Append and Read — Weave Docs

Strand::new chooses file storage when a path is configured and memory storage otherwise. Appends return a zero-based sequence number. A header contains version, sequence, length, byte offset, previous-block hash, writer public key, timestamp and signature; it does not directly contain the Merkle root.

This example is checked against source signatures; it was not compiled or run during this documentation pass.

use strand::{Strand, StrandConfig};

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let dir = tempfile::tempdir()?;
    let cfg = StrandConfig::new().with_storage(dir.path());
    let mut strand = Strand::new(cfg).await?;

    // Append a batch of blocks; the returned seq is the new tail index.
    for (i, payload) in ["genesis", "block-one", "block-two"].iter().enumerate() {
        let seq = strand.append(payload.as_bytes()).await?;
        assert_eq!(seq, i as u64);
    }

    // Random-access read returns the exact bytes that were appended.
    let block_one = strand.get(1).await?;
    assert_eq!(block_one, b"block-one");

    // Read the signed block header separately from its payload.
    let header = strand.get_header(2).await?;
    println!(
        "strand len={} latest_seq={} discovery_key={}",
        strand.len(),
        2,
        hex::encode(strand.discovery_key()),
    );
    println!(
        "header seq={} length={} writer={}",
        header.seq,
        header.length,
        hex::encode(header.writer_public_key),
    );
    Ok(())
}

Source declarations