5a9d8c792b
V2 is compliant with api.openshift.com design guidelines. Errors are predefined, have codes, and are queryable. All requests have an operationId set: a unique identifier which is sortable by time. This is added to the response in case of an error. All returned objects have the href, id, and kind field set.
55 lines
1.5 KiB
Go
55 lines
1.5 KiB
Go
package ksuid
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import (
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"encoding/binary"
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"errors"
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"math"
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)
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// Sequence is a KSUID generator which produces a sequence of ordered KSUIDs
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// from a seed.
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//
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// Up to 65536 KSUIDs can be generated by for a single seed.
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//
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// A typical usage of a Sequence looks like this:
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//
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// seq := ksuid.Sequence{
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// Seed: ksuid.New(),
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// }
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// id, err := seq.Next()
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//
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// Sequence values are not safe to use concurrently from multiple goroutines.
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type Sequence struct {
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// The seed is used as base for the KSUID generator, all generated KSUIDs
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// share the same leading 18 bytes of the seed.
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Seed KSUID
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count uint32 // uint32 for overflow, only 2 bytes are used
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}
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// Next produces the next KSUID in the sequence, or returns an error if the
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// sequence has been exhausted.
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func (seq *Sequence) Next() (KSUID, error) {
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id := seq.Seed // copy
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count := seq.count
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if count > math.MaxUint16 {
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return Nil, errors.New("too many IDs were generated")
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}
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seq.count++
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return withSequenceNumber(id, uint16(count)), nil
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}
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// Bounds returns the inclusive min and max bounds of the KSUIDs that may be
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// generated by the sequence. If all ids have been generated already then the
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// returned min value is equal to the max.
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func (seq *Sequence) Bounds() (min KSUID, max KSUID) {
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count := seq.count
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if count > math.MaxUint16 {
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count = math.MaxUint16
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}
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return withSequenceNumber(seq.Seed, uint16(count)), withSequenceNumber(seq.Seed, math.MaxUint16)
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}
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func withSequenceNumber(id KSUID, n uint16) KSUID {
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binary.BigEndian.PutUint16(id[len(id)-2:], n)
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return id
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}
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