Package io.opentelemetry.sdk.common

Interface Clock

@ThreadSafe
public interface Clock

Interface for getting the current time.

Method Summary

Modifier and Type	Method	Description
static Clock	getDefault()	Returns a default Clock which reads from system time.
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.
default long	now(boolean highPrecision)	Returns the current epoch timestamp in nanos from this clock.

Method Details

getDefault

static Clock getDefault()

Returns a default Clock which reads from system time.

now

long now()

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 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 now(boolean) with highPrecision=true.

now

default long now(boolean highPrecision)

Returns the current epoch timestamp in nanos from this clock.

This overload of 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 now() javadoc for details on usage.

Since:

1.38.0

nanoTime

long nanoTime()

Returns a time measurement with nanosecond precision that can only be used to calculate elapsed time.