fix hlen/hdel race condition

Change-Id: Ib82e6e9f0c66d2df80d68fd00e0c6ec6b46a037b
This commit is contained in:
onestraw 2019-01-16 16:45:04 +08:00
parent 9a5fac67ed
commit f2ab706f10

View file

@ -727,23 +727,34 @@ func (ps *peerStore) collectGarbage(cutoff time.Time) error {
return err
}
// use WATCH to avoid race condition
// https://redis.io/topics/transactions
_, err = conn.Do("WATCH", ihStr)
if err != nil {
return err
}
ihLen, err := conn.Do("HLEN", ihStr)
if err != nil {
return err
}
if ihLen.(int64) == 0 {
_, err := conn.Do("DEL", ihStr)
// Empty hashes are not shown among existing keys,
// in other words, it's removed automatically after `HDEL` the last field.
//_, err := conn.Do("DEL", ihStr)
conn.Send("MULTI")
conn.Send("HDEL", group, ihStr)
conn.Send("DECR", ps.infohashCountKey(group))
_, err = redis.Values(conn.Do("EXEC"))
if err != nil {
return err
}
log.Debug("storage: deleting infohash", log.Fields{
"Group": group,
"Hkey": ihStr,
})
_, err = conn.Do("HDEL", group, ihStr)
if err != nil {
return err
log.Error("storage: Redis EXEC failure, maybe caused by WATCH, ignored", log.Fields{
"group": group,
"infohash": ihStr,
"error": err,
})
}
} else {
conn.Do("UNWATCH", ihStr)
}
}
}