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/cc @3pointer @overvenus Would you take a look? Thanks! |
lance6716
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lance6716
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Maybe also consider client crash / storage response lost scenario.
PutAndVerify/MC.tla
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| \* MV CONSTANT definitions CLIENTS | ||
| const_171964209906974000 == |
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this TLA spec is not heavy, can you add more clients?
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I run it with 3 clients and no error reported. Also if someone wants to verify with more clients, he may modify the model constants manually.
I prefer keeping two clients by default because the state transform graph can still be read by a human... Starting from 3 the state transform gets too complex to be read...
PutAndVerify/WriteAndVerify.tla
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| (* Delete the file when aborted. *) | ||
| RollBack(c) == /\ clState[c] = "aborted" | ||
| /\ storage[c] /= "none" |
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In fact not. This won't create new states but just adding arrows between states.
However our implmentation includes this, so I left it here.
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@lance6716 I added crashing and RWLock cases to the model, PTAL and thanks~ |
PutAndVerify/WriteAndVerify.tla
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| /\ clState' = [ clState EXCEPT ![c] = "committed" ] | ||
| /\ UNCHANGED << clFavor >> | ||
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| BeRO(c) == /\ clState[c] = "begin" |
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what's the actual meaning of BeRO? client can generate "empty-ro" in storage but I don't know why it should exist
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BeRO means become a "read-only" node. Then the algorithm become a implementation of RWLock instead of Mutex.
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Generally, there can be many storage slots contains "written-ro" or exactly one storage slot contains "written". (RWLock)
Signed-off-by: Hillium <yu745514916@live.com>
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Relative PR / Issues:
A draft doc:
https://github.com/pingcap/tidb/blob/dda8f114335d94ce3430aee77e42bd39ec155b63/docs/design/2024-10-11-put-and-verify-transactions-for-external-storages.md