gotosocial/vendor/github.com/rs/xid/id.go
Dominik Süß 9d0df426da
[feature] S3 support ()
* feat: vendor minio client

* feat: introduce storage package with s3 support

* feat: serve s3 files directly

this saves a lot of bandwith as the files are fetched from the object
store directly

* fix: use explicit local storage in tests

* feat: integrate s3 storage with the main server

* fix: add s3 config to cli tests

* docs: explicitly set values in example config

also adds license header to the storage package

* fix: use better http status code on s3 redirect

HTTP 302 Found is the best fit, as it signifies that the resource
requested was found but not under its presumed URL

307/TemporaryRedirect would mean that this resource is usually located
here, not in this case

303/SeeOther indicates that the redirection does not link to the
requested resource but to another page

* refactor: use context in storage driver interface
2022-07-03 12:08:30 +02:00

365 lines
11 KiB
Go

// Package xid is a globally unique id generator suited for web scale
//
// Xid is using Mongo Object ID algorithm to generate globally unique ids:
// https://docs.mongodb.org/manual/reference/object-id/
//
// - 4-byte value representing the seconds since the Unix epoch,
// - 3-byte machine identifier,
// - 2-byte process id, and
// - 3-byte counter, starting with a random value.
//
// The binary representation of the id is compatible with Mongo 12 bytes Object IDs.
// The string representation is using base32 hex (w/o padding) for better space efficiency
// when stored in that form (20 bytes). The hex variant of base32 is used to retain the
// sortable property of the id.
//
// Xid doesn't use base64 because case sensitivity and the 2 non alphanum chars may be an
// issue when transported as a string between various systems. Base36 wasn't retained either
// because 1/ it's not standard 2/ the resulting size is not predictable (not bit aligned)
// and 3/ it would not remain sortable. To validate a base32 `xid`, expect a 20 chars long,
// all lowercase sequence of `a` to `v` letters and `0` to `9` numbers (`[0-9a-v]{20}`).
//
// UUID is 16 bytes (128 bits), snowflake is 8 bytes (64 bits), xid stands in between
// with 12 bytes with a more compact string representation ready for the web and no
// required configuration or central generation server.
//
// Features:
//
// - Size: 12 bytes (96 bits), smaller than UUID, larger than snowflake
// - Base32 hex encoded by default (16 bytes storage when transported as printable string)
// - Non configured, you don't need set a unique machine and/or data center id
// - K-ordered
// - Embedded time with 1 second precision
// - Unicity guaranteed for 16,777,216 (24 bits) unique ids per second and per host/process
//
// Best used with xlog's RequestIDHandler (https://godoc.org/github.com/rs/xlog#RequestIDHandler).
//
// References:
//
// - http://www.slideshare.net/davegardnerisme/unique-id-generation-in-distributed-systems
// - https://en.wikipedia.org/wiki/Universally_unique_identifier
// - https://blog.twitter.com/2010/announcing-snowflake
package xid
import (
"bytes"
"crypto/md5"
"crypto/rand"
"database/sql/driver"
"encoding/binary"
"errors"
"fmt"
"hash/crc32"
"io/ioutil"
"os"
"sort"
"sync/atomic"
"time"
)
// Code inspired from mgo/bson ObjectId
// ID represents a unique request id
type ID [rawLen]byte
const (
encodedLen = 20 // string encoded len
rawLen = 12 // binary raw len
// encoding stores a custom version of the base32 encoding with lower case
// letters.
encoding = "0123456789abcdefghijklmnopqrstuv"
)
var (
// ErrInvalidID is returned when trying to unmarshal an invalid ID
ErrInvalidID = errors.New("xid: invalid ID")
// objectIDCounter is atomically incremented when generating a new ObjectId
// using NewObjectId() function. It's used as a counter part of an id.
