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[fix](trx-frontend-http): avoid double JSON parse/serialize in /events

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inject_frontend_meta was calling serde_json::from_str + to_string on
every state update, adding two full JSON round-trips per SSE event.
Replace with string-level injection: strip the closing }, serialize only
the extra meta fields once, and re-close the object. The state JSON is
now serialized exactly once per update.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Signed-off-by: Stan Grams <sjg@haxx.space>
This commit is contained in:
Stan Grams
2026-03-09 21:46:37 +01:00
parent 75355c75a5
commit 824434e27e
1 changed files with 31 additions and 48 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/trx-client/trx-frontend/trx-frontend-http/src/api.rs
+31 -48
View File
@@ -98,58 +98,41 @@ pub async fn status_api(
.body(json))
}
/// Inject `"clients": N` into a JSON object string.
/// Append frontend meta fields to an already-serialised JSON object string.
///
/// Avoids a full parse→modify→reserialise cycle (two serde round-trips per
/// event) by working directly at the string level: strip the closing `}`,
/// serialize only the extra fields once, and re-close the object.
fn inject_frontend_meta(json: &str, meta: FrontendMeta) -> String {
let mut value: serde_json::Value = match serde_json::from_str(json) {
Ok(v) => v,
Err(_) => return json.to_string(),
};
let Some(map) = value.as_object_mut() else {
let trimmed = json.trim_end();
let Some(base) = trimmed.strip_suffix('}') else {
return json.to_string();
};
map.insert("clients".to_string(), serde_json::json!(meta.http_clients));
map.insert(
"rigctl_clients".to_string(),
serde_json::json!(meta.rigctl_clients),
);
if let Some(addr) = meta.rigctl_addr {
map.insert("rigctl_addr".to_string(), serde_json::json!(addr));
}
if let Some(rig_id) = meta.active_rig_id {
map.insert("active_rig_id".to_string(), serde_json::json!(rig_id));
}
map.insert("rig_ids".to_string(), serde_json::json!(meta.rig_ids));
if let Some(owner) = meta.owner_callsign {
map.insert("owner_callsign".to_string(), serde_json::json!(owner));
}
if let Some(url) = meta.owner_website_url {
map.insert("owner_website_url".to_string(), serde_json::json!(url));
}
if let Some(name) = meta.owner_website_name {
map.insert("owner_website_name".to_string(), serde_json::json!(name));
}
if let Some(url) = meta.ais_vessel_url_base {
map.insert("ais_vessel_url_base".to_string(), serde_json::json!(url));
}
map.insert(
"show_sdr_gain_control".to_string(),
serde_json::json!(meta.show_sdr_gain_control),
);
map.insert(
"initial_map_zoom".to_string(),
serde_json::json!(meta.initial_map_zoom),
);
map.insert(
"spectrum_coverage_margin_hz".to_string(),
serde_json::json!(meta.spectrum_coverage_margin_hz),
);
map.insert(
"spectrum_usable_span_ratio".to_string(),
serde_json::json!(meta.spectrum_usable_span_ratio),
);
serde_json::to_string(&value).unwrap_or_else(|_| json.to_string())
// Build only the extra key-value pairs as a JSON fragment.
let mut extra = serde_json::Map::new();
extra.insert("clients".into(), serde_json::json!(meta.http_clients));
extra.insert("rigctl_clients".into(), serde_json::json!(meta.rigctl_clients));
if let Some(v) = meta.rigctl_addr { extra.insert("rigctl_addr".into(), serde_json::json!(v)); }
if let Some(v) = meta.active_rig_id { extra.insert("active_rig_id".into(), serde_json::json!(v)); }
extra.insert("rig_ids".into(), serde_json::json!(meta.rig_ids));
if let Some(v) = meta.owner_callsign { extra.insert("owner_callsign".into(), serde_json::json!(v)); }
if let Some(v) = meta.owner_website_url { extra.insert("owner_website_url".into(), serde_json::json!(v)); }
if let Some(v) = meta.owner_website_name { extra.insert("owner_website_name".into(), serde_json::json!(v)); }
if let Some(v) = meta.ais_vessel_url_base { extra.insert("ais_vessel_url_base".into(), serde_json::json!(v)); }
extra.insert("show_sdr_gain_control".into(), serde_json::json!(meta.show_sdr_gain_control));
extra.insert("initial_map_zoom".into(), serde_json::json!(meta.initial_map_zoom));
extra.insert("spectrum_coverage_margin_hz".into(), serde_json::json!(meta.spectrum_coverage_margin_hz));
extra.insert("spectrum_usable_span_ratio".into(), serde_json::json!(meta.spectrum_usable_span_ratio));
// Serialize the extra map, strip its outer braces, and splice in.
let extra_json = match serde_json::to_string(&extra) {
Ok(s) => s,
Err(_) => return json.to_string(),
};
// extra_json = {"k":v,...} → strip { and }
let inner = &extra_json[1..extra_json.len() - 1];
format!("{base},{inner}}}")
}
fn frontend_meta_from_context(