1import time
2import threading
3
4class SnowflakeGenerator:
5    def __init__(self, datacenter_id, worker_id, sequence=0):
6        self.datacenter_id = datacenter_id
7        self.worker_id = worker_id
8        self.sequence = sequence
9
10        self.last_timestamp = -1
11        self.epoch = 1288834974657
12
13        self.datacenter_id_bits = 5
14        self.worker_id_bits = 5
15        self.sequence_bits = 12
16
17        self.max_datacenter_id = -1 ^ (-1 << self.datacenter_id_bits)
18        self.max_worker_id = -1 ^ (-1 << self.worker_id_bits)
19
20        self.worker_id_shift = self.sequence_bits
21        self.datacenter_id_shift = self.sequence_bits + self.worker_id_bits
22        self.timestamp_left_shift = self.sequence_bits + self.worker_id_bits + self.datacenter_id_bits
23        self.sequence_mask = -1 ^ (-1 << self.sequence_bits)
24
25        self._lock = threading.Lock()
26
27    def _til_next_millis(self, last_timestamp):
28        timestamp = self._get_timestamp()
29        while timestamp <= last_timestamp:
30            timestamp = self._get_timestamp()
31        return timestamp
32
33    def _get_timestamp(self):
34        return int(time.time() * 1000)
35
36    def next_id(self):
37        with self._lock:
38            timestamp = self._get_timestamp()
39
40            if timestamp < self.last_timestamp:
41                raise ValueError("時計が逆に進みました。IDの生成を拒否します")
42
43            if timestamp == self.last_timestamp:
44                self.sequence = (self.sequence + 1) & self.sequence_mask
45                if self.sequence == 0:
46                    timestamp = self._til_next_millis(self.last_timestamp)
47            else:
48                self.sequence = 0
49
50            self.last_timestamp = timestamp
51
52            return ((timestamp - self.epoch) << self.timestamp_left_shift) | \
53                   (self.datacenter_id << self.datacenter_id_shift) | \
54                   (self.worker_id << self.worker_id_shift) | \
55                   self.sequence
56
57## 使用例
58generator = SnowflakeGenerator(datacenter_id=1, worker_id=1)
59snowflake_id = generator.next_id()
60print(f"生成されたスノーフレークID: {snowflake_id}")
61

1import java.util.concurrent.locks.Lock;
2import java.util.concurrent.locks.ReentrantLock;
3
4public class SnowflakeGenerator {
5    private final long epoch;
6    private final long datacenterIdBits;
7    private final long workerIdBits;
8    private final long sequenceBits;
9    private final long maxDatacenterId;
10    private final long maxWorkerId;
11    private final long workerIdShift;
12    private final long datacenterIdShift;
13    private final long timestampLeftShift;
14    private final long sequenceMask;
15
16    private long datacenterId;
17    private long workerId;
18    private long sequence = 0L;
19    private long lastTimestamp = -1L;
20
21    private final Lock lock = new ReentrantLock();
22
23    public SnowflakeGenerator(long datacenterId, long workerId) {
24        this.epoch = 1288834974657L;
25        this.datacenterIdBits = 5L;
26        this.workerIdBits = 5L;
27        this.sequenceBits = 12L;
28
29        this.maxDatacenterId = ~(-1L << datacenterIdBits);
30        this.maxWorkerId = ~(-1L << workerIdBits);
31
32        this.workerIdShift = sequenceBits;
33        this.datacenterIdShift = sequenceBits + workerIdBits;
34        this.timestampLeftShift = sequenceBits + workerIdBits + datacenterIdBits;
35        this.sequenceMask = ~(-1L << sequenceBits);
36
37        if (datacenterId > maxDatacenterId || datacenterId < 0) {
38            throw new IllegalArgumentException("datacenterIdはmaxDatacenterIdより大きくなることも0未満になることもできません");
39        }
40        if (workerId > maxWorkerId || workerId < 0) {
41            throw new IllegalArgumentException("workerIdはmaxWorkerIdより大きくなることも0未満になることもできません");
42        }
43        this.datacenterId = datacenterId;
44        this.workerId = workerId;
45    }
46
47    public long nextId() {
48        lock.lock();
49        try {
50            long timestamp = timeGen();
51            if (timestamp < lastTimestamp) {
52                throw new RuntimeException("時計が逆に進みました。IDの生成を拒否します");
53            }
54
55            if (lastTimestamp == timestamp) {
56                sequence = (sequence + 1) & sequenceMask;
57                if (sequence == 0) {
58                    timestamp = tilNextMillis(lastTimestamp);
59                }
60            } else {
61                sequence = 0L;
62            }
63
64            lastTimestamp = timestamp;
65
66            return ((timestamp - epoch) << timestampLeftShift) |
67                   (datacenterId << datacenterIdShift) |
68                   (workerId << workerIdShift) |
69                   sequence;
70        } finally {
71            lock.unlock();
72        }
73    }
74
75    private long tilNextMillis(long lastTimestamp) {
76        long timestamp = timeGen();
77        while (timestamp <= lastTimestamp) {
78            timestamp = timeGen();
79        }
80        return timestamp;
81    }
82
83    private long timeGen() {
84        return System.currentTimeMillis();
85    }
86
87    public static void main(String[] args) {
88        SnowflakeGenerator generator = new SnowflakeGenerator(1, 1);
89        long id = generator.nextId();
90        System.out.println("生成されたスノーフレークID: " + id);
91    }
92}
93