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[dlms_meter] Batch UART reads to reduce per-loop overhead

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Replace byte-at-a-time read_byte() calls with batched read_array()
in loop(). Each read_byte() internally chains through
read_array(data, 1) -> check_read_timeout_(1) -> available(),
resulting in ~3 UART driver calls per byte. Batching into a 64-byte
stack buffer reduces this to ~3 calls per loop iteration regardless
of how many bytes are available.

Also uses vector insert() for bulk append instead of per-byte
push_back(), and caps reads to remaining buffer capacity upfront
to avoid over-reading from UART.
This commit is contained in:
J. Nick Koston
2026-02-07 00:22:00 +01:00
parent 86f91eed2f
commit cfbeea9983
1 changed files with 20 additions and 7 deletions
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27
esphome/components/dlms_meter/dlms_meter.cpp
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@@ -28,15 +28,28 @@ void DlmsMeterComponent::dump_config() {
void DlmsMeterComponent::loop() {
// Read while data is available, netznoe uses two frames so allow 2x max frame length
while (this->available()) {
if (this->receive_buffer_.size() >= MBUS_MAX_FRAME_LENGTH * 2) {
int avail = this->available();
if (avail > 0) {
size_t remaining = MBUS_MAX_FRAME_LENGTH * 2 - this->receive_buffer_.size();
if (remaining == 0) {
ESP_LOGW(TAG, "Receive buffer full, dropping remaining bytes");
break;
} else {
// Read all available bytes in batches to reduce UART call overhead.
// Cap reads to remaining buffer capacity.
if (static_cast<size_t>(avail) > remaining) {
avail = remaining;
}
uint8_t buf[64];
while (avail > 0) {
size_t to_read = std::min(static_cast<size_t>(avail), sizeof(buf));
if (!this->read_array(buf, to_read)) {
break;
}
avail -= to_read;
this->receive_buffer_.insert(this->receive_buffer_.end(), buf, buf + to_read);
this->last_read_ = millis();
}
}
uint8_t c;
this->read_byte(&c);
this->receive_buffer_.push_back(c);
this->last_read_ = millis();
}
if (!this->receive_buffer_.empty() && millis() - this->last_read_ > this->read_timeout_) {