Class SystemClock

    • Constructor Summary

      Constructors 
      Modifier Constructor Description
      private SystemClock()  
    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      (package private) static Clock getInstance()
      Returns a SystemClock.
      long nanoTime()
      Returns a time measurement with nanosecond precision that can only be used to calculate elapsed time.
      long now()
      Returns the current epoch timestamp in nanos from this clock.
      long now​(boolean highPrecision)
      Returns the current epoch timestamp in nanos from this clock.
      java.lang.String toString()  
      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
    • Field Detail

    • Constructor Detail

      • SystemClock

        private SystemClock()
    • Method Detail

      • now

        public long now()
        Description copied from interface: Clock
        Returns the current epoch timestamp in nanos from this clock. This timestamp should only be used to compute a current time. To compute a duration, timestamps should always be obtained using Clock.nanoTime(). For example, this usage is correct.
        
         long startNanos = clock.nanoTime();
         // Spend time...
         long durationNanos = clock.nanoTime() - startNanos;
         

        This usage is NOT correct.

        
         long startNanos = clock.now();
         // Spend time...
         long durationNanos = clock.now() - startNanos;
         

        Calling this is equivalent to calling Clock.now(boolean) with highPrecision=true.

        Specified by:
        now in interface Clock
      • now

        public long now​(boolean highPrecision)
        Description copied from interface: Clock
        Returns the current epoch timestamp in nanos from this clock.

        This overload of Clock.now() includes a highPrecision argument which specifies whether the implementation should attempt to resolve higher precision at the potential expense of performance. For example, in java 9+ its sometimes possible to resolve ns precision higher than the ms precision of System.currentTimeMillis(), but doing so incurs a performance penalty which some callers may wish to avoid. In contrast, we don't currently know if resolving ns precision is possible in java 8, regardless of the value of highPrecision.

        See Clock.now() javadoc for details on usage.

        Specified by:
        now in interface Clock
      • nanoTime

        public long nanoTime()
        Description copied from interface: Clock
        Returns a time measurement with nanosecond precision that can only be used to calculate elapsed time.
        Specified by:
        nanoTime in interface Clock
      • toString

        public java.lang.String toString()
        Overrides:
        toString in class java.lang.Object