The scheduler was already managing SchedulerItem lifecycle explicitly
through its object pool (recycle_item_main_loop_ / get_item_from_pool_locked_).
The unique_ptr wrapper added overhead (11 destructor call sites on the hot path)
without providing safety — if a lifecycle path was missed, the unique_ptr would
silently delete the item and cause needless heap allocations instead of pool reuse.
Replace unique_ptr<SchedulerItem, SchedulerItemDeleter> with raw SchedulerItem*
throughout. Every item is now explicitly recycled to the pool or deleted via
delete_item_(). This eliminates all 11 unique_ptr destructor calls from the hot
path and saves ~256 bytes of firmware.
Add debug leak detection under ESPHOME_DEBUG_SCHEDULER: a live-item counter
verified at the end of every call() cycle asserts that all allocated items are
accounted for in items_, to_add_, defer_queue_, or the pool. This turns silent
heap churn from missed lifecycle management into an immediate assert failure
caught by integration tests.
Also moves the retry-cancelled check before item allocation in set_timer_common_
to avoid needless alloc+delete on the cold retry path, and fixes a thread-safety
issue where recycle_item_main_loop_ (main-loop-only) was called from
set_timer_common_ which can run on non-main-loop threads.
Enable debug_scheduler: true in all 18 scheduler integration test fixtures.
Co-authored-by: J. Nick Koston <nick@koston.org>
Co-authored-by: pre-commit-ci-lite[bot] <117423508+pre-commit-ci-lite[bot]@users.noreply.github.com>
Co-authored-by: J. Nick Koston <nick@home-assistant.io>
Replace std::vector<uint8_t> with a minimal APIBuffer class for the
shared protobuf write buffer, frame helper receive buffer (rx_buf_),
and noise handshake prologue buffer.
std::vector::resize() zero-fills new bytes via memset. Every byte is
immediately overwritten by the protobuf encoder or socket reads,
making the zero-fill pure waste. APIBuffer skips zero-initialization
on resize() and uses make_unique_for_overwrite where available.
Also removes a dead write_raw_ template overload from api_frame_helper.h.
Add inject_to_rx_buffer_delayed() to uart_mock which stages bytes
that aren't visible to available() until the delay elapses. This
simulates USB packet delivery latency.
The test uses a 40ms delay which is:
- Greater than the old ~2ms timeout (fails without fix)
- Less than the new 50ms fallback timeout (passes with fix)
- Add test fixture simulating USB UART (no rx_full_threshold set)
with a 20ms gap between response chunks
- Make rx_full_threshold optional in uart_mock
- Extract MODBUS_BITS_PER_CHAR and MS_PER_SEC constexprs
J. Nick Koston