Bitcoin slices

ZERO allocations parse library for Bitcoin data structures such as [bsl::Transaction]s, [bsl::Block]s and others available in the [bsl] module.

Data is accessed by providing [Visitor] structs for the data the user is interested in.

// Calculate the amount of outputs in mainnet block 702861 in satoshi
use bitcoin_slices::{bsl, Visit, Visitor};
struct Sum(pub u64);
impl Visitor for Sum {
    fn visit_tx_out(&mut self, _vout: usize, tx_out: &bsl::TxOut) -> core::ops::ControlFlow<()>  {
        self.0 += tx_out.value();
        core::ops::ControlFlow::Continue(())
    }
}
let mut sum = Sum(0);
let block_bytes: &[u8] = bitcoin_test_data::blocks::mainnet_702861();
let block = bsl::Block::visit(block_bytes, &mut sum).unwrap();
assert_eq!(sum.0, 2_883_682_728_990)

Data structures are read-only and parsed data must be in memory, no streaming API.

Tradeoffs

Check the CONS before using this library, use rust-bitcoin if they are too restrictive for your case.

Pros

• Deserialization is amazingly fast, since no allocation is made during parsing.
• Serialization is instant, since a slice of the serialized data is kept in the structure.
• [bsl] types are suitable for db key and values, in fact there is a specific redb feature
• hashing a little faster because slice are ready without the need of re-serializing data.
• No mandatory dependency.
• No standard.
• Calculate txid and block hash via optional dep bitcoin_hashes or sha2.
• Visitor pattern to visit just what you are interested in.

Cons

• Full data must be in memory, there is no streaming (Read/Write) API.
• Data structure are read-only, cannot be modified.
• Visitor pattern requires user-built data structure for visiting.

Features

Hashing

Use feature sha2 or bitcoin_hashes to calculate hashes of blocks and transactions. The former is faster, the latter is more likely to be in your tree if you work with rust-bitcoin ecosystem's crates.

redb

With the redb feature activated some type allows to be used as value and key in the redb database. Bitcoin slices types are well suited to be used as key and values in the database because conversion from/to slices is immediate.

#[cfg(feature = "redb")]
{
    use bitcoin_slices::{bsl, redb, Parse, redb::ReadableTable};
    const UTXOS_TABLE: redb::TableDefinition<bsl::OutPoint, bsl::TxOut> = redb::TableDefinition::new("utxos");
    let path = tempfile::NamedTempFile::new().unwrap().into_temp_path();
    let db = redb::Database::create(path).unwrap();
    let write_txn = db.begin_write().unwrap();
    let tx_out_bytes = hex_lit::hex!("ffffffffffffffff0100");
    let out_point_bytes = [0u8; 36];
    let tx_out = bsl::TxOut::parse(&tx_out_bytes).unwrap().parsed_owned();
    let out_point = bsl::OutPoint::parse(&out_point_bytes).unwrap().parsed_owned();
    {
        let mut table = write_txn.open_table(UTXOS_TABLE).unwrap();
        table.insert(&out_point, &tx_out).unwrap();
    }
    write_txn.commit().unwrap();

    let read_txn = db.begin_read().unwrap();
    let table = read_txn.open_table(UTXOS_TABLE).unwrap();
    assert_eq!(table.get(&out_point).unwrap().unwrap().value(), tx_out);
}

rust-bitcoin

With the feature bitcoin activated some types allows to be converted in the rust-bitcoin counterpart: for example bsl::TxOut could be converted in bitcoin::TxOut. You may think if you need bitcoin::TxOut you can decode the bytes directly into it without using this library, and it is mostly true, but sometimes it may be convenient to use both types, for example using bitcoin slices with datatabases, but you may need to access fields more conveniently than writing a visitor for it and thus convert to rust-bitcoin types. Moreover, conversions may leverage type invariants and be faster than starting from a generic byte stream.

#[cfg(feature = "bitcoin")]
{
    use bitcoin_slices::{bsl, bitcoin, Parse};

    let tx_out_bytes = hex_lit::hex!("ffffffffffffffff0100");
    let tx_out = bsl::TxOut::parse(&tx_out_bytes).unwrap().parsed_owned();
    let tx_out_bitcoin: bitcoin::TxOut =
        bitcoin::consensus::deserialize(&tx_out_bytes[..]).unwrap();

    let tx_out_back: bitcoin::TxOut = tx_out.into();

    assert_eq!(tx_out_back, tx_out_bitcoin);
}

Test

cargo test

Bench

Criterion is used for benching mainly because we are not required to use nightly, and it is also nicer.

cargo bench --all-features

To have compact results, similar to standard libtests launch with:

cargo bench --bench benches --all-features -- --output-format bencher

test tx_deserialize/slices       ... bench:          29 ns/iter (+/- 0)
test tx_deserialize/bitcoin      ... bench:         211 ns/iter (+/- 0)

test tx_id/slices_bitcoin_hashes ... bench:         183 ns/iter (+/- 0)
test tx_id/slices_sha2           ... bench:         158 ns/iter (+/- 0)
test tx_id/bitcoin               ... bench:         234 ns/iter (+/- 1)

test block_deserialize/slices    ... bench:      230872 ns/iter (+/- 1686)
test block_deserialize/bitcoin   ... bench:     1462784 ns/iter (+/- 115792)

test block_sum_outputs/slices    ... bench:      235757 ns/iter (+/- 1318)
test block_sum_outputs/bitcoin   ... bench:     1459730 ns/iter (+/- 95817)

test hash_block_txs/slices       ... bench:      881940 ns/iter (+/- 4961)
test hash_block_txs/slices_sha2  ... bench:      789365 ns/iter (+/- 932)
test hash_block_txs/bitcoin      ... bench:     2301561 ns/iter (+/- 15406)

test find_tx/slices              ... bench:      406519 ns/iter (+/- 1423)
test find_tx/bitcoin             ... bench:     1826147 ns/iter (+/- 122216)

test block_hash/slices           ... bench:         112 ns/iter (+/- 0)
test block_hash/bitcoin          ... bench:         146 ns/iter (+/- 2)

• benches variants with /bitcoin use rust-bitcoin
• benches ending with /slices_sha2 use this lib and sha2 lib instead of bitcoin_hashes

Comparison against rust-bitcoin

block_deserialize is almost 10 times faster then block_deserialize_bitcoin. It may see unfair comparison since you can't for example iterate transactions from the resulted object in case of block_deserialize, but looking at the sum_outputs example where a visitor is used to access every outputs in a block we se there isn't noticeable difference.

Hashing

block_hash and block_hash_bitcoin use the same code to hash, however bitcoin_slice is about 7% faster because use a slice already available instead of serializing back data. Similar results apply between txid and txid_bitcoin. The performance increase is more notable (30%) between hash_block_txs and hash_block_txs_bitcoin.

*_sha2 are not really representative on virtual CI machines since they are not hardware-accellerated.

Fuzz

Use cargo fuzz Run fuzzing with transaction as target.

cargo +nightly fuzz run transaction

Other target available in fuzz/fuzz_targets

Minimize corpus:

cargo +nightly fuzz cmin transaction

Doc

To build docs:

RUSTDOCFLAGS="--cfg docsrs" cargo +nightly doc --all-features --open

MSRV

Minimum Supported Rust Version of this crate is 1.60.0 without redb,slice_cache features, (double check with what is running in the CI) With slice_cache feature MSRV is 1.64.0. With redb feature MSRV is 1.66.0.

Previous work and credits

• Bitiodine use similar visitor pattern (parser credited to Mathias Svensson)
• Some previous work on the idea to parse while reducing allocations in this PR
• Matt Corallo mentioned something like this in a comment in that PR