Extract lock-free queue and event pool to core helpers

esphome/components/esp32_ble/ble.cpp

@@ -1,7 +1,6 @@
 #ifdef USE_ESP32
 
 #include "ble.h"
-#include "ble_event_pool.h"
 
 #include "esphome/core/application.h"
 #include "esphome/core/helpers.h"

esphome/components/esp32_ble/ble.h

@@ -12,8 +12,8 @@
 #include "esphome/core/helpers.h"
 
 #include "ble_event.h"
-#include "ble_event_pool.h"
+#include "esphome/core/lock_free_queue.h"
-#include "queue.h"
+#include "esphome/core/event_pool.h"
 
 #ifdef USE_ESP32
 
@@ -148,8 +148,8 @@ class ESP32BLE : public Component {
   std::vector<BLEStatusEventHandler *> ble_status_event_handlers_;
   BLEComponentState state_{BLE_COMPONENT_STATE_OFF};
 
-  LockFreeQueue<BLEEvent, MAX_BLE_QUEUE_SIZE> ble_events_;
+  esphome::LockFreeQueue<BLEEvent, MAX_BLE_QUEUE_SIZE> ble_events_;
-  BLEEventPool<MAX_BLE_QUEUE_SIZE> ble_event_pool_;
+  esphome::EventPool<BLEEvent, MAX_BLE_QUEUE_SIZE> ble_event_pool_;
   BLEAdvertising *advertising_{};
   esp_ble_io_cap_t io_cap_{ESP_IO_CAP_NONE};
   uint32_t advertising_cycle_time_{};

esphome/components/esp32_ble/ble_event.h

@@ -139,6 +139,9 @@ class BLEEvent {
   // Default constructor for pre-allocation in pool
   BLEEvent() : type_(GAP) {}
 
+  // Invoked on return to EventPool
+  void clear() { this->cleanup_heap_data(); }
+
   // Clean up any heap-allocated data
   void cleanup_heap_data() {
     if (this->type_ == GAP) {

esphome/core/event_pool.h

@@ -4,22 +4,20 @@
 
 #include <atomic>
 #include <cstddef>
-#include "ble_event.h"
-#include "queue.h"
 #include "esphome/core/helpers.h"
+#include "esphome/core/lock_free_queue.h"
 
 namespace esphome {
-namespace esp32_ble {
 
-// BLE Event Pool - On-demand pool of BLEEvent objects to avoid heap fragmentation
+// Event Pool - On-demand pool of objects to avoid heap fragmentation
 // Events are allocated on first use and reused thereafter, growing to peak usage
-template<uint8_t SIZE> class BLEEventPool {
+template<class T, uint8_t SIZE> class EventPool {
  public:
-  BLEEventPool() : total_created_(0) {}
+  EventPool() : total_created_(0) {}
 
-  ~BLEEventPool() {
+  ~EventPool() {
     // Clean up any remaining events in the free list
-    BLEEvent *event;
+    T *event;
     while ((event = this->free_list_.pop()) != nullptr) {
       delete event;
     }
@@ -27,9 +25,9 @@ template<uint8_t SIZE> class BLEEventPool {
 
   // Allocate an event from the pool
   // Returns nullptr if pool is full
-  BLEEvent *allocate() {
+  T *allocate() {
     // Try to get from free list first
-    BLEEvent *event = this->free_list_.pop();
+    T *event = this->free_list_.pop();
     if (event != nullptr)
       return event;
 
@@ -40,7 +38,7 @@ template<uint8_t SIZE> class BLEEventPool {
     }
 
     // Use internal RAM for better performance
-    RAMAllocator<BLEEvent> allocator(RAMAllocator<BLEEvent>::ALLOC_INTERNAL);
+    RAMAllocator<T> allocator(RAMAllocator<T>::ALLOC_INTERNAL);
     event = allocator.allocate(1);
 
     if (event == nullptr) {
@@ -49,24 +47,25 @@ template<uint8_t SIZE> class BLEEventPool {
     }
 
     // Placement new to construct the object
-    new (event) BLEEvent();
+    new (event) T();
     this->total_created_++;
     return event;
   }
 
