chore: add example how to delete keys without a ttl

example/del-keys-without-ttl/main.go

@@ -0,0 +1,142 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"sync"
+
+	"github.com/go-redis/redis/v8"
+)
+
+func main() {
+	ctx := context.Background()
+
+	rdb := redis.NewClient(&redis.Options{
+		Addr: ":6379",
+	})
+
+	ch := make(chan string, 100)
+	var wg sync.WaitGroup
+
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+		deleted, err := process(ctx, rdb, ch)
+		if err != nil {
+			panic(err)
+		}
+		fmt.Println("deleted", deleted, "keys")
+	}()
+
+	iter := rdb.Scan(ctx, 0, "", 0).Iterator()
+	for iter.Next(ctx) {
+		ch <- iter.Val()
+	}
+	if err := iter.Err(); err != nil {
+		panic(err)
+	}
+
+	close(ch)
+	wg.Wait()
+}
+
+func process(ctx context.Context, rdb *redis.Client, in <-chan string) (int, error) {
+	var wg sync.WaitGroup
+
+	out := make(chan string, 100)
+	defer func() {
+		close(out)
+		wg.Wait()
+	}()
+
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+		if err := del(ctx, rdb, out); err != nil {
+			panic(err)
+		}
+	}()
+
+	var deleted int
+
+	keys := make([]string, 0, 100)
+	for key := range in {
+		keys = append(keys, key)
+		if len(keys) < 100 {
+			continue
+		}
+
+		var err error
+		keys, err = checkTTL(ctx, rdb, keys)
+		if err != nil {
+			return 0, err
+		}
+
+		for _, key := range keys {
+			out <- key
+		}
+		deleted += len(keys)
+
+		keys = keys[:0]
+	}
+
+	if len(keys) > 0 {
+		keys, err := checkTTL(ctx, rdb, keys)
+		if err != nil {
+			return 0, err
+		}
+
+		for _, key := range keys {
+			out <- key
+		}
+		deleted += len(keys)
+	}
+
+	return deleted, nil
+}
+
+func checkTTL(ctx context.Context, rdb *redis.Client, keys []string) ([]string, error) {
+	cmds, err := rdb.Pipelined(ctx, func(pipe redis.Pipeliner) error {
+		for _, key := range keys {
+			pipe.TTL(ctx, key)
+		}
+		return nil
+	})
+	if err != nil {
+		return nil, err
+	}
+
+	for i := len(cmds) - 1; i >= 0; i-- {
+		d, err := cmds[i].(*redis.DurationCmd).Result()
+		if err != nil {
+			return nil, err
+		}
+		if d != -1 {
+			keys = append(keys[:i], keys[i+1:]...)
+		}
+	}
+
+	return keys, nil
+}
+
+func del(ctx context.Context, rdb *redis.Client, in <-chan string) error {
+	pipe := rdb.Pipeline()
+
+	for key := range in {
+		pipe.Del(ctx, key)
+
+		if pipe.Len() < 100 {
+			continue
+		}
+
+		if _, err := pipe.Exec(ctx); err != nil {
+			return err
+		}
+	}
+
+	if _, err := pipe.Exec(ctx); err != nil {
+		return err
+	}
+
+	return nil
+}