Module utxos

The FilterParser and UtxoParser parser must be used together in order to track UTXOs as they move through the tx graph, giving you a map between:

• bitcoin::TxIn -> Amount
• bitcoin::TxOut -> OutStatus::Spent or OutStatus::Unspent

This allows you to easily compute values such as mining fees and find all unspent txs. The FilterParser creates a ScalableCuckooFilter which allows us to track all unspent UTXOs with low memory-overhead similar to a bloom filter.

The filter is written to a file which is loaded into memory by UtxoParser, allowing us to track the flow of all transaction amounts from inputs with a far lower memory overhead and no performance hit of using an on-disk lookup table.

Example usage:

use bitcoin_block_parser::*;
use bitcoin_block_parser::utxos::*;

// Note you only need to write the filter to a file once
let parser = FilterParser::new();
for _ in parser.parse_dir("/path/to/blocks").unwrap() {}
parser.write("filter.bin").unwrap();

let parser = UtxoParser::new("filter.bin").unwrap();
// for every block
for block in parser.parse_dir("/path/to/blocks").unwrap() {
  let block = block.unwrap();
  // for every transaction
  for (tx, txid) in block.transactions() {
    let outs = block.output_status(txid).iter().zip(tx.output.iter());
    let inputs = block.input_amount(txid).iter().zip(tx.input.iter());
    // for every output in the transaction
    for (status, output) in outs {
      if *status == OutStatus::Unspent {
        let script = &output.script_pubkey;
        println!("{:?} has {} unspent funds", script, output.value);
      }
    }
    // for every input in the transaction
    for (amount, input) in inputs {
      let outpoint = &input.previous_output;
      println!("{:?} has {} input funds", outpoint, amount);
    }
  }
}

Structs

• FilterParser
  A parser that writes a probabilistic filter of unspent ShortOutPoint. See the module docs for example usage.
• OutPointFilter
  Wrapper for a filter that implements Serialize and Send
• ShortOutPoint
  Shortened OutPoint to save memory
• UtxoBlock
  Contains a block that has been parsed with frequently needed UTXO information
• UtxoParser
  Parser that tracks unspent outputs and input amounts to produce UtxoBlock

Enums

• OutStatus
  Indicates what happens to this output