Documentation
¶
Index ¶
- Constants
- Variables
- func MaxTime() uint64
- func Now() uint64
- func Time(ms uint64) time.Time
- func Timestamp(t time.Time) uint64
- type MonotonicEntropy
- type MonotonicReader
- type ULID
- func MustNew(ms uint64, entropy io.Reader) ULID
- func MustParse(ulid string) ULID
- func MustParseStrict(ulid string) ULID
- func New(ms uint64, entropy io.Reader) (id ULID, err error)
- func NewReverse(ms uint64) (id ULID, err error)
- func Parse(ulid string) (id ULID, err error)
- func ParseStrict(ulid string) (id ULID, err error)
- func (id ULID) Compare(other ULID) int
- func (id ULID) Entropy() []byte
- func (id ULID) MarshalBinary() ([]byte, error)
- func (id ULID) MarshalBinaryTo(dst []byte) error
- func (id ULID) MarshalText() ([]byte, error)
- func (id ULID) MarshalTextTo(dst []byte) error
- func (id *ULID) Scan(src interface{}) error
- func (id *ULID) SetEntropy(e []byte) error
- func (id *ULID) SetTime(ms uint64) error
- func (id ULID) String() string
- func (id ULID) Time() uint64
- func (id ULID) TimeString() string
- func (id *ULID) UnmarshalBinary(data []byte) error
- func (id *ULID) UnmarshalText(v []byte) error
- func (id ULID) Value() (driver.Value, error)
- type ZeroReader
Constants ¶
const EncodedSize = 26
EncodedSize is the length of a text encoded ULID.
const Encoding = "0123456789ABCDEFGHJKMNPQRSTVWXYZ"
Encoding is the base 32 encoding alphabet used in ULID strings.
Variables ¶
var ( // ErrDataSize is returned when parsing or unmarshaling ULIDs with the wrong // data size. ErrDataSize = errors.New("ulid: bad data size when unmarshaling") // ErrInvalidCharacters is returned when parsing or unmarshaling ULIDs with // invalid Base32 encodings. ErrInvalidCharacters = errors.New("ulid: bad data characters when unmarshaling") // ErrBufferSize is returned when marshalling ULIDs to a buffer of insufficient // size. ErrBufferSize = errors.New("ulid: bad buffer size when marshaling") // ErrBigTime is returned when constructing an ULID with a time that is larger // than MaxTime. ErrBigTime = errors.New("ulid: time too big") // ErrOverflow is returned when unmarshaling a ULID whose first character is // larger than 7, thereby exceeding the valid bit depth of 128. ErrOverflow = errors.New("ulid: overflow when unmarshaling") // ErrMonotonicOverflow is returned by a Monotonic entropy source when // incrementing the previous ULID's entropy bytes would result in overflow. ErrMonotonicOverflow = errors.New("ulid: monotonic entropy overflow") // ErrScanValue is returned when the value passed to scan cannot be unmarshaled // into the ULID. ErrScanValue = errors.New("ulid: source value must be a string or byte slice") )
Functions ¶
func MaxTime ¶
func MaxTime() uint64
MaxTime returns the maximum Unix time in milliseconds that can be encoded in an ULID.
func Now ¶
func Now() uint64
Now is a convenience function that returns the current UTC time in Unix milliseconds. Equivalent to:
Timestamp(time.Now().UTC())
Types ¶
type MonotonicEntropy ¶
MonotonicEntropy is an opaque type that provides monotonic entropy.
func Monotonic ¶
func Monotonic(entropy io.Reader, inc uint64) *MonotonicEntropy
Monotonic returns an entropy source that is guaranteed to yield strictly increasing entropy bytes for the same ULID timestamp. On conflicts, the previous ULID entropy is incremented with a random number between 1 and `inc` (inclusive).
The provided entropy source must actually yield random bytes or else monotonic reads are not guaranteed to terminate, since there isn't enough randomness to compute an increment number.
When `inc == 0`, it'll be set to a secure default of `math.MaxUint32`. The lower the value of `inc`, the easier the next ULID within the same millisecond is to guess. If your code depends on ULIDs having secure entropy bytes, then don't go under this default unless you know what you're doing.
