txscript: Optimize removeOpcodeRaw
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f5d78e8b10
commit
90b8c2cb51
2 changed files with 42 additions and 4 deletions
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@ -269,6 +269,8 @@ func DisasmString(script []byte) (string, error) {
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// removeOpcode will remove any opcode matching ``opcode'' from the opcode
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// stream in pkscript
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//
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// DEPRECATED. Use removeOpcodeRaw instead.
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func removeOpcode(pkscript []parsedOpcode, opcode byte) []parsedOpcode {
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retScript := make([]parsedOpcode, 0, len(pkscript))
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for _, pop := range pkscript {
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@ -279,6 +281,43 @@ func removeOpcode(pkscript []parsedOpcode, opcode byte) []parsedOpcode {
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return retScript
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}
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// removeOpcodeRaw will return the script after removing any opcodes that match
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// `opcode`. If the opcode does not appear in script, the original script will
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// be returned unmodified. Otherwise, a new script will be allocated to contain
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// the filtered script. This metehod assumes that the script parses
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// successfully.
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//
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// NOTE: This function is only valid for version 0 scripts. Since the function
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// does not accept a script version, the results are undefined for other script
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// versions.
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func removeOpcodeRaw(script []byte, opcode byte) []byte {
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// Avoid work when possible.
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if len(script) == 0 {
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return script
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}
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const scriptVersion = 0
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var result []byte
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var prevOffset int32
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tokenizer := MakeScriptTokenizer(scriptVersion, script)
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for tokenizer.Next() {
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if tokenizer.Opcode() == opcode {
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if result == nil {
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result = make([]byte, 0, len(script))
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result = append(result, script[:prevOffset]...)
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}
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} else if result != nil {
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result = append(result, script[prevOffset:tokenizer.ByteIndex()]...)
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}
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prevOffset = tokenizer.ByteIndex()
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}
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if result == nil {
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return script
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}
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return result
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}
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// isCanonicalPush returns true if the opcode is either not a push instruction
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// or the data associated with the push instruction uses the smallest
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// instruction to do the job. False otherwise.
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@ -3981,13 +3981,12 @@ func TestRemoveOpcodes(t *testing.T) {
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// tstRemoveOpcode is a convenience function to parse the provided
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// raw script, remove the passed opcode, then unparse the result back
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// into a raw script.
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const scriptVersion = 0
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tstRemoveOpcode := func(script []byte, opcode byte) ([]byte, error) {
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pops, err := parseScript(script)
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if err != nil {
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if err := checkScriptParses(scriptVersion, script); err != nil {
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return nil, err
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}
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pops = removeOpcode(pops, opcode)
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return unparseScript(pops)
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return removeOpcodeRaw(script, opcode), nil
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}
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for _, test := range tests {
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