minio/docs/debugging/hash-set/main.go

131 lines
3.7 KiB
Go

// Copyright (c) 2015-2021 MinIO, Inc.
//
// This file is part of MinIO Object Storage stack
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
package main
import (
"bufio"
"bytes"
"encoding/binary"
"flag"
"fmt"
"hash/crc32"
"log"
"os"
"strings"
"github.com/dchest/siphash"
"github.com/google/uuid"
)
// hashes the key returning an integer based on the input algorithm.
// This function currently supports
// - SIPMOD
func sipHashMod(key string, cardinality int, id [16]byte) int {
if cardinality <= 0 {
return -1
}
// use the faster version as per siphash docs
// https://github.com/dchest/siphash#usage
k0, k1 := binary.LittleEndian.Uint64(id[0:8]), binary.LittleEndian.Uint64(id[8:16])
sum64 := siphash.Hash(k0, k1, []byte(key))
return int(sum64 % uint64(cardinality))
}
// hashOrder - hashes input key to return consistent
// hashed integer slice. Returned integer order is salted
// with an input key. This results in consistent order.
// NOTE: collisions are fine, we are not looking for uniqueness
// in the slices returned.
func hashOrder(key string, cardinality int) []int {
if cardinality <= 0 {
// Returns an empty int slice for cardinality < 0.
return nil
}
nums := make([]int, cardinality)
keyCrc := crc32.Checksum([]byte(key), crc32.IEEETable)
start := int(keyCrc % uint32(cardinality))
for i := 1; i <= cardinality; i++ {
nums[i-1] = 1 + ((start + i) % cardinality)
}
return nums
}
var (
file, object, deploymentID, prefix string
setCount, shards int
verbose bool
)
func main() {
flag.StringVar(&file, "file", "", "Read all objects from file, newline separated")
flag.StringVar(&prefix, "prefix", "", "Add prefix to all objects")
flag.StringVar(&object, "object", "", "Select an object")
flag.StringVar(&deploymentID, "deployment-id", "", "MinIO deployment ID, obtained from 'format.json'")
flag.IntVar(&setCount, "set-count", 0, "Total set count")
flag.IntVar(&shards, "shards", 0, "Total shards count")
flag.BoolVar(&verbose, "v", false, "Display all objects")
flag.Parse()
if deploymentID == "" {
log.Fatalln("deployment ID is mandatory")
}
if setCount == 0 {
log.Fatalln("set count cannot be zero")
}
id := uuid.MustParse(deploymentID)
if file != "" {
distrib := make([][]string, setCount)
b, err := os.ReadFile(file)
if err != nil {
log.Fatalln(err)
}
b = bytes.ReplaceAll(b, []byte("\r"), []byte{})
sc := bufio.NewScanner(bytes.NewBuffer(b))
for sc.Scan() {
object = strings.TrimSpace(sc.Text())
set := sipHashMod(prefix+object, setCount, id)
distrib[set] = append(distrib[set], prefix+object)
}
for set, files := range distrib {
fmt.Println("Set:", set+1, "Objects:", len(files))
if !verbose {
continue
}
for _, s := range files {
fmt.Printf("\t%s\n", s)
}
}
os.Exit(0)
}
if object == "" {
log.Fatalln("object name is mandatory")
}
if shards != 0 {
fmt.Println("Erasure distribution for the object", hashOrder(prefix+object, shards))
}
fmt.Println("Erasure setNumber for the object", sipHashMod(prefix+object, setCount, id)+1)
}