Ja.

utils.cpp

@@ -1,17 +1,36 @@
-
 #include "utils.h"
+
+#include <QJsonDocument>
+#include <QJsonObject>
+#include <QString>
+
 #include <chrono>
+#include <cstdarg>
+#include <cstdio>
+#include <vector>
 
 typedef struct {
     std::chrono::time_point<std::chrono::system_clock> start;
 } timer;
 
-
-
 static int _log_level = LOG_INFO;
 static timer *_timer = nullptr;
 
+static QString formattedMessage(const char *format, va_list args)
+{
+    va_list countArgs;
+    va_copy(countArgs, args);
+    const int length = std::vsnprintf(nullptr, 0, format, countArgs);
+    va_end(countArgs);
 
+    if (length < 0) {
+        return QString::fromUtf8(format);
+    }
+
+    std::vector<char> buffer(static_cast<size_t>(length) + 1);
+    std::vsnprintf(buffer.data(), buffer.size(), format, args);
+    return QString::fromUtf8(buffer.data(), length);
+}
 
 extern "C" {
 int logLevel()
@@ -27,27 +46,48 @@ void setLogLevel(int l)
 const char *logIndicator(int l)
 {
     switch(l) {
-    case LOG_ERROR:   return "ERROR  ";
-    case LOG_INFO:    return "INFO   ";
-    case LOG_DEBUG:   return "DEBUG  ";
-    case LOG_WARNING: return "WARNING";
+    case LOG_ERROR:   return "error";
+    case LOG_INFO:    return "info";
+    case LOG_DEBUG:   return "debug";
+    case LOG_WARNING: return "warning";
     }
-    return "UNKNOWN";
+    return "unknown";
 }
 
-void logElapsed()
+double logElapsedSeconds()
 {
     if (_timer == nullptr) {
         _timer = new timer;
         _timer->start = std::chrono::system_clock::now();
     }
 
-    auto c = std::chrono::system_clock::now();
-    auto duration = c - _timer->start;
-    auto milliseconds
+    const auto current = std::chrono::system_clock::now();
+    const auto milliseconds
         = std::chrono::duration_cast<std::chrono::milliseconds>(
-              duration)
+              current - _timer->start)
               .count();
-    fprintf(stderr, "%8.3lf: ", milliseconds/ 1000.0);
+    return milliseconds / 1000.0;
+}
+
+void logMessage(int level, const char *format, ...)
+{
+    if (logLevel() < level) {
+        return;
+    }
+
+    va_list args;
+    va_start(args, format);
+    const QString message = formattedMessage(format, args);
+    va_end(args);
+
+    QJsonObject object;
+    object.insert(QStringLiteral("topic"), QStringLiteral("webview-backend"));
+    object.insert(QStringLiteral("level"), QString::fromLatin1(logIndicator(level)));
+    object.insert(QStringLiteral("elapsed"), logElapsedSeconds());
+    object.insert(QStringLiteral("message"), message);
+
+    const QByteArray json = QJsonDocument(object).toJson(QJsonDocument::Compact);
+    std::fprintf(stderr, "json:%s\n", json.constData());
+    std::fflush(stderr);
 }
 }