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Code Issues Releases Wiki Activity

[web_server_idf] Reduce flash by eliminating temporary string allocations in event formatting (#11658)

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Co-authored-by: Clyde Stubbs <2366188+clydebarrow@users.noreply.github.com>
This commit is contained in:
J. Nick Koston
2025-11-02 19:23:03 -06:00
committed by GitHub
parent 3f05fd82e5
commit cf76c3a747
1 changed files with 21 additions and 10 deletions
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31
esphome/components/web_server_idf/web_server_idf.cpp
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@@ -4,6 +4,7 @@
#include <memory> #include <memory>
#include <cstring> #include <cstring>
#include <cctype> #include <cctype>
#include <cinttypes>
#include "esphome/core/helpers.h" #include "esphome/core/helpers.h"
#include "esphome/core/log.h" #include "esphome/core/log.h"
@@ -245,8 +246,8 @@ void AsyncWebServerRequest::redirect(const std::string &url) {
} }
void AsyncWebServerRequest::init_response_(AsyncWebServerResponse *rsp, int code, const char *content_type) { void AsyncWebServerRequest::init_response_(AsyncWebServerResponse *rsp, int code, const char *content_type) {
// Set status code - use constants for common codes to avoid string allocation // Set status code - use constants for common codes, default to 500 for unknown codes
const char *status = nullptr; const char *status;
switch (code) { switch (code) {
case 200: case 200:
status = HTTPD_200; status = HTTPD_200;
@@ -258,9 +259,10 @@ void AsyncWebServerRequest::init_response_(AsyncWebServerResponse *rsp, int code
status = HTTPD_409; status = HTTPD_409;
break; break;
default: default:
status = HTTPD_500;
break; break;
} }
httpd_resp_set_status(*this, status == nullptr ? to_string(code).c_str() : status); httpd_resp_set_status(*this, status);
if (content_type && *content_type) { if (content_type && *content_type) {
httpd_resp_set_type(*this, content_type); httpd_resp_set_type(*this, content_type);
@@ -348,7 +350,13 @@ void AsyncWebServerResponse::addHeader(const char *name, const char *value) {
httpd_resp_set_hdr(*this->req_, name, value); httpd_resp_set_hdr(*this->req_, name, value);
} }
void AsyncResponseStream::print(float value) { this->print(to_string(value)); } void AsyncResponseStream::print(float value) {
// Use stack buffer to avoid temporary string allocation
// Size: sign (1) + digits (10) + decimal (1) + precision (6) + exponent (5) + null (1) = 24, use 32 for safety
char buf[32];
int len = snprintf(buf, sizeof(buf), "%f", value);
this->content_.append(buf, len);
}
void AsyncResponseStream::printf(const char *fmt, ...) { void AsyncResponseStream::printf(const char *fmt, ...) {
va_list args; va_list args;
@@ -593,16 +601,19 @@ bool AsyncEventSourceResponse::try_send_nodefer(const char *message, const char
event_buffer_.append(chunk_len_header); event_buffer_.append(chunk_len_header);
// Use stack buffer for formatting numeric fields to avoid temporary string allocations
// Size: "retry: " (7) + max uint32 (10 digits) + CRLF (2) + null (1) = 20 bytes, use 32 for safety
constexpr size_t num_buf_size = 32;
char num_buf[num_buf_size];
if (reconnect) { if (reconnect) {
event_buffer_.append("retry: ", sizeof("retry: ") - 1); int len = snprintf(num_buf, num_buf_size, "retry: %" PRIu32 CRLF_STR, reconnect);
event_buffer_.append(to_string(reconnect)); event_buffer_.append(num_buf, len);
event_buffer_.append(CRLF_STR, CRLF_LEN);
} }
if (id) { if (id) {
event_buffer_.append("id: ", sizeof("id: ") - 1); int len = snprintf(num_buf, num_buf_size, "id: %" PRIu32 CRLF_STR, id);
event_buffer_.append(to_string(id)); event_buffer_.append(num_buf, len);
event_buffer_.append(CRLF_STR, CRLF_LEN);
} }
if (event && *event) { if (event && *event) {