Implementation example of SpringBoot custom snowflake algorithm generation ID
Snowflake is a distributed algorithm that generates unique IDs, introduced by Twitter. It can generate non-repetitive, chronological globally unique IDs. A typical Snowflake ID consists of 64 bits, usually divided as follows:
- 1-bit sign bit (always 0, indicating a positive number)
- 41-bit timestamp (millisecond level, indicating the offset of the current time relative to a certain start time)
- 10-bit machine ID (usually divided into data center ID and machine ID)
- 12-bit serial number (represents a counter within milliseconds)
Below is a custom snowflake algorithm to generate unique IDs. This implementation is similar to Twitter's Snowflake algorithm, with thread safety in mind.
public class SnowflakeIDGenerator {
// Start timestamp (2020-01-01 00:00:00) private final long twepoch = 1577836800000L;
// The number of bits occupied by each part private final long workerIdBits = 5L;
private final long datacenterIdBits = 5L;
private final long sequenceBits = 12L;
// Maximum value private final long maxWorkerId = -1L ^ (-1L << workerIdBits);
private final long maxDatacenterId = -1L ^ (-1L << datacenterIdBits);
// Displacement private final long workerIdShift = sequenceBits;
private final long datacenterIdShift = sequenceBits + workerIdBits;
private final long timestampLeftShift = sequenceBits + workerIdBits + datacenterIdBits;
// Mask private final long sequenceMask = -1L ^ (-1L << sequenceBits);
private long workerId;
private long datacenterId;
private long sequence = 0L;
private long lastTimestamp = -1L;
public SnowflakeIDGenerator(long workerId, long datacenterId) {
if (workerId > maxWorkerId || workerId < 0) {
throw new IllegalArgumentException(("worker Id can't be greater than %d or less than 0", maxWorkerId));
}
if (datacenterId > maxDatacenterId || datacenterId < 0) {
throw new IllegalArgumentException(("datacenter Id can't be greater than %d or less than 0", maxDatacenterId));
}
= workerId;
= datacenterId;
}
public synchronized long nextId() {
long timestamp = timeGen();
if (timestamp < lastTimestamp) {
throw new RuntimeException(("Clock moved backwards. Refusing to generate id for %d milliseconds", lastTimestamp - timestamp));
}
if (lastTimestamp == timestamp) {
sequence = (sequence + 1) & sequenceMask;
if (sequence == 0) {
timestamp = tilNextMillis(lastTimestamp);
}
} else {
sequence = 0L;
}
lastTimestamp = timestamp;
return ((timestamp - twepoch) << timestampLeftShift)
| (datacenterId << datacenterIdShift)
| (workerId << workerIdShift)
| sequence;
}
protected long tilNextMillis(long lastTimestamp) {
long timestamp = timeGen();
while (timestamp <= lastTimestamp) {
timestamp = timeGen();
}
return timestamp;
}
protected long timeGen() {
return ();
}
public static void main(String[] args) {
SnowflakeIDGenerator generator = new SnowflakeIDGenerator(1, 1);
for (int i = 0; i < 10; i++) {
(());
}
}
}
illustrate
-
Initialization parameters:
-
twepoch: Custom starting timestamp (can be any time in the past), ensuring that the generated ID is unique and ordered. -
workerIdBitsanddatacenterIdBits: The number of bits (usually 5 bits) of the work node ID and the data center ID, respectively. -
sequenceBits: The number of digits representing the serial number (usually 12 digits).
-
-
Maximum value calculation:
-
maxWorkerIdandmaxDatacenterId: The maximum value calculated based on the number of digits to ensure that the ID is within a reasonable range.
-
-
Displacement amount:
-
workerIdShift,datacenterIdShift,timestampLeftShift: Used to move each part of the data to the correct position.
-
-
Mask:
-
sequenceMask: Make sure the serial number is cycling between 0 and 4095.
-
-
method:
-
nextId: Generate unique IDs and use synchronization blocks to ensure thread safety. -
tilNextMillis: Wait until the next millisecond. -
timeGen: Get the current timestamp.
-
Example of usage
Run the above code and you will see the generated unique IDs, which are incremented in chronological order, each ID contains information about the timestamp, data center ID, worker node ID, and serial number.
This is the end of this article about the implementation example of SpringBoot custom snowflake algorithm generation ID generation. For more related SpringBoot snowflake algorithm generation ID content, please search for my previous articles or continue browsing the related articles below. I hope everyone will support me in the future!
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