lbcd/txscript/error_test.go
Dave Collins c997417978
txscript: Introduce zero-alloc script tokenizer.
This implements an efficient and zero-allocation script tokenizer that
is exported to both provide a new capability to tokenize scripts to
external consumers of the API as well as to serve as a base for
refactoring the existing highly inefficient internal code.

It is important to note that this tokenizer is intended to be used in
consensus critical code in the future, so it must exactly follow the
existing semantics.

The current script parsing mechanism used throughout the txscript module
is to fully tokenize the scripts into an array of internal parsed
opcodes which are then examined and passed around in order to implement
virtually everything related to scripts.

While that approach does simplify the analysis of certain scripts and
thus provide some nice properties in that regard, it is both extremely
inefficient in many cases, and makes it impossible for external
consumers of the API to implement any form of custom script analysis
without manually implementing a bunch of error prone tokenizing code or,
alternatively, the script engine exposing internal structures.

For example, as shown by profiling the total memory allocations of an
initial sync, the existing script parsing code allocates a total of
around 295.12GB, which equates to around 50% of all allocations
performed.  The zero-alloc tokenizer this introduces will allow that to
be reduced to virtually zero.

The following is a before and after comparison of tokenizing a large
script with a high opcode count using the existing code versus the
tokenizer this introduces for both speed and memory allocations:

benchmark                    old ns/op     new ns/op     delta
BenchmarkScriptParsing-8     63464         677           -98.93%

benchmark                    old allocs     new allocs     delta
BenchmarkScriptParsing-8     1              0              -100.00%

benchmark                    old bytes     new bytes     delta
BenchmarkScriptParsing-8     311299        0             -100.00%

The following is an overview of the changes:

- Introduce new error code ErrUnsupportedScriptVersion
- Implement zero-allocation script tokenizer
- Add a full suite of tests to ensure the tokenizer works as intended
  and follows the required consensus semantics
- Add an example of using the new tokenizer to count the number of
  opcodes in a script
- Update README.md to include the new example
- Update script parsing benchmark to use the new tokenizer
2021-11-16 18:45:22 -08:00

