Goleveldb recently had a PR in where memory allocation was reduced
drastically (github.com/syndtr/goleveldb/pull/367). Update goleveldb
to use that PR.
This converts the executeOpcode function defined on the engine to accept
an opcode and data slice instead of a parsed opcode as a step towards
removing the parsed opcode struct and associated supporting code altogether.
It also updates all callers accordingly.
This refactors the script engine to store and step through raw scripts
by making using of the new zero-allocation script tokenizer as opposed
to the less efficient method of storing and stepping through parsed
opcodes. It also improves several aspects while refactoring such as
optimizing the disassembly trace, showing all scripts in the trace in
the case of execution failure, and providing additional comments
describing the purpose of each field in the engine.
It should be noted that this is a step towards removing the parsed
opcode struct and associated supporting code altogether, however, in
order to ease the review process, this retains the struct and all
function signatures for opcode execution which make use of an individual
parsed opcode. Those will be updated in future commits.
The following is an overview of the changes:
- Modify internal engine scripts slice to use raw scripts instead of
parsed opcodes
- Introduce a tokenizer to the engine to track the current script
- Remove no longer needed script offset parameter from the engine since
that is tracked by the tokenizer
- Add an opcode index counter for disassembly purposes to the engine
- Update check for valid program counter to only consider the script
index
- Update tests for bad program counter accordingly
- Rework the NewEngine function
- Store the raw scripts
- Setup the initial tokenizer
- Explicitly check against version 0 instead of DefaultScriptVersion
which would break consensus if changed
- Check the scripts parse according to version 0 semantics to retain
current consensus rules
- Improve comments throughout
- Rework the Step function
- Use the tokenizer and raw scripts
- Create a parsed opcode on the fly for now to retain existing
opcode execution function signatures
- Improve comments throughout
- Update the Execute function
- Explicitly check against version 0 instead of DefaultScriptVersion
which would break consensus if changed
- Improve the disassembly tracing in the case of error
- Update the CheckErrorCondition function
- Modify clean stack error message to make sense in all cases
- Improve the comments
- Update the DisasmPC and DisasmScript functions on the engine
- Use the tokenizer
- Optimize construction via the use of strings.Builder
- Modify the subScript function to return the raw script bytes since the
parsed opcodes are no longer stored
- Update the various signature checking opcodes to use the raw opcode
data removal and signature hash calculation functions since the
subscript is now a raw script
- opcodeCheckSig
- opcodeCheckMultiSig
- opcodeCheckSigAlt
This converts the engine's current program counter disasembly to make
use of the standalone disassembly function to remove the dependency on
the parsed opcode struct.
It also updates the tests accordingly.
This converts the checkMinimalDataPush function defined on a parsed
opcode to a standalone function which accepts an opcode and data slice
instead in order to make it more flexible for raw script analysis.
It also updates all callers accordingly.
This converts the isConditional function defined on a parsed opcode to a
standalone function named isOpcodeConditional which accepts an opcode as
a byte instead in order to make it more flexible for raw script
analysis.
It also updates all callers accordingly.
This converts the alwaysIllegal function defined on a parsed opcode to a
standalone function named isOpcodeAlwaysIllegal which accepts an opcode
as a byte instead in order to make it more flexible for raw script
analysis.
It also updates all callers accordingly.
This converts the isDisabled function defined on a parsed opcode to a
standalone function which accepts an opcode as a byte instead in order
to make it more flexible for raw script analysis.
It also updates all callers accordingly.
This introduces a new function named removeOpcodeByDataRaw which accepts
the raw scripts and data to remove versus requiring the parsed opcodes
to both significantly optimize it as well as make it more flexible for
working with raw scripts.
There are several places in the rest of the code that currently only
have access to the parsed opcodes, so this only introduces the function
for use in the future and deprecates the existing one.
Note that, in practice, the script will never actually contain the data
that is intended to be removed since the function is only used during
signature verification to remove the signature itself which would
require some incredibly non-standard code to create.
Thus, as an optimization, it avoids allocating a new script unless there
is actually a match that needs to be removed.
