Problem: roadblocks for parallel transaction execution

[yihuang]

Proposal: Clear the roadblocks for parallel transaction execution

Current behavior:

We are trying block-stm parallel transaction execution and have identified a few roadblocks.

The main thing would be the three accumulating states in the transient stores: tx index, log size, block bloom, total gas used.

Desired behavior:

Each transaction should not unnecessarily share states, we can't control what account and contract state the transaction want to access, but other than that, we should have zero shared states.

Use case:

To have better performance in block-stm parallel execution.

Design

• total gas used is easy to change, we only want to accumulate the gas used within the current tx in the first place, so we'll simply append the tx index to the key, and we can even remote the ResetTransientGasUsed, cleaner than before.
• block bloom is also fine, we append the txindex/msgindex to the key, then iterate and combine them in end-blocker.
• log size, iterate the tx results after all executed, re-assign the log index in the rsp.Logs
• tx index, iterate the tx results after all executed, insert the tx index event

[yihuang]

duplicated: #432