org.argeo.app.api/src/org/argeo/app/api/IdRange.java

   1 package org.argeo.app.api;
   2
   3 import java.util.HashSet;
   4 import java.util.Set;
   5 import java.util.concurrent.ThreadLocalRandom;
   6
   7 /** A range of numerical IDs (typically numerical uid or gid). */
   8 public class IdRange {
   9         // see https://systemd.io/UIDS-GIDS/#special-distribution-uid-ranges
  10         final static long MIN_INCLUDED = Long.parseUnsignedLong("66000");
  11         final static long MAX_EXCLUDED = Long.parseUnsignedLong("4294967294");
  12
  13         // We use long as a de facto unsigned int
  14
  15         /** included */
  16         private final long min;
  17         /** included */
  18         private final long max;
  19
  20         public IdRange(long min, long max) {
  21                 this.min = min;
  22                 this.max = max;
  23         }
  24
  25         public IdRange(long minPow10) {
  26                 this(minPow10, maxFromMinPow10(minPow10));
  27         }
  28
  29         public long getMin() {
  30                 return min;
  31         }
  32
  33         public long getMax() {
  34                 return max;
  35         }
  36
  37         @Override
  38         public int hashCode() {
  39                 return (int) min;
  40         }
  41
  42         @Override
  43         public boolean equals(Object obj) {
  44                 if (obj instanceof IdRange idRange) {
  45                         return min == idRange.min && max == idRange.max;
  46                 } else
  47                         return false;
  48         }
  49
  50         @Override
  51         public String toString() {
  52                 return "[" + Long.toUnsignedString(min) + "," + Long.toUnsignedString(max) + "]";
  53         }
  54
  55         /*
  56          * RANGE GENERATION
  57          */
  58         public static synchronized Set<IdRange> randomRanges10000(int count, Set<IdRange> forbiddenRanges) {
  59                 Set<IdRange> res = new HashSet<>();
  60
  61                 for (int i = 0; i < count; i++) {
  62                         IdRange newRange = null;
  63                         do {
  64                                 newRange = randomRange10000();
  65                         } while (overlap(newRange, res) || overlap(newRange, forbiddenRanges));
  66                         res.add(newRange);
  67                 }
  68                 return res;
  69         }
  70
  71         public static synchronized IdRange randomRange10000() {
  72                 // TODO make it more generic
  73                 long minPred = 7l;
  74                 long maxPred = 429496l;
  75
  76                 long rand = ThreadLocalRandom.current().nextLong(minPred, maxPred);
  77                 long min = rand * 10000l;
  78                 return new IdRange(min);
  79         }
  80
  81         public static boolean overlap(IdRange idRange, Set<IdRange> idRanges) {
  82                 for (IdRange other : idRanges) {
  83                         if (overlap(idRange, other))
  84                                 return true;
  85                 }
  86                 return false;
  87         }
  88
  89         public static boolean overlap(IdRange idRange, IdRange other) {
  90                 // see
  91                 // https://stackoverflow.com/questions/3269434/whats-the-most-efficient-way-to-test-if-two-ranges-overlap
  92                 return idRange.min <= other.max && other.min <= idRange.max;
  93         }
  94
  95         /*
  96          * UTILITIES
  97          */
  98
  99         private static long maxFromMinPow10(long minPow10) {
 100                 if ((minPow10 % 100) != 0) {
 101                         throw new IllegalArgumentException(minPow10 + " must at least ends with two zeroes");
 102                 }
 103                 int exp = 2;
 104                 exp: for (int i = exp + 1; i < 10; i++) {
 105                         if ((minPow10 % pow10(i)) != 0)
 106                                 break exp;
 107                         exp++;
 108                 }
 109 //              System.out.println(exp);
 110
 111                 long max = minPow10 + pow10(exp) - 1;
 112                 return max;
 113         }
 114
 115         /** Power of 10. */
 116         private static long pow10(int exp) {
 117                 if (exp == 0)
 118                         return 1;
 119                 else
 120                         return 10 * pow10(exp - 1);
 121         }
 122
 123         public static void main(String... args) {
 124                 System.out.println(maxFromMinPow10(100));
 125                 System.out.println(maxFromMinPow10(78500));
 126                 System.out.println(maxFromMinPow10(716850000));
 127
 128 //              System.out.println(pow10(6));
 129 //              System.out.println(maxFromMinPow10(12));
 130 //              System.out.println(maxFromMinPow10(124));
 131 //              System.out.println(maxFromMinPow10(99814565));
 132         }
 133 }