Finally, it updates the tests to use the new function.
This converts SignTxOutput and supporting funcs, namely sign,
mergeScripts and mergeMultiSig, to make use of the new tokenizer as well
as some recently added funcs that deal with raw scripts in order to
remove the reliance on parsed opcodes as a step towards utlimately
removing them altogether and updates the comments to explicitly call out
the script version semantics.
It is worth noting that this has the side effect of optimizing the
function as well, however, since this change is not focused on the
optimization aspects, no benchmarks are provided.
This moves the function definition for mergeMultiSig so it is more
consistent with the preferred order used through the codebase. In
particular, the functions are defined before they're first used and
generally as close as possible to the first use when they're defined in
the same file.
This completes the process of converting the ExtractPkScriptAddr
function to use the optimized extraction functions recently introduced
as part of the typeOfScript conversion.
In particular, this cleans up the final remaining case for non-standard
transactions. The method now returns NonStandardTy direclty if no other
branch was taken.
The following is a before and after comparison of attempting to extract
pkscript addrs from a very large, non-standard script.
benchmark old ns/op new ns/op delta
BenchmarkExtractPkScriptAddrsLarge-8 60713 17.0 -99.97%
BenchmarkExtractPkScriptAddrs-8 289 17.0 -94.12%
benchmark old allocs new allocs delta
BenchmarkExtractPkScriptAddrsLarge-8 1 0 -100.00%
BenchmarkExtractPkScriptAddrs-8 1 0 -100.00%
benchmark old bytes new bytes delta
BenchmarkExtractPkScriptAddrsLarge-8 311299 0 -100.00%
BenchmarkExtractPkScriptAddrs-8 768 0 -100.00%
This continues the process of converting the ExtractPkScriptAddrs
function to use the optimized extraction functions recently introduced
as part of the typeOfScript conversion.
In particular, this converts the extract of witness-pay-to-script-hash
scripts.
This continues the process of converting the ExtractPkScriptAddrs
function to use the optimized extraction functions recently introduced
as part of the typeOfScript conversion.
In particular, this converts the extraction for witness-pubkey-hash
scripts.
This continues the process of converting the ExtractPkScriptAddrs
function to use the optimized extraction functions recently introduced
as part of the typeOfScript conversion.
In particular, this converts the detection for nulldata scripts, removes
the slow path fallback code since it is the final case, and modifies the
comment to call out the script version semantics.
The following is a before and after comparison of analyzing both a
typical standard script and a very large non-standard script:
benchmark old ns/op new ns/op delta
-----------------------------------------------------------------------
BenchmarkExtractPkScriptAddrsLarge 132400 44.4 -99.97%
BenchmarkExtractPkScriptAddrs 1265 231 -81.74%
benchmark old allocs new allocs delta
-----------------------------------------------------------------------
BenchmarkExtractPkScriptAddrsLarge 1 0 -100.00%
BenchmarkExtractPkScriptAddrs 5 2 -60.00%
benchmark old bytes new bytes delta
-----------------------------------------------------------------------
BenchmarkExtractPkScriptAddrsLarge 466944 0 -100.00%
BenchmarkExtractPkScriptAddrs 1600 48 -97.00%
This continues the process of converting the ExtractPkScriptAddrs
function to use the optimized extraction functions recently introduced
as part of the typeOfScript conversion.
In particular, this converts the detection for multisig scripts.
Also, since the remaining slow path cases are all recursive calls,
the parsed opcodes are no longer used, so parsing is removed.
This continues the process of converting the ExtractPkScriptAddrs
function to use the optimized extraction functions recently introduced
as part of the typeOfScript conversion.
In particular, this converts the detection for pay-to-pubkey scripts.
This continues the process of converting the ExtractPkScriptAddrs
function to use the optimized extraction functions recently introduced
as part of the typeOfScript conversion.
In particular, this converts the detection for pay-to-pubkey-hash
scripts.
This begins the process of converting the ExtractPkScriptAddrs function
to use the optimized extraction functions recently introduced as part of
the typeOfScript conversion.
