components-contrib/bindings/azure/servicebusqueues/servicebusqueues.go

/*
Copyright 2021 The Dapr 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 servicebusqueues

import (
	"context"
	"errors"
	"fmt"
	"net/url"
	"reflect"
	"sync"
	"sync/atomic"
	"time"

	servicebus "github.com/Azure/azure-sdk-for-go/sdk/messaging/azservicebus"

	"github.com/dapr/components-contrib/bindings"
	impl "github.com/dapr/components-contrib/internal/component/azure/servicebus"
	contribMetadata "github.com/dapr/components-contrib/metadata"
	"github.com/dapr/kit/logger"
)

const (
	correlationID = "correlationID"
	label         = "label"
	id            = "id"
)

// AzureServiceBusQueues is an input/output binding reading from and sending events to Azure Service Bus queues.
type AzureServiceBusQueues struct {
	metadata *impl.Metadata
	client   *impl.Client
	logger   logger.Logger
	closed   atomic.Bool
	wg       sync.WaitGroup
	closeCh  chan struct{}
}

// NewAzureServiceBusQueues returns a new AzureServiceBusQueues instance.
func NewAzureServiceBusQueues(logger logger.Logger) bindings.InputOutputBinding {
	return &AzureServiceBusQueues{
		logger:  logger,
		closeCh: make(chan struct{}),
	}
}

// Init parses connection properties and creates a new Service Bus Queue client.
func (a *AzureServiceBusQueues) Init(ctx context.Context, metadata bindings.Metadata) (err error) {
	a.metadata, err = impl.ParseMetadata(metadata.Properties, a.logger, (impl.MetadataModeBinding | impl.MetadataModeQueues))
	if err != nil {
		return err
	}

	a.client, err = impl.NewClient(a.metadata, metadata.Properties)
	if err != nil {
		return err
	}

	// Will do nothing if DisableEntityManagement is false
	err = a.client.EnsureQueue(ctx, a.metadata.QueueName)
	if err != nil {
		return err
	}

	return nil
}

func (a *AzureServiceBusQueues) Operations() []bindings.OperationKind {
	return []bindings.OperationKind{
		bindings.CreateOperation,
	}
}

func (a *AzureServiceBusQueues) Invoke(ctx context.Context, req *bindings.InvokeRequest) (*bindings.InvokeResponse, error) {
	return a.client.PublishBinding(ctx, req, a.metadata.QueueName, a.logger)
}

func (a *AzureServiceBusQueues) Read(ctx context.Context, handler bindings.Handler) error {
	if a.closed.Load() {
		return errors.New("binding is closed")
	}

	// Reconnection backoff policy
	bo := a.client.ReconnectionBackoff()

	a.wg.Add(1)
	go func() {
		defer a.wg.Done()
		logMsg := "queue " + a.metadata.QueueName

		// Reconnect loop.
		for {
			sub := impl.NewSubscription(impl.SubscriptionOptions{
				MaxActiveMessages:     a.metadata.MaxActiveMessages,
				TimeoutInSec:          a.metadata.TimeoutInSec,
				MaxBulkSubCount:       nil,
				MaxRetriableEPS:       a.metadata.MaxRetriableErrorsPerSec,
				MaxConcurrentHandlers: a.metadata.MaxConcurrentHandlers,
				Entity:                "queue " + a.metadata.QueueName,
				LockRenewalInSec:      a.metadata.LockRenewalInSec,
				RequireSessions:       false, // Sessions not supported for queues yet.
			}, a.logger)

			// Blocks until a successful connection (or until context is canceled)
			receiver, err := sub.Connect(ctx, func() (impl.Receiver, error) {
				a.logger.Debug("Connecting to " + logMsg)
				r, rErr := a.client.GetClient().NewReceiverForQueue(a.metadata.QueueName, nil)
				if rErr != nil {
					return nil, rErr
				}
				return impl.NewMessageReceiver(r), nil
			})
			if err != nil {
				// Realistically, the only time we should get to this point is if the context was canceled, but let's log any other error we may get.
				if errors.Is(err, context.Canceled) {
					a.logger.Warnf("Error reading from Azure Service Bus Queue binding: %s", err.Error())
				}
				return
			}

			// ReceiveAndBlock will only return with an error that it cannot handle internally. The subscription connection is closed when this method returns.
			// If that occurs, we will log the error and attempt to re-establish the subscription connection until we exhaust the number of reconnect attempts.
			err = sub.ReceiveBlocking(
				ctx,
				a.getHandlerFn(handler),
				receiver,
				bo.Reset, // Reset the backoff when the subscription is successful and we have received the first message
				logMsg,
			)
			if err != nil && !errors.Is(err, context.Canceled) {
				a.logger.Errorf("Error from receiver: %v", err)
			}

			wait := bo.NextBackOff()
			a.logger.Warnf("Subscription to queue %s lost connection, attempting to reconnect in %s...", a.metadata.QueueName, wait)
			select {
			case <-time.After(wait):
				// nop
			case <-ctx.Done():
				a.logger.Debug("Context canceled; will not reconnect")
				return
			case <-a.closeCh:
				a.logger.Debug("Component is closing; will not reconnect")
				return
			}
		}
	}()

	return nil
}

func (a *AzureServiceBusQueues) getHandlerFn(handler bindings.Handler) impl.HandlerFn {
	return func(ctx context.Context, asbMsgs []*servicebus.ReceivedMessage) ([]impl.HandlerResponseItem, error) {
		if len(asbMsgs) != 1 {
			return nil, fmt.Errorf("expected 1 message, got %d", len(asbMsgs))
		}

		msg := asbMsgs[0]
		metadata := make(map[string]string)
		metadata[id] = msg.MessageID
		if msg.CorrelationID != nil {
			metadata[correlationID] = *msg.CorrelationID
		}
		if msg.Subject != nil {
			metadata[label] = *msg.Subject
		}

		// Passthrough any custom metadata to the handler.
		for key, val := range msg.ApplicationProperties {
			if stringVal, ok := val.(string); ok {
				// Escape the key and value to ensure they are valid URL query parameters.
				// This is necessary for them to be sent as HTTP Metadata.
				metadata[url.QueryEscape(key)] = url.QueryEscape(stringVal)
			}
		}

		_, err := handler(ctx, &bindings.ReadResponse{
			Data:     msg.Body,
			Metadata: metadata,
		})
		return []impl.HandlerResponseItem{}, err
	}
}

func (a *AzureServiceBusQueues) Close() (err error) {
	if a.closed.CompareAndSwap(false, true) {
		close(a.closeCh)
	}
	a.logger.Debug("Closing component")
	a.client.Close(a.logger)
	a.wg.Wait()
	return nil
}

// GetComponentMetadata returns the metadata of the component.
func (a *AzureServiceBusQueues) GetComponentMetadata() (metadataInfo contribMetadata.MetadataMap) {
	metadataStruct := impl.Metadata{}
	contribMetadata.GetMetadataInfoFromStructType(reflect.TypeOf(metadataStruct), &metadataInfo, contribMetadata.BindingType)
	delete(metadataInfo, "consumerID") // only applies to topics, not queues
	return
}