org.enodeframework.common.extensions.SystemClock Maven / Gradle / Ivy
package org.enodeframework.common.extensions;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicLong;
/**
* 高并发场景下System.currentTimeMillis()的性能问题优化
*/
public class SystemClock {
private final long period;
private final AtomicLong now;
private SystemClock(long period) {
this.period = period;
this.now = new AtomicLong(System.currentTimeMillis());
scheduleClockUpdating();
}
private static SystemClock instance() {
return InstanceHolder.INSTANCE;
}
public static long now() {
return instance().currentTimeMillis();
}
private void scheduleClockUpdating() {
ScheduledExecutorService scheduler = Executors.newSingleThreadScheduledExecutor(runnable -> {
Thread thread = new Thread(runnable, "System Clock");
thread.setDaemon(true);
return thread;
});
scheduler.scheduleAtFixedRate(() -> now.set(System.currentTimeMillis()), period, period, TimeUnit.MILLISECONDS);
}
private long currentTimeMillis() {
return now.get();
}
private static class InstanceHolder {
public static final SystemClock INSTANCE = new SystemClock(1);
}
}