void TraceEvent::AppendValueAsJSON()

in src/kudu/util/debug/trace_event_impl.cc [692:757]

• 54 lines of code
• 20 McCabe index (conditional complexity)

void TraceEvent::AppendValueAsJSON(unsigned char type,
                                   TraceEvent::TraceValue value,
                                   std::string* out) {
  switch (type) {
    case TRACE_VALUE_TYPE_BOOL:
      *out += value.as_bool ? "true" : "false";
      break;
    case TRACE_VALUE_TYPE_UINT:
      SubstituteAndAppend(out, "$0", static_cast<uint64_t>(value.as_uint));
      break;
    case TRACE_VALUE_TYPE_INT:
      SubstituteAndAppend(out, "$0", static_cast<int64_t>(value.as_int));
      break;
    case TRACE_VALUE_TYPE_DOUBLE: {
      // FIXME: base/json/json_writer.cc is using the same code,
      //        should be made into a common method.
      std::string real;
      double val = value.as_double;
      if (MathLimits<double>::IsFinite(val)) {
        real = strings::Substitute("$0", val);
        // Ensure that the number has a .0 if there's no decimal or 'e'.  This
        // makes sure that when we read the JSON back, it's interpreted as a
        // real rather than an int.
        if (real.find('.') == std::string::npos &&
            real.find('e') == std::string::npos &&
            real.find('E') == std::string::npos) {
          real.append(".0");
        }
        // The JSON spec requires that non-integer values in the range (-1,1)
        // have a zero before the decimal point - ".52" is not valid, "0.52" is.
        if (real[0] == '.') {
          real.insert(0, "0");
        } else if (real.length() > 1 && real[0] == '-' && real[1] == '.') {
          // "-.1" bad "-0.1" good
          real.insert(1, "0");
        }
      } else if (MathLimits<double>::IsNaN(val)){
        // The JSON spec doesn't allow NaN and Infinity (since these are
        // objects in EcmaScript).  Use strings instead.
        real = "\"NaN\"";
      } else if (val < 0) {
        real = "\"-Infinity\"";
      } else {
        real = "\"Infinity\"";
      }
      SubstituteAndAppend(out, "$0", real);
      break;
    }
    case TRACE_VALUE_TYPE_POINTER:
      // JSON only supports double and int numbers.
      // So as not to lose bits from a 64-bit pointer, output as a hex string.
      StringAppendF(out, "\"0x%" PRIx64 "\"", static_cast<uint64_t>(
                                     reinterpret_cast<intptr_t>(
                                     value.as_pointer)));
      break;
    case TRACE_VALUE_TYPE_STRING:
    case TRACE_VALUE_TYPE_COPY_STRING:
      *out += "\"";
      JsonEscape(value.as_string ? value.as_string : "NULL", out);
      *out += "\"";
      break;
    default:
      LOG(FATAL) << "Don't know how to print this value";
      break;
  }
}