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add http.request span + slow receive logging for latency diagnosis
server-side search is 0-2.5ms but TTFB is 1-2.5s for some requests.
the new http.request span wraps the full request lifecycle including
receiveHead(), and logs a warning when receive takes >100ms. this
will reveal whether the delay is in Fly proxy, connection queueing,
or request reading.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
+17
backend/src/server.zig
+17
backend/src/server.zig
···
26
var server = http.Server.init(reader.interface(), &writer.interface);
27
28
while (true) {
29
var request = server.receiveHead() catch |err| {
30
if (err != error.HttpConnectionClosing and err != error.EndOfStream) {
31
logfire.debug("http receive error: {}", .{err});
32
}
33
return;
34
};
35
handleRequest(&server, &request) catch |err| {
36
logfire.err("request error: {}", .{err});
37
return;
38
};
39
if (!request.head.keep_alive) return;
40
}
41
}
···
26
var server = http.Server.init(reader.interface(), &writer.interface);
27
28
while (true) {
29
+
const recv_start = std.time.microTimestamp();
30
var request = server.receiveHead() catch |err| {
31
if (err != error.HttpConnectionClosing and err != error.EndOfStream) {
32
logfire.debug("http receive error: {}", .{err});
33
}
34
return;
35
};
36
+
const recv_us = std.time.microTimestamp() - recv_start;
37
+
const target = request.head.target;
38
+
39
+
// log slow receives — this captures time waiting for the request to arrive
40
+
if (recv_us > 100_000) { // > 100ms
41
+
logfire.warn("http.receive slow: {d}ms | {s}", .{ @divTrunc(recv_us, 1000), target });
42
+
}
43
+
44
+
const req_span = logfire.span("http.request", .{
45
+
.target = target,
46
+
.receive_ms = @divTrunc(recv_us, 1000),
47
+
});
48
+
49
handleRequest(&server, &request) catch |err| {
50
logfire.err("request error: {}", .{err});
51
+
req_span.end();
52
return;
53
};
54
+
req_span.end();
55
+
56
if (!request.head.keep_alive) return;
57
}
58
}