topic.go

package servicebus

//	MIT License
//
//	Copyright (c) Microsoft Corporation. All rights reserved.
//
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//	of this software and associated documentation files (the "Software"), to deal
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//
//	The above copyright notice and this permission notice shall be included in all
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//
//	THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
//	IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
//	FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
//	AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
//	LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
//	OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
//	SOFTWARE

import (
	"context"
	"encoding/xml"
	"errors"
	"io/ioutil"
	"net/http"
	"sync"
	"time"

	"github.com/Azure/azure-amqp-common-go/log"
	"github.com/Azure/azure-sdk-for-go/services/servicebus/mgmt/2017-04-01/servicebus"
	"github.com/Azure/azure-service-bus-go/atom"
	"github.com/Azure/go-autorest/autorest/date"
	"github.com/Azure/go-autorest/autorest/to"
)

type (
	// Topic in contrast to queues, in which each message is processed by a single consumer, topics and subscriptions
	// provide a one-to-many form of communication, in a publish/subscribe pattern. Useful for scaling to very large
	// numbers of recipients, each published message is made available to each subscription registered with the topic.
	// Messages are sent to a topic and delivered to one or more associated subscriptions, depending on filter rules
	// that can be set on a per-subscription basis. The subscriptions can use additional filters to restrict the
	// messages that they want to receive. Messages are sent to a topic in the same way they are sent to a queue,
	// but messages are not received from the topic directly. Instead, they are received from subscriptions. A topic
	// subscription resembles a virtual queue that receives copies of the messages that are sent to the topic.
	// Messages are received from a subscription identically to the way they are received from a queue.
	Topic struct {
		*entity
		sender   *sender
		senderMu sync.Mutex
	}

	// TopicManager provides CRUD functionality for Service Bus Topics
	TopicManager struct {
		*entityManager
	}

	// TopicEntity is the Azure Service Bus description of a Topic for management activities
	TopicEntity struct {
		*TopicDescription
		Name string
	}

	// topicFeed is a specialized feed containing Topic Entries
	topicFeed struct {
		*atom.Feed
		Entries []topicEntry `xml:"entry"`
	}

	// topicEntry is a specialized Topic feed entry
	topicEntry struct {
		*atom.Entry
		Content *topicContent `xml:"content"`
	}

	// topicContent is a specialized Topic body for an Atom entry
	topicContent struct {
		XMLName          xml.Name         `xml:"content"`
		Type             string           `xml:"type,attr"`
		TopicDescription TopicDescription `xml:"TopicDescription"`
	}

	// TopicDescription is the content type for Topic management requests
	TopicDescription struct {
		XMLName xml.Name `xml:"TopicDescription"`
		BaseEntityDescription
		DefaultMessageTimeToLive            *string                  `xml:"DefaultMessageTimeToLive,omitempty"`            // DefaultMessageTimeToLive - ISO 8601 default message time span to live value. This is the duration after which the message expires, starting from when the message is sent to Service Bus. This is the default value used when TimeToLive is not set on a message itself.
		MaxSizeInMegabytes                  *int32                   `xml:"MaxSizeInMegabytes,omitempty"`                  // MaxSizeInMegabytes - The maximum size of the queue in megabytes, which is the size of memory allocated for the queue. Default is 1024.
		RequiresDuplicateDetection          *bool                    `xml:"RequiresDuplicateDetection,omitempty"`          // RequiresDuplicateDetection - A value indicating if this queue requires duplicate detection.
		DuplicateDetectionHistoryTimeWindow *string                  `xml:"DuplicateDetectionHistoryTimeWindow,omitempty"` // DuplicateDetectionHistoryTimeWindow - ISO 8601 timeSpan structure that defines the duration of the duplicate detection history. The default value is 10 minutes.
		EnableBatchedOperations             *bool                    `xml:"EnableBatchedOperations,omitempty"`             // EnableBatchedOperations - Value that indicates whether server-side batched operations are enabled.
		SizeInBytes                         *int64                   `xml:"SizeInBytes,omitempty"`                         // SizeInBytes - The size of the queue, in bytes.
		FilteringMessagesBeforePublishing   *bool                    `xml:"FilteringMessagesBeforePublishing,omitempty"`
		IsAnonymousAccessible               *bool                    `xml:"IsAnonymousAccessible,omitempty"`
		Status                              *servicebus.EntityStatus `xml:"Status,omitempty"`
		CreatedAt                           *date.Time               `xml:"CreatedAt,omitempty"`
		UpdatedAt                           *date.Time               `xml:"UpdatedAt,omitempty"`
		SupportOrdering                     *bool                    `xml:"SupportOrdering,omitempty"`
		AutoDeleteOnIdle                    *string                  `xml:"AutoDeleteOnIdle,omitempty"`
		EnablePartitioning                  *bool                    `xml:"EnablePartitioning,omitempty"`
		EnableSubscriptionPartitioning      *bool                    `xml:"EnableSubscriptionPartitioning,omitempty"`
		EnableExpress                       *bool                    `xml:"EnableExpress,omitempty"`
		CountDetails                        *CountDetails            `xml:"CountDetails,omitempty"`
	}