The returned type isn't safe for concurrent use.
func (*MonotonicEntropy) MonotonicRead ¶
func (m *MonotonicEntropy) MonotonicRead(ms uint64, entropy []byte) (err error)
MonotonicRead implements the MonotonicReader interface.
type MonotonicReader ¶
MonotonicReader is an interface that should yield monotonically increasing entropy into the provided slice for all calls with the same ms parameter. If a MonotonicReader is provided to the New constructor, its MonotonicRead method will be used instead of Read.
type ULID ¶
type ULID [16]byte
An ULID is a 16 byte Universally Unique Lexicographically Sortable Identifier
The components are encoded as 16 octets. Each component is encoded with the MSB first (network byte order). 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 32_bit_uint_time_high | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 16_bit_uint_time_low | 16_bit_uint_random | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 32_bit_uint_random | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 32_bit_uint_random | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
func MustNew ¶
MustNew is a convenience function equivalent to New that panics on failure instead of returning an error.
func MustParse ¶
MustParse is a convenience function equivalent to Parse that panics on failure instead of returning an error.
func MustParseStrict ¶
MustParseStrict is a convenience function equivalent to ParseStrict that panics on failure instead of returning an error.
func New ¶
New returns an ULID with the given Unix milliseconds timestamp and an optional entropy source. Use the Timestamp function to convert a time.Time to Unix milliseconds.
ErrBigTime is returned when passing a timestamp bigger than MaxTime. Reading from the entropy source may also return an error.
Safety for concurrent use is only dependent on the safety of the entropy source.
func NewReverse ¶
func Parse ¶
Parse parses an encoded ULID, returning an error in case of failure.
ErrDataSize is returned if the len(ulid) is different from an encoded ULID's length. Invalid encodings produce undefined ULIDs. For a version that returns an error instead, see ParseStrict.
func ParseStrict ¶
ParseStrict parses an encoded ULID, returning an error in case of failure.
It is like Parse, but additionally validates that the parsed ULID consists only of valid base32 characters. It is slightly slower than Parse.
ErrDataSize is returned if the len(ulid) is different from an encoded ULID's length. Invalid encodings return ErrInvalidCharacters.
func (ULID) Compare ¶
Compare returns an integer comparing id and other lexicographically. The result will be 0 if id==other, -1 if id < other, and +1 if id > other.
func (ULID) MarshalBinary ¶
MarshalBinary implements the encoding.BinaryMarshaler interface by returning the ULID as a byte slice.
func (ULID) MarshalBinaryTo ¶
MarshalBinaryTo writes the binary encoding of the ULID to the given buffer. ErrBufferSize is returned when the len(dst) != 16.
func (ULID) MarshalText ¶
MarshalText implements the encoding.TextMarshaler interface by returning the string encoded ULID.
func (ULID) MarshalTextTo ¶
MarshalTextTo writes the ULID as a string to the given buffer. ErrBufferSize is returned when the len(dst) != 26.
func (*ULID) Scan ¶
Scan implements the sql.Scanner interface. It supports scanning a string or byte slice.
func (*ULID) SetEntropy ¶
SetEntropy sets the ULID entropy to the passed byte slice. ErrDataSize is returned if len(e) != 10.
func (*ULID) SetTime ¶
SetTime sets the time component of the ULID to the given Unix time in milliseconds.
func (ULID) String ¶
String returns a lexicographically sortable string encoded ULID (26 characters, non-standard base 32) e.g. 01AN4Z07BY79KA1307SR9X4MV3 Format: tttttttttteeeeeeeeeeeeeeee where t is time and e is entropy
func (ULID) Time ¶
Time returns the Unix time in milliseconds encoded in the ULID. Use the top level Time function to convert the returned value to a time.Time.
func (ULID) TimeString ¶
MarshalTextTo writes the ULID as a string to the given buffer. ErrBufferSize is returned when the len(dst) != 26.
func (*ULID) UnmarshalBinary ¶
UnmarshalBinary implements the encoding.BinaryUnmarshaler interface by copying the passed data and converting it to an ULID. ErrDataSize is returned if the data length is different from ULID length.
func (*ULID) UnmarshalText ¶
UnmarshalText implements the encoding.TextUnmarshaler interface by parsing the data as string encoded ULID.
ErrDataSize is returned if the len(v) is different from an encoded ULID's length. Invalid encodings produce undefined ULIDs.
func (ULID) Value ¶
Value implements the sql/driver.Valuer interface. This returns the value represented as a byte slice. If instead a string is desirable, a wrapper type can be created that calls String().
// stringValuer wraps a ULID as a string-based driver.Valuer.
type stringValuer ULID
func (id stringValuer) Value() (driver.Value, error) {
return ULID(id).String(), nil
}
// Example usage.
db.Exec("...", stringValuer(id))
type ZeroReader ¶
type ZeroReader struct {
Nonce uint64
}
Source Files