In order to ease the review process, the detection of each script type
will be converted in a separate commit such that the script is only
parsed as a fallback for the cases that are not already converted to
more efficient variants.
In particular, this converts the detection for pay-to-script-hash
scripts.
This converts the ExtractAtomicSwapDataPushes function to make use of
the new tokenizer instead of the far less efficient parseScript thereby
significantly optimizing the function.
The new implementation is designed such that it should be fairly easy to
move the function into the atomic swap tools where it more naturally
belongs now that the tokenizer makes it possible to analyze scripts
outside of the txscript module. Consequently, this also deprecates the
function.
The following is a before and after comparison of attempting to extract
from both a typical atomic swap script and a very large non-atomic swap
script:
benchmark old ns/op new ns/op delta
BenchmarkExtractAtomicSwapDataPushesLarge-8 61332 44.4 -99.93%
BenchmarkExtractAtomicSwapDataPushes-8 990 260 -73.74%
benchmark old allocs new allocs delta
BenchmarkExtractAtomicSwapDataPushesLarge-8 1 0 -100.00%
BenchmarkExtractAtomicSwapDataPushes-8 2 1 -50.00%
benchmark old bytes new bytes delta
BenchmarkExtractAtomicSwapDataPushesLarge-8 311299 0 -100.00%
BenchmarkExtractAtomicSwapDataPushes-8 3168 96 -96.97%
This renames the canonicalPush function to isCanonicalPush and converts
it to accept an opcode as a byte and the associate data as a byte slice
instead of the internal parse opcode data struct in order to make it
more flexible for raw script analysis.
It also updates all callers and tests accordingly.
This converts the PushedData function to make use of the new tokenizer
instead of the far less efficient parseScript thereby significantly
optimizing the function.
Also, the comment is modified to explicitly call out the script version
semantics.
The following is a before and after comparison of extracting the data
from a very large script:
benchmark old ns/op new ns/op delta
BenchmarkPushedData-8 64837 1790 -97.24%
benchmark old allocs new allocs delta
BenchmarkPushedData-8 7 6 -14.29%
benchmark old bytes new bytes delta
BenchmarkPushedData-8 312816 1520 -99.51%
This converts the CalcMultiSigStats function to make use of the new
extractMultisigScriptDetails function instead of the far less efficient
parseScript thereby significantly optimizing the function.
The tests are also updated accordingly.
The following is a before and after comparison of analyzing a standard
multisig script:
benchmark old ns/op new ns/op delta
---------------------------------------------------------------
BenchmarkCalcMultiSigStats 972 79.5 -91.82%
benchmark old allocs new allocs delta
---------------------------------------------------------------
BenchmarkCalcMultiSigStats 1 0 -100.00%
benchmark old bytes new bytes delta
---------------------------------------------------------------
BenchmarkCalcMultiSigStats 2304 0 -100.00%
This converts CalcScriptInfo and dependent expectedInputs to make use of
the new script tokenizer as well as several of the other recently added
raw script analysis functions in order to remove the reliance on parsed
opcodes as a step towards utlimately removing them altogether.
It is worth noting that this has the side effect of significantly
optimizing the function as well, however, since it is deprecated, no
benchmarks are provided.
This concludes the process of converting the typeOfScript function to
use a combination of raw script analysis and the new tokenizer instead
of the far less efficient parsed opcodes.
In particular, it converts the detection of witness script hash scripts
to use raw script analysis and the new tokenizer.
With all of the limbs now useing optimized variants, the following is a
before an after comparison of calling GetScriptClass on a large script:
benchmark old ns/op new ns/op delta
BenchmarkGetScriptClass-8 61515 15.3 -99.98%
benchmark old allocs new allocs delta
BenchmarkGetScriptClass-8 1 0 -100.00%
benchmark old bytes new bytes delta
BenchmarkGetScriptClass-8 311299 0 -100.00%
This continues the process of converting the typeOfScript function to
use a combination of raw script analysis and the new tokenizer instead
of the far less efficient parsed opcodes.
