R4R: Add new error type and script center for customized scripts feature

[abelliumnt]

Add new error type for BEP12
bnb-chain/node#605

[unclezoro]

scriptsCenter . the name is a bit weird..

[abelliumnt]

Any suggested names?

[unclezoro]

scriptsHub is better

[rickyyangz]

if you want this Script a common script object, you should not put it here.

[rickyyangz]

auth is not a good package to put the Script type.

[abelliumnt]

auth is not a good package to put the Script type.

Any suggested package?

[darren-liu]

I suggest we do not cache this Tx, as this is to tax ALL transactions for just a few of transactions among all the send.

We can still decode the Tx from txBytes when we figure out the receive address is really set the flag, which should be only a very small subset of the total transaction universe.

[abelliumnt]

The tx is just an interface. It won't call cause too much data copy operation.
Previously, I have done an optimization as you said. But for future scripts, it's much likely they need to decode tx too. Now the implementation can provide a general solution for all future scripts. So I think it is better. @rickyyangz What do you think about this?

[darren-liu]

make sense. but can we have a small test on how much it takes for a context.WithTx(tx)?

[rickyyangz]

as discussed, let us remove the WithTxBytes as it is no use for us. cosmos itself uses it for the gas calculation which is no need for us. So we can make room for the WithTx

[rickyyangz]

The WithTx itself is not very costly, but adding more contexts will make the context query slower as the context is a chain and query starts from the last context.
So we need to consider the order of these contexts.

[abelliumnt]

goos: darwin
goarch: amd64
pkg: github.com/cosmos/cosmos-sdk/types
BenchmarkContext-12          	 1000000	      1973 ns/op
BenchmarkContextWithTx-12    	 1000000	      2164 ns/op
PASS

goos: darwin
goarch: amd64
pkg: github.com/cosmos/cosmos-sdk/types
BenchmarkContext-12          	 1000000	      1964 ns/op
BenchmarkContextWithTx-12    	 1000000	      1947 ns/op
PASS

The benchmark result is not stable. But it seems that the WithTx will not result in significant performance degradation. So we don't need to concern the performance degradation.