Code-C++-Snowflake
#include <iostream>
#include <chrono>
#include <stdexcept>
class Snowflake {
private:
// 雪花算法的各个参数
static constexpr int64_t workerIdBits = 5;
static constexpr int64_t datacenterIdBits = 5;
static constexpr int64_t sequenceBits = 12;
static constexpr int64_t maxWorkerId = -1 ^ (-1 << workerIdBits);
static constexpr int64_t maxDatacenterId = -1 ^ (-1 << datacenterIdBits);
static constexpr int64_t sequenceMask = -1 ^ (-1 << sequenceBits);
// sequenceMask =0b111111111111
int64_t workerId;
int64_t datacenterId;
int64_t sequence = 0;
int64_t lastTimestamp = -1;
public:
Snowflake(int64_t workerId, int64_t datacenterId)
: workerId(workerId), datacenterId(datacenterId) {}
int64_t generateId() {
// 获取当前时间戳（毫秒级）
auto timestamp = std::chrono::duration_cast<std::chrono::milliseconds>(
std::chrono::system_clock::now().time_since_epoch()).count();
if (timestamp < lastTimestamp) {
throw std::runtime_error("Invalid system clock!");
}
if (timestamp == lastTimestamp) {
sequence = (sequence + 1) & sequenceMask;
if (sequence == 0) {
timestamp = waitNextMillis(lastTimestamp);
}
} else {
sequence = 0;
}
lastTimestamp = timestamp;
// 生成最终的唯一ID
int64_t uniqueId = (timestamp << (workerIdBits + datacenterIdBits + sequenceBits)) |
(datacenterId << (workerIdBits + sequenceBits)) |
(workerId << sequenceBits) |
sequence;
return uniqueId;
}
private:
int64_t waitNextMillis(int64_t lastTimestamp) {
auto timestamp = std::chrono::duration_cast<std::chrono::milliseconds>(
std::chrono::system_clock::now().time_since_epoch()).count();
while (timestamp <= lastTimestamp) {
timestamp = std::chrono::duration_cast<std::chrono::milliseconds>(
std::chrono::system_clock::now().time_since_epoch()).count();
}
return timestamp;
}
};
int main() {
Snowflake snowflake(1, 1);
for (int i = 0; i < 10; i++) {
int64_t uniqueId = snowflake.generateId();
std::cout << uniqueId << std::endl;
}
return 0;
}