In particular, it converts the detection of witness pubkey hash scripts
to use raw script analysis and the new tokenizer.
The following is a before and after comparison of analyzing a large
script:
benchmark old ns/op new ns/op delta
BenchmarkIsWitnessPubKeyHash-8 61688 62839 +1.87%
benchmark old allocs new allocs delta
BenchmarkIsWitnessPubKeyHash-8 1 1 +0.00%
benchmark old bytes new bytes delta
BenchmarkIsWitnessPubKeyHash-8 311299 311299 +0.00%
This continues the process of converting the typeOfScript function to
use a combination of raw script analysize and the tokenizer instead of
parsed opcode, with the intent of significanty optimizing the function.
In particular, it converts the detection of null data scripts to use raw
script analysis.
This continues the process of converting the typeOfScript function to
use a combination of raw script analysis and the new tokenizer instead
of the far less efficient parsed opcodes.
In particular, it converts the detection of pay-to-pubkey-hash scripts
to use raw script analysis.
This continues the process of converting the typeOfScript function to
use a combination of raw script analysis and the new tokenizer instead
of the face less efficient parsed opcodes, with the intent of
significantly optimizing the function.
In particular, it converts the detection of pay-to-pubkey scripts to use
raw script analysis.
This continues the process of converting the typeOfScript function to
use a combination of raw script analysis and the new tokenizer instead
of the far less efficient parsed opcodes.
In particular, for this commit, since the ability to detect multisig
scripts via the new tokenizer is now available, the function is simply
updated to make use of it.
This begins the process of converting the typeOfScript function to use a
combination of raw script analysis and the new tokenizer instead of the
far less efficient parsed opcodes with the intent of significantly
optimizing the function.
In order to ease the review process, each script type will be converted
in a separate commit and the typeOfScript function will be updated such
that the script is only parsed as a fallback for the cases that are not
already converted to more efficient raw script variants.
In particular, for this commit, since the ability to detect
pay-to-script-hash via raw script analysis is now available, the
function is simply updated to make use of it.
This converts the typeOfScript function to accept a script version and
raw script instead of an array of internal parsed opcodes in order to
make it more flexible for raw script analysis.
Also, this adds a comment to CalcScriptInfo to call out the specific
version semantics and deprecates the function since nothing currently
uses it, and the relevant information can now be obtained by callers
more directly through the use of the new script tokenizer.
All other callers are updated accordingly.
This converts the GetWitnessSigOpCount function to use a combination of
raw script analysis and the new tokenizer instead of the far less
efficeint parseScript, thereby significantly optimizing the funciton.
In particular, it use the recently added countSigOpsv0 in precise mode
to avoid calling paseScript.
This converts the GetPreciseSigOpCount function to use a combination of
raw script analysis and the new tokenizer instead of the far less
efficient parseScript thereby significantly optimizing the function.
In particular it uses the recently converted isScriptHashScript,
IsPushOnlyScript, and countSigOpsV0 functions along with the recently
added finalOpcodeData functions.
It also modifies the comment to explicitly call out the script version
semantics.
The following is a before and after comparison of analyzing a large
script:
benchmark old ns/op new ns/op delta
BenchmarkGetPreciseSigOpCount-8 130223 742 -99.43%
benchmark old allocs new allocs delta
BenchmarkGetPreciseSigOpCount-8 3 0 -100.00%
benchmark old bytes new bytes delta
BenchmarkGetPreciseSigOpCount-8 623367 0 -100.00%
This converts the GetSigOpCount function to make use of the new
tokenizer instead of the far less efficient parseScript thereby
significantly optimizing the function.
A new function named countSigOpsV0 which accepts the raw script is
introduced to perform the bulk of the work so it can be reused for
precise signature operation counting as well in a later commit. It
retains the same semantics in terms of counting the number of signature
operations either up to the first parse error or the end of the script
in the case it parses successfully as required by consensus.
Finally, this also deprecates the getSigOpCount function that requires
opcodes in favor of the new function and modifies the comment on
GetSigOpCount to explicitly call out the script version semantics.
