feat: Add in-memory blockstore

[fl0rek]

closes #162

[oblique]

lgtm

[oblique]

I'm confused. Why Block couldn't be a simpler? Like this:

pub trait Block<const S: usize>: Sync + Send {
    fn cid(&self) -> CidGeneric<S>;
    fn data(&self) -> &[u8];
}

[oblique]

I tried this and works:

blockstore/src/lib.rs

pub trait Blockstore {
    // ....

    async fn put_many<const S: usize, B, I>(&self, blocks: I) -> Result<()>
    where
        B: Block<S>,
        I: IntoIterator<Item = B> + Send,
        <I as IntoIterator>::IntoIter: Send,
    {
        for b in blocks {
            let cid = b.cid()?;
            self.put_keyed(&cid, b.data()).await?;
        }
        Ok(())
    }
    
    // ...
}

pub trait Block<const S: usize>: Sync + Send {
    fn cid(&self) -> Result<CidGeneric<S>, CidError>;
    fn data(&self) -> &[u8];
}

types/src/share.rs

impl Block<NMT_ID_SIZE> for Share {
    fn cid(&self) -> Result<CidGeneric<NMT_ID_SIZE>, CidError> {
        let hasher = NamespacedSha2Hasher::with_ignore_max_ns(true);
        let digest = hasher.hash_leaf(self.as_ref()).iter().collect::<Vec<_>>();

        // size is correct, so unwrap is safe
        let hash = Multihash::wrap(NMT_CODEC, &digest).unwrap();

        Ok(CidGeneric::new_v1(NMT_MULTIHASH_CODE, hash))
    }

    fn data(&self) -> &[u8] {
        &self.data
    }
}

I prefer this simpler API for the end users

[oblique]

lgtm

[zvolin]

🎸