42bc847479
This optimizes and cleans up significant portions of the CheckTransactionInputs function to avoid a lot extra allocations, remove redundant checks, better document its semantics, and make the code easier to reason about. In addition, it renames a lot of the error constants involved in said function to use the ticket/vote/revocation terminology and improve their readability. Even though several of the checks have been rearranged for efficiency and readability purposes, all consensus semantics have been retained. One of the primary changes is to reduce the reliance on the stake package for consensus validation. Not only is more desirable to have the bulk of the validation related to the blockchain in the blockchain package, but it also allows the code to be more specific, which enables better optimization opportunities as well as eliminates the need for a lot of redundant checks that are simply unnecessary. The stake identification functions are also part of consensus and have not been modified, however, the actual validation related to all of their inputs, such as ensuring commitments are observed, are now in the blockchain package itself. Since the only thing using the related verification functions is now done in blockchain, this also removes the VerifyStakingPkhsAndAmounts, VerifySStxAmounts, and related tests from the stake package. Another significant change is the addition of new functions for efficiently and specifically identifying the form of the scripts required by stake transactions in order to reduce the dependence on the standard code in txscript. Standard code should _NOT_ be used in consensus code as the two are not the same thing. It should be noted that these changes break compatibility with the current v1 blockchain and stake modules, so they will need a major version bump prior to the next release. Finally, all tests in the repository have been updated for the error name changes as well as change in expected error in some cases due to the reordering of the validation checks. |
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|---|---|---|
| .. | ||
| chaingen | ||
| fullblocktests | ||
| indexers | ||
| internal | ||
| stake | ||
| testdata | ||
| accept.go | ||
| agendas_test.go | ||
| bench_test.go | ||
| blockindex_test.go | ||
| blockindex.go | ||
| chain_test.go | ||
| chain.go | ||
| chainio_test.go | ||
| chainio.go | ||
| chainquery.go | ||
| chainview_test.go | ||
| chainview.go | ||
| checkpoints.go | ||
| common_test.go | ||
| compress_test.go | ||
| compress.go | ||
| difficulty_test.go | ||
| difficulty.go | ||
| doc.go | ||
| error_test.go | ||
| error.go | ||
| example_test.go | ||
| fullblocks_test.go | ||
| fullblocksstakeversion_test.go | ||
| go.mod | ||
| go.sum | ||
| log.go | ||
| mediantime_test.go | ||
| mediantime.go | ||
| merkle_test.go | ||
| merkle.go | ||
| notifications.go | ||
| process.go | ||
| prune.go | ||
| README.md | ||
| scriptval.go | ||
| sequencelock_test.go | ||
| sequencelock.go | ||
| stakeext.go | ||
| stakenode.go | ||
| stakeversion_test.go | ||
| stakeversion.go | ||
| subsidy_test.go | ||
| subsidy.go | ||
| thresholdstate_test.go | ||
| thresholdstate.go | ||
| timesorter_test.go | ||
| timesorter.go | ||
| upgrade.go | ||
| utxoviewpoint.go | ||
| validate_test.go | ||
| validate.go | ||
| votebits_test.go | ||
| votebits.go | ||
blockchain
Package blockchain implements Decred block handling and chain selection rules.
The test coverage is currently only around 60%, but will be increasing over
time. See test_coverage.txt for the gocov coverage report. Alternatively, if
you are running a POSIX OS, you can run the cov_report.sh script for a
real-time report. Package blockchain is licensed under the liberal ISC license.
There is an associated blog post about the release of this package here.
This package has intentionally been designed so it can be used as a standalone package for any projects needing to handle processing of blocks into the decred block chain.
Installation and Updating
$ go get -u github.com/decred/dcrd/blockchain
Decred Chain Processing Overview
Before a block is allowed into the block chain, it must go through an intensive series of validation rules. The following list serves as a general outline of those rules to provide some intuition into what is going on under the hood, but is by no means exhaustive:
- Reject duplicate blocks
- Perform a series of sanity checks on the block and its transactions such as verifying proof of work, timestamps, number and character of transactions, transaction amounts, script complexity, and merkle root calculations
- Compare the block against predetermined checkpoints for expected timestamps and difficulty based on elapsed time since the checkpoint
- Save the most recent orphan blocks for a limited time in case their parent blocks become available
- Stop processing if the block is an orphan as the rest of the processing depends on the block's position within the block chain
- Perform a series of more thorough checks that depend on the block's position within the block chain such as verifying block difficulties adhere to difficulty retarget rules, timestamps are after the median of the last several blocks, all transactions are finalized, checkpoint blocks match, and block versions are in line with the previous blocks
- Determine how the block fits into the chain and perform different actions accordingly in order to ensure any side chains which have higher difficulty than the main chain become the new main chain
- When a block is being connected to the main chain (either through reorganization of a side chain to the main chain or just extending the main chain), perform further checks on the block's transactions such as verifying transaction duplicates, script complexity for the combination of connected scripts, coinbase maturity, double spends, and connected transaction values
- Run the transaction scripts to verify the spender is allowed to spend the coins
- Insert the block into the block database
Examples
-
ProcessBlock Example
Demonstrates how to create a new chain instance and use ProcessBlock to attempt to add a block to the chain. This example intentionally attempts to insert a duplicate genesis block to illustrate how an invalid block is handled. -
CompactToBig Example
Demonstrates how to convert the compact "bits" in a block header which represent the target difficulty to a big integer and display it using the typical hex notation. -
BigToCompact Example
Demonstrates how to convert how to convert a target difficulty into the compact "bits" in a block header which represent that target difficulty.
License
Package blockchain is licensed under the copyfree ISC License.