133 lines
4.3 KiB
Go

// Copyright (c) 2017 The btcsuite 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.
package txscript
import (
"testing"
)
// TestErrorCodeStringer tests the stringized output for the ErrorCode type.
func TestErrorCodeStringer(t *testing.T) {
t.Parallel()
tests := []struct {
in ErrorCode
want string
}{
{ErrInternal, "ErrInternal"},
{ErrInvalidFlags, "ErrInvalidFlags"},
{ErrInvalidIndex, "ErrInvalidIndex"},
{ErrUnsupportedAddress, "ErrUnsupportedAddress"},
{ErrTooManyRequiredSigs, "ErrTooManyRequiredSigs"},
{ErrTooMuchNullData, "ErrTooMuchNullData"},
{ErrUnsupportedScriptVersion, "ErrUnsupportedScriptVersion"},
{ErrNotMultisigScript, "ErrNotMultisigScript"},
{ErrEarlyReturn, "ErrEarlyReturn"},
{ErrEmptyStack, "ErrEmptyStack"},
{ErrEvalFalse, "ErrEvalFalse"},
{ErrScriptUnfinished, "ErrScriptUnfinished"},
{ErrInvalidProgramCounter, "ErrInvalidProgramCounter"},
{ErrScriptTooBig, "ErrScriptTooBig"},
{ErrElementTooBig, "ErrElementTooBig"},
{ErrTooManyOperations, "ErrTooManyOperations"},
{ErrStackOverflow, "ErrStackOverflow"},
{ErrInvalidPubKeyCount, "ErrInvalidPubKeyCount"},
{ErrInvalidSignatureCount, "ErrInvalidSignatureCount"},
{ErrNumberTooBig, "ErrNumberTooBig"},
{ErrVerify, "ErrVerify"},
{ErrEqualVerify, "ErrEqualVerify"},
{ErrNumEqualVerify, "ErrNumEqualVerify"},
{ErrCheckSigVerify, "ErrCheckSigVerify"},
{ErrCheckMultiSigVerify, "ErrCheckMultiSigVerify"},
{ErrDisabledOpcode, "ErrDisabledOpcode"},
{ErrReservedOpcode, "ErrReservedOpcode"},
{ErrMalformedPush, "ErrMalformedPush"},
{ErrInvalidStackOperation, "ErrInvalidStackOperation"},
{ErrUnbalancedConditional, "ErrUnbalancedConditional"},
{ErrMinimalData, "ErrMinimalData"},
{ErrInvalidSigHashType, "ErrInvalidSigHashType"},
{ErrSigTooShort, "ErrSigTooShort"},
{ErrSigTooLong, "ErrSigTooLong"},
{ErrSigInvalidSeqID, "ErrSigInvalidSeqID"},
{ErrSigInvalidDataLen, "ErrSigInvalidDataLen"},
{ErrSigMissingSTypeID, "ErrSigMissingSTypeID"},
{ErrSigMissingSLen, "ErrSigMissingSLen"},
{ErrSigInvalidSLen, "ErrSigInvalidSLen"},
{ErrSigInvalidRIntID, "ErrSigInvalidRIntID"},
{ErrSigZeroRLen, "ErrSigZeroRLen"},
{ErrSigNegativeR, "ErrSigNegativeR"},
{ErrSigTooMuchRPadding, "ErrSigTooMuchRPadding"},
{ErrSigInvalidSIntID, "ErrSigInvalidSIntID"},
{ErrSigZeroSLen, "ErrSigZeroSLen"},
{ErrSigNegativeS, "ErrSigNegativeS"},
{ErrSigTooMuchSPadding, "ErrSigTooMuchSPadding"},
{ErrSigHighS, "ErrSigHighS"},
{ErrNotPushOnly, "ErrNotPushOnly"},
{ErrSigNullDummy, "ErrSigNullDummy"},
{ErrPubKeyType, "ErrPubKeyType"},
{ErrCleanStack, "ErrCleanStack"},
{ErrNullFail, "ErrNullFail"},
{ErrDiscourageUpgradableNOPs, "ErrDiscourageUpgradableNOPs"},
{ErrNegativeLockTime, "ErrNegativeLockTime"},
{ErrUnsatisfiedLockTime, "ErrUnsatisfiedLockTime"},
{ErrWitnessProgramEmpty, "ErrWitnessProgramEmpty"},
{ErrWitnessProgramMismatch, "ErrWitnessProgramMismatch"},
{ErrWitnessProgramWrongLength, "ErrWitnessProgramWrongLength"},
{ErrWitnessMalleated, "ErrWitnessMalleated"},
{ErrWitnessMalleatedP2SH, "ErrWitnessMalleatedP2SH"},
{ErrWitnessUnexpected, "ErrWitnessUnexpected"},
{ErrMinimalIf, "ErrMinimalIf"},
{ErrWitnessPubKeyType, "ErrWitnessPubKeyType"},
{ErrDiscourageUpgradableWitnessProgram, "ErrDiscourageUpgradableWitnessProgram"},
{0xffff, "Unknown ErrorCode (65535)"},
}
// Detect additional error codes that don't have the stringer added.
if len(tests)-1 != int(numErrorCodes) {
t.Errorf("It appears an error code was added without adding an " +
"associated stringer test")
}
t.Logf("Running %d tests", len(tests))
for i, test := range tests {
result := test.in.String()
if result != test.want {
t.Errorf("String #%d\n got: %s want: %s", i, result,
test.want)
continue
}
}
}
// TestError tests the error output for the Error type.
func TestError(t *testing.T) {
t.Parallel()
tests := []struct {
in Error
want string
}{
{
Error{Description: "some error"},
"some error",
},
{
Error{Description: "human-readable error"},
"human-readable error",
},
}
t.Logf("Running %d tests", len(tests))
for i, test := range tests {
result := test.in.Error()
if result != test.want {
t.Errorf("Error #%d\n got: %s want: %s", i, result,
test.want)
continue
}
}
}