Class SystemClock

java.lang.Object

io.opentelemetry.sdk.common.SystemClock

All Implemented Interfaces:

Clock

@ThreadSafe
final class SystemClock
extends Object
implements Clock

A Clock that uses JavaVersionSpecific.currentTimeNanos() and System.nanoTime().

Field Summary

Fields

Modifier and Type	Field	Description
private static final SystemClock	INSTANCE

Constructor Summary

Constructors

Modifier	Constructor	Description
private	SystemClock()

Method Summary

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.
String	toString()

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Details

INSTANCE

private static final SystemClock INSTANCE

Constructor Details

SystemClock

private SystemClock()

Method Details

getInstance

static Clock getInstance()

Returns a SystemClock.

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 String toString()

Overrides:

toString in class Object