| 1 | package dmg.util; |
| 2 | |
| 3 | /** |
| 4 | * Utility class to generate a monotonically increasing sequence of |
| 5 | * values. |
| 6 | * |
| 7 | * Under the right conditions, this sequence has a high likelihood to |
| 8 | * also be monotonically increasing between restarts. This is the case |
| 9 | * when |
| 10 | * |
| 11 | * - Time goes forward. |
| 12 | * |
| 13 | * - The frequency at which values are generated between two restarts |
| 14 | * A and B is lower than 1000 Hz. |
| 15 | * |
| 16 | * The main reason for using time as a component is to avoid having to |
| 17 | * maintain persistent state. |
| 18 | */ |
| 19 | public class TimebasedCounter |
| 20 | { |
| 21 | private long _last; |
| 22 | |
| 23 | public synchronized long next() |
| 24 | { |
| 25 | return (_last = Math.max(_last + 1, System.currentTimeMillis())); |
| 26 | } |
| 27 | } |