125 lines
2.6 KiB
Go
125 lines
2.6 KiB
Go
package event
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import (
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"errors"
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"fmt"
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"sync"
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)
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type Aggregate interface {
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// ApplyEvent applies the event to the aggrigate state
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ApplyEvent(...Event)
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StreamID() string
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AggregateRootInterface
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}
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// Raise adds new uncommitted events
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func Raise(a Aggregate, lis ...Event) {
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lis = NewEvents(lis...)
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SetStreamID(a.StreamID(), lis...)
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a.raise(lis...)
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a.ApplyEvent(lis...)
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}
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// Append adds new committed events
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func Append(a Aggregate, lis ...Event) {
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a.append(lis...)
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a.ApplyEvent(lis...)
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}
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// CheckVersion returns an error if the version does not match.
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func CheckVersion(a Aggregate, version uint64) error {
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if version != uint64(a.StreamVersion()) {
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return fmt.Errorf("version wrong, got (proposed) %d != (expected) %d", version, a.StreamVersion())
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}
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return nil
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}
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// NotExists returns error if there are no events present.
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func NotExists(a Aggregate) error {
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if a.StreamVersion() != 0 {
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return fmt.Errorf("%w, got version == %d", ErrShouldNotExist, a.StreamVersion())
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}
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return nil
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}
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type AggregateRootInterface interface {
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// Events returns the aggrigate events
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// pass true for only uncommitted events
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Events(bool) Events
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// StreamVersion returns last commit events
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StreamVersion() uint64
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// Version returns the current aggrigate version. (committed + uncommitted)
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Version() uint64
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raise(lis ...Event)
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append(lis ...Event)
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Commit()
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}
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var _ AggregateRootInterface = &AggregateRoot{}
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type AggregateRoot struct {
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events Events
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streamVersion uint64
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mu sync.RWMutex
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}
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func (a *AggregateRoot) Commit() {
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a.streamVersion = uint64(len(a.events))
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}
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func (a *AggregateRoot) StreamVersion() uint64 {
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return a.streamVersion
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}
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func (a *AggregateRoot) Events(new bool) Events {
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a.mu.RLock()
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defer a.mu.RUnlock()
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events := a.events
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if new {
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events = events[a.streamVersion:]
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}
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lis := make(Events, len(events))
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copy(lis, events)
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return lis
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}
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func (a *AggregateRoot) Version() uint64 {
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return uint64(len(a.events))
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}
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//lint:ignore U1000 is called by embeded interface
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func (a *AggregateRoot) raise(lis ...Event) { //nolint
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a.mu.Lock()
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defer a.mu.Unlock()
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a.posStartAt(lis...)
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a.events = append(a.events, lis...)
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}
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//lint:ignore U1000 is called by embeded interface
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func (a *AggregateRoot) append(lis ...Event) {
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a.mu.Lock()
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defer a.mu.Unlock()
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a.posStartAt(lis...)
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a.events = append(a.events, lis...)
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a.streamVersion += uint64(len(lis))
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}
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func (a *AggregateRoot) posStartAt(lis ...Event) {
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for i, e := range lis {
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m := e.EventMeta()
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m.Position = a.streamVersion + uint64(i) + 1
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e.SetEventMeta(m)
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}
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}
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var ErrShouldNotExist = errors.New("should not exist")
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