Key Value Operations

get returns Option<Vec<u8>>; put publishes an updated B-tree root and delete removes a key from the current tree. The root metadata is distinct from append-only historical nodes. The cache is an optimization, not the source of truth. These operations do not imply multi-operation atomic transactions or distributed key claims.

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

use lens::{Lens, LensConfig};
use std::sync::Arc;
use strand::{Strand, StrandConfig};
use tokio::sync::RwLock as AsyncRwLock;

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    // Lens wraps an arc-shared Strand. The Strand can be opened against a temp
    // directory for tests or against persistent storage for production.
    let dir = tempfile::tempdir()?;
    let strand = Strand::new(StrandConfig::new().with_storage(dir.path())).await?;
    let lens = Lens::new(Arc::new(AsyncRwLock::new(strand)), LensConfig::default()).await?;

    // put / get / delete are the three primitive KV operations on the B-tree.
    lens.put(b"theme", b"dark").await?;
    lens.put(b"locale", b"en-US").await?;

    let theme = lens.get(b"theme").await?;
    assert_eq!(theme.as_deref(), Some(b"dark".as_slice()));

    lens.delete(b"theme").await?;
    let theme_after = lens.get(b"theme").await?;
    assert!(theme_after.is_none());

    let metrics = lens.metrics_snapshot();
    println!(
        "puts={} deletes={} cache_hits={}",
        metrics.puts_total,
        metrics.deletes_total,
        lens.cache_stats().hits,
    );
    Ok(())
}

Source declarations