	// TopicManagementOption represents named options for assisting Topic creation
	TopicManagementOption func(*TopicDescription) error

	// TopicOption represents named options for assisting Topic message handling
	TopicOption func(*Topic) error
)

// NewTopicManager creates a new TopicManager for a Service Bus Namespace
func (ns *Namespace) NewTopicManager() *TopicManager {
	return &TopicManager{
		entityManager: newEntityManager(ns.getHTTPSHostURI(), ns.TokenProvider),
	}
}

// Delete deletes a Service Bus Topic entity by name
func (tm *TopicManager) Delete(ctx context.Context, name string) error {
	span, ctx := tm.startSpanFromContext(ctx, "sb.TopicManager.Delete")
	defer span.Finish()

	res, err := tm.entityManager.Delete(ctx, "/"+name)
	if res != nil {
		defer res.Body.Close()
	}

	return err
}

// Put creates or updates a Service Bus Topic
func (tm *TopicManager) Put(ctx context.Context, name string, opts ...TopicManagementOption) (*TopicEntity, error) {
	span, ctx := tm.startSpanFromContext(ctx, "sb.TopicManager.Put")
	defer span.Finish()

	td := new(TopicDescription)
	for _, opt := range opts {
		if err := opt(td); err != nil {
			log.For(ctx).Error(err)
			return nil, err
		}
	}

	td.ServiceBusSchema = to.StringPtr(serviceBusSchema)

	qe := &topicEntry{
		Entry: &atom.Entry{
			AtomSchema: atomSchema,
		},
		Content: &topicContent{
			Type:             applicationXML,
			TopicDescription: *td,
		},
	}

	reqBytes, err := xml.Marshal(qe)
	if err != nil {
		log.For(ctx).Error(err)
		return nil, err
	}

	reqBytes = xmlDoc(reqBytes)
	res, err := tm.entityManager.Put(ctx, "/"+name, reqBytes)
	if res != nil {
		defer res.Body.Close()
	}

	if err != nil {
		log.For(ctx).Error(err)
		return nil, err
	}

	b, err := ioutil.ReadAll(res.Body)
	if err != nil {
		log.For(ctx).Error(err)
		return nil, err
	}

	var entry topicEntry
	err = xml.Unmarshal(b, &entry)
	if err != nil {
		return nil, formatManagementError(b)
	}
	return topicEntryToEntity(&entry), nil
}

// List fetches all of the Topics for a Service Bus Namespace
func (tm *TopicManager) List(ctx context.Context) ([]*TopicEntity, error) {
	span, ctx := tm.startSpanFromContext(ctx, "sb.TopicManager.List")
	defer span.Finish()

	res, err := tm.entityManager.Get(ctx, `/$Resources/Topics`)
	if res != nil {
		defer res.Body.Close()
	}

	if err != nil {
		log.For(ctx).Error(err)
		return nil, err
	}

	b, err := ioutil.ReadAll(res.Body)
	if err != nil {
		log.For(ctx).Error(err)
		return nil, err
	}

	var feed topicFeed
	err = xml.Unmarshal(b, &feed)
	if err != nil {
		return nil, formatManagementError(b)
	}

	topics := make([]*TopicEntity, len(feed.Entries))
	for idx, entry := range feed.Entries {
		topics[idx] = topicEntryToEntity(&entry)
	}
	return topics, nil
}

// Get fetches a Service Bus Topic entity by name
func (tm *TopicManager) Get(ctx context.Context, name string) (*TopicEntity, error) {
	span, ctx := tm.startSpanFromContext(ctx, "sb.TopicManager.Get")
	defer span.Finish()

	res, err := tm.entityManager.Get(ctx, name)
	if res != nil {
		defer res.Body.Close()
	}

	if err != nil {
		log.For(ctx).Error(err)
		return nil, err
	}

	if res.StatusCode == http.StatusNotFound {
		return nil, nil
	}

	b, err := ioutil.ReadAll(res.Body)
	if err != nil {
		log.For(ctx).Error(err)
		return nil, err
	}

	var entry topicEntry
	err = xml.Unmarshal(b, &entry)
	if err != nil {
		if isEmptyFeed(b) {
			return nil, nil
		}
		return nil, formatManagementError(b)
	}
	return topicEntryToEntity(&entry), nil
}

func topicEntryToEntity(entry *topicEntry) *TopicEntity {
	return &TopicEntity{
		TopicDescription: &entry.Content.TopicDescription,
		Name:             entry.Title,
	}
}

