net/raft: save snapshot position first #1312
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PTAL CoreOS confirmed this in etcd-io/etcd#8088. |
tessr
approved these changes
Jun 13, 2017
net/raft/raft.go
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| err = walobj.SaveSnapshot(walpb.Snapshot{ | ||
| Index: raftSnap.Metadata.Index, | ||
| Term: raftSnap.Metadata.Term, | ||
| }) | ||
| if err != nil { | ||
| return 0, nil, errors.Wrap(err) | ||
| } | ||
| err := sv.saveSnapshot(&raftSnap) |
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I wonder if sv.saveSnapshot and wal.SaveSnapshot could be consolidated somehow, to prevent us from accidentally doing these in the wrong order. (They always get executed together, right?)
Save the snapshot position to the WAL before saving the snapshot data to disk. On boot, we open the WAL at the most recently saved snapshot's position. If we don't save the position to the WAL first, we might open the WAL at a snapshot position that was never saved to the WAL. We might want to wait until the CoreOS folks confirm this in etcd-io/etcd#8082.
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Save the snapshot position to the WAL before saving the snapshot data to
disk. On boot, we open the WAL at the most recently saved snapshot's
position. If we don't save the position to the WAL first, we might open
the WAL at a snapshot position that was never saved to the WAL.
See etcd-io/etcd#8082, etcd-io/etcd#8088.