The following is a before and after comparison of analyzing a large
script:
benchmark old ns/op new ns/op delta
BenchmarkGetSigOpCount-8 61051 677 -98.89%
benchmark old allocs new allocs delta
BenchmarkGetSigOpCount-8 1 0 -100.00%
benchmark old bytes new bytes delta
BenchmarkGetSigOpCount-8 311299 0 -100.00%
This moves the check for non push-only pay-to-script-hash signature
scripts before the script parsing logic when creating a new engine
instance to avoid the extra overhead in the error case.
This modifies the check for whether or not a pay-to-script-hash
signature script is a push only script to make use of the new and more
efficient raw script function.
Also, since the script will have already been checked further above when
the ScriptVerifySigPushOnly flags is set, avoid checking it again in
that case.
Backport of af67951b9a66df3aac1bf3d6376af0730287bbf2
This converts the IsUnspendable function to make use of a combination of
raw script analysis and the new tokenizer instead of the far less
efficient parseScript thereby significantly optimizing the function.
It is important to note that this new implementation intentionally has a
semantic difference from the existing implementation in that it will now
report scripts that are larger than the max allowed script size are
unspendable as well.
Finally, the comment is modified to explicitly call out the script
version semantics.
Note: this function was recently optimized in master, so the gains here
are less noticable than other optimizations.
The following is a before and after comparison of analyzing a large
script:
benchmark old ns/op new ns/op delta
BenchmarkIsUnspendable-8 656 584 -10.98%
benchmark old allocs new allocs delta
BenchmarkIsUnspendable-8 1 0 -100.00%
benchmark old bytes new bytes delta
BenchmarkIsUnspendable-8 1 0 -100.00%
This converts the IsNullData function to analyze the raw script instead
of using the far less efficient parseScript, thereby significantly
optimizing the function.
The following is a before and after comparison of analyzing a large
script:
benchmark old ns/op new ns/op delta
BenchmarkIsNullDataScript-8 62495 2.65 -100.00%
benchmark old allocs new allocs delta
BenchmarkIsNullDataScript-8 1 0 -100.00%
benchmark old bytes new bytes delta
BenchmarkIsNullDataScript-8 311299 0 -100.00%
This converts the IsPayToWitnessScriptHash function to analyze the raw
script instead of using the far less efficient parseScript, thereby
significantly optimizing the function.
In order to accomplish this, it introduces two new functions. The first
one is named extractWitnessScriptHash and works with the raw script byte
to simultaneously deteremine if the script is a p2wsh script, and in the
case that is is, extract and return the hash. The second new function is
named isWitnessScriptHashScript and is defined in terms of the former.
The extract function approach was chosed because it is common for
callers to want to only extract relevant details from a script if the
script is of the specific type. Extracting those details requires
performing the exact same checks to ensure the script is of the correct
type, so it is more efficient to combine the two into one and define the
type determination in terms of the result, so long as the extraction
does not require allocations.
Finally, this also deprecates the isWitnessScriptHash function that
requires opcodes in favor of the new functions and modifies the comment
on IsPayToWitnessScriptHash to call out the script version semantics.
The following is a before and after comparison of executing
IsPayToWitnessScriptHash on a large script:
benchmark old ns/op new ns/op delta
BenchmarkIsWitnessScriptHash-8 62774 0.63 -100.00%
benchmark old allocs new allocs delta
BenchmarkIsWitnessScriptHash-8 1 0 -100.00%
benchmark old bytes new bytes delta
BenchmarkIsWitnessScriptHash-8 311299 0 -100.00%
This converts the IsPayToWitnessPubKeyHash function to analyze the raw
script instead of the far less efficient parseScript, thereby
significantly optimizing the function.
In order to accomplish this, it introduces two new functions. The first
one is named extractWitnessPubKeyHash and works with the raw script
bytes to simultaneously deteremine if the script is a p2wkh, and in case
it is, extract and return the hash. The second new function is name
isWitnessPubKeyHashScript which is defined in terms of the former.
