/
reactor_handler.go
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/
reactor_handler.go
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// Copyright 2022 Monoskope 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 eventhandler
import (
"context"
"sync"
"time"
"github.com/cenkalti/backoff"
"github.com/finleap-connect/monoskope/internal/gateway/auth"
apiEs "github.com/finleap-connect/monoskope/pkg/api/eventsourcing"
es "github.com/finleap-connect/monoskope/pkg/eventsourcing"
"github.com/finleap-connect/monoskope/pkg/logger"
"github.com/google/uuid"
)
type reactorEventHandler struct {
log logger.Logger
esClient apiEs.EventStoreClient
reactor es.Reactor
waitGroup sync.WaitGroup
}
// NewReactorEventHandler creates an EventHandler which automates storing Events in the EventStore when a Reactor has emitted any.
func NewReactorEventHandler(esClient apiEs.EventStoreClient, reactor es.Reactor) *reactorEventHandler {
return &reactorEventHandler{
log: logger.WithName("reactorEventHandler"),
esClient: esClient,
reactor: reactor,
}
}
// HandleEvent implements the HandleEvent method of the es.EventHandler interface.
func (m *reactorEventHandler) HandleEvent(ctx context.Context, event es.Event) error {
m.waitGroup.Add(1)
eventsChannel := make(chan es.Event)
go m.handle(ctx, eventsChannel)
return m.reactor.HandleEvent(ctx, event, eventsChannel)
}
// Stop waits for all goroutines to finish
func (m *reactorEventHandler) Stop() {
m.waitGroup.Wait()
}
func (m *reactorEventHandler) handle(ctx context.Context, events <-chan es.Event) {
defer m.waitGroup.Done()
for ev := range events { // Read events from channel
err := checkUserId(ev)
if err != nil {
m.log.Error(err, "Event metadata do not contain user information.")
continue
}
params := backoff.NewExponentialBackOff()
params.MaxElapsedTime = 60 * time.Second
err = backoff.Retry(func() error {
if err := m.storeEvent(ctx, ev); err != nil {
m.log.Error(err, "Failed to send event to EventStore. Retrying...", "AggregateID", ev.AggregateID(), "AggregateType", ev.AggregateType(), "EventType", ev.EventType())
return err
}
return nil
}, params)
if err != nil {
m.log.Error(err, "Failed to send event to EventStore")
}
}
}
func (m *reactorEventHandler) storeEvent(ctx context.Context, event es.Event) error {
// Create stream to send events to store.
stream, err := m.esClient.Store(ctx)
if err != nil {
m.log.Error(err, "Failed to connect to EventStore.")
return err
}
// Convert to proto event
protoEvent := es.NewProtoFromEvent(event)
// Send event to store
err = stream.Send(protoEvent)
if err != nil {
m.log.Error(err, "Failed to send event.")
return err
}
// Close connection
_, err = stream.CloseAndRecv()
if err != nil {
m.log.Error(err, "Failed to close connection with EventStore.")
}
return nil
}
func checkUserId(event es.Event) error {
_, err := uuid.Parse(event.Metadata()[auth.HeaderAuthId])
return err
}