github.com/coocood/badger@v1.5.1-0.20200528065104-c02ac3616d04/cache/z/rtutil.go (about) 1 // MIT License 2 3 // Copyright (c) 2019 Ewan Chou 4 5 // Permission is hereby granted, free of charge, to any person obtaining a copy 6 // of this software and associated documentation files (the "Software"), to deal 7 // in the Software without restriction, including without limitation the rights 8 // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 9 // copies of the Software, and to permit persons to whom the Software is 10 // furnished to do so, subject to the following conditions: 11 12 // The above copyright notice and this permission notice shall be included in all 13 // copies or substantial portions of the Software. 14 15 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 16 // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 17 // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 18 // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 19 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 20 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE 21 // SOFTWARE. 22 23 package z 24 25 import ( 26 "unsafe" 27 ) 28 29 // NanoTime returns the current time in nanoseconds from a monotonic clock. 30 //go:linkname NanoTime runtime.nanotime 31 func NanoTime() int64 32 33 // CPUTicks is a faster alternative to NanoTime to measure time duration. 34 //go:linkname CPUTicks runtime.cputicks 35 func CPUTicks() int64 36 37 type stringStruct struct { 38 str unsafe.Pointer 39 len int 40 } 41 42 //go:noescape 43 //go:linkname memhash runtime.memhash 44 func memhash(p unsafe.Pointer, h, s uintptr) uintptr 45 46 // MemHash is the hash function used by go map, it utilizes available hardware instructions(behaves 47 // as aeshash if aes instruction is available). 48 // NOTE: The hash seed changes for every process. So, this cannot be used as a persistent hash. 49 func MemHash(data []byte) uint64 { 50 ss := (*stringStruct)(unsafe.Pointer(&data)) 51 return uint64(memhash(ss.str, 0, uintptr(ss.len))) 52 } 53 54 // MemHashString is the hash function used by go map, it utilizes available hardware instructions 55 // (behaves as aeshash if aes instruction is available). 56 // NOTE: The hash seed changes for every process. So, this cannot be used as a persistent hash. 57 func MemHashString(str string) uint64 { 58 ss := (*stringStruct)(unsafe.Pointer(&str)) 59 return uint64(memhash(ss.str, 0, uintptr(ss.len))) 60 } 61 62 // FastRand is a fast thread local random function. 63 //go:linkname FastRand runtime.fastrand 64 func FastRand() uint32