// This id is initialized with a random value.
objectIDCounter = randInt()
// machineId stores machine id generated once and used in subsequent calls
// to NewObjectId function.
machineID = readMachineID()
// pid stores the current process id
pid = os.Getpid()
nilID ID
// dec is the decoding map for base32 encoding
dec [256]byte
)
func init() {
for i := 0; i < len(dec); i++ {
dec[i] = 0xFF
}
for i := 0; i < len(encoding); i++ {
dec[encoding[i]] = byte(i)
}
// If /proc/self/cpuset exists and is not /, we can assume that we are in a
// form of container and use the content of cpuset xor-ed with the PID in
// order get a reasonable machine global unique PID.
b, err := ioutil.ReadFile("/proc/self/cpuset")
if err == nil && len(b) > 1 {
pid ^= int(crc32.ChecksumIEEE(b))
}
}
// readMachineId generates machine id and puts it into the machineId global
// variable. If this function fails to get the hostname, it will cause
// a runtime error.
func readMachineID() []byte {
id := make([]byte, 3)
hid, err := readPlatformMachineID()
if err != nil || len(hid) == 0 {
hid, err = os.Hostname()
}
if err == nil && len(hid) != 0 {
hw := md5.New()
hw.Write([]byte(hid))
copy(id, hw.Sum(nil))
} else {
// Fallback to rand number if machine id can't be gathered
if _, randErr := rand.Reader.Read(id); randErr != nil {
panic(fmt.Errorf("xid: cannot get hostname nor generate a random number: %v; %v", err, randErr))
}
}
return id
}
// randInt generates a random uint32
func randInt() uint32 {
b := make([]byte, 3)
if _, err := rand.Reader.Read(b); err != nil {
panic(fmt.Errorf("xid: cannot generate random number: %v;", err))
}
return uint32(b[0])<<16 | uint32(b[1])<<8 | uint32(b[2])
}
// New generates a globally unique ID
func New() ID {
return NewWithTime(time.Now())
}
// NewWithTime generates a globally unique ID with the passed in time
func NewWithTime(t time.Time) ID {
var id ID
// Timestamp, 4 bytes, big endian
binary.BigEndian.PutUint32(id[:], uint32(t.Unix()))
// Machine, first 3 bytes of md5(hostname)
id[4] = machineID[0]
id[5] = machineID[1]
id[6] = machineID[2]
// Pid, 2 bytes, specs don't specify endianness, but we use big endian.
id[7] = byte(pid >> 8)
id[8] = byte(pid)
// Increment, 3 bytes, big endian
i := atomic.AddUint32(&objectIDCounter, 1)
id[9] = byte(i >> 16)
id[10] = byte(i >> 8)
id[11] = byte(i)
return id
}
// FromString reads an ID from its string representation
func FromString(id string) (ID, error) {
i := &ID{}
err := i.UnmarshalText([]byte(id))
return *i, err
}
// String returns a base32 hex lowercased with no padding representation of the id (char set is 0-9, a-v).
func (id ID) String() string {
text := make([]byte, encodedLen)
encode(text, id[:])
return string(text)
}
// MarshalText implements encoding/text TextMarshaler interface
func (id ID) MarshalText() ([]byte, error) {
text := make([]byte, encodedLen)
encode(text, id[:])
return text, nil
}
// MarshalJSON implements encoding/json Marshaler interface
func (id ID) MarshalJSON() ([]byte, error) {
if id.IsNil() {
return []byte("null"), nil
}
text, err := id.MarshalText()
return []byte(`"` + string(text) + `"`), err
}
// encode by unrolling the stdlib base32 algorithm + removing all safe checks
func encode(dst, id []byte) {
dst[0] = encoding[id[0]>>3]
dst[1] = encoding[(id[1]>>6)&0x1F|(id[0]<<2)&0x1F]
dst[2] = encoding[(id[1]>>1)&0x1F]
dst[3] = encoding[(id[2]>>4)&0x1F|(id[1]<<4)&0x1F]
dst[4] = encoding[id[3]>>7|(id[2]<<1)&0x1F]
dst[5] = encoding[(id[3]>>2)&0x1F]
dst[6] = encoding[id[4]>>5|(id[3]<<3)&0x1F]
dst[7] = encoding[id[4]&0x1F]
dst[8] = encoding[id[5]>>3]
dst[9] = encoding[(id[6]>>6)&0x1F|(id[5]<<2)&0x1F]
dst[10] = encoding[(id[6]>>1)&0x1F]
dst[11] = encoding[(id[7]>>4)&0x1F|(id[6]<<4)&0x1F]
dst[12] = encoding[id[8]>>7|(id[7]<<1)&0x1F]
dst[13] = encoding[(id[8]>>2)&0x1F]
dst[14] = encoding[(id[9]>>5)|(id[8]<<3)&0x1F]
dst[15] = encoding[id[9]&0x1F]
