147 lines
2.6 KiB
Go
147 lines
2.6 KiB
Go
package event
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import (
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"crypto/rand"
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"encoding"
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"encoding/json"
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"fmt"
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"io"
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"strings"
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"sync"
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"time"
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ulid "github.com/oklog/ulid/v2"
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)
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var pool = sync.Pool{
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New: func() interface{} { return ulid.Monotonic(rand.Reader, 0) },
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}
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func getULID() ulid.ULID {
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var entropy io.Reader = rand.Reader
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if e, ok := pool.Get().(io.Reader); ok {
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entropy = e
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defer pool.Put(e)
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}
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return ulid.MustNew(ulid.Now(), entropy)
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}
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type Event interface {
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EventMeta() Meta
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SetEventMeta(Meta)
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encoding.BinaryMarshaler
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encoding.BinaryUnmarshaler
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}
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// Events is a list of events
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type Events []Event
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func NewEvents(lis ...Event) Events {
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for i, e := range lis {
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meta := e.EventMeta()
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meta.Position = uint64(i)
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meta.EventID = getULID()
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e.SetEventMeta(meta)
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}
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return lis
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}
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func (lis Events) StreamID() string {
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if len(lis) == 0 {
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return ""
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}
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return lis.First().EventMeta().StreamID
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}
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func (lis Events) SetStreamID(streamID string) {
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SetStreamID(streamID, lis...)
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}
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func (lis Events) First() Event {
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if len(lis) == 0 {
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return NilEvent
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}
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return lis[0]
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}
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func (lis Events) Rest() Events {
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if len(lis) == 0 {
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return nil
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}
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return lis[1:]
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}
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func (lis Events) Last() Event {
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if len(lis) == 0 {
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return NilEvent
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}
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return lis[len(lis)-1]
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}
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func TypeOf(e Event) string {
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if ie, ok := e.(interface{ UnwrapEvent() Event }); ok {
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e = ie.UnwrapEvent()
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}
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if e, ok := e.(interface{ EventType() string }); ok {
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return e.EventType()
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}
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// Default to printed representation for unnamed types
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return strings.Trim(fmt.Sprintf("%T", e), "*")
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}
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type streamID string
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func (s streamID) StreamID() string {
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return string(s)
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}
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func StreamID(e Event) streamID {
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return streamID(e.EventMeta().StreamID)
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}
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func SetStreamID(id string, lis ...Event) {
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for _, e := range lis {
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meta := e.EventMeta()
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meta.StreamID = id
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e.SetEventMeta(meta)
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}
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}
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func EventID(e Event) ulid.ULID {
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return e.EventMeta().EventID
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}
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func SetEventID(e Event, id ulid.ULID) {
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meta := e.EventMeta()
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meta.EventID = id
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e.SetEventMeta(meta)
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}
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func SetPosition(e Event, i uint64) {
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meta := e.EventMeta()
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meta.Position = i
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e.SetEventMeta(meta)
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}
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type Meta struct {
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EventID ulid.ULID
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StreamID string
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Position uint64
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}
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func (m Meta) Created() time.Time {
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return ulid.Time(m.EventID.Time())
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}
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func (m Meta) GetEventID() string { return m.EventID.String() }
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type nilEvent struct{}
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func (*nilEvent) EventMeta() Meta {
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return Meta{}
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}
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func (*nilEvent) SetEventMeta(eventMeta Meta) {}
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var NilEvent = &nilEvent{}
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func (e *nilEvent) MarshalBinary() ([]byte, error) {
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return json.Marshal(e)
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}
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func (e *nilEvent) UnmarshalBinary(b []byte) error {
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return json.Unmarshal(b, e)
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}
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