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| 1 | +using System; |
| 2 | +using System.Collections.Generic; |
| 3 | +using System.Diagnostics.CodeAnalysis; |
| 4 | + |
| 5 | +#if NET6_0_OR_GREATER |
| 6 | +using System.Runtime.Intrinsics; |
| 7 | +using System.Runtime.Intrinsics.X86; |
| 8 | +#endif |
| 9 | + |
| 10 | +namespace BitFaster.Caching.Benchmarks.Lfu |
| 11 | +{ |
| 12 | + internal class CmSketchNoPin<T, I> |
| 13 | + where T : notnull |
| 14 | + where I : struct, IsaProbe |
| 15 | + { |
| 16 | + private const long ResetMask = 0x7777777777777777L; |
| 17 | + private const long OneMask = 0x1111111111111111L; |
| 18 | + |
| 19 | + private long[] table; |
| 20 | + private int sampleSize; |
| 21 | + private int blockMask; |
| 22 | + private int size; |
| 23 | + |
| 24 | + private readonly IEqualityComparer<T> comparer; |
| 25 | + |
| 26 | + /// <summary> |
| 27 | + /// Initializes a new instance of the CmSketch class with the specified maximum size and equality comparer. |
| 28 | + /// </summary> |
| 29 | + /// <param name="maximumSize">The maximum size.</param> |
| 30 | + /// <param name="comparer">The equality comparer.</param> |
| 31 | + public CmSketchNoPin(long maximumSize, IEqualityComparer<T> comparer) |
| 32 | + { |
| 33 | + EnsureCapacity(maximumSize); |
| 34 | + this.comparer = comparer; |
| 35 | + } |
| 36 | + |
| 37 | + /// <summary> |
| 38 | + /// Gets the reset sample size. |
| 39 | + /// </summary> |
| 40 | + public int ResetSampleSize => this.sampleSize; |
| 41 | + |
| 42 | + /// <summary> |
| 43 | + /// Gets the size. |
| 44 | + /// </summary> |
| 45 | + public int Size => this.size; |
| 46 | + |
| 47 | + /// <summary> |
| 48 | + /// Estimate the frequency of the specified value, up to the maximum of 15. |
| 49 | + /// </summary> |
| 50 | + /// <param name="value">The value.</param> |
| 51 | + /// <returns>The estimated frequency of the value.</returns> |
| 52 | + public int EstimateFrequency(T value) |
| 53 | + { |
| 54 | +#if NET48 |
| 55 | + return EstimateFrequencyStd(value); |
| 56 | +#else |
| 57 | + |
| 58 | + I isa = default; |
| 59 | + |
| 60 | + if (isa.IsAvx2Supported) |
| 61 | + { |
| 62 | + return EstimateFrequencyAvx(value); |
| 63 | + } |
| 64 | + else |
| 65 | + { |
| 66 | + return EstimateFrequencyStd(value); |
| 67 | + } |
| 68 | +#endif |
| 69 | + } |
| 70 | + |
| 71 | + /// <summary> |
| 72 | + /// Increment the count of the specified value. |
| 73 | + /// </summary> |
| 74 | + /// <param name="value">The value.</param> |
| 75 | + public void Increment(T value) |
| 76 | + { |
| 77 | +#if NET48 |
| 78 | + IncrementStd(value); |
| 79 | +#else |
| 80 | + |
| 81 | + I isa = default; |
| 82 | + |
| 83 | + if (isa.IsAvx2Supported) |
| 84 | + { |
| 85 | + IncrementAvx(value); |
| 86 | + } |
| 87 | + else |
| 88 | + { |
| 89 | + IncrementStd(value); |
| 90 | + } |
| 91 | +#endif |
| 92 | + } |
| 93 | + |
| 94 | + /// <summary> |
| 95 | + /// Clears the count for all items. |
| 96 | + /// </summary> |
| 97 | + public void Clear() |
| 98 | + { |
| 99 | + table = new long[table.Length]; |
| 100 | + size = 0; |
| 101 | + } |
| 102 | + |
| 103 | + // [MemberNotNull(nameof(table))] |
| 104 | + private void EnsureCapacity(long maximumSize) |
| 105 | + { |
| 106 | + int maximum = (int)Math.Min(maximumSize, int.MaxValue >> 1); |
| 107 | + |
| 108 | + table = new long[Math.Max(BitOps.CeilingPowerOfTwo(maximum), 8)]; |
| 109 | + blockMask = (int)((uint)table.Length >> 3) - 1; |
| 110 | + sampleSize = (maximumSize == 0) ? 10 : (10 * maximum); |
| 111 | + |
| 112 | + size = 0; |
| 113 | + } |
| 114 | + |
| 115 | + private unsafe int EstimateFrequencyStd(T value) |
| 116 | + { |
| 117 | + var count = stackalloc int[4]; |
| 118 | + int blockHash = Spread(comparer.GetHashCode(value)); |
| 119 | + int counterHash = Rehash(blockHash); |
| 120 | + int block = (blockHash & blockMask) << 3; |
| 121 | + |
| 122 | + for (int i = 0; i < 4; i++) |
| 123 | + { |
| 124 | + int h = (int)((uint)counterHash >> (i << 3)); |
| 125 | + int index = (h >> 1) & 15; |
| 126 | + int offset = h & 1; |
| 127 | + count[i] = (int)(((ulong)table[block + offset + (i << 1)] >> (index << 2)) & 0xfL); |
| 128 | + } |
| 129 | + return Math.Min(Math.Min(count[0], count[1]), Math.Min(count[2], count[3])); |
| 130 | + } |
| 131 | + |
| 132 | + private unsafe void IncrementStd(T value) |
| 133 | + { |
| 134 | + var index = stackalloc int[8]; |
| 135 | + int blockHash = Spread(comparer.GetHashCode(value)); |
| 136 | + int counterHash = Rehash(blockHash); |
| 137 | + int block = (blockHash & blockMask) << 3; |
| 138 | + |
| 139 | + for (int i = 0; i < 4; i++) |
| 140 | + { |
| 141 | + int h = (int)((uint)counterHash >> (i << 3)); |
| 142 | + index[i] = (h >> 1) & 15; |
| 143 | + int offset = h & 1; |
| 144 | + index[i + 4] = block + offset + (i << 1); |
| 145 | + } |
| 146 | + |
| 147 | + bool added = |
| 148 | + IncrementAt(index[4], index[0]) |
| 149 | + | IncrementAt(index[5], index[1]) |
| 150 | + | IncrementAt(index[6], index[2]) |
| 151 | + | IncrementAt(index[7], index[3]); |
| 152 | + |
| 153 | + if (added && (++size == sampleSize)) |
| 154 | + { |
| 155 | + Reset(); |
| 156 | + } |
| 157 | + } |
| 158 | + |
| 159 | + // Applies another round of hashing for additional randomization |
| 160 | + private static int Rehash(int x) |
| 161 | + { |
| 162 | + x = (int)(x * 0x31848bab); |
| 163 | + x ^= (int)((uint)x >> 14); |
| 164 | + return x; |
| 165 | + } |
| 166 | + |
| 167 | + // Applies a supplemental hash functions to defends against poor quality hash. |
| 168 | + private static int Spread(int x) |
| 169 | + { |
| 170 | + x ^= (int)((uint)x >> 17); |
| 171 | + x = (int)(x * 0xed5ad4bb); |
| 172 | + x ^= (int)((uint)x >> 11); |
| 173 | + x = (int)(x * 0xac4c1b51); |
| 174 | + x ^= (int)((uint)x >> 15); |
| 175 | + return x; |
| 176 | + } |
| 177 | + |
| 178 | + private bool IncrementAt(int i, int j) |
| 179 | + { |
| 180 | + int offset = j << 2; |
| 181 | + long mask = (0xfL << offset); |
| 182 | + |
| 183 | + if ((table[i] & mask) != mask) |
| 184 | + { |
| 185 | + table[i] += (1L << offset); |
| 186 | + return true; |
| 187 | + } |
| 188 | + |
| 189 | + return false; |
| 190 | + } |
| 191 | + |
| 192 | + private void Reset() |
| 193 | + { |
| 194 | + // unroll, almost 2x faster |
| 195 | + int count0 = 0; |
| 196 | + int count1 = 0; |
| 197 | + int count2 = 0; |
| 198 | + int count3 = 0; |
| 199 | + |
| 200 | + for (int i = 0; i < table.Length; i += 4) |
| 201 | + { |
| 202 | + count0 += BitOps.BitCount(table[i] & OneMask); |
| 203 | + count1 += BitOps.BitCount(table[i + 1] & OneMask); |
| 204 | + count2 += BitOps.BitCount(table[i + 2] & OneMask); |
| 205 | + count3 += BitOps.BitCount(table[i + 3] & OneMask); |
| 206 | + |
| 207 | + table[i] = (long)((ulong)table[i] >> 1) & ResetMask; |
| 208 | + table[i + 1] = (long)((ulong)table[i + 1] >> 1) & ResetMask; |
| 209 | + table[i + 2] = (long)((ulong)table[i + 2] >> 1) & ResetMask; |
| 210 | + table[i + 3] = (long)((ulong)table[i + 3] >> 1) & ResetMask; |
| 211 | + } |
| 212 | + |
| 213 | + count0 = (count0 + count1) + (count2 + count3); |
| 214 | + |
| 215 | + size = (size - (count0 >> 2)) >> 1; |
| 216 | + } |
| 217 | + |
| 218 | +#if NET6_0_OR_GREATER |
| 219 | + private unsafe int EstimateFrequencyAvx(T value) |
| 220 | + { |
| 221 | + int blockHash = Spread(comparer.GetHashCode(value)); |
| 222 | + int counterHash = Rehash(blockHash); |
| 223 | + int block = (blockHash & blockMask) << 3; |
| 224 | + |
| 225 | + Vector128<int> h = Vector128.Create(counterHash); |
| 226 | + h = Avx2.ShiftRightLogicalVariable(h.AsUInt32(), Vector128.Create(0U, 8U, 16U, 24U)).AsInt32(); |
| 227 | + |
| 228 | + var index = Avx2.ShiftRightLogical(h, 1); |
| 229 | + index = Avx2.And(index, Vector128.Create(15)); // j - counter index |
| 230 | + Vector128<int> offset = Avx2.And(h, Vector128.Create(1)); |
| 231 | + Vector128<int> blockOffset = Avx2.Add(Vector128.Create(block), offset); // i - table index |
| 232 | + blockOffset = Avx2.Add(blockOffset, Vector128.Create(0, 2, 4, 6)); // + (i << 1) |
| 233 | + |
| 234 | + fixed (long* tablePtr = table) |
| 235 | + { |
| 236 | + Vector256<long> tableVector = Avx2.GatherVector256(tablePtr, blockOffset, 8); |
| 237 | + index = Avx2.ShiftLeftLogical(index, 2); |
| 238 | + |
| 239 | + // convert index from int to long via permute |
| 240 | + Vector256<long> indexLong = Vector256.Create(index, Vector128<int>.Zero).AsInt64(); |
| 241 | + Vector256<int> permuteMask2 = Vector256.Create(0, 4, 1, 5, 2, 5, 3, 7); |
| 242 | + indexLong = Avx2.PermuteVar8x32(indexLong.AsInt32(), permuteMask2).AsInt64(); |
| 243 | + tableVector = Avx2.ShiftRightLogicalVariable(tableVector, indexLong.AsUInt64()); |
| 244 | + tableVector = Avx2.And(tableVector, Vector256.Create(0xfL)); |
| 245 | + |
| 246 | + Vector256<int> permuteMask = Vector256.Create(0, 2, 4, 6, 1, 3, 5, 7); |
| 247 | + Vector128<ushort> count = Avx2.PermuteVar8x32(tableVector.AsInt32(), permuteMask) |
| 248 | + .GetLower() |
| 249 | + .AsUInt16(); |
| 250 | + |
| 251 | + // set the zeroed high parts of the long value to ushort.Max |
| 252 | +#if NET6_0 |
| 253 | + count = Avx2.Blend(count, Vector128<ushort>.AllBitsSet, 0b10101010); |
| 254 | +#else |
| 255 | + count = Avx2.Blend(count, Vector128.Create(ushort.MaxValue), 0b10101010); |
| 256 | +#endif |
| 257 | + |
| 258 | + return Avx2.MinHorizontal(count).GetElement(0); |
| 259 | + } |
| 260 | + } |
| 261 | + |
| 262 | + private unsafe void IncrementAvx(T value) |
| 263 | + { |
| 264 | + int blockHash = Spread(comparer.GetHashCode(value)); |
| 265 | + int counterHash = Rehash(blockHash); |
| 266 | + int block = (blockHash & blockMask) << 3; |
| 267 | + |
| 268 | + Vector128<int> h = Vector128.Create(counterHash); |
| 269 | + h = Avx2.ShiftRightLogicalVariable(h.AsUInt32(), Vector128.Create(0U, 8U, 16U, 24U)).AsInt32(); |
| 270 | + |
| 271 | + Vector128<int> index = Avx2.ShiftRightLogical(h, 1); |
| 272 | + index = Avx2.And(index, Vector128.Create(15)); // j - counter index |
| 273 | + Vector128<int> offset = Avx2.And(h, Vector128.Create(1)); |
| 274 | + Vector128<int> blockOffset = Avx2.Add(Vector128.Create(block), offset); // i - table index |
| 275 | + blockOffset = Avx2.Add(blockOffset, Vector128.Create(0, 2, 4, 6)); // + (i << 1) |
| 276 | + |
| 277 | + fixed (long* tablePtr = table) |
| 278 | + { |
| 279 | + Vector256<long> tableVector = Avx2.GatherVector256(tablePtr, blockOffset, 8); |
| 280 | + |
| 281 | + // j == index |
| 282 | + index = Avx2.ShiftLeftLogical(index, 2); |
| 283 | + Vector256<long> offsetLong = Vector256.Create(index, Vector128<int>.Zero).AsInt64(); |
| 284 | + |
| 285 | + Vector256<int> permuteMask = Vector256.Create(0, 4, 1, 5, 2, 5, 3, 7); |
| 286 | + offsetLong = Avx2.PermuteVar8x32(offsetLong.AsInt32(), permuteMask).AsInt64(); |
| 287 | + |
| 288 | + // mask = (0xfL << offset) |
| 289 | + Vector256<long> fifteen = Vector256.Create(0xfL); |
| 290 | + Vector256<long> mask = Avx2.ShiftLeftLogicalVariable(fifteen, offsetLong.AsUInt64()); |
| 291 | + |
| 292 | + // (table[i] & mask) != mask) |
| 293 | + // Note masked is 'equal' - therefore use AndNot below |
| 294 | + Vector256<long> masked = Avx2.CompareEqual(Avx2.And(tableVector, mask), mask); |
| 295 | + |
| 296 | + // 1L << offset |
| 297 | + Vector256<long> inc = Avx2.ShiftLeftLogicalVariable(Vector256.Create(1L), offsetLong.AsUInt64()); |
| 298 | + |
| 299 | + // Mask to zero out non matches (add zero below) - first operand is NOT then AND result (order matters) |
| 300 | + inc = Avx2.AndNot(masked, inc); |
| 301 | + |
| 302 | + Vector256<byte> result = Avx2.CompareEqual(masked.AsByte(), Vector256<byte>.Zero); |
| 303 | + bool wasInc = Avx2.MoveMask(result.AsByte()) == unchecked((int)(0b1111_1111_1111_1111_1111_1111_1111_1111)); |
| 304 | + |
| 305 | + tablePtr[blockOffset.GetElement(0)] += inc.GetElement(0); |
| 306 | + tablePtr[blockOffset.GetElement(1)] += inc.GetElement(1); |
| 307 | + tablePtr[blockOffset.GetElement(2)] += inc.GetElement(2); |
| 308 | + tablePtr[blockOffset.GetElement(3)] += inc.GetElement(3); |
| 309 | + |
| 310 | + if (wasInc && (++size == sampleSize)) |
| 311 | + { |
| 312 | + Reset(); |
| 313 | + } |
| 314 | + } |
| 315 | + } |
| 316 | +#endif |
| 317 | + } |
| 318 | +} |
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