The extract function is approach was chosen because it is common for
callers to want to only extract relevant details from the script if the
script is of the specific type. Extracting those details requires the
exact same checks to ensure the script is of the correct type, so it is
more efficient to combine the two and define the type determination in
terms of the result so long as the extraction does not require
allocations.
Finally, this deprecates the isWitnessPubKeyHash function that requires
opcodes in favor of the new functions and modifies the comment on
IsPayToWitnessPubKeyHash to explicitly call out the script version
semantics.
The following is a before and after comparison of executing
IsPayToWitnessPubKeyHash on a large script:
benchmark old ns/op new ns/op delta
BenchmarkIsWitnessPubKeyHash-8 68927 0.53 -100.00%
benchmark old allocs new allocs delta
BenchmarkIsWitnessPubKeyHash-8 1 0 -100.00%
benchmark old bytes new bytes delta
BenchmarkIsWitnessPubKeyHash-8 311299 0 -100.00%
This converts the IsPushOnlyScript function to make use of the new
tokenizer instead of the far less efficient parseScript thereby
significantly optimizing the function.
It also deprecates the isPushOnly function that requires opcodes in
favor of the new function and modifies the comment on IsPushOnlyScript
to explicitly call out the script version semantics.
The following is a before and after comparison of analyzing a large
script:
benchmark old ns/op new ns/op delta
BenchmarkIsPushOnlyScript-8 62412 622 -99.00%
benchmark old allocs new allocs delta
BenchmarkIsPushOnlyScript-8 1 0 -100.00%
benchmark old bytes new bytes delta
BenchmarkIsPushOnlyScript-8 311299 0 -100.00%
This converts the IsMultisigSigScript function to analyze the raw script
and make use of the new tokenizer instead of the far less efficient
parseScript thereby significantly optimizing the function.
In order to accomplish this, it first rejects scripts that can't
possibly fit the bill due to the final byte of what would be the redeem
script not being the appropriate opcode or the overall script not having
enough bytes. Then, it uses a new function that is introduced named
finalOpcodeData that uses the tokenizer to return any data associated
with the final opcode in the signature script (which will be nil for
non-push opcodes or if the script fails to parse) and analyzes it as if
it were a redeem script when it is non nil.
It is also worth noting that this new implementation intentionally has
the same semantic difference from the existing implementation as the
updated IsMultisigScript function in regards to allowing zero pubkeys
whereas previously it incorrectly required at least one pubkey.
Finally, the comment is modified to explicitly call out the script
version semantics.
The following is a before and after comparison of analyzing a large
script that is not a multisig script and both a 1-of-2 multisig public
key script (which should be false) and a signature script comprised of a
pay-to-script-hash 1-of-2 multisig redeem script (which should be true):
benchmark old ns/op new ns/op delta
BenchmarkIsMultisigSigScriptLarge-8 69328 2.93 -100.00%
BenchmarkIsMultisigSigScript-8 2375 146 -93.85%
benchmark old allocs new allocs delta
BenchmarkIsMultisigSigScriptLarge-8 5 0 -100.00%
BenchmarkIsMultisigSigScript-8 3 0 -100.00%
benchmark old bytes new bytes delta
BenchmarkIsMultisigSigScriptLarge-8 330035 0 -100.00%
BenchmarkIsMultisigSigScript-8 9472 0 -100.00%
This converts the IsMultisigScript function to make use of the new
tokenizer instead of the far less efficient parseScript thereby
significantly optimizing the function.
In order to accomplish this, it introduces two new functions. The first
one is named extractMultisigScriptDetails and works with the raw script
bytes to simultaneously determine if the script is a multisignature
script, and in the case it is, extract and return the relevant details.
The second new function is named isMultisigScript and is defined in
terms of the former.
The extract function accepts the script version, raw script bytes, and a
flag to determine whether or not the public keys should also be
extracted. The flag is provided because extracting pubkeys results in
an allocation that the caller might wish to avoid.
