Exemplo n.º 1
0
        public bool MappingPhase(out uint hashSeed, out uint maxBucketSize)
        {
            var  hl                = new uint[3];
            var  mapItems          = new MapItem[_m];
            uint mappingIterations = 1000;
            var  rdm               = new Random(111);

            maxBucketSize = 0;
            for (; ;)
            {
                mappingIterations--;
                hashSeed = (uint)rdm.Next((int)_m); // ((cmph_uint32)rand() % this->_m);

                BucketsClean();

                _keySource.Rewind();

                uint i;
                for (i = 0; i < _m; i++)
                {
                    JenkinsHash.HashVector(hashSeed, _keySource.Read(), hl);

                    uint g = hl[0] % _nbuckets;
                    mapItems[i].F         = hl[1] % _n;
                    mapItems[i].H         = hl[2] % (_n - 1) + 1;
                    mapItems[i].BucketNum = g;

                    _buckets[g].Size++;
                    if (_buckets[g].Size > maxBucketSize)
                    {
                        maxBucketSize = _buckets[g].Size;
                    }
                }
                _buckets[0].ItemsList = 0;
                for (i = 1; i < _nbuckets; i++)
                {
                    _buckets[i].ItemsList = _buckets[i - 1].ItemsList + _buckets[i - 1].Size;
                    _buckets[i - 1].Size  = 0;
                }
                _buckets[i - 1].Size = 0;
                for (i = 0; i < _m; i++)
                {
                    if (!BucketsInsert(mapItems, i))
                    {
                        break;
                    }
                }
                if (i == _m)
                {
                    return(true); // SUCCESS
                }

                if (mappingIterations == 0)
                {
                    return(false);
                }
            }
        }
Exemplo n.º 2
0
        /// <summary>
        /// Compute the hash value associate with the key
        /// </summary>
        /// <param name="key">key from the original key set</param>
        /// <returns>Hash value (0 &gt; hash &gt; N)</returns>
        public uint Search(byte[] key)
        {
            var hl = new uint[3];

            JenkinsHash.HashVector(_hashSeed, key, hl);
            var g = hl[0] % _nbuckets;
            var f = hl[1] % _n;
            var h = hl[2] % (_n - 1) + 1;

            var disp      = _cs.Query(g);
            var probe0Num = disp % _n;
            var probe1Num = disp / _n;
            var position  = (uint)((f + ((ulong)h) * probe0Num + probe1Num) % _n);

            return(position);
        }