samer@0: 
samer@0: package saml.sched;
samer@0: 
samer@0: public class HRTimer {
samer@0: 
samer@2: 	private static long min_sleep=1200000; // 1.2 ms
samer@2: 	private static long wake_before=500000; // 0.5ms
samer@0: 
samer@0: 	public static void setMinimumSleepTime(long t) { min_sleep=t; }
samer@0: 	public static void setWakePrealarm(long t) { wake_before=t; }
samer@0: 
samer@0: 	public static long now() { return System.nanoTime(); }
samer@0: 	public static long sleepUntil(long t1) throws Exception {
samer@0: 		long t0=System.nanoTime();
samer@0: 		long dt=t1-t0;
samer@0: 		// System.out.println("need to wait for " + dt +"ns");
samer@0: 		if (dt>min_sleep) {
samer@0: 			long sleep_time=dt-wake_before;
samer@0: 			long millis=sleep_time/1000000;
samer@0: 			int  nanos=(int)(sleep_time-millis*1000000);
samer@0: 			// System.out.println("will sleep for "+millis+"ms + "+nanos+"ns");
samer@0: 			Thread.sleep(millis,nanos); 
samer@0: 		}
samer@0: 
samer@0: 		// go into a tight loop for the last few microseconds
samer@0: 		t0=System.nanoTime();
samer@0: 		// System.out.println("need to spin for "+(t1-t0)+"ns");
samer@0: 		while (t0<t1) t0=System.nanoTime();
samer@0: 		return t0-t1;
samer@0: 	}
samer@0: 	
samer@0: 	public static long estimateMinSleep() throws Exception {
samer@0: 		long t0,t1;
samer@0: 
samer@0: 		t0=System.nanoTime();
samer@0: 		Thread.sleep(0,1); 
samer@0: 		t1=System.nanoTime();
samer@0: 		return t1-t0;
samer@0: 	}
samer@0: 
samer@0: 	public static long estimateGranularity() {
samer@0: 		long t0, t1;
samer@0: 		t0=System.nanoTime();
samer@0: 		t1=System.nanoTime();
samer@0: 		return t1-t0;
samer@0: 	}
samer@0: };