Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Compaction and trace wrappers do not compose. #242

Closed
frankmcsherry opened this issue Jan 7, 2020 · 0 comments
Closed

Compaction and trace wrappers do not compose. #242

frankmcsherry opened this issue Jan 7, 2020 · 0 comments

Comments

@frankmcsherry
Copy link
Member

@frankmcsherry frankmcsherry commented Jan 7, 2020

As discussed in #234, the combination of timestamp manipulating trace wrappers and compaction interact badly, in that a trace wrapper may inaccurately summarize frontiers back to the wrapped trace, resulting in the re-wrapped timestamps being farther forward than correctness allows.

In the particular example there, the AltNeu wrapper, which extends timestamps with a bit indicating "old" or "new", takes a frontier of AltNeu::alt(2) and communicates upwards that this means that the frontier it cares about is now [2], which is not correct as one can still distinguish AltNeu::neu(1) from AltNeu::neu(2).

A bit of light thinking suggests that this is not a problem for the product order wrapper, but some more formalism is clearly needed here.

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Projects
None yet
1 participant
You can’t perform that action at this time.