github.com/coocood/badger@v1.5.1-0.20200528065104-c02ac3616d04/cache/z/z.go (about) 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 raw := []byte(k) 40 return MemHash(raw), xxhash.Sum64(raw) 41 case []byte: 42 return MemHash(k), xxhash.Sum64(k) 43 case byte: 44 return uint64(k), 0 45 case int: 46 return uint64(k), 0 47 case int32: 48 return uint64(k), 0 49 case uint32: 50 return uint64(k), 0 51 case int64: 52 return uint64(k), 0 53 default: 54 panic("Key type not supported") 55 } 56 }