Use smaller atomic types for ESP32 BLE Tracker ring buffer indices (#9106)

esphome/components/esp32_ble_tracker/esp32_ble_tracker.cpp

@@ -122,10 +122,10 @@ void ESP32BLETracker::loop() {
   // Consumer side: This runs in the main loop thread
   if (this->scanner_state_ == ScannerState::RUNNING) {
     // Load our own index with relaxed ordering (we're the only writer)
-    size_t read_idx = this->ring_read_index_.load(std::memory_order_relaxed);
+    uint8_t read_idx = this->ring_read_index_.load(std::memory_order_relaxed);
 
     // Load producer's index with acquire to see their latest writes
-    size_t write_idx = this->ring_write_index_.load(std::memory_order_acquire);
+    uint8_t write_idx = this->ring_write_index_.load(std::memory_order_acquire);
 
     while (read_idx != write_idx) {
       // Process one result at a time directly from ring buffer
@@ -409,11 +409,11 @@ void ESP32BLETracker::gap_scan_event_handler(const BLEScanResult &scan_result) {
     // IMPORTANT: Only this thread writes to ring_write_index_
 
     // Load our own index with relaxed ordering (we're the only writer)
-    size_t write_idx = this->ring_write_index_.load(std::memory_order_relaxed);
-    size_t next_write_idx = (write_idx + 1) % SCAN_RESULT_BUFFER_SIZE;
+    uint8_t write_idx = this->ring_write_index_.load(std::memory_order_relaxed);
+    uint8_t next_write_idx = (write_idx + 1) % SCAN_RESULT_BUFFER_SIZE;
 
     // Load consumer's index with acquire to see their latest updates
-    size_t read_idx = this->ring_read_index_.load(std::memory_order_acquire);
+    uint8_t read_idx = this->ring_read_index_.load(std::memory_order_acquire);
 
     // Check if buffer is full
     if (next_write_idx != read_idx) {

esphome/components/esp32_ble_tracker/esp32_ble_tracker.h

@@ -289,9 +289,9 @@ class ESP32BLETracker : public Component,
   // Consumer: ESPHome main loop (loop() method)
   // This design ensures zero blocking in the BT callback and prevents scan result loss
   BLEScanResult *scan_ring_buffer_;
-  std::atomic<size_t> ring_write_index_{0};      // Written only by BT callback (producer)
-  std::atomic<size_t> ring_read_index_{0};       // Written only by main loop (consumer)
-  std::atomic<size_t> scan_results_dropped_{0};  // Tracks buffer overflow events
+  std::atomic<uint8_t> ring_write_index_{0};       // Written only by BT callback (producer)
+  std::atomic<uint8_t> ring_read_index_{0};        // Written only by main loop (consumer)
+  std::atomic<uint16_t> scan_results_dropped_{0};  // Tracks buffer overflow events
 
   esp_bt_status_t scan_start_failed_{ESP_BT_STATUS_SUCCESS};
   esp_bt_status_t scan_set_param_failed_{ESP_BT_STATUS_SUCCESS};