bug in WatchTree for etcd

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Assessment

Difficulty
4/5
Estimated time
3-5 days
Newbie friendliness
28/100
Issue type
Bug
Clarity
Mostly clear
Activity status
Stale
Tech stack
go
Domain
backend, distributed-systems

Research direction

Start by tracing WatchTree, the etcd client watch event, and the subsequent List request. Reproduce or test the case where List reaches a raft-lagging server and returns unchanged KVPair values. Done means WatchTree observes a consistent state by routing List to the event's server or enforcing the required raft index, with tests covering the race.

Written by the indexing model from the issue text.

Description

WatchTree uses List on the target directory after receiving a watch event from the etcd client. There is no guarantee that the server that receives the later List request is the same one that triggered the previous Watch event. If the one that receives the List event is behind in the raft replication stream, the WatchTree chan will return an unchanged set of KVPair's. This can be fixed by either sending the List to the same server, or ensuring that whatever server receives the List command has a raft index >= the server that sent the Watch update.

Dominant language
Go
Stars
847
Forks
204
No merged PRs in 30d

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