Add message queue service factory (#1537)

pkg/mqtrigger/factory/factory.go

@@ -0,0 +1,62 @@
+/*
+Copyright 2020 The Fission 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 factory
+
+import (
+	"sync"
+
+	"github.com/pkg/errors"
+	"go.uber.org/zap"
+
+	fv1 "github.com/fission/fission/pkg/apis/core/v1"
+	"github.com/fission/fission/pkg/mqtrigger/messageQueue"
+)
+
+var (
+	messageQueueFactories = make(map[fv1.MessageQueueType]MessageQueueFactory)
+	lock                  = sync.Mutex{}
+)
+
+type (
+	MessageQueueFactory interface {
+		Create(logger *zap.Logger, config messageQueue.Config, routerURL string) (messageQueue.MessageQueue, error)
+	}
+)
+
+func Register(mqType fv1.MessageQueueType, factory MessageQueueFactory) {
+	lock.Lock()
+	defer lock.Unlock()
+
+	if factory == nil {
+		panic("Nil message queue factory")
+	}
+
+	_, registered := messageQueueFactories[mqType]
+	if registered {
+		panic("Message queue factory already register")
+	}
+
+	messageQueueFactories[mqType] = factory
+}
+
+func Create(logger *zap.Logger, mqType fv1.MessageQueueType, mqConfig messageQueue.Config, routerUrl string) (messageQueue.MessageQueue, error) {
+	factory, registered := messageQueueFactories[mqType]
+	if !registered {
+		return nil, errors.Errorf("no supported message queue type found for %q", mqType)
+	}
+	return factory.Create(logger, mqConfig, routerUrl)
+}