/
redis_checkpoint.go
53 lines (43 loc) · 1.53 KB
/
redis_checkpoint.go
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package connector
import (
"fmt"
"log"
"gopkg.in/redis.v5"
)
// RedisCheckpoint implements the Checkpont interface.
// Used to enable the Pipeline.ProcessShard to checkpoint it's progress
// while reading records from Kinesis stream.
type RedisCheckpoint struct {
AppName string
StreamName string
client *redis.Client
sequenceNumber string
}
// CheckpointExists determines if a checkpoint for a particular Shard exists.
// Typically used to determine whether we should start processing the shard with
// TRIM_HORIZON or AFTER_SEQUENCE_NUMBER (if checkpoint exists).
func (c *RedisCheckpoint) CheckpointExists(shardID string) bool {
val, _ := c.client.Get(c.key(shardID)).Result()
if val != "" {
c.sequenceNumber = val
return true
}
return false
}
// SequenceNumber returns the current checkpoint stored for the specified shard.
func (c *RedisCheckpoint) SequenceNumber() string {
return c.sequenceNumber
}
// SetCheckpoint stores a checkpoint for a shard (e.g. sequence number of last record processed by application).
// Upon failover, record processing is resumed from this point.
func (c *RedisCheckpoint) SetCheckpoint(shardID string, sequenceNumber string) {
err := c.client.Set(c.key(shardID), sequenceNumber, 0).Err()
if err != nil {
log.Printf("redis checkpoint set error: %v", err)
}
c.sequenceNumber = sequenceNumber
}
// key generates a unique Redis key for storage of Checkpoint.
func (c *RedisCheckpoint) key(shardID string) string {
return fmt.Sprintf("%v:checkpoint:%v:%v", c.AppName, c.StreamName, shardID)
}