Line data    Source code

       1             : #include "id_generator.h"
       2             : 
       3             : #include <bitset>
       4             : #include <chrono>
       5             : 
       6             : #include "random.h"
       7             : 
       8             : namespace datadog {
       9             : namespace tracing {
      10             : namespace {
      11             : 
      12             : class DefaultIDGenerator : public IDGenerator {
      13             :   const bool trace_id_128_bit_;
      14             : 
      15             :  public:
      16         593 :   explicit DefaultIDGenerator(bool trace_id_128_bit)
      17         593 :       : trace_id_128_bit_(trace_id_128_bit) {}
      18             : 
      19       82791 :   TraceID trace_id(const TimePoint& start) const override {
      20       82791 :     TraceID result;
      21       82791 :     result.low = random_uint64();
      22       82791 :     if (trace_id_128_bit_) {
      23             :       // Highest 32 bits contain a unix timestamp (the trace start time).
      24       82791 :       const auto since_epoch = start.wall.time_since_epoch();
      25             :       const auto seconds =
      26       82791 :           std::chrono::duration_cast<std::chrono::seconds>(since_epoch).count();
      27             :       // The farthest we'll go back is the unix epoch.
      28       82791 :       const std::uint64_t unsigned_seconds = seconds < 0 ? 0 : seconds;
      29       82791 :       result.high = unsigned_seconds << 32;
      30             :     } else {
      31             :       // In 64-bit mode, zero the most significant bit for compatibility with
      32             :       // older tracers that can't accept values above
      33             :       // `numeric_limits<int64_t>::max()`.
      34           0 :       std::bitset<64> bits = result.low;
      35           0 :       bits[63] = 0;
      36           0 :       result.low = bits.to_ullong();
      37             :     }
      38       82791 :     return result;
      39             :   }
      40             : 
      41         119 :   std::uint64_t span_id() const override {
      42             :     // Zero the most significant bit for compatibility with older tracers that
      43             :     // can't accept values above `numeric_limits<int64_t>::max()`.
      44         119 :     std::bitset<64> bits = random_uint64();
      45         119 :     bits[63] = 0;
      46         238 :     return bits.to_ullong();
      47             :   }
      48             : };
      49             : 
      50             : }  // namespace
      51             : 
      52         593 : std::shared_ptr<const IDGenerator> default_id_generator(bool trace_id_128_bit) {
      53         593 :   return std::make_shared<DefaultIDGenerator>(trace_id_128_bit);
      54             : }
      55             : 
      56             : }  // namespace tracing
      57             : }  // namespace datadog