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e8090e57a2
It has often been tedious to test the interactions between multi-member Raft groups, especially when many steps were required to reach a certain scenario. Often, this boilerplate was as boring as it is hard to write and hard to maintain, making it attractive to resort to shortcuts whenever possible, which in turn tended to undercut how meaningful and maintainable the tests ended up being - that is, if the tests were even written, which sometimes they weren't. This change introduces a datadriven framework specifically for testing deterministically the interaction between multiple members of a raft group with the goal of reducing the friction for writing these tests to near zero. In the near term, this will be used to add thorough testing for joint consensus (which is already available today, but wildly undertested), but just converting an existing test into this framework has shown that the concise representation and built-in inspection of log messages highlights unexpected behavior much more readily than the previous unit tests did (the test in question is `snapshot_succeed_via_app_resp`; the reader is invited to compare the old and new version of it). The main building block is `InteractionEnv`, which holds on to the state of the whole system and exposes various relevant methods for manipulating it, including but not limited to adding nodes, delivering and dropping messages, and proposing configuration changes. All of this is extensible so that in the future I hope to use it to explore the phenomena discussed in https://github.com/etcd-io/etcd/issues/7625#issuecomment-488798263 which requires injecting appropriate "crash points" in the Ready handling loop. Discussions of the "what if X happened in state Y" can quickly be made concrete by "scripting up an interaction test". Additionally, this framework is intentionally not kept internal to the raft package.. Though this is in its infancy, a goal is that it should be possible for a suite of interaction tests to allow applications to validate that their Storage implementation behaves accordingly, simply by running a raft-provided interaction suite against their Storage.
118 lines
3.5 KiB
Plaintext
118 lines
3.5 KiB
Plaintext
log-level info
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----
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ok
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add-nodes 3 voters=(1,2,3) index=2
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----
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INFO 1 switched to configuration voters=(1 2 3)
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INFO 1 became follower at term 0
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INFO newRaft 1 [peers: [1,2,3], term: 0, commit: 2, applied: 2, lastindex: 2, lastterm: 1]
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INFO 2 switched to configuration voters=(1 2 3)
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INFO 2 became follower at term 0
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INFO newRaft 2 [peers: [1,2,3], term: 0, commit: 2, applied: 2, lastindex: 2, lastterm: 1]
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INFO 3 switched to configuration voters=(1 2 3)
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INFO 3 became follower at term 0
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INFO newRaft 3 [peers: [1,2,3], term: 0, commit: 2, applied: 2, lastindex: 2, lastterm: 1]
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campaign 1
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----
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INFO 1 is starting a new election at term 0
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INFO 1 became candidate at term 1
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INFO 1 received MsgVoteResp from 1 at term 1
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INFO 1 [logterm: 1, index: 2] sent MsgVote request to 2 at term 1
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INFO 1 [logterm: 1, index: 2] sent MsgVote request to 3 at term 1
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stabilize
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----
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> 1 handling Ready
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Ready MustSync=true:
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Lead:0 State:StateCandidate
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HardState Term:1 Vote:1 Commit:2
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Messages:
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1->2 MsgVote Term:1 Log:1/2
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1->3 MsgVote Term:1 Log:1/2
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> delivering messages
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1->2 MsgVote Term:1 Log:1/2
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INFO 2 [term: 0] received a MsgVote message with higher term from 1 [term: 1]
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INFO 2 became follower at term 1
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INFO 2 [logterm: 1, index: 2, vote: 0] cast MsgVote for 1 [logterm: 1, index: 2] at term 1
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> delivering messages
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1->3 MsgVote Term:1 Log:1/2
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INFO 3 [term: 0] received a MsgVote message with higher term from 1 [term: 1]
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INFO 3 became follower at term 1
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INFO 3 [logterm: 1, index: 2, vote: 0] cast MsgVote for 1 [logterm: 1, index: 2] at term 1
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> 2 handling Ready
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Ready MustSync=true:
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HardState Term:1 Vote:1 Commit:2
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Messages:
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2->1 MsgVoteResp Term:1 Log:0/0
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> 3 handling Ready
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Ready MustSync=true:
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HardState Term:1 Vote:1 Commit:2
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Messages:
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3->1 MsgVoteResp Term:1 Log:0/0
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> delivering messages
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2->1 MsgVoteResp Term:1 Log:0/0
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INFO 1 received MsgVoteResp from 2 at term 1
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INFO 1 has received 2 MsgVoteResp votes and 0 vote rejections
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INFO 1 became leader at term 1
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3->1 MsgVoteResp Term:1 Log:0/0
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> 1 handling Ready
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Ready MustSync=true:
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Lead:1 State:StateLeader
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Entries:
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1/3 EntryNormal ""
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Messages:
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1->2 MsgApp Term:1 Log:1/2 Commit:2 Entries:[1/3 EntryNormal ""]
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1->3 MsgApp Term:1 Log:1/2 Commit:2 Entries:[1/3 EntryNormal ""]
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> delivering messages
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1->2 MsgApp Term:1 Log:1/2 Commit:2 Entries:[1/3 EntryNormal ""]
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> delivering messages
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1->3 MsgApp Term:1 Log:1/2 Commit:2 Entries:[1/3 EntryNormal ""]
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> 2 handling Ready
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Ready MustSync=true:
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Lead:1 State:StateFollower
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Entries:
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1/3 EntryNormal ""
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Messages:
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2->1 MsgAppResp Term:1 Log:0/3
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> 3 handling Ready
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Ready MustSync=true:
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Lead:1 State:StateFollower
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Entries:
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1/3 EntryNormal ""
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Messages:
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3->1 MsgAppResp Term:1 Log:0/3
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> delivering messages
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2->1 MsgAppResp Term:1 Log:0/3
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3->1 MsgAppResp Term:1 Log:0/3
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> 1 handling Ready
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Ready MustSync=false:
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HardState Term:1 Vote:1 Commit:3
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CommittedEntries:
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1/3 EntryNormal ""
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Messages:
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1->2 MsgApp Term:1 Log:1/3 Commit:3
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1->3 MsgApp Term:1 Log:1/3 Commit:3
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> delivering messages
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1->2 MsgApp Term:1 Log:1/3 Commit:3
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> delivering messages
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1->3 MsgApp Term:1 Log:1/3 Commit:3
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> 2 handling Ready
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Ready MustSync=false:
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HardState Term:1 Vote:1 Commit:3
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CommittedEntries:
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1/3 EntryNormal ""
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Messages:
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2->1 MsgAppResp Term:1 Log:0/3
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> 3 handling Ready
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Ready MustSync=false:
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HardState Term:1 Vote:1 Commit:3
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CommittedEntries:
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1/3 EntryNormal ""
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Messages:
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3->1 MsgAppResp Term:1 Log:0/3
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> delivering messages
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2->1 MsgAppResp Term:1 Log:0/3
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3->1 MsgAppResp Term:1 Log:0/3
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