Merge branch 'integration' into memory_api

esphome/core/scheduler.cpp

@@ -79,8 +79,22 @@ void HOT Scheduler::set_timer_common_(Component *component, SchedulerItem::Type
     return;
   }
 
+  // Get fresh timestamp BEFORE taking lock - millis_64_ may need to acquire lock itself
+  const uint64_t now = this->millis_64_(millis());
+
+  // Take lock early to protect scheduler_item_pool_ access
+  LockGuard guard{this->lock_};
+
   // Create and populate the scheduler item
-  auto item = make_unique<SchedulerItem>();
+  std::unique_ptr<SchedulerItem> item;
+  if (!this->scheduler_item_pool_.empty()) {
+    // Reuse from pool
+    item = std::move(this->scheduler_item_pool_.back());
+    this->scheduler_item_pool_.pop_back();
+  } else {
+    // Allocate new if pool is empty
+    item = make_unique<SchedulerItem>();
+  }
   item->component = component;
   item->set_name(name_cstr, !is_static_string);
   item->type = type;
@@ -99,7 +113,6 @@ void HOT Scheduler::set_timer_common_(Component *component, SchedulerItem::Type
   // Single-core platforms don't need thread-safe defer handling
   if (delay == 0 && type == SchedulerItem::TIMEOUT) {
     // Put in defer queue for guaranteed FIFO execution
-    LockGuard guard{this->lock_};
     if (!skip_cancel) {
       this->cancel_item_locked_(component, name_cstr, type);
     }
@@ -108,9 +121,6 @@ void HOT Scheduler::set_timer_common_(Component *component, SchedulerItem::Type
   }
 #endif /* not ESPHOME_THREAD_SINGLE */
 
-  // Get fresh timestamp for new timer/interval - ensures accurate scheduling
-  const auto now = this->millis_64_(millis());  // Fresh millis() call
-
   // Type-specific setup
   if (type == SchedulerItem::INTERVAL) {
     item->interval = delay;
@@ -142,8 +152,6 @@ void HOT Scheduler::set_timer_common_(Component *component, SchedulerItem::Type
   }
 #endif /* ESPHOME_DEBUG_SCHEDULER */
 
-  LockGuard guard{this->lock_};
-
   // For retries, check if there's a cancelled timeout first
   if (is_retry && name_cstr != nullptr && type == SchedulerItem::TIMEOUT &&
       (has_cancelled_timeout_in_container_(this->items_, component, name_cstr, /* match_retry= */ true) ||
@@ -335,11 +343,11 @@ void HOT Scheduler::call(uint32_t now) {
 #ifdef ESPHOME_THREAD_MULTI_ATOMICS
     const auto last_dbg = this->last_millis_.load(std::memory_order_relaxed);
     const auto major_dbg = this->millis_major_.load(std::memory_order_relaxed);
-    ESP_LOGD(TAG, "Items: count=%zu, now=%" PRIu64 " (%" PRIu16 ", %" PRIu32 ")", this->items_.size(), now_64,
+    ESP_LOGD(TAG, "Items: count=%zu, pool=%zu, now=%" PRIu64 " (%" PRIu16 ", %" PRIu32 ")", this->items_.size(),
-             major_dbg, last_dbg);
+             this->scheduler_item_pool_.size(), now_64, major_dbg, last_dbg);
 #else  /* not ESPHOME_THREAD_MULTI_ATOMICS */
-    ESP_LOGD(TAG, "Items: count=%zu, now=%" PRIu64 " (%" PRIu16 ", %" PRIu32 ")", this->items_.size(), now_64,
+    ESP_LOGD(TAG, "Items: count=%zu, pool=%zu, now=%" PRIu64 " (%" PRIu16 ", %" PRIu32 ")", this->items_.size(),
-             this->millis_major_, this->last_millis_);
+             this->scheduler_item_pool_.size(), now_64, this->millis_major_, this->last_millis_);
 #endif /* else ESPHOME_THREAD_MULTI_ATOMICS */
     // Cleanup before debug output
     this->cleanup_();
@@ -380,10 +388,13 @@ void HOT Scheduler::call(uint32_t now) {
 
     std::vector<std::unique_ptr<SchedulerItem>> valid_items;
 
-    // Move all non-removed items to valid_items
+    // Move all non-removed items to valid_items, recycle removed ones
     for (auto &item : this->items_) {
-      if (!item->remove) {
+      if (!is_item_removed_(item.get())) {
         valid_items.push_back(std::move(item));
+      } else {
+        // Recycle removed items
+        this->recycle_item_(std::move(item));
       }
     }
 
