forked from looplab/eventhorizon
/
saga.go
79 lines (67 loc) · 2.17 KB
/
saga.go
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// Copyright (c) 2014 - The Event Horizon authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package domain
import (
"context"
"sync"
eh "github.com/looplab/eventhorizon"
"github.com/looplab/eventhorizon/eventhandler/saga"
)
// ResponseSagaType is the type of the saga.
const ResponseSagaType saga.Type = "ResponseSaga"
// ResponseSaga is a saga that confirmes all accepted invites until a guest
// limit has been reached.
type ResponseSaga struct {
acceptedGuests map[eh.UUID]bool
acceptedGuestsMu sync.RWMutex
guestLimit int
}
// NewResponseSaga returns a new ResponseSage with a guest limit.
func NewResponseSaga(guestLimit int) *ResponseSaga {
return &ResponseSaga{
acceptedGuests: map[eh.UUID]bool{},
guestLimit: guestLimit,
}
}
// SagaType implements the SagaType method of the Saga interface.
func (s *ResponseSaga) SagaType() saga.Type {
return ResponseSagaType
}
// RunSaga implements the Run saga method of the Saga interface.
func (s *ResponseSaga) RunSaga(ctx context.Context, event eh.Event) []eh.Command {
switch event.EventType() {
case InviteAcceptedEvent:
// Do nothing for already accepted guests.
s.acceptedGuestsMu.RLock()
ok, _ := s.acceptedGuests[event.AggregateID()]
s.acceptedGuestsMu.RUnlock()
if ok {
return nil
}
// Deny the invite if the guest list is full.
if len(s.acceptedGuests) >= s.guestLimit {
return []eh.Command{
&DenyInvite{ID: event.AggregateID()},
}
}
// Confirm the invite when there is space left.
s.acceptedGuestsMu.Lock()
s.acceptedGuests[event.AggregateID()] = true
s.acceptedGuestsMu.Unlock()
return []eh.Command{
&ConfirmInvite{ID: event.AggregateID()},
}
}
return nil
}