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This adds functions to calculate a merkle root to the blockchain/standalone module. Rather than copying the existing functions from blockchain, it introduces new optimized functions that have simpler code and are also generally easier to use. The new functions simply return the calculated root instead of all of the intermediate hashes which no known callers were actually using anyway. It also adds a basic usage example, benchmarks, updates the documentation and includes comprehensive tests. As can be seen by the benchmarks below, the new code isn't significantly faster in terms of execution speed since it is still dominated by the actual hashing, however, it does significantly reduce the number of allocations which reduces pressure on the GC, particularly during bursty situations such as IBD. It also scales much better to larger numbers of transactions. The following is a before and after comparison of calculating merkle roots for various numbers of leaves: benchmark old ns/op new ns/op delta --------------------------------------------------------------- BenchmarkCalcMerkleRoot/20 25637 24287 -5.27% BenchmarkCalcMerkleRoot/1000 1252749 1209130 -3.48% BenchmarkCalcMerkleRoot/2000 2601754 2343198 -9.94% BenchmarkCalcMerkleRoot/4000 4873969 4629169 -5.02% BenchmarkCalcMerkleRoot/8000 9831116 9270095 -5.71% BenchmarkCalcMerkleRoot/16000 19172545 19067585 -0.55% BenchmarkCalcMerkleRoot/32000 37980323 35746500 -5.88% benchmark old allocs new allocs delta ---------------------------------------------------------------- BenchmarkCalcMerkleRoot/20 106 64 -39.62% BenchmarkCalcMerkleRoot/1000 5006 3004 -39.99% BenchmarkCalcMerkleRoot/2000 10006 6004 -40.00% BenchmarkCalcMerkleRoot/4000 20006 12004 -40.00% BenchmarkCalcMerkleRoot/8000 40006 24004 -40.00% BenchmarkCalcMerkleRoot/16000 80006 48004 -40.00% BenchmarkCalcMerkleRoot/32000 160006 96004 -40.00% benchmark old bytes new bytes delta ---------------------------------------------------------------- BenchmarkCalcMerkleRoot/20 6896 4432 -35.73% BenchmarkCalcMerkleRoot/1000 320688 208272 -35.05% BenchmarkCalcMerkleRoot/2000 641072 416272 -35.07% BenchmarkCalcMerkleRoot/4000 1281840 832272 -35.07% BenchmarkCalcMerkleRoot/8000 2563376 1664272 -35.07% BenchmarkCalcMerkleRoot/16000 5126448 3328272 -35.08% BenchmarkCalcMerkleRoot/32000 10252592 6656273 -35.08% |
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|---|---|---|
| .. | ||
| chaingen | ||
| fullblocktests | ||
| indexers | ||
| internal | ||
| stake | ||
| standalone | ||
| 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
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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.
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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.
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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.