From d3e5936a3a5253a4c98d882973f9480f9b45645d Mon Sep 17 00:00:00 2001
From: Tetsuya Shiota <tetsuya.shiota.1231@gmail.com>
Date: Mon, 6 Sep 2021 16:49:41 +0900
Subject: [PATCH] update: use SScan instead of SMembers Command

---
 pkg/backend/redis/task.go | 41 ++++++++++++++++++++++++++-------------
 1 file changed, 28 insertions(+), 13 deletions(-)

diff --git a/pkg/backend/redis/task.go b/pkg/backend/redis/task.go
index dec1c6d..d96951e 100644
--- a/pkg/backend/redis/task.go
+++ b/pkg/backend/redis/task.go
@@ -38,11 +38,12 @@ import (
 )
 
 const (
-	KB                 = 1 << 10
-	PayloadMaxSizeInKB = 1
-	MessageMaxSizeInKB = 1
-	HistoryLengthMax   = 10
-	MaxNameLength      = 1024
+	KB                     = 1 << 10
+	PayloadMaxSizeInKB     = 1
+	MessageMaxSizeInKB     = 1
+	HistoryLengthMax       = 10
+	MaxNameLength          = 1024
+	taskOperationChunkSize = 1024
 )
 
 func (b *Backend) ensureQueueAndWorkerExists(queueUID, workerUID uuid.UUID) (*taskqueue.TaskQueue, *worker.Worker, error) {
@@ -162,10 +163,7 @@ func (b *Backend) getTasksByUIDs(queueUID string, taskUIDs []string, filter func
 }
 
 func (b *Backend) getTasks(queueUID string, filter func(*task.Task) bool, lggr zerolog.Logger) ([]*task.Task, error) {
-	taskUIDs, err := b.Client.SMembers(b.tasksKey(queueUID)).Result()
-	if err == redis.Nil {
-		return []*task.Task{}, nil
-	}
+	taskUIDs, err := b.allTaskUIDsByQueueUID(b.Client, queueUID)
 	if err != nil {
 		return nil, err
 	}
@@ -938,10 +936,7 @@ func (b *Backend) allTasksKeysForDeleteQueue(rds redis.Cmdable, queueUID string)
 		b.deadletterQueueKey(queueUID),
 		b.pendingTaskQueueKey(queueUID),
 	}
-	taskUIDs, err := rds.SMembers(b.tasksKey(queueUID)).Result()
-	if err == redis.Nil {
-		return []string{}, nil
-	}
+	taskUIDs, err := b.allTaskUIDsByQueueUID(rds, queueUID)
 	if err != nil {
 		return []string{}, err
 	}
@@ -950,3 +945,23 @@ func (b *Backend) allTasksKeysForDeleteQueue(rds redis.Cmdable, queueUID string)
 	}
 	return keysToDelete, nil
 }
+
+func (b *Backend) allTaskUIDsByQueueUID(rds redis.Cmdable, queueUID string) ([]string, error) {
+	var cursor uint64
+	var taskUIDs []string
+	for {
+		keys, nextCursor, err := rds.SScan(b.tasksKey(queueUID), cursor, "", taskOperationChunkSize).Result()
+		if err == redis.Nil {
+			return []string{}, nil
+		}
+		if err != nil {
+			return []string{}, err
+		}
+		taskUIDs = append(taskUIDs, keys...)
+		cursor = nextCursor
+		if cursor == 0 {
+			break
+		}
+	}
+	return taskUIDs, nil
+}