182 lines
3.4 KiB
Go
182 lines
3.4 KiB
Go
package main
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import (
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"context"
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stdSQL "database/sql"
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"encoding/json"
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"log"
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"time"
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driver "github.com/go-sql-driver/mysql"
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"github.com/ThreeDotsLabs/watermill"
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"github.com/ThreeDotsLabs/watermill-kafka/v3/pkg/kafka"
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"github.com/ThreeDotsLabs/watermill-sql/v4/pkg/sql"
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"github.com/ThreeDotsLabs/watermill/message"
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"github.com/ThreeDotsLabs/watermill/message/router/middleware"
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"github.com/ThreeDotsLabs/watermill/message/router/plugin"
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)
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var (
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logger = watermill.NewStdLogger(false, false)
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kafkaTopic = "events"
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mysqlTable = "events"
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)
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func main() {
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router, err := message.NewRouter(message.RouterConfig{}, logger)
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if err != nil {
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panic(err)
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}
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router.AddPlugin(plugin.SignalsHandler)
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router.AddMiddleware(middleware.Recoverer)
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db := createDB()
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subscriber := createSubscriber(db)
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publisher := createPublisher()
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router.AddHandler(
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"mysql-to-kafka",
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mysqlTable,
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subscriber,
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kafkaTopic,
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publisher,
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func(msg *message.Message) ([]*message.Message, error) {
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consumedEvent := event{}
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err := json.Unmarshal(msg.Payload, &consumedEvent)
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if err != nil {
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return nil, err
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}
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log.Printf("received event %+v with UUID %s", consumedEvent, msg.UUID)
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return []*message.Message{msg}, nil
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},
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)
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go func() {
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<-router.Running()
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simulateEvents(db)
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}()
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if err := router.Run(context.Background()); err != nil {
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panic(err)
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}
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}
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func createDB() *stdSQL.DB {
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conf := driver.NewConfig()
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conf.Net = "tcp"
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conf.User = "root"
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conf.Addr = "mysql"
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conf.DBName = "watermill"
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db, err := stdSQL.Open("mysql", conf.FormatDSN())
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if err != nil {
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panic(err)
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}
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err = db.Ping()
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if err != nil {
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panic(err)
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}
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return db
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}
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func createSubscriber(db *stdSQL.DB) message.Subscriber {
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sub, err := sql.NewSubscriber(
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sql.BeginnerFromStdSQL(db),
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sql.SubscriberConfig{
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SchemaAdapter: sql.DefaultMySQLSchema{},
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OffsetsAdapter: sql.DefaultMySQLOffsetsAdapter{},
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InitializeSchema: true,
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},
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logger,
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)
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if err != nil {
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panic(err)
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}
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return sub
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}
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func createPublisher() message.Publisher {
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pub, err := kafka.NewPublisher(
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kafka.PublisherConfig{
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Brokers: []string{"kafka:9092"},
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Marshaler: kafka.DefaultMarshaler{},
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},
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logger,
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)
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if err != nil {
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panic(err)
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}
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return pub
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}
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type event struct {
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Name string `json:"name"`
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OccurredAt string `json:"occurred_at"`
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}
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func simulateEvents(db *stdSQL.DB) {
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for {
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tx, err := db.Begin()
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if err != nil {
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panic(err)
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}
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// In an actual application, this is the place where some aggregate would be persisted
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// using the same transaction.
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// tx.Exec("INSERT INTO (...)")
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err = publishEvent(tx)
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if err != nil {
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rollbackErr := tx.Rollback()
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if rollbackErr != nil {
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panic(rollbackErr)
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}
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panic(err)
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}
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err = tx.Commit()
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if err != nil {
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panic(err)
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}
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time.Sleep(time.Second)
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}
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}
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// publishEvent publishes a new event.
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// To publish the event in a separate transaction, a new SQL Publisher
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// has to be created each time, passing the proper transaction handle.
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func publishEvent(tx *stdSQL.Tx) error {
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pub, err := sql.NewPublisher(
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sql.TxFromStdSQL(tx),
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sql.PublisherConfig{
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SchemaAdapter: sql.DefaultMySQLSchema{},
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}, logger)
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if err != nil {
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return err
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}
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e := event{
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Name: "UserSignedUp",
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OccurredAt: time.Now().UTC().Format(time.RFC3339),
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}
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payload, err := json.Marshal(e)
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if err != nil {
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return err
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}
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return pub.Publish(mysqlTable, message.NewMessage(
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watermill.NewUUID(),
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payload,
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))
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}
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