterator initial_state;
// Constructor/destructor do nothing - use placement new/explicit destructor
IteratorUnion() {}
~IteratorUnion() {}
} iterator_storage_;
// Helper methods for iterator lifecycle management
void destroy_active_iterator_();
void begin_iterator_(ActiveIterator type);
#ifdef USE_CAMERA
std::unique_ptr<camera::CameraImageReader> image_reader_;
#endif
@@ -619,7 +635,9 @@ class APIConnection final : public APIServerConnection {
// 2-byte types immediately after flags_ (no padding between them)
uint16_t client_api_version_major_{0};
uint16_t client_api_version_minor_{0};
// Total: 2 (flags) + 2 + 2 = 6 bytes, then 2 bytes padding to next 4-byte boundary
// 1-byte type to fill padding
ActiveIterator active_iterator_{ActiveIterator::NONE};
// Total: 2 (flags) + 2 + 2 + 1 = 7 bytes, then 1 byte padding to next 4-byte boundary
uint32_t get_batch_delay_ms_() const;
// Message will use 8 more bytes than the minimum size, and typical