@@ -469,6 +480,9 @@ void HOT Scheduler::call(uint32_t now) {
         // Add new item directly to to_add_
         // since we have the lock held
         this->to_add_.push_back(std::move(item));
+      } else {
+        // Timeout completed - recycle it
+        this->recycle_item_(std::move(item));
       }
     }
   }
@@ -518,6 +532,10 @@ size_t HOT Scheduler::cleanup_() {
 }
 void HOT Scheduler::pop_raw_() {
   std::pop_heap(this->items_.begin(), this->items_.end(), SchedulerItem::cmp);
+
+  // Instead of destroying, recycle the item
+  this->recycle_item_(std::move(this->items_.back()));
+
   this->items_.pop_back();
 }
 
@@ -552,18 +570,14 @@ bool HOT Scheduler::cancel_item_locked_(Component *component, const char *name_c
 
   // Check all containers for matching items
 #ifndef ESPHOME_THREAD_SINGLE
-  // Only check defer queue for timeouts (intervals never go there)
+  // Cancel and immediately recycle items in defer queue
   if (type == SchedulerItem::TIMEOUT) {
-    for (auto &item : this->defer_queue_) {
+    total_cancelled +=
-      if (this->matches_item_(item, component, name_cstr, type, match_retry)) {
+        this->cancel_and_recycle_from_container_(this->defer_queue_, component, name_cstr, type, match_retry);
-        this->mark_item_removed_(item.get());
-        total_cancelled++;
-      }
-    }
   }
 #endif /* not ESPHOME_THREAD_SINGLE */
 
-  // Cancel items in the main heap
+  // Cancel items in the main heap (can't recycle immediately due to heap structure)
   for (auto &item : this->items_) {
     if (this->matches_item_(item, component, name_cstr, type, match_retry)) {
       this->mark_item_removed_(item.get());
@@ -572,14 +586,8 @@ bool HOT Scheduler::cancel_item_locked_(Component *component, const char *name_c
     }
   }
 
-  // Cancel items in to_add_
+  // Cancel and immediately recycle items in to_add_ since they're not in heap yet
-  for (auto &item : this->to_add_) {
+  total_cancelled += this->cancel_and_recycle_from_container_(this->to_add_, component, name_cstr, type, match_retry);
-    if (this->matches_item_(item, component, name_cstr, type, match_retry)) {
-      this->mark_item_removed_(item.get());
-      total_cancelled++;
-      // Don't track removals for to_add_ items
-    }
-  }
 
   return total_cancelled > 0;
 }
@@ -747,4 +755,24 @@ bool HOT Scheduler::SchedulerItem::cmp(const std::unique_ptr<SchedulerItem> &a,
   return a->next_execution_ > b->next_execution_;
 }
 
+void Scheduler::recycle_item_(std::unique_ptr<SchedulerItem> item) {
+  if (!item)
+    return;
+
+  // Pool size of 8 is a balance between memory usage and performance:
+  // - Small enough to not waste memory on simple configs (1-2 timers)
+  // - Large enough to handle complex setups with multiple sensors/components
+  // - Prevents system-wide stalls from heap allocation/deallocation that can
+  //   disrupt task synchronization and cause dropped events
+  static constexpr size_t MAX_POOL_SIZE = 8;
+  if (this->scheduler_item_pool_.size() < MAX_POOL_SIZE) {
+    // Clear callback to release captured resources
+    item->callback = nullptr;
+    // Clear dynamic name if any
+    item->clear_dynamic_name();
+    this->scheduler_item_pool_.push_back(std::move(item));
+  }
+  // else: unique_ptr will delete the item when it goes out of scope
+}
+
 }  // namespace esphome

esphome/core/scheduler.h

@@ -5,6 +5,7 @@
 #include <memory>
 #include <cstring>
 #include <deque>
+#include <array>
 #ifdef ESPHOME_THREAD_MULTI_ATOMICS
 #include <atomic>
 #endif
@@ -142,11 +143,7 @@ class Scheduler {
     }
 
     // Destructor to clean up dynamic names
-    ~SchedulerItem() {
+    ~SchedulerItem() { clear_dynamic_name(); }
-      if (name_is_dynamic) {
-        delete[] name_.dynamic_name;
-      }
-    }
 
