tom | a708318 | 2014-09-25 21:38:03 -0700 | [diff] [blame] | 1 | package org.onlab.util; |
| 2 | |
| 3 | import java.util.Objects; |
| 4 | |
| 5 | import static com.google.common.base.MoreObjects.toStringHelper; |
| 6 | import static com.google.common.base.Preconditions.checkArgument; |
| 7 | |
| 8 | /** |
| 9 | * Counting mechanism capable of tracking occurrences and rates. |
| 10 | */ |
| 11 | public class Counter { |
| 12 | |
| 13 | private long total = 0; |
| 14 | private long start = System.currentTimeMillis(); |
| 15 | private long end = 0; |
| 16 | |
| 17 | /** |
| 18 | * Creates a new counter. |
| 19 | */ |
| 20 | public Counter() { |
| 21 | } |
| 22 | |
| 23 | /** |
| 24 | * Creates a new counter in a specific state. If non-zero end time is |
| 25 | * specified, the counter will be frozen. |
| 26 | * |
| 27 | * @param start start time |
| 28 | * @param total total number of items to start with |
| 29 | * @param end end time; if non-ze |
| 30 | */ |
| 31 | public Counter(long start, long total, long end) { |
| 32 | checkArgument(start <= end, "Malformed interval: start > end"); |
| 33 | checkArgument(total >= 0, "Total must be non-negative"); |
| 34 | this.start = start; |
| 35 | this.total = total; |
| 36 | this.end = end; |
| 37 | } |
| 38 | |
| 39 | /** |
| 40 | * Resets the counter, by zeroing out the count and restarting the timer. |
| 41 | */ |
| 42 | public synchronized void reset() { |
| 43 | end = 0; |
| 44 | total = 0; |
| 45 | start = System.currentTimeMillis(); |
| 46 | } |
| 47 | |
| 48 | /** |
| 49 | * Freezes the counter in the current state including the counts and times. |
| 50 | */ |
| 51 | public synchronized void freeze() { |
| 52 | end = System.currentTimeMillis(); |
| 53 | } |
| 54 | |
| 55 | /** |
| 56 | * Adds the specified number of occurrences to the counter. No-op if the |
| 57 | * counter has been frozen. |
| 58 | * |
| 59 | * @param count number of occurrences |
| 60 | */ |
| 61 | public synchronized void add(long count) { |
| 62 | checkArgument(count >= 0, "Count must be non-negative"); |
| 63 | if (end == 0L) { |
| 64 | total += count; |
| 65 | } |
| 66 | } |
| 67 | |
| 68 | /** |
| 69 | * Returns the number of occurrences per second. |
| 70 | * |
| 71 | * @return throughput in occurrences per second |
| 72 | */ |
| 73 | public synchronized double throughput() { |
| 74 | return total / duration(); |
| 75 | } |
| 76 | |
| 77 | /** |
| 78 | * Returns the total number of occurrences counted. |
| 79 | * |
| 80 | * @return number of counted occurrences |
| 81 | */ |
| 82 | public synchronized long total() { |
| 83 | return total; |
| 84 | } |
| 85 | |
| 86 | /** |
| 87 | * Returns the duration expressed in fractional number of seconds. |
| 88 | * |
| 89 | * @return fractional number of seconds since the last reset |
| 90 | */ |
| 91 | public synchronized double duration() { |
| 92 | // Protect against 0 return by artificially setting duration to 1ms |
| 93 | long duration = (end == 0L ? System.currentTimeMillis() : end) - start; |
| 94 | return (duration == 0 ? 1 : duration) / 1000.0; |
| 95 | } |
| 96 | |
| 97 | @Override |
| 98 | public int hashCode() { |
| 99 | return Objects.hash(total, start, end); |
| 100 | } |
| 101 | |
| 102 | @Override |
| 103 | public boolean equals(Object obj) { |
| 104 | if (this == obj) { |
| 105 | return true; |
| 106 | } |
| 107 | if (obj instanceof Counter) { |
| 108 | final Counter other = (Counter) obj; |
| 109 | return Objects.equals(this.total, other.total) && |
| 110 | Objects.equals(this.start, other.start) && |
| 111 | Objects.equals(this.end, other.end); |
| 112 | } |
| 113 | return false; |
| 114 | } |
| 115 | |
| 116 | @Override |
| 117 | public String toString() { |
| 118 | return toStringHelper(this) |
| 119 | .add("total", total) |
| 120 | .add("start", start) |
| 121 | .add("end", end) |
| 122 | .toString(); |
| 123 | } |
| 124 | } |