fastid.go

package fastid

const (
	// DefaultEpoch is an epoch for a default generator.
	DefaultEpoch = 1500000000000

	// WorkerIDBits is how many bits are used for worked ID.
	WorkerIDBits = uint(10)
	// SequenceBits is how many bits are used for sequence number.
	SequenceBits = uint(12)

	workerIDShift  = SequenceBits
	timestampShift = SequenceBits + WorkerIDBits

	// MaxWorkerID is a max possible worked ID.
	MaxWorkerID = (1 << WorkerIDBits) - 1
	// MaxSequenceID is a max possible sequence number.
	MaxSequenceID = (1 << SequenceBits) - 1
	sequenceMask  = (1 << SequenceBits) - 1
)

// ID represents an ID value.
type ID uint64

// Parts returns ID's parts(timestamp, sequence number, worker id).
func (id ID) Parts() (int64, int, int) {
	return id.Timestamp(), id.Sequence(), id.WorkerID()
}

// Timestamp returns ID's timestamp (unix ms).
func (id ID) Timestamp() int64 {
	return int64(id) >> timestampShift
}

// Sequence returns ID's sequence number.
func (id ID) Sequence() int {
	return int(id) & sequenceMask
}

// WorkerID returns ID's worker id.
func (id ID) WorkerID() int {
	return int(id) >> workerIDShift
}

var defaultGenerator, _ = NewGenerator(DefaultEpoch, 0)

// Next returns a next ID.
func Next() ID {
	return defaultGenerator.Next()
}

// LastID returns a last generated ID.
func LastID() ID {
	return ID(defaultGenerator.lastID)
}

// LastTimestamp returns a last generated timestamp.
func LastTimestamp() int64 {
	return int64(defaultGenerator.lastTimestamp)
}