Re: [I] gocql RetryPolicies still don't use query idempotence [cassandra-gocql-driver]

["Rikkuru (via GitHub)" <gi...@apache.org>]

Rikkuru commented on issue #1803:
URL: https://github.com/apache/cassandra-gocql-driver/issues/1803#issuecomment-2325019139

   > Please share an exec query you are using to reproduce the issue, if you tried multiple queries provide them as well.
   
   Hi I have an axample 
   
   main.go (go 1.21.11 ,  github.com/gocql/gocql v1.6.0)
   
   there is a  loop to wait for scylladb start and second loop to have time to down one of the nodes 
   ```
   package main
   
   import (
   	"context"
   	"fmt"
   	"time"
   
   	"github.com/gocql/gocql"
   )
   
   type MyRetryPolicy struct {
   }
   
   func (*MyRetryPolicy) Attempt(q gocql.RetryableQuery) bool {
   	if q.Attempts() > 2 {
   		return false
   	}
   	return true
   }
   
   func (*MyRetryPolicy) GetRetryType(error) gocql.RetryType {
   	return gocql.Retry
   }
   
   type LoggingObserver struct{}
   
   func (*LoggingObserver) ObserveQuery(ctx context.Context, q gocql.ObservedQuery) {
   	fmt.Printf("observer attempt: %d err: %s\n", q.Attempt, q.Err)
   }
   
   func main() {
   	cluster := gocql.NewCluster("some-scylla", "some-scylla3", "some-scylla2")
   	var err error
   	var s *gocql.Session
   	for i := 1; i <= 100; i++ {
   		fmt.Printf("%d attempt\n", i)
   		s, err = gocql.NewSession(*cluster)
   		if err == nil {
   			break
   		}
   		time.Sleep(1 * time.Second)
   	}
   	if err != nil {
   		fmt.Printf("session err: %s\n", err)
   		return
   	}
   	defer s.Close()
   
   	fmt.Printf("CONNECTED!")
   
   	time.Sleep(60 * time.Second)
   	for i := 1; i <= 100; i++ {
   		q := s.Query("INSERT INTO  mykeyspace.events(event_id, time, args) VALUES (?,?,?)", 1, gocql.UUIDFromTime(time.Now()), "test")
   
   		q.RetryPolicy(&MyRetryPolicy{})
   		q.Observer(&LoggingObserver{})
   		q.Consistency(gocql.All)
   
   		fmt.Printf("%d QUERY IsIdempotent: %v\n", i, q.IsIdempotent())
   
   		err = q.Exec()
   		if err != nil {
   			fmt.Printf("exec err: %s\n", err)
   		}
   		time.Sleep(1 * time.Second)
   	}
   }
   ```
   
   cql init for scylla 
   ```
   CREATE KEYSPACE mykeyspace WITH replication = {'class': 'NetworkTopologyStrategy', 'datacenter1': '3'}  AND durable_writes = true;
   CREATE TABLE mykeyspace.events (event_id int, time timeuuid, args text, PRIMARY KEY ((event_id), time));
   ```
   
   docker-compose for nodes and main.go 
   ```
   version: '3'
   
   services:
     some-scylla:
       image: scylladb/scylla:5.1
       container_name: some-scylla
       command: --overprovisioned 1 --smp 1
       ports:
         - 9042:9042
   
     some-scylla2:
       image: scylladb/scylla:5.1
       container_name: some-scylla2
       command: --seeds=some-scylla --overprovisioned 1 --smp 1
   
     some-scylla3:
       image: scylladb/scylla:5.1
       container_name: some-scylla3
       command: --seeds=some-scylla --overprovisioned 1 --smp 1
   
     myapp2:
       image: golang:1.21.11
       container_name: myapp2
       command: go run /app/main.go
       working_dir: /app
       volumes:
       - ./:/app
   
   ```
   
   
   I can see in log that query is retried 
   ```
   2024-09-02 18:40:30 90 QUERY IsIdempotent: false
   2024-09-02 18:40:30 observer attempt: 0 err: Cannot achieve consistency level for cl ALL. Requires 3, alive 2
   2024-09-02 18:40:30 observer attempt: 1 err: Cannot achieve consistency level for cl ALL. Requires 3, alive 2
   2024-09-02 18:40:30 observer attempt: 2 err: Cannot achieve consistency level for cl ALL. Requires 3, alive 2
   2024-09-02 18:40:30 exec err: Cannot achieve consistency level for cl ALL. Requires 3, alive 2
   ```


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