     // Delete copy operations to prevent accidental copies
     SchedulerItem(const SchedulerItem &) = delete;
@@ -159,13 +156,19 @@ class Scheduler {
     // Helper to get the name regardless of storage type
     const char *get_name() const { return name_is_dynamic ? name_.dynamic_name : name_.static_name; }
 
+    // Helper to clear dynamic name if allocated
+    void clear_dynamic_name() {
+      if (name_is_dynamic && name_.dynamic_name) {
+        delete[] name_.dynamic_name;
+        name_.dynamic_name = nullptr;
+        name_is_dynamic = false;
+      }
+    }
+
     // Helper to set name with proper ownership
     void set_name(const char *name, bool make_copy = false) {
       // Clean up old dynamic name if any
-      if (name_is_dynamic && name_.dynamic_name) {
+      clear_dynamic_name();
-        delete[] name_.dynamic_name;
-        name_is_dynamic = false;
-      }
 
       if (!name) {
         // nullptr case - no name provided
@@ -240,10 +243,13 @@ class Scheduler {
   void execute_item_(SchedulerItem *item, uint32_t now);
 
   // Helper to check if item should be skipped
-  bool should_skip_item_(const SchedulerItem *item) const {
+  bool should_skip_item_(SchedulerItem *item) const {
-    return item->remove || (item->component != nullptr && item->component->is_failed());
+    return is_item_removed_(item) || (item->component != nullptr && item->component->is_failed());
   }
 
+  // Helper to recycle a SchedulerItem
+  void recycle_item_(std::unique_ptr<SchedulerItem> item);
+
   // Helper to check if item is marked for removal (platform-specific)
   // Returns true if item should be skipped, handles platform-specific synchronization
   // For ESPHOME_THREAD_MULTI_NO_ATOMICS platforms, the caller must hold the scheduler lock before calling this
@@ -280,14 +286,33 @@ class Scheduler {
   bool has_cancelled_timeout_in_container_(const Container &container, Component *component, const char *name_cstr,
                                            bool match_retry) const {
     for (const auto &item : container) {
-      if (item->remove && this->matches_item_(item, component, name_cstr, SchedulerItem::TIMEOUT, match_retry,
+      if (is_item_removed_(item.get()) &&
-                                              /* skip_removed= */ false)) {
+          this->matches_item_(item, component, name_cstr, SchedulerItem::TIMEOUT, match_retry,
+                              /* skip_removed= */ false)) {
         return true;
       }
     }
     return false;
   }
 
+  // Template helper to cancel and recycle items from a container
+  template<typename Container>
+  size_t cancel_and_recycle_from_container_(Container &container, Component *component, const char *name_cstr,
+                                            SchedulerItem::Type type, bool match_retry) {
+    size_t cancelled = 0;
+    for (auto it = container.begin(); it != container.end();) {
+      if (this->matches_item_(*it, component, name_cstr, type, match_retry)) {
+        // Recycle the cancelled item immediately
+        this->recycle_item_(std::move(*it));
+        it = container.erase(it);
+        cancelled++;
+      } else {
+        ++it;
+      }
+    }
+    return cancelled;
+  }
+
   Mutex lock_;
   std::vector<std::unique_ptr<SchedulerItem>> items_;
   std::vector<std::unique_ptr<SchedulerItem>> to_add_;
@@ -297,6 +322,16 @@ class Scheduler {
 #endif                                                      /* ESPHOME_THREAD_SINGLE */
   uint32_t to_remove_{0};
 
+  // Memory pool for recycling SchedulerItem objects to reduce heap churn.
+  // Design decisions:
+  // - std::vector is used instead of a fixed array because many systems only need 1-2 scheduler items
+  // - The vector grows dynamically up to MAX_POOL_SIZE (8) only when needed, saving memory on simple setups
+  // - This approach balances memory efficiency for simple configs with performance for complex ones
+  // - The pool significantly reduces heap fragmentation which is critical because heap allocation/deallocation
+  //   can stall the entire system, causing timing issues and dropped events for any components that need
+  //   to synchronize between tasks (see https://github.com/esphome/backlog/issues/52)
+  std::vector<std::unique_ptr<SchedulerItem>> scheduler_item_pool_;
+
 #ifdef ESPHOME_THREAD_MULTI_ATOMICS
   /*
    * Multi-threaded platforms with atomic support: last_millis_ needs atomic for lock-free updates