Make parse_characteristics and parse_descriptors lazy to reduce memory pressure (#4063)

esphome/components/bluetooth_proxy/bluetooth_proxy.cpp

@@ -72,11 +72,15 @@ void BluetoothProxy::loop() {
       api::BluetoothGATTService service_resp;
       service_resp.uuid = {service->uuid.get_128bit_high(), service->uuid.get_128bit_low()};
       service_resp.handle = service->start_handle;
+      if (!service->parsed)
+        service->parse_characteristics();
       for (auto &characteristic : service->characteristics) {
         api::BluetoothGATTCharacteristic characteristic_resp;
         characteristic_resp.uuid = {characteristic->uuid.get_128bit_high(), characteristic->uuid.get_128bit_low()};
         characteristic_resp.handle = characteristic->handle;
         characteristic_resp.properties = characteristic->properties;
+        if (!characteristic->parsed)
+          characteristic->parse_descriptors();
         for (auto &descriptor : characteristic->descriptors) {
           api::BluetoothGATTDescriptor descriptor_resp;
           descriptor_resp.uuid = {descriptor->uuid.get_128bit_high(), descriptor->uuid.get_128bit_low()};
@@ -87,6 +91,13 @@ void BluetoothProxy::loop() {
       }
       resp.services.push_back(std::move(service_resp));
       api::global_api_server->send_bluetooth_gatt_services(resp);
+      // Descriptors are rarely used and can be quite large so we clear them
+      // after sending them to save memory. If something actually needs them
+      // it can parse them again.
+      for (auto &characteristic : service->characteristics) {
+        characteristic->parsed = false;
+        characteristic->descriptors.clear();
+      }
       connection->send_service_++;
     }
   }

esphome/components/esp32_ble_client/ble_characteristic.cpp

@@ -17,6 +17,7 @@ BLECharacteristic::~BLECharacteristic() {
 }
 
 void BLECharacteristic::parse_descriptors() {
+  this->parsed = true;
   uint16_t offset = 0;
   esp_gattc_descr_elem_t result;
 
@@ -49,6 +50,8 @@ void BLECharacteristic::parse_descriptors() {
 }
 
 BLEDescriptor *BLECharacteristic::get_descriptor(espbt::ESPBTUUID uuid) {
+  if (!this->parsed)
+    this->parse_descriptors();
   for (auto &desc : this->descriptors) {
     if (desc->uuid == uuid)
       return desc;
@@ -59,6 +62,8 @@ BLEDescriptor *BLECharacteristic::get_descriptor(uint16_t uuid) {
   return this->get_descriptor(espbt::ESPBTUUID::from_uint16(uuid));
 }
 BLEDescriptor *BLECharacteristic::get_descriptor_by_handle(uint16_t handle) {
+  if (!this->parsed)
+    this->parse_descriptors();
   for (auto &desc : this->descriptors) {
     if (desc->handle == handle)
       return desc;

esphome/components/esp32_ble_client/ble_characteristic.h

@@ -18,6 +18,7 @@ class BLEService;
 class BLECharacteristic {
  public:
   ~BLECharacteristic();
+  bool parsed = false;
   espbt::ESPBTUUID uuid;
   uint16_t handle;
   esp_gatt_char_prop_t properties;

esphome/components/esp32_ble_client/ble_client_base.cpp

@@ -135,6 +135,7 @@ bool BLEClientBase::gattc_event_handler(esp_gattc_cb_event_t event, esp_gatt_if_
       for (auto &svc : this->services_)
         delete svc;  // NOLINT(cppcoreguidelines-owning-memory)
       this->services_.clear();
+      esp_ble_gattc_cache_clean(this->remote_bda_);
       this->set_state(espbt::ClientState::IDLE);
       break;
     }
@@ -154,7 +155,6 @@ bool BLEClientBase::gattc_event_handler(esp_gattc_cb_event_t event, esp_gatt_if_
                  svc->uuid.to_string().c_str());
         ESP_LOGI(TAG, "[%d] [%s]  start_handle: 0x%x  end_handle: 0x%x", this->connection_index_,
                  this->address_str_.c_str(), svc->start_handle, svc->end_handle);
-        svc->parse_characteristics();
       }
       this->set_state(espbt::ClientState::CONNECTED);
       this->state_ = espbt::ClientState::ESTABLISHED;
@@ -287,6 +287,8 @@ BLECharacteristic *BLEClientBase::get_characteristic(uint16_t service, uint16_t
 
 BLECharacteristic *BLEClientBase::get_characteristic(uint16_t handle) {
   for (auto *svc : this->services_) {
+    if (!svc->parsed)
+      svc->parse_characteristics();
     for (auto *chr : svc->characteristics) {
       if (chr->handle == handle)
         return chr;
@@ -298,6 +300,8 @@ BLECharacteristic *BLEClientBase::get_characteristic(uint16_t handle) {
 BLEDescriptor *BLEClientBase::get_config_descriptor(uint16_t handle) {
   auto *chr = this->get_characteristic(handle);
   if (chr != nullptr) {
+    if (!chr->parsed)
+      chr->parse_descriptors();
     for (auto &desc : chr->descriptors) {
       if (desc->uuid.get_uuid().uuid.uuid16 == 0x2902)
         return desc;
@@ -323,7 +327,11 @@ BLEDescriptor *BLEClientBase::get_descriptor(uint16_t service, uint16_t chr, uin
 
 BLEDescriptor *BLEClientBase::get_descriptor(uint16_t handle) {
   for (auto *svc : this->services_) {
+    if (!svc->parsed)
+      svc->parse_characteristics();
     for (auto *chr : svc->characteristics) {
+      if (!chr->parsed)
+        chr->parse_descriptors();
       for (auto *desc : chr->descriptors) {
         if (desc->handle == handle)
           return desc;

esphome/components/esp32_ble_client/ble_service.cpp

@@ -11,6 +11,8 @@ namespace esp32_ble_client {
 static const char *const TAG = "esp32_ble_client";
 
 BLECharacteristic *BLEService::get_characteristic(espbt::ESPBTUUID uuid) {
+  if (!this->parsed)
+    this->parse_characteristics();
   for (auto &chr : this->characteristics) {
     if (chr->uuid == uuid)
       return chr;
@@ -28,6 +30,7 @@ BLEService::~BLEService() {
 }
 
 void BLEService::parse_characteristics() {
+  this->parsed = true;
   uint16_t offset = 0;
   esp_gattc_char_elem_t result;
 
@@ -57,7 +60,6 @@ void BLEService::parse_characteristics() {
     ESP_LOGI(TAG, "[%d] [%s]  characteristic %s, handle 0x%x, properties 0x%x", this->client->get_connection_index(),
              this->client->address_str().c_str(), characteristic->uuid.to_string().c_str(), characteristic->handle,
              characteristic->properties);
-    characteristic->parse_descriptors();
     offset++;
   }
 }

esphome/components/esp32_ble_client/ble_service.h

@@ -18,6 +18,7 @@ class BLEClientBase;
 class BLEService {
  public:
   ~BLEService();
+  bool parsed = false;
   espbt::ESPBTUUID uuid;
   uint16_t start_handle;
   uint16_t end_handle;