feat: op-conductor strongly consistent reads

[BrianBland]

Description

Adds a raft.Barrier call to RaftConsensus.LatestUnsafePayload() to ensure that the latest unsafe payload is always read in a strongly consistent fashion. With this change, both writes (CommitUnsafePayload) and reads (LatestUnsafePayload) depend on the leader's fully-applied FSM, ensuring that a change in leadership does not result in an accidental rollback to a previous head value.

Tests

Added a basic raft_fsm test for the Snapshot method, and refactored the other raft_fsm tests to better evaluate state changes. This does not (yet) include any tests validating the change of read consistency.

[coderabbitai]

Walkthrough

Walkthrough

The changes across the op-conductor module enhance error handling, logging, and consistency in payload management functions. Key updates include refining error messages, adding error returns to methods, and improving logging for debugging purposes. These modifications aim to strengthen the robustness and traceability of operations within the OpConductor and Consensus components, particularly around handling execution payloads and consensus state management.

Changes

File(s)	Change Summary
op-conductor/conductor/service.go op-conductor/consensus/iface.go op-conductor/consensus/mocks/Consensus.go	Renamed error constants, refined error messages, added error handling for retrieving the latest unsafe payload, and enhanced logging. Updated interfaces for stronger consistency guarantees.
op-conductor/consensus/raft.go	Improved initialization, leadership determination, logging, and error handling in methods like CommitUnsafePayload and LatestUnsafePayload.
op-conductor/consensus/raft_fsm.go	Added logging and a new initialization function for unsafeHeadTracker to enhance tracking and logging capabilities.
op-conductor/consensus/raft_fsm_test.go	Updated function parameters, introduced new dependencies for logging, and added test cases for improved coverage.
op-conductor/conductor/service_test.go op-conductor/consensus/raft_test.go	Enhanced test coverage and error handling to ensure robustness in testing scenarios.

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Recent Review Details

Configuration used: .coderabbit.yml
Review profile: CHILL

Commits

Files that changed from the base of the PR and between f349095 and c2d7a32.

Files selected for processing (3)

• op-conductor/conductor/service.go (6 hunks)
• op-conductor/conductor/service_test.go (6 hunks)
• op-conductor/rpc/api.go (1 hunks)

Files skipped from review due to trivial changes (1)

• op-conductor/rpc/api.go

Files skipped from review as they are similar to previous changes (1)

• op-conductor/conductor/service.go

Additional comments not posted (8)

op-conductor/conductor/service_test.go (8)

301-301: Ensure proper error handling in LatestUnsafePayload call.

This issue has been previously flagged and remains valid. Ensure that the test cases handle potential errors returned by LatestUnsafePayload.

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Line range hint 301-354: The test scenario TestScenario1 is well-implemented.

This test correctly simulates the state transitions and interactions with the mocked Consensus interface when a leadership change occurs due to a mismatch in unsafe head.

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321-354: The test scenario TestScenario1Err is well-implemented.

This test correctly handles errors from LatestUnsafePayload and verifies the system's response to such errors, ensuring robustness in error scenarios.

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Line range hint 355-392: The test scenario TestScenario2 is correctly implemented.

This test ensures that a follower that becomes healthy does not change its leader status or start sequencing, which is the expected behavior.

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Line range hint 392-449: The test scenario TestScenario3 is well-implemented.

This test effectively simulates the transition of a healthy follower to a sequencing leader, ensuring that the system behaves as expected under these conditions.

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Line range hint 431-449: The test scenario TestScenario4 is correctly implemented.

This test effectively handles retries and error scenarios, ensuring that the system can recover and proceed correctly when the latest unsafe payload is initially unavailable.

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Line range hint 449-703: The test scenario TestScenario5 is well-implemented.

This test correctly simulates the behavior of a leader that receives an unhealthy update, ensuring that it steps down and stops sequencing as expected.

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703-703: The test scenario TestFailureAndRetry3 is well-implemented.

This test effectively simulates a complex sequence of events where a follower becomes a leader and starts sequencing, then becomes healthy again, ensuring that the system behaves as expected under these conditions.

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[coderabbitai]

Actionable comments posted: 1

[coderabbitai]

Actionable comments posted: 1