Creating a new BinReader for every instruction is a bit too much and it adds
about 1% overhead on block import (and actually is quite visible in the VM
profiling statistics). So use a bit more ugly but efficient method.
go vet is not happy about them:
pkg/io/binaryReader.go:92:21: method ReadByte() byte should have signature ReadByte() (byte, error)
pkg/io/binaryWriter.go:75:21: method WriteByte(u8 byte) should have signature WriteByte(byte) error
This seriously improves the serialization/deserialization performance for
several reasons:
* no time spent in `binary` reflection
* no memory allocations being made on every read/write
* uses fast ReadBytes everywhere it's appropriate
It also makes Fixed8 Serializable just for convenience.
This change (closely related to the neo-project/neo#1321 proposal) speeds up
1.4M mainnet blocks import by 30%. Basically, we're eliminating key decoding
for block's multisignature that has the same keys most of the time.
Things I don't like about this patch:
* yet another parameter for verifyHashAgainstScript()
* vm keys are not copied in/out
But it's rather simple and solves the problem for this particular case, so I
think it's worth it.
Before this patch on block import we could easily be spending more than 6
seconds out of 30 in Uint256 encoding for UnspentBalance, now it's completely
off the radar.
This allows easier reuse of opcodes and in some cases allows to eliminate
dependencies on the whole vm package, like in compiler that only needs opcodes
and doesn't care about VM for any other purpose.
And yes, they're opcodes because an instruction is a whole thing with
operands, that's what context.Next() returns.
When encountering already seen stack item we should fail
only if it is a collection. Duplicate Integers or ByteArrays are ok
because they can't lead to recursion.
Make inspect work with avms by default and with go files if told so. In the
end this makes our CLI interface more consistent and usable. Drop useless
CompileAndInspect() compiler method along the way.
VM should be responsible for code execution and in case anyone interested in additional logging or errors they could handle them like we do it iin cli.
