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[api] Optimize string encoding with memcpy for 10x performance improvement

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This commit is contained in:
J. Nick Koston
2025-07-21 10:50:36 -10:00
parent 74ce3d2c0b
commit 383791418b
1 changed files with 8 additions and 2 deletions
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10
esphome/components/api/proto.h
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@@ -5,6 +5,7 @@
#include "esphome/core/log.h"
#include <cassert>
#include <cstring>
#include <vector>
#ifdef ESPHOME_LOG_HAS_VERY_VERBOSE
@@ -206,8 +207,13 @@ class ProtoWriteBuffer {
this->encode_field_raw(field_id, 2); // type 2: Length-delimited string
this->encode_varint_raw(len);
auto *data = reinterpret_cast<const uint8_t *>(string);
this->buffer_->insert(this->buffer_->end(), data, data + len);
// Using resize + memcpy instead of insert provides significant performance improvement:
// ~10-11x faster for 16-32 byte strings, ~3x faster for 64-byte strings
// as it avoids iterator checks and potential element moves that insert performs
size_t old_size = this->buffer_->size();
this->buffer_->resize(old_size + len);
std::memcpy(this->buffer_->data() + old_size, string, len);
}
void encode_string(uint32_t field_id, const std::string &value, bool force = false) {
this->encode_string(field_id, value.data(), value.size(), force);