// NewTopic creates a new Topic Sender
func (ns *Namespace) NewTopic(ctx context.Context, name string, opts ...TopicOption) (*Topic, error) {
	span, ctx := ns.startSpanFromContext(ctx, "sb.Namespace.NewTopic")
	defer span.Finish()

	topic := &Topic{
		entity: &entity{
			namespace: ns,
			Name:      name,
		},
	}

	for _, opt := range opts {
		if err := opt(topic); err != nil {
			log.For(ctx).Error(err)
			return nil, err
		}
	}

	return topic, nil
}

// Send sends messages to the Topic
func (t *Topic) Send(ctx context.Context, event *Message, opts ...SendOption) error {
	span, ctx := t.startSpanFromContext(ctx, "sb.Topic.Send")
	defer span.Finish()

	err := t.ensureSender(ctx)
	if err != nil {
		log.For(ctx).Error(err)
		return err
	}
	return t.sender.Send(ctx, event, opts...)
}

// Close the underlying connection to Service Bus
func (t *Topic) Close(ctx context.Context) error {
	span, ctx := t.startSpanFromContext(ctx, "sb.Topic.Close")
	defer span.Finish()

	if t.sender != nil {
		return t.sender.Close(ctx)
	}

	return nil
}

func (t *Topic) ensureSender(ctx context.Context) error {
	span, ctx := t.startSpanFromContext(ctx, "sb.Topic.ensureSender")
	defer span.Finish()

	t.senderMu.Lock()
	defer t.senderMu.Unlock()

	if t.sender == nil {
		s, err := t.namespace.newSender(ctx, t.Name)
		if err != nil {
			log.For(ctx).Error(err)
			return err
		}
		t.sender = s
	}
	return nil
}

// TopicWithMaxSizeInMegabytes configures the maximum size of the topic in megabytes (1 * 1024 - 5 * 1024), which is the size of
// the memory allocated for the topic. Default is 1 MB (1 * 1024).
func TopicWithMaxSizeInMegabytes(size int) TopicManagementOption {
	return func(t *TopicDescription) error {
		if size < 1*Megabytes || size > 5*Megabytes {
			return errors.New("TopicWithMaxSizeInMegabytes: must be between 1 * Megabytes and 5 * Megabytes")
		}
		size32 := int32(size)
		t.MaxSizeInMegabytes = &size32
		return nil
	}
}

// TopicWithPartitioning configures the topic to be partitioned across multiple message brokers.
func TopicWithPartitioning() TopicManagementOption {
	return func(t *TopicDescription) error {
		t.EnablePartitioning = ptrBool(true)
		return nil
	}
}

// TopicWithOrdering configures the topic to support ordering of messages.
func TopicWithOrdering() TopicManagementOption {
	return func(t *TopicDescription) error {
		t.SupportOrdering = ptrBool(true)
		return nil
	}
}

// TopicWithDuplicateDetection configures the topic to detect duplicates for a given time window. If window
// is not specified, then it uses the default of 10 minutes.
func TopicWithDuplicateDetection(window *time.Duration) TopicManagementOption {
	return func(t *TopicDescription) error {
		t.RequiresDuplicateDetection = ptrBool(true)
		if window != nil {
			t.DuplicateDetectionHistoryTimeWindow = durationTo8601Seconds(window)
		}
		return nil
	}
}

// TopicWithExpress configures the topic to hold a message in memory temporarily before writing it to persistent storage.
func TopicWithExpress() TopicManagementOption {
	return func(t *TopicDescription) error {
		t.EnableExpress = ptrBool(true)
		return nil
	}
}

// TopicWithBatchedOperations configures the topic to batch server-side operations.
func TopicWithBatchedOperations() TopicManagementOption {
	return func(t *TopicDescription) error {
		t.EnableBatchedOperations = ptrBool(true)
		return nil
	}
}

// TopicWithAutoDeleteOnIdle configures the topic to automatically delete after the specified idle interval. The
// minimum duration is 5 minutes.
func TopicWithAutoDeleteOnIdle(window *time.Duration) TopicManagementOption {
	return func(t *TopicDescription) error {
		if window != nil {
			if window.Minutes() < 5 {
				return errors.New("TopicWithAutoDeleteOnIdle: window must be greater than 5 minutes")
			}
			t.AutoDeleteOnIdle = durationTo8601Seconds(window)
		}
		return nil
	}
}

// TopicWithMessageTimeToLive configures the topic to set a time to live on messages. This is the duration after which
// the message expires, starting from when the message is sent to Service Bus. This is the default value used when
// TimeToLive is not set on a message itself. If nil, defaults to 14 days.
func TopicWithMessageTimeToLive(window *time.Duration) TopicManagementOption {
	return func(t *TopicDescription) error {
		if window == nil {
			duration := time.Duration(14 * 24 * time.Hour)
			window = &duration
		}
		t.DefaultMessageTimeToLive = durationTo8601Seconds(window)
		return nil
	}
}