xpertss.ds.utils.TimeProvider Maven / Gradle / Ivy
package xpertss.ds.utils;
/**
* A time provider that can be used to obtain clock times and a high resolution
* nano time.
*
* This tool enables better testing by allowing a time provider to be stubbed
* at runtime.
*
* User: cfloersch
* Date: 12/18/12
*/
public abstract class TimeProvider {
private static final InheritableThreadLocal cache = new InheritableThreadLocal();
private static final TimeProvider system = new SystemTime();
/**
* @return The current time in milliseconds.
* @see System#currentTimeMillis()
*/
public abstract long milliTime();
/**
* @return The current value of the nanosecond timer.
* @see System#nanoTime()
*/
public abstract long nanoTime();
/**
* Used to provide a TimeProvider stub that will be returned by the calling
* thread and all of its child threads. This allows an alternative to the
* system time provider to be used within the context of a unit test where
* precise times are needed for testing.
*/
public static void stub(TimeProvider stub)
{
cache.set(stub);
}
/**
* Clear any stubbed time providers that may be associated with the calling
* thread.
*/
public static void clear() { cache.set(null); }
/**
* Get the default time provider for the calling thread. If a stub has not
* been defined this will return the system time provider.
*/
public static TimeProvider get()
{
TimeProvider stub = cache.get();
return (stub == null) ? system : stub;
}
private static class SystemTime extends TimeProvider {
@Override
public long milliTime()
{
return System.currentTimeMillis();
}
@Override
public long nanoTime()
{
return System.nanoTime();
}
}
}