tlaplus / tlaplus/CommunityModules
VectorClock!CausalOrder does not tolerate message loss
Open
Nobody has claimed this yet.
enhancement
- Dominant language
- TLA
- Stars
- 315
- Forks
- 48
- Avg merge
- 13h 27m
- Merged PRs (30d)
- 2
Description
Error: TLC threw an unexpected exception.
This was probably caused by an error in the spec or model.
See the User Output or TLC Console for clues to what happened.
The exception was a java.lang.RuntimeException
: Attempted to apply the operator overridden by the Java method
public static tlc2.value.impl.Value tlc2.overrides.VectorClocks.causalOrder(tlc2.value.impl.TupleValue,tlc2.value.impl.OpValue,tlc2.value.impl.OpValue,tlc2.value.impl.OpValue),
but it produced the following error:
Index: 16, Size: 16
Support message loss, i.e., gaps in the otherwise monotonically increasing vector clock values.
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First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start with modules/VectorClocks.tla lines 27-56 and the Java override in modules/tlc2/overrides/VectorClocks.java lines 100-181. Reproduce the TLC failure with message loss and trace how causalOrder handles gaps in vector-clock values. Done means the model tolerates lost messages without the reported Index: 16, Size: 16 exception.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- java
- Domain
- tooling
- Issue type
- Bug
- Difficulty
- 3/5
- Estimated time
- 1-2 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 42/100