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https://github.com/FlipsideCrypto/dcrd.git
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f860883562
chaincfg/v2 modified the Params type to contain the required payouts created by the miner of the block at height 1. However, it was discovered that, due to code generation issues of the Go compiler, this caused the package's weight (measured by github.com/jondot/goweight) to explode to 7.7 MB. This appears to be due to an enormous amount of function calls, all of which could panic, when building the large slice literal. This improves the compiled size of the package by using code generation techniques to optimize the memory layout and code transformation of the subsidy values each time a params function is called. A single string contains all scripts for subsidy payouts concatenated together, in hex encoding, and a slice contains the index in the script data and the required payout amount. This is iterated in a loop to create a []TokenPayout each time it is needed. The new size of the compiled package using Go 1.12.7 on OpenBSD/amd64 is 379 kB, a reduction of 7.32 MB, and about 5% of the original size.
98 lines
2.2 KiB
Go
98 lines
2.2 KiB
Go
// Copyright (c) 2019 The Decred developers
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// Use of this source code is governed by an ISC
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// license that can be found in the LICENSE file.
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//+build ignore
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package main
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import (
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"bytes"
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"encoding/hex"
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"fmt"
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"io"
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"log"
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"os"
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"strings"
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"github.com/decred/dcrd/chaincfg/v2"
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)
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type payout struct {
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offset int
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amount int64
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}
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type payouts []payout
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func (p payouts) GoString() string {
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var s strings.Builder
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s.WriteString("[]blockOnePayout{\n")
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for i := range p {
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s.WriteString("\t")
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s.WriteString(fmt.Sprintf("{offset: %#v, amount: %#v}", p[i].offset, p[i].amount))
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s.WriteString(",\n")
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}
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s.WriteString("}")
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return s.String()
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}
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type printer func(format string, args ...interface{})
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func main() {
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buf := new(bytes.Buffer)
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p := func(format string, args ...interface{}) {
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fmt.Fprintf(buf, format, args...)
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}
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p("// autogenerated by generatesubsidytable.go; do not edit\n\n")
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p("package chaincfg\n")
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for _, g := range []struct {
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name string
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tokenPayouts []chaincfg.TokenPayout
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}{
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{"MainNetParams", chaincfg.MainNetSubsidyDefinition},
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{"TestNet3Params", chaincfg.TestNet3SubsidyDefinition},
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{"SimNetParams", chaincfg.SimNetSubsidyDefinition},
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{"RegNetParams", chaincfg.RegNetSubsidyDefinition},
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} {
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p("\n")
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defs(p, g.name, g.tokenPayouts)
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}
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out, err := os.Create("subsidytables.go")
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if err != nil {
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log.Fatal(err)
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}
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_, err = io.Copy(out, buf)
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if err != nil {
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log.Fatal(err)
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}
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}
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func defs(p printer, paramsName string, tokenPayouts []chaincfg.TokenPayout) {
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var scripts strings.Builder
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var payouts payouts
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var offset int
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for _, t := range tokenPayouts {
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if t.ScriptVersion != 0 {
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log.Fatalf("this tool only generates code where all scripts are version 0")
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}
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_, err := scripts.WriteString(hex.EncodeToString(t.Script))
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if err != nil {
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log.Panic(err)
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}
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offset += len(t.Script)
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payouts = append(payouts, payout{
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offset: offset,
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amount: t.Amount,
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})
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}
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p("const blockOnePayoutScripts_%s = %#v\n\n", paramsName, scripts.String())
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p("var blockOnePayouts_%s = %#v\n\n", paramsName, payouts)
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p("func tokenPayouts_%s() []TokenPayout {\n"+
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"\treturn tokenPayouts(blockOnePayoutScripts_%[1]s, blockOnePayouts_%[1]s)\n"+
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"}\n", paramsName)
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}
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