github.com/deanMdreon/kafka-go@v0.4.32/example_consumergroup_test.go (about)

     1  package kafka_test
     2  
     3  import (
     4  	"context"
     5  	"fmt"
     6  	"os"
     7  
     8  	"github.com/deanMdreon/kafka-go"
     9  )
    10  
    11  func ExampleGeneration_Start_consumerGroupParallelReaders() {
    12  	group, err := kafka.NewConsumerGroup(kafka.ConsumerGroupConfig{
    13  		ID:      "my-group",
    14  		Brokers: []string{"kafka:9092"},
    15  		Topics:  []string{"my-topic"},
    16  	})
    17  	if err != nil {
    18  		fmt.Printf("error creating consumer group: %+v\n", err)
    19  		os.Exit(1)
    20  	}
    21  	defer group.Close()
    22  
    23  	for {
    24  		gen, err := group.Next(context.TODO())
    25  		if err != nil {
    26  			break
    27  		}
    28  
    29  		assignments := gen.Assignments["my-topic"]
    30  		for _, assignment := range assignments {
    31  			partition, offset := assignment.ID, assignment.Offset
    32  			gen.Start(func(ctx context.Context) {
    33  				// create reader for this partition.
    34  				reader := kafka.NewReader(kafka.ReaderConfig{
    35  					Brokers:   []string{"127.0.0.1:9092"},
    36  					Topic:     "my-topic",
    37  					Partition: partition,
    38  				})
    39  				defer reader.Close()
    40  
    41  				// seek to the last committed offset for this partition.
    42  				reader.SetOffset(offset)
    43  				for {
    44  					msg, err := reader.ReadMessage(ctx)
    45  					switch err {
    46  					case kafka.ErrGenerationEnded:
    47  						// generation has ended.  commit offsets.  in a real app,
    48  						// offsets would be committed periodically.
    49  						gen.CommitOffsets(map[string]map[int]int64{"my-topic": {partition: offset + 1}})
    50  						return
    51  					case nil:
    52  						fmt.Printf("received message %s/%d/%d : %s\n", msg.Topic, msg.Partition, msg.Offset, string(msg.Value))
    53  						offset = msg.Offset
    54  					default:
    55  						fmt.Printf("error reading message: %+v\n", err)
    56  					}
    57  				}
    58  			})
    59  		}
    60  	}
    61  }
    62  
    63  func ExampleGeneration_CommitOffsets_overwriteOffsets() {
    64  	group, err := kafka.NewConsumerGroup(kafka.ConsumerGroupConfig{
    65  		ID:      "my-group",
    66  		Brokers: []string{"kafka:9092"},
    67  		Topics:  []string{"my-topic"},
    68  	})
    69  	if err != nil {
    70  		fmt.Printf("error creating consumer group: %+v\n", err)
    71  		os.Exit(1)
    72  	}
    73  	defer group.Close()
    74  
    75  	gen, err := group.Next(context.TODO())
    76  	if err != nil {
    77  		fmt.Printf("error getting next generation: %+v\n", err)
    78  		os.Exit(1)
    79  	}
    80  	err = gen.CommitOffsets(map[string]map[int]int64{
    81  		"my-topic": {
    82  			0: 123,
    83  			1: 456,
    84  			3: 789,
    85  		},
    86  	})
    87  	if err != nil {
    88  		fmt.Printf("error committing offsets next generation: %+v\n", err)
    89  		os.Exit(1)
    90  	}
    91  }