The extract function approach was chosen because it is common for
callers to want to only extract relevant details from a script if the
script is of the specific type. Extracting those details requires
performing the exact same checks to ensure the script is of the correct
type, so it is more efficient to combine the two into one and define the
type determination in terms of the result so long as the extraction does
not require allocations.
It is important to note that this new implementation intentionally has a
semantic difference from the existing implementation in that it will now
correctly identify a multisig script with zero pubkeys whereas
previously it incorrectly required at least one pubkey. This change is
acceptable because the function only deals with standardness rather than
consensus rules.
Finally, this also deprecates the isMultiSig function that requires
opcodes in favor of the new functions and deprecates the error return on
the export IsMultisigScript function since it really does not make sense
given the purpose of the function.
The following is a before and after comparison of analyzing both a large
script that is not a multisig script and a 1-of-2 multisig public key
script:
benchmark old ns/op new ns/op delta
BenchmarkIsMultisigScriptLarge-8 64166 5.52 -99.99%
BenchmarkIsMultisigScript-8 630 59.4 -90.57%
benchmark old allocs new allocs delta
BenchmarkIsMultisigScriptLarge-8 1 0 -100.00%
BenchmarkIsMultisigScript-8 1 0 -100.00%
benchmark old bytes new bytes delta
BenchmarkIsMultisigScriptLarge-8 311299 0 -100.00%
BenchmarkIsMultisigScript-8 2304 0 -100.00%
This converts the IsPayToScriptHash function to analyze the raw script
instead of using the far less efficient parseScript thereby
significantly optimizing the function.
In order to accomplish this, it introduces two new functions. The first
one is named extractScriptHash and works with the raw script bytes to
simultaneously determine if the script is a p2sh script, and in the case
it is, extract and return the hash. The second new function is named
isScriptHashScript and is defined in terms of the former.
The extract function approach was chosen because it is common for
callers to want to only extract relevant details from a script if the
script is of the specific type. Extracting those details requires
performing the exact same checks to ensure the script is of the correct
type, so it is more efficient to combine the two into one and define the
type determination in terms of the result so long as the extraction does
not require allocations.
Finally, this also deprecates the isScriptHash function that requires
opcodes in favor of the new functions and modifies the comment on
IsPayToScriptHash to explicitly call out the script version semantics.
The following is a before and after comparison of analyzing a large
script that is not a p2sh script:
benchmark old ns/op new ns/op delta
BenchmarkIsPayToScriptHash-8 62393 0.60 -100.00%
benchmark old allocs new allocs delta
BenchmarkIsPayToScriptHash-8 1 0 -100.00%
benchmark old bytes new bytes delta
BenchmarkIsPayToScriptHash-8 311299 0 -100.00%
This converts the IsPayToPubKeyHash function to analyze the raw script
instead of using the far less efficient parseScript, thereby
significantly optimization the function.
In order to accomplish this, it introduces two new functions. The first
one is named extractPubKeyHash and works with the raw script bytes
to simultaneously determine if the script is a pay-to-pubkey-hash script,
and in the case it is, extract and return the hash. The second new
function is named isPubKeyHashScript and is defined in terms of the
former.
The extract function approach was chosen because it is common for
callers to want to only extract relevant details from a script if the
script is of the specific type. Extracting those details requires
performing the exact same checks to ensure the script is of the correct
type, so it is more efficient to combine the two into one and define the
type determination in terms of the result so long as the extraction does
not require allocations.
The following is a before and after comparison of analyzing a large
script:
benchmark old ns/op new ns/op delta
BenchmarkIsPubKeyHashScript-8 62228 0.45 -100.00%
benchmark old allocs new allocs delta
BenchmarkIsPubKeyHashScript-8 1 0 -100.00%
benchmark old bytes new bytes delta
BenchmarkIsPubKeyHashScript-8 311299 0 -100.00%
This converts the IsPayToScriptHash function to analyze the raw script
instead of using the far less efficient parseScript, thereby
significantly optimizing the function.
