Reduce synchronization scope when generating the TSID

[vladmihalcea]

Currently, the TsidFactory.create method is synchronized:

public synchronized Tsid create() {

	final long _time = getTime() << RANDOM_BITS;
	final long _node = (long) this.node << this.counterBits;
	final long _counter = (long) this.counter & this.counterMask;

	return new Tsid(_time | _node | _counter);
}

But, the synchronized is needed for getTime only. So, it is getTime that should be synchronized instead because of the timestamp monotonicity issues:

private synchronized long getTime() {

	long time = clock.millis();

	if (time <= this.lastTime) {
		this.counter++;
		// Carry is 1 if an overflow occurs after ++.
		int carry = this.counter >>> this.counterBits;
		this.counter = this.counter & this.counterMask;
		time = this.lastTime + carry; // increment time
	} else {
		// If the system clock has advanced as expected,
		// simply reset the counter to a new random value.
		this.counter = this.getRandomCounter();
	}

	// save current time
	this.lastTime = time;

	// adjust to the custom epoch
	return time - this.customEpoch;
}

This will reduce the scope of the Thread contention, especially when using a ThreadLocalRandom generator.

[fabiolimace]

I did as you suggested, Vlad. Thanks for the tip!

[fabiolimace]

Released v5.2.2. 🎉

[vladmihalcea]

Thanks. I plan on creating a Tsid Hibernate generator based on your Tsid.

[fabiolimace]

This is going to be great!

Take what you need from this project and use it on your own. Go ahead and make a better TSID!

I don't intend to add more features here. From now on, this project will only be maintained. I'm getting tired.

I wish you good luck!

[vladmihalcea]

All the best 👍