envoy log macros

tmp.cc

// use "clang -lstdc++ xxx.cc && ./a.out" to run & test

#include <unistd.h>

#include <atomic>
#include <chrono>
#include <iostream>

using namespace std::chrono_literals;

#define ENVOY_LOG(...) std::cerr << "logline" << std::endl;

#define ENVOY_LOG_FIRST_N(LEVEL, N, ...)                                                           \
  do {                                                                                             \
    static std::atomic<uint64_t>* countdown = new std::atomic<uint64_t>(N);                        \
    if (countdown->fetch_sub(1) > 0) {                                                             \
      ENVOY_LOG(LEVEL, ##__VA_ARGS__);                                                             \
    }                                                                                              \
  } while (0)

#define ENVOY_LOG_ONCE(LEVEL, ...) ENVOY_LOG_FIRST_N(LEVEL, 1, ##__VA_ARGS__)

#define ENVOY_LOG_EVERY_NTH(LEVEL, N, ...)                                                         \
  do {                                                                                             \
    static std::atomic<uint64_t>* count = new std::atomic<uint64_t>(1);                            \
    if ((count->fetch_add(1) % N) == 0) {                                                          \
      ENVOY_LOG(LEVEL, ##__VA_ARGS__);                                                             \
    }                                                                                              \
  } while (0)

#define ENVOY_LOG_PERIODIC(LEVEL, CHRONO_DURATION, ...)                                            \
  do {                                                                                             \
    static std::atomic<std::chrono::steady_clock::time_point>* last_hit =                          \
        new std::atomic<std::chrono::steady_clock::time_point>();                                  \
    auto last = last_hit->load();                                                                  \
    const auto now = std::chrono::steady_clock::now();                                             \
    if ((now - last) > CHRONO_DURATION && last_hit->compare_exchange_strong(last, now)) {          \
      ENVOY_LOG(LEVEL, ##__VA_ARGS__);                                                             \
    }                                                                                              \
  } while (0)

int main() {
  int i = 0;
  std::cerr << "expect four" << std::endl;
  while (i++ < 100) {
    ENVOY_LOG_FIRST_N("1", 2, "foo");
    ENVOY_LOG_FIRST_N("2", 2, "foo");
  }

  i = 0;
  std::cerr << "expect 8" << std::endl;
  while (i++ < 40) {
    ENVOY_LOG_EVERY_NTH("1", 10, "foo");
    ENVOY_LOG_EVERY_NTH("2", 10, "foo");
  }

  i = 0;
  std::cerr << "expect 6" << std::endl;
  while (i++ < 200) {
    ENVOY_LOG_PERIODIC("1", 0.1s, "foo");
    ENVOY_LOG_PERIODIC("2", 0.1s, "foo");
    usleep(1000);
  }
}