dst[16] = encoding[id[10]>>3]
dst[17] = encoding[(id[11]>>6)&0x1F|(id[10]<<2)&0x1F]
dst[18] = encoding[(id[11]>>1)&0x1F]
dst[19] = encoding[(id[11]<<4)&0x1F]
}
// UnmarshalText implements encoding/text TextUnmarshaler interface
func (id *ID) UnmarshalText(text []byte) error {
if len(text) != encodedLen {
return ErrInvalidID
}
for _, c := range text {
if dec[c] == 0xFF {
return ErrInvalidID
}
}
decode(id, text)
return nil
}
// UnmarshalJSON implements encoding/json Unmarshaler interface
func (id *ID) UnmarshalJSON(b []byte) error {
s := string(b)
if s == "null" {
*id = nilID
return nil
}
return id.UnmarshalText(b[1 : len(b)-1])
}
// decode by unrolling the stdlib base32 algorithm + removing all safe checks
func decode(id *ID, src []byte) {
id[0] = dec[src[0]]<<3 | dec[src[1]]>>2
id[1] = dec[src[1]]<<6 | dec[src[2]]<<1 | dec[src[3]]>>4
id[2] = dec[src[3]]<<4 | dec[src[4]]>>1
id[3] = dec[src[4]]<<7 | dec[src[5]]<<2 | dec[src[6]]>>3
id[4] = dec[src[6]]<<5 | dec[src[7]]
id[5] = dec[src[8]]<<3 | dec[src[9]]>>2
id[6] = dec[src[9]]<<6 | dec[src[10]]<<1 | dec[src[11]]>>4
id[7] = dec[src[11]]<<4 | dec[src[12]]>>1
id[8] = dec[src[12]]<<7 | dec[src[13]]<<2 | dec[src[14]]>>3
id[9] = dec[src[14]]<<5 | dec[src[15]]
id[10] = dec[src[16]]<<3 | dec[src[17]]>>2
id[11] = dec[src[17]]<<6 | dec[src[18]]<<1 | dec[src[19]]>>4
}
// Time returns the timestamp part of the id.
// It's a runtime error to call this method with an invalid id.
func (id ID) Time() time.Time {
// First 4 bytes of ObjectId is 32-bit big-endian seconds from epoch.
secs := int64(binary.BigEndian.Uint32(id[0:4]))
return time.Unix(secs, 0)
}
// Machine returns the 3-byte machine id part of the id.
// It's a runtime error to call this method with an invalid id.
func (id ID) Machine() []byte {
return id[4:7]
}
// Pid returns the process id part of the id.
// It's a runtime error to call this method with an invalid id.
func (id ID) Pid() uint16 {
return binary.BigEndian.Uint16(id[7:9])
}
// Counter returns the incrementing value part of the id.
// It's a runtime error to call this method with an invalid id.
func (id ID) Counter() int32 {
b := id[9:12]
// Counter is stored as big-endian 3-byte value
return int32(uint32(b[0])<<16 | uint32(b[1])<<8 | uint32(b[2]))
}
// Value implements the driver.Valuer interface.
func (id ID) Value() (driver.Value, error) {
if id.IsNil() {
return nil, nil
}
b, err := id.MarshalText()
return string(b), err
}
// Scan implements the sql.Scanner interface.
func (id *ID) Scan(value interface{}) (err error) {
switch val := value.(type) {
case string:
return id.UnmarshalText([]byte(val))
case []byte:
return id.UnmarshalText(val)
case nil:
*id = nilID
return nil
default:
return fmt.Errorf("xid: scanning unsupported type: %T", value)
}
}
// IsNil Returns true if this is a "nil" ID
func (id ID) IsNil() bool {
return id == nilID
}
// NilID returns a zero value for `xid.ID`.
func NilID() ID {
return nilID
}
// Bytes returns the byte array representation of `ID`
func (id ID) Bytes() []byte {
return id[:]
}
// FromBytes convert the byte array representation of `ID` back to `ID`
func FromBytes(b []byte) (ID, error) {
var id ID
if len(b) != rawLen {
return id, ErrInvalidID
}
copy(id[:], b)
return id, nil
}
// Compare returns an integer comparing two IDs. It behaves just like `bytes.Compare`.
// The result will be 0 if two IDs are identical, -1 if current id is less than the other one,
// and 1 if current id is greater than the other.
func (id ID) Compare(other ID) int {
return bytes.Compare(id[:], other[:])
}
type sorter []ID
func (s sorter) Len() int {
return len(s)
}
func (s sorter) Less(i, j int) bool {
return s[i].Compare(s[j]) < 0
}
func (s sorter) Swap(i, j int) {
s[i], s[j] = s[j], s[i]
}
// Sort sorts an array of IDs inplace.
// It works by wrapping `[]ID` and use `sort.Sort`.
func Sort(ids []ID) {
sort.Sort(sorter(ids))
}