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Split LockFreeQueue into base and notifying variants to reduce memory usage

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J. Nick Koston 2025-07-05 08:58:41 -05:00
parent f98e28a8a2
commit e173b7f0c2
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1 changed files with 20 additions and 3 deletions
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23
esphome/core/lock_free_queue.h
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@ -118,9 +118,26 @@ template<class T, uint8_t SIZE> class NotifyingLockFreeQueue : public LockFreeQu
bool was_empty; bool was_empty;
bool result = this->push_internal_(element, was_empty); bool result = this->push_internal_(element, was_empty);
// Notify if push succeeded and queue was empty // Notify optimization: only notify if we need to
if (result && task_to_notify_ != nullptr && was_empty) { if (result && task_to_notify_ != nullptr) {
xTaskNotifyGive(task_to_notify_); 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 current_tail = this->tail_.load(std::memory_order_relaxed);
uint8_t head_after = this->head_.load(std::memory_order_acquire);
// We just pushed, so go back one position to get the old tail
uint8_t previous_tail = (current_tail + SIZE - 1) % SIZE;
if (head_after == previous_tail) {
// Consumer just caught up to where tail was - might go to sleep, must notify
// Note: There's a benign race here - between reading head_after and calling
// xTaskNotifyGive(), the consumer could advance further. This would result
// in an unnecessary wake-up, but is harmless and extremely rare in practice.
xTaskNotifyGive(task_to_notify_);
}
// Otherwise: consumer is still behind, no need to notify
}
} }
return result; return result;