Serialization and struct improvements
This set improves serialization/deserialization performance and, more
importantly, simplifies memory management for some structures avoiding
useless copying.
It adds some percents to the 1,4M blocks import test.
It can't be really solved in many cases (it's used in P2P protocol and we have
to follow the usual conventions there) and in most of the cases we don't care
about the difference between nil slice and zero-length slice.
It makes very little sense having pointers here, these structures MUST have
some kind of key and this key is not gonna be wandering somewhere on its
own. Fixes a part of #519.
It reduces heap pressure a little for these elements as we don't have to
allocate/free them individually. And they're directly tied to transactions or
block, not being shared or anything like that, so it makes little sense for
them to be pointer-based. It only makes building transactions a little easier,
but that's obviously a minor usecase.
reflect.MethodByName is a rather expensive function especially when
called on hot path. This became obvious during profiling of db restore.
This commit replaces reflection with a cast to an interface.
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.
Which speeds it up at least twofold for a typical 32-bytes write (and that's
for a very naïve test that allocates new BufBinWriter on every iteration):
pkg: github.com/CityOfZion/neo-go/pkg/io
BenchmarkWriteBytes-8 10000000 124 ns/op
BenchmarkWriteBytesOld-8 5000000 251 ns/op
When 74590551 introduced this code we had no proper caching layer, so there
were these strange fallbacks in the code. fc0031e5 should'd removed them, but
failed to do so, so do it now and fix processing of transactions that touch
storage for the same key (address) in the same block.
To use opcode definitions you have to import whole vm package that you might
not care about at all. So this moves opcodes to their own package under vm, fixes
and deduplicate related code and moves compiler package up one level.
Drop wif.GetVerificationScript(), drop
smartcontract.CreateSignatureRedeemScript(), add GetVerificationScript()
directly to the PublicKey and use it everywhere.
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.