   // Return an event to the pool for reuse
-  void release(BLEEvent *event) {
+  void release(T *event) {
     if (event != nullptr) {
+      // Clean up the event's allocated memory
+      event->clear();
       this->free_list_.push(event);
     }
   }
 
  private:
-  LockFreeQueue<BLEEvent, SIZE> free_list_;  // Free events ready for reuse
+  LockFreeQueue<T, SIZE> free_list_;  // Free events ready for reuse
-  uint8_t total_created_;                    // Total events created (high water mark)
+  uint8_t total_created_;             // Total events created (high water mark)
 };
 
-}  // namespace esp32_ble
 }  // namespace esphome
 
 #endif

esphome/core/lock_free_queue.h

@@ -4,23 +4,25 @@
 
 #include <atomic>
 #include <cstddef>
+#include <freertos/FreeRTOS.h>
+#include <freertos/task.h>
 
 /*
- * BLE events come in from a separate Task (thread) in the ESP32 stack. Rather
+ * Lock-free queue for single-producer single-consumer scenarios.
- * than using mutex-based locking, this lock-free queue allows the BLE
+ * This allows one thread to push items and another to pop them without
- * task to enqueue events without blocking. The main loop() then processes
+ * blocking each other.
- * these events at a safer time.
  *
  * This is a Single-Producer Single-Consumer (SPSC) lock-free ring buffer.
- * The BLE task is the only producer, and the main loop() is the only consumer.
+ * Common use cases:
+ * - BLE events: BLE task produces, main loop consumes
+ * - MQTT messages: main task produces, MQTT thread consumes
  */
 
 namespace esphome {
-namespace esp32_ble {
 
 template<class T, uint8_t SIZE> class LockFreeQueue {
  public:
-  LockFreeQueue() : head_(0), tail_(0), dropped_count_(0) {}
+  LockFreeQueue() : head_(0), tail_(0), dropped_count_(0), task_to_notify_(nullptr) {}
 
   bool push(T *element) {
     if (element == nullptr)
@@ -29,14 +31,37 @@ template<class T, uint8_t SIZE> class LockFreeQueue {
     uint8_t current_tail = tail_.load(std::memory_order_relaxed);
     uint8_t next_tail = (current_tail + 1) % SIZE;
 
-    if (next_tail == head_.load(std::memory_order_acquire)) {
+    // Read head before incrementing tail
+    uint8_t head_before = head_.load(std::memory_order_acquire);
+
+    if (next_tail == head_before) {
       // Buffer full
       dropped_count_.fetch_add(1, std::memory_order_relaxed);
       return false;
     }
 
+    // Check if queue was empty before push
+    bool was_empty = (current_tail == head_before);
+
     buffer_[current_tail] = element;
     tail_.store(next_tail, std::memory_order_release);
+
+    // Notify optimization: only notify if we need to
+    if (task_to_notify_ != nullptr) {
+      if (was_empty) {
+        // Queue was empty - consumer might be going to sleep, must notify
+        xTaskNotifyGive(task_to_notify_);
+      } else {
+        // Queue wasn't empty - check if consumer has caught up to previous tail
+        uint8_t head_after = head_.load(std::memory_order_acquire);
+        if (head_after == current_tail) {
+          // Consumer just caught up to where tail was - might go to sleep, must notify
+          xTaskNotifyGive(task_to_notify_);
+        }
+        // Otherwise: consumer is still behind, no need to notify
+      }
+    }
+
     return true;
   }
 
@@ -69,6 +94,8 @@ template<class T, uint8_t SIZE> class LockFreeQueue {
     return next_tail == head_.load(std::memory_order_acquire);
   }
 
+  void set_task_to_notify(TaskHandle_t task) { task_to_notify_ = task; }
+
  protected:
   T *buffer_[SIZE];
   // Atomic: written by producer (push/increment), read+reset by consumer (get_and_reset)
@@ -77,9 +104,10 @@ template<class T, uint8_t SIZE> class LockFreeQueue {
   std::atomic<uint8_t> head_;
   // Atomic: written by producer (push), read by consumer (pop) to check if empty
   std::atomic<uint8_t> tail_;
+  // Task handle for notification (optional)
+  TaskHandle_t task_to_notify_;
 };
 
-}  // namespace esp32_ble
 }  // namespace esphome
 
 #endif