In order to accomplish this, it introduces four new functions:
extractCompressedPubKey, extractUncompressedPubKey, extractPubKey, and
isPubKeyScript. The extractPubKey function makes use of
extractCompressedPubKey and extractUncompressedPubKey to combine their
functionality as a convenience and isPubKeyScript is defined in terms of
extractPubKey.
The extractCompressedPubKey works with the raw script bytes to
simultaneously determine if the script is a pay-to-compressed-pubkey
script, and in the case it is, extract and return the raw compressed
pubkey bytes.
Similarly, the extractUncompressedPubKey works in the same way except it
determines if the script is a pay-to-uncompressed-pubkey script and
returns the raw uncompressed pubkey bytes in the case it is.
The extract function approach was chosen because it is common for
callers to want to only extract relevant details from a script if the
script is of the specific type. Extracting those details requires
performing the exact same checks to ensure the script is of the correct
type, so it is more efficient to combine the two into one and define the
type determination in terms of the result so long as the extraction does
not require allocations.
The following is a before and after comparison of analyzing a large
script:
benchmark old ns/op new ns/op delta
BenchmarkIsPubKeyScript-8 62323 2.97 -100.00%
benchmark old allocs new allocs delta
BenchmarkIsPubKeyScript-8 1 0 -100.00%
benchmark old bytes new bytes delta
BenchmarkIsPubKeyScript-8 311299 0 -100.00%
This converts the asSmallInt function to accept an opcode as a byte
instead of the internal opcode data struct in order to make it more
flexible for raw script analysis.
It also updates all callers accordingly.
This converts the isSmallInt function to accept an opcode as a byte
instead of the internal opcode data struct in order to make it more
flexible for raw script analysis.
The comment is modified to explicitly call out the script version
semantics.
Finally, it updates all callers accordingly.
This converts the tests for calculating signature hashes to use the
exported function which handles the raw script versus the now deprecated
variant requiring parsed opcodes.
Backport of 06f769ef72e6042e7f2b5ff1c512ef1371d615e5
This modifies the CalcSignatureHash function to make use of the new
signature hash calculation function that accepts raw scripts without
needing to first parse them. Consequently, it also doubles as a slight
optimization to the execution time and a significant reduction in the
number of allocations.
In order to convert the CalcScriptHash function and keep the same
semantics, a new function named checkScriptParses is introduced which
will quickly determine if a script can be fully parsed without failure
and return the parse failure in the case it can't.
The following is a before and after comparison of analyzing a large
multiple input transaction:
benchmark old ns/op new ns/op delta
BenchmarkCalcSigHash-8 3627895 3619477 -0.23%
benchmark old allocs new allocs delta
BenchmarkCalcSigHash-8 1335 801 -40.00%
benchmark old bytes new bytes delta
BenchmarkCalcSigHash-8 1373812 1293354 -5.86%
This introduces a new function named calcSignatureHashRaw which accepts
the raw script bytes to calculate the script hash versus requiring the
parsed opcode only to unparse them later in order to make it more
flexible for working with raw scripts.
Since there are several places in the rest of the code that currently
only have access to the parsed opcodes, this modifies the existing
calcSignatureHash to first unparse the script before calling the new
function.
Backport of decred/dcrd:f306a72a16eaabfb7054a26f9d9f850b87b00279
This converts the DisasmString function to make use of the new
zero-allocation script tokenizer instead of the far less efficient
parseScript thereby significantly optimizing the function.
In order to facilitate this, the opcode disassembly functionality is
split into a separate function called disasmOpcode that accepts the
opcode struct and data independently as opposed to requiring a parsed
opcode. The new function also accepts a pointer to a string builder so
the disassembly can be more efficiently be built.
While here, the comment is modified to explicitly call out the script
version semantics.
The following is a before and after comparison of a large script:
benchmark old ns/op new ns/op delta
BenchmarkDisasmString-8 102902 40124 -61.01%
benchmark old allocs new allocs delta
BenchmarkDisasmString-8 46 51 +10.87%
benchmark old bytes new bytes delta
BenchmarkDisasmString-8 389324 130552 -66.47%
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
