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.
