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txscript: Optimize ExtractCoinbaseNullData.

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This converts the ExtractCoinbaseNullData function to make use of the
new tokenizer instead of the far less efficient parseScript thereby
significantly optimizing the function.

The following is a before and after comparison of analyzing a typical
coinbase script:

benchmark                        old ns/op    new ns/op    delta
-------------------------------------------------------------------
BenchmarkExactCoinbaseNullData   227          31.0         -86.34%

benchmark                        old allocs   new allocs   delta
-------------------------------------------------------------------
BenchmarkExactCoinbaseNullData   1            0            -100.00%

benchmark                        old bytes    new bytes    delta
-------------------------------------------------------------------
BenchmarkExactCoinbaseNullData   448          0            -100.00%
This commit is contained in:
Dave Collins 2019-03-13 01:12:08 -05:00
parent ccd0a92bc1
commit 6a0a77fd81
No known key found for this signature in database
GPG Key ID: B8904D9D9C93D1F2
1 changed files with 14 additions and 11 deletions
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25
txscript/consensus.go
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@ -1,5 +1,5 @@
// Copyright (c) 2015-2016 The btcsuite developers
// Copyright (c) 2015-2017 The Decred developers
// Copyright (c) 2015-2019 The Decred developers
// Use of this source code is governed by an ISC
// license that can be found in the LICENSE file.
@ -25,12 +25,11 @@ const (
// ExtractCoinbaseNullData ensures the passed script is a nulldata script as
// required by the consensus rules for the coinbase output that is used to
// ensure the coinbase has a unique hash and returns the data it pushes.
//
// NOTE: This function is only valid for version 0 scripts. Since the function
// does not accept a script version, the results are undefined for other script
// versions.
func ExtractCoinbaseNullData(pkScript []byte) ([]byte, error) {
pops, err := parseScript(pkScript)
if err != nil {
return nil, err
}
// The nulldata in the coinbase must be a single OP_RETURN followed by a
// data push up to maxUniqueCoinbaseNullDataSize bytes.
//
@ -44,14 +43,18 @@ func ExtractCoinbaseNullData(pkScript []byte) ([]byte, error) {
// height to be encoded as a 4-byte little-endian uint32 pushed via a normal
// data push, as opposed to using the normal number handling semantics of
// scripts, so this is specialized to accommodate that.
if len(pops) == 1 && pops[0].opcode.value == OP_RETURN {
const scriptVersion = 0
if len(pkScript) == 1 && pkScript[0] == OP_RETURN {
return nil, nil
}
if len(pops) == 2 && pops[0].opcode.value == OP_RETURN &&
pops[1].opcode.value <= OP_PUSHDATA4 && len(pops[1].data) <=
maxUniqueCoinbaseNullDataSize {
if len(pkScript) > 1 && pkScript[0] == OP_RETURN {
tokenizer := MakeScriptTokenizer(scriptVersion, pkScript[1:])
if tokenizer.Next() && tokenizer.Done() &&
tokenizer.Opcode() <= OP_PUSHDATA4 &&
len(tokenizer.Data()) <= maxUniqueCoinbaseNullDataSize {
return pops[1].data, nil
return tokenizer.Data(), nil
}
}
str := fmt.Sprintf("script %x is not well-formed coinbase nulldata",