Revert "Replace Kip103ContractCaller by BlockchainContractCaller"

[blukat29]

Proposed changes

This reverts commit 15fb12b.

BlockchainContractCaller as-is was not appropriate to substitute Kip103ContractCaller.

• Kip103ContractCaller, in its implementation, increments the caller.From nonce in CallContract
• BlockchainContractCaller does not
• This difference caused the Baobab sync test failure.

This PR revives Kip103ContractCaller as a quick fix.

Types of changes

• Bugfix
• New feature or enhancement
• Others

Checklist

• I have read the CONTRIBUTING GUIDELINES doc
• I have signed the CLA
• Lint and unit tests pass locally with my changes ($ make test)
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)
• Any dependent changes have been merged and published in downstream modules

Related issues

Further comments

[hyunsooda]

I have two questions:

1. I'm struggling to understand the discrepancy between this and old versions' code.
   I got that there's an inconsistent state between Finalize() call's one and the contract caller's one. The last block's state (contract caller's state) was used for the KIP-103 contract read. Here, even the current transactions created different state compared to the last block's state, the read operation of KIP-103 with the state at last block seems not correlated. So, I'm now confusing how two different states are created here. The RebalanceTreasury() function modifies the currently being modified state and read the contract storage with the last block's state. The final state should not be different if the reading the KIP-103 contract does not have effect by the current state and I think there's no any correlation. If no, the memo logging must be different.

2. If we consider a scenario where no transactions occur at the KIP-103 activation block number, could this error potentially go unnoticed or be overlooked to some extent?

[blukat29]

@hyunsooda Good question.

There was a bug, a side effect, in Kip103ContractCaller where the nonce of 0x0 account was incremented during contract calls. BlockchainContractCaller does not have the bug. That's why the memo and account balances were all correct yet sync test failed.