Crate blocks_iterator

Blocks iterator

Iterates over Bitcoin blocks, decoding data inside Bitcoin Core’s blocks directory.

Features:

• Blocks are returned in height order, it avoids following reorgs (see Config::max_reorg parameter)
• Blocks come with extra data BlockExtra like all block’s previous outputs, it allows computing transactions fee or verifying scripts in the blockchain.

Note:

Bitcoin Core 28.0 introduced xoring of bitcoin blocks and this project doesn’t yet support reading the blocks directory when xored. You can disable xoring in core via -blocksxor=0.

Iteration modes

In rust programs

Used as a library blocks could be iterated via the iter() method like:

// "blocks" dir contains first 400 testnet blocks
let conf = blocks_iterator::Config::new("../blocks", bitcoin::Network::Testnet);
let mut total_fee = 0u64;
for b in blocks_iterator::iter(conf) {
  total_fee += b.fee().expect("fee available cause we are keeping prevouts");
}

// Only a bunch of tx with fee exists on testnet with height < 400
// in blocks: 385, 387, 389, 390, 392, 394
assert_eq!(total_fee, 450_000u64);

When the task to be performed is computational costly, like verifying spending conditions, it is suggested to parallelize the execution like it’s done with rayon (or similar) in the verify example (note par_bridge() call).

Through Pipes

Other than inside Rust programs, ordered blocks with previous outputs could be iterated using Unix pipes.

$ cargo build --release
$ cargo build --release --examples
$ ./target/release/blocks_iterator_cli --blocks-dir ~/.bitcoin/testnet3/blocks --network testnet --max-reorg 40 --stop-at-height 200000 | ./target/release/examples/with_pipe
...
[2023-03-31T15:01:23Z INFO  with_pipe] Max number of txs: 6287 block: 0000000000bc915505318327aa0f18568ce024702a024d7c4a3ecfe80a893d6c
[2023-03-31T15:01:23Z INFO  with_pipe] total missing reward: 50065529986 in 100 blocks
[2023-03-31T15:01:23Z INFO  with_pipe] most_output tx is 640e22b5ddee1f6d2d701e37877027221ba5b36027634a2e3c3ee1569b4aa179 with #outputs: 10001

If you have more consumer process you can concatenate pipes by passing stdout to PipeIterator::new or using tee utility to split the stdout of blocks_iterator. The latter is better because it doesn’t require re-serialization of the data.

Binary version

When using pipes, data is serialized and deserialized.

blocks_iterator 1.x produce serialized BlockExtra with version 0 and read version 0. blocks_iterator 2.x produce serialized BlockExtra with version 1 and read version 0 and 1. The binary format has been changed so that version 1 can deserialize only the block bytes, without instantiating the Block struct. By doing so, light clients can use bitcoin_slices to visit the block data in faster way.

Memory requirements and performance

Running (cargo run --release -- --network X --blocks-dir Y >/dev/null) on threadripper 1950X, Testnet @ 2130k, Mainnet @ 705k. Spinning disk. Take following benchmarks with a grain of salt since they refer to older versions.

Network	--skip--prevout	--max-reorg	utxo-db	Memory	Time
Mainnet	true	6	no	33MB	1h:00m
Mainnet	false	6	no	5.3GB	1h:29m
Mainnet	false	6	1 run	201MB	9h:42m
Mainnet	false	6	2 run	113MB	1h:05m
Testnet	true	40	no	123MB	3m:03s
Testnet	false	40	no	1.4GB	8m:02s
Testnet	false	40	1 run	247MB	16m:12s
Testnet	false	40	2 run	221MB	8m:32s

Doc

To build docs:

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

Examples

Run examples with:

cargo run --release --example verify

• heaviest find the transaction with greatest weight
• most_output find the transaction with most output
• outputs_versions Count outputs witness version
• signatures_in_witness Count signatures in witness
• verify verify transactions in blocks using libbitcoin-consensus. Consumers are run in parallel fashion.

Version 1.0 meaning

The 1.0 is not to be intended as battle-tested production-ready library, the binary format of BlockExtra changed and I wanted to highlight it with major version rollout.

Similar projects

• bitcoin-iterate this project inspired blocks_iterator, the differences are:
  • It is C-based
  • It’s more suited for shell piping, while blocks_iterator can be used with piping but also as a rust library
  • It doesn’t give previous outputs information
  • It is making two passage over blocks*.dat serially, while blocks_iterator is doing two passes in parallel.
• rust-bitcoin-indexer this project requires longer setup times (about 9 hours indexing) and a postgre database, once the indexing is finished it allows fast queries on relational database.
• electrs specifically intended for the Electrum protocol

MSRV

Check minimum rust version run in CI, as of Aug 2023 is:

• 1.60.0 without features (needs some pinning, check CI)
• 1.67.0 with features.

Re-exports

pub use bitcoin;

pub use fxhash;

pub use glob;

pub use log;

Structs

BlockExtra

The bitcoin block and additional metadata returned by the crate::iter() method

Config

Configuration parameters, most important the bitcoin blocks directory

FsBlock

Before reorder we keep only the position of the block in the file system and data relative to the block hash, the previous hash and the following hash (populated during reorder phase) We will need to read the block from disk again, but by doing so we will avoid using too much memory in the OutOfOrderBlocks map.

PeriodCounter

Contains counter and instants to provide per period stats over transaction and blocks processed

Periodic

Utility used to return true after period

PipeIterator

Iterator to use un Unix-style pipe composition when receiving BlockExtra from stdin and optionally propogating those to stdout

Enums

Error

Functions

iter

Return an Iterator of BlockExtra read from blocks*.dat contained in the config.blocks_dir Blocks returned are iterated in order, starting from the genesis to the highest block (minus config.max_reorg) in the directory, unless config.stop_at_height is specified.

periodic_log_levelDeprecated

Utility method usually returning log::Level::Debug but when i is divisible by every returns log::Level::Info