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[ota] Pack deferred state args into uint32 to avoid heap allocation

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The notify_state_deferred_ lambda captured [this, state, progress, error]
(16 bytes on 32-bit), exceeding std::function SBO and forcing a heap
allocation on every OTA progress update.

Pack the three values into a single uint32_t:
- state (8 bits) + error (8 bits) + progress as fixed-point (16 bits)

The lambda now captures [this, packed] (8 bytes), fitting in SBO.
Progress resolution of 0.01% is more than adequate for OTA reporting.
This commit is contained in:
J. Nick Koston
2026-03-18 08:52:44 -10:00
parent 9a80c980cb
commit 9498c554bf
1 changed files with 9 additions and 1 deletions
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esphome/components/ota/ota_backend.h
+9 -1
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@@ -74,7 +74,15 @@ class OTAComponent : public Component {
* (like web_server OTA) to ensure listeners execute in the main loop.
*/
void notify_state_deferred_(OTAState state, float progress, uint8_t error) {
this->defer([this, state, progress, error]() { this->notify_state_(state, progress, error); });
// Pack state, error, and progress into a single uint32_t so the lambda
// captures only [this, packed] (8 bytes) — fits in std::function SBO.
// Layout: [state:8][error:8][progress_fixed:16] where progress is 0–10000 (0.01% resolution)
uint32_t packed = (static_cast<uint32_t>(state) << 24) | (static_cast<uint32_t>(error) << 16) |
static_cast<uint16_t>(progress * 100.0f);
this->defer([this, packed]() {
this->notify_state_(static_cast<OTAState>(packed >> 24), static_cast<float>(packed & 0xFFFF) / 100.0f,
static_cast<uint8_t>(packed >> 16));
});
}
std::vector<OTAStateListener *> state_listeners_;