1 /* 2 * Copyright 2019 Dgraph Labs, Inc. and Contributors 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package z 18 19 import ( 20 "github.com/cespare/xxhash" 21 ) 22 23 // TODO: Figure out a way to re-use memhash for the second uint64 hash, we 24 // already know that appending bytes isn't reliable for generating a 25 // second hash (see Ristretto PR #88). 26 // 27 // We also know that while the Go runtime has a runtime memhash128 28 // function, it's not possible to use it to generate [2]uint64 or 29 // anything resembling a 128bit hash, even though that's exactly what 30 // we need in this situation. 31 func KeyToHash(key interface{}) (uint64, uint64) { 32 if key == nil { 33 return 0, 0 34 } 35 switch k := key.(type) { 36 case uint64: 37 return k, 0 38 case string: 39 return MemHashString(k), xxhash.Sum64String(k) 40 case []byte: 41 return MemHash(k), xxhash.Sum64(k) 42 case byte: 43 return uint64(k), 0 44 case int: 45 return uint64(k), 0 46 case int32: 47 return uint64(k), 0 48 case uint32: 49 return uint64(k), 0 50 case int64: 51 return uint64(k), 0 52 default: 53 panic("Key type not supported") 54 } 55 } 56