message_dispatcher.go

/*
Copyright 2020 The Knative 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 inmemorychannel

import (
	"context"
	"time"

	"go.uber.org/zap"

	"knative.dev/eventing/pkg/channel/multichannelfanout"
	"knative.dev/eventing/pkg/kncloudevents"
)

type MessageDispatcher interface {
	GetHandler(ctx context.Context) multichannelfanout.MultiChannelMessageHandler
}

type InMemoryMessageDispatcher struct {
	handler              multichannelfanout.MultiChannelMessageHandler
	httpBindingsReceiver *kncloudevents.HTTPMessageReceiver
	writeTimeout         time.Duration
	logger               *zap.Logger
}

type InMemoryMessageDispatcherArgs struct {
	Port                       int
	ReadTimeout                time.Duration
	WriteTimeout               time.Duration
	Handler                    multichannelfanout.MultiChannelMessageHandler
	Logger                     *zap.Logger
	HTTPMessageReceiverOptions []kncloudevents.HTTPMessageReceiverOption
}

// GetHandler gets the current multichannelfanout.MessageHandler to delegate all HTTP
// requests to.
func (d *InMemoryMessageDispatcher) GetHandler(ctx context.Context) multichannelfanout.MultiChannelMessageHandler {
	return d.handler
}

// Start starts the inmemory dispatcher's message processing.
// This is a blocking call.
func (d *InMemoryMessageDispatcher) Start(ctx context.Context) error {
	return d.httpBindingsReceiver.StartListen(kncloudevents.WithShutdownTimeout(ctx, d.writeTimeout), d.handler)
}

// WaitReady blocks until the dispatcher's server is ready to receive requests.
func (d *InMemoryMessageDispatcher) WaitReady() {
	<-d.httpBindingsReceiver.Ready
}

func NewMessageDispatcher(args *InMemoryMessageDispatcherArgs) *InMemoryMessageDispatcher {
	// TODO set read timeouts?
	bindingsReceiver := kncloudevents.NewHTTPMessageReceiver(
		args.Port,
		args.HTTPMessageReceiverOptions...,
	)

	dispatcher := &InMemoryMessageDispatcher{
		handler:              args.Handler,
		httpBindingsReceiver: bindingsReceiver,
		logger:               args.Logger,
		writeTimeout:         args.WriteTimeout